Antibacterial Synthetic Peptides Derived from Bovine Lactoferricin Exhibit Cytotoxic Effect against MDA-MB-468 and MDA-MB-231 Breast Cancer Cell Lines.

PubMed

Vargas Casanova, Yerly; Rodríguez Guerra, Jorge Antonio; Umaña Pérez, Yadi Adriana; Leal Castro, Aura Lucía; Almanzar Reina, Giovanni; García Castañeda, Javier Eduardo; Rivera Monroy, Zuly Jenny

2017-09-29

Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B, containing the RRWQWR motif, were designed, synthesized, purified, and characterized using RP-HPLC chromatography and MALDI-TOF mass spectrometry. The antibacterial activity of the designed peptides against E. coli (ATCC 11775 and 25922) and their cytotoxic effect against MDA-MB-468 and MDA-MB-231 breast cancer cell lines were evaluated. Dimeric and tetrameric peptides showed higher antibacterial activity in both bacteria strains than linear peptides. The dimeric peptide (RRWQWR)₂K-Ahx exhibited the highest antibacterial activity against the tested bacterial strains. Furthermore, the peptides with high antibacterial activity exhibited significant cytotoxic effect against the tested breast cancer cell lines. This cytotoxic effect was fast and dependent on the peptide concentration. The tetrameric molecule containing RRWQWR motif has an optimal cytotoxic effect at a concentration of 22 µM. The evaluated dimeric and tetrameric peptides could be considered as candidates for developing new therapeutic agents against breast cancer. Polyvalence of linear sequences could be considered as a novel and versatile strategy for obtaining molecules with high anticancer activity.

Interaction of antimicrobial peptides with bacterial polysaccharides from lung pathogens.

PubMed

Herasimenka, Yury; Benincasa, Monica; Mattiuzzo, Maura; Cescutti, Paola; Gennaro, Renato; Rizzo, Roberto

2005-07-01

The interaction of two cathelicidin antimicrobial peptides, LL-37 and SMAP-29, with three bacterial polysaccharides, respectively, produced by Pseudomonas aeruginosa, Burkholderia cepacia and Klebsiella pneumoniae, was investigated to identify possible mechanisms adopted by lung pathogens to escape the action of innate immunity effectors. In vitro assays indicated that the antibacterial activity of both peptides was inhibited to a variable extent by the three polysaccharides. Circular dichroism experiments showed that these induced an alpha-helical conformation in the two peptides, with the polysaccharides from K. pneumoniae and B. cepacia showing, respectively, the highest and the lowest effect. Fluorescence measurements also indicated the presence of peptide-polysaccharide interactions. A model is proposed in which the binding of peptides to the polysaccharide molecules induces, at low polysaccharide to peptide ratios, a higher order of aggregation, due to peptide-peptide interactions. Overall, these results suggest that binding of the peptides by the polysaccharides produced by lung pathogens can contribute to the impairment of peptide-based innate defenses of airway surface.

Towards the Development of Synthetic Antibiotics: Designs Inspired by Natural Antimicrobial Peptides.

PubMed

Azmi, Fazren; Skwarczynski, Mariusz; Toth, Istvan

2016-01-01

Virtually every living organism produces gene-encoded antimicrobial peptides (AMPs) that provide an immediate defence against pathogen invasion. Many AMPs have been isolated and used as antibiotics that are effective against multidrug-resistant bacteria. Although encouraging, AMPs have such poor drug-like properties that their application for clinical use is restricted. In turn, this has diverted research to the development of synthetic molecules that retain the therapeutic efficacy of AMPs but are endowed with greater biological stability and safety profiles. Most of the synthetic molecules, either based on a peptidic or non-peptidic scaffold, have been designed to mimic the amphiphilic properties of native AMPs, which are widely believed to be the key determinant of their antibacterial activity. In this review, the structural, chemical and biophysical features that govern the biological activities of various synthetic designs are discussed extensively. Recent innovative approaches from the literature that exhibit novel concepts towards the development of new synthetic antibacterial agents, including the engineered delivery platform incorporated with AMP mimetics, are also emphasised.

Cloning, expression, and purification of a new antimicrobial peptide gene from Musca domestica larva.

PubMed

Pei, Zhihua; Sun, Xiaoning; Tang, Yan; Wang, Kai; Gao, Yunhang; Ma, Hongxia

2014-10-01

Musca domestica (Diptera: Muscidae), the housefly, exhibits unique immune defences and can produce antimicrobial peptides upon stimulation with bacteria. Based on the cDNA library constructed using the suppression subtractive hybridization (SSH) method, a 198-bp antimicrobial peptide gene, which we named MDAP-2, was amplified by rapid amplification of cDNA ends (RACE) from M. domestica larvae stimulated with Salmonella pullorum (Enterobacteriaceae: Salmonella). In the present study, the full-length MDAP-2 gene was cloned and inserted into a His-tagged Escherichia coli prokaryotic expression system to enable production of the recombinant peptide. The recombinant MDAP-2 peptide was purified using Ni-NTA HisTrap FF crude column chromatography. The bacteriostatic activity of the recombinant purified MDAP-2 protein was assessed. The results indicated that MDAP-2 had in vitro antibacterial activity against all of the tested Gram- bacteria from clinical isolates, including E. coli (Enterobacteriaceae: Escherichia), one strain of S. pullorum (Enterobacteriaceae: Salmonella), and one strain of Pasteurella multocida. DNA sequencing and BLAST analysis showed that the MDAP-2 antimicrobial peptide gene was not homologous to any other antimicrobial peptide genes in GenBank. The antibacterial mechanisms of the newly discovered MDAP-2 peptide warrant further study. Copyright © 2014 Elsevier B.V. All rights reserved.

Crystal structure of an EfPDF complex with Met-Ala-Ser based on crystallographic packing.

PubMed

Nam, Ki Hyun; Kim, Kook-Han; Kim, Eunice Eun Kyeong; Hwang, Kwang Yeon

2009-04-17

PDF (peptide deformylase) plays a critical role in the production of mature proteins by removing the N-formyl polypeptide of nascent proteins in the prokaryote cell system. This protein is essential for bacterial growth, making it an attractive target for the design of new antibiotics. Accordingly, PDF has been evaluated as a drug target; however, architectural mechanism studies of PDF have not yet fully elucidated its molecular function. We recently reported the crystal structure of PDF produced by Enterococcus faecium [K.H. Nam, J.I. Ham, A. Priyadarshi, E.E. Kim, N. Chung, K.Y. Hwang, "Insight into the antibacterial drug design and architectural mechanism of peptide recognition from the E. faecium peptide deformylase structure", Proteins 74 (2009) 261-265]. Here, we present the crystal structure of the EfPDF complex with MAS (Met-Ser-Ala), thereby not only delineating the architectural mechanism for the recognition of mimic-peptides by N-terminal cleaved expression peptide, but also suggesting possible targets for rational design of antibacterial drugs. In addition to their implications for drug design, these structural studies will facilitate elucidation of the architectural mechanism responsible for the peptide recognition of PDF.

Characterization of putative class II bacteriocins identified from a non-bacteriocin-producing strain Lactobacillus casei ATCC 334.

PubMed

Kuo, Yang-Cheng; Liu, Cheng-Feng; Lin, Jhao-Fen; Li, An-Chieh; Lo, Ta-Chun; Lin, Thy-Hou

2013-01-01

Several putative class II bacteriocin-like genes were identified in Lactobacillus casei ATCC 334, all of which might encode peptides with a double-glycine leader. Six peptides encoded by these genes were heterologously expressed in Escherichia coli and then partially purified in order to test their bacteriocin activity. The results revealed that the mature LSEI_2163 peptide was a class IId bacteriocin that exhibited antimicrobial activity against some lactobacilli and several Listeria species. Similarly, mature LSEI_2386 was a putative pheromone peptide that also had significant bacteriocin activity against several Listeria species. The activities of both peptides tolerated 121°C for 30 min but not treatment with proteinase K or trypsin. The two Cys residues located at positions 4 and 24 in the mature LSEI_2163 peptide were shown by mass spectrometry to form a disulfide bridge, which was required for optimal antibacterial activity. However, replacement of one or both Cys with Ser would cause significant reduction of the antibacterial activity, the reduction being greater when only one of the Cys residues (C4S) was replaced than when both (C4S/C24S) were replaced.

Effect of amino acid substitution on biological activity of cyanophlyctin-β and brevinin-2R

NASA Astrophysics Data System (ADS)

Ghorani-Azam, Adel; Balali-Mood, Mahdi; Aryan, Ehsan; Karimi, Gholamreza; Riahi-Zanjani, Bamdad

2018-04-01

Antimicrobial peptides (AMPs), as ancient immune components, are found in almost all types of living organisms. They are bioactive components with strong antibacterial, antiviral, and anti-tumor properties. In this study, we designed three sequences of antimicrobial peptides to study the effects of structural changes in biological activity compared with original peptides, cyanophlyctin β, and brevinin-2R. For antibacterial activity, two Gram-positive (Staphylococcus aureus and S. epidermidis) and two Gram-negative bacteria (Escherichia coli and Pseudomonas aeroginosa) were assayed. Unlike cyanophlyctin β and brevinin-2R, the synthesized peptide (brevinin-M1, brevinin-M2 and brevinin-M3) showed no considerable antibacterial properties. Hemolytic activity of these peptides was also ignorable even at very high concentrations of 2 mg/ml. However, after proteolytic digestion by trypsin, the peptides showed antibacterial activity comparable to their original template sequences. Structural prediction suggested that the motif sequence responsible for antibacterial activity may be re-exposed to bacterial cell membrane after proteolytic digestion. Also, findings showed that only a small change in primary sequence and therefore structure of peptides may result in a significant alteration in biological activity.

Elucidation of sevadicin, a novel non-ribosomal peptide secondary metabolite produced by the honey bee pathogenic bacterium Paenibacillus larvae.

PubMed

Garcia-Gonzalez, Eva; Müller, Sebastian; Ensle, Paul; Süssmuth, Roderich D; Genersch, Elke

2014-05-01

American foulbrood (AFB) caused by the bee pathogenic bacterium Paenibacillus larvae is the most devastating bacterial disease of honey bees worldwide. From AFB-dead larvae, pure cultures of P. larvae can normally be cultivated indicating that P. larvae is able to defend its niche against all other bacteria present. Recently, comparative genome analysis within the species P. larvae suggested the presence of gene clusters coding for multi-enzyme complexes, such as non-ribosomal peptide synthetases (NRPSs). The products of these enzyme complexes are known to have a wide range of biological activities including antibacterial activities. We here present our results on antibacterial activity exhibited by vegetative P. larvae and the identification and analysis of a novel antibacterially active P. larvae tripeptide (called sevadicin; Sev) produced by a NRPS encoded by a gene cluster found in the genome of P. larvae. Identification of Sev was ultimately achieved by comparing the secretome of wild-type P. larvae with knockout mutants of P. larvae lacking production of Sev. Subsequent mass spectrometric studies, enantiomer analytics and chemical synthesis revealed the sequence and configuration of the tripeptide, D-Phe-D-ALa-Trp, which was shown to have antibacterial activity. The relevance of our findings is discussed in respect to host-pathogen interactions. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

A novel antimicrobial peptide derived from modified N-terminal domain of bovine lactoferrin: design, synthesis, activity against multidrug-resistant bacteria and Candida.

PubMed

Mishra, Biswajit; Leishangthem, Geeta Devi; Gill, Kamaldeep; Singh, Abhay K; Das, Swagata; Singh, Kusum; Xess, Immaculata; Dinda, Amit; Kapil, Arti; Patro, Ishan K; Dey, Sharmistha

2013-02-01

Lactoferrin (LF) is believed to contribute to the host's defense against microbial infections. This work focuses on the antibacterial and antifungal activities of a designed peptide, L10 (WFRKQLKW) by modifying the first eight N-terminal residues of bovine LF by selective homologous substitution of amino acids on the basis of hydrophobicity, L10 has shown potent antibacterial and antifungal properties against clinically isolated extended spectrum beta lactamases (ESBL), producing gram-negative bacteria as well as Candida strains with minimal inhibitory concentrations (MIC) ranging from 1 to 8 μg/mL and 6.5 μg/mL, respectively. The peptide was found to be least hemolytic at a concentration of 800 μg/mL. Interaction with lipopolysaccharide (LPS) and lipid A (LA) suggests that the peptide targets the membrane of gram-negative bacteria. The membrane interactive nature of the peptide, both antibacterial and antifungal, was further confirmed by visual observations employing electron microscopy. Further analyses, by means of propidium iodide based flow cytometry, also supported the membrane permeabilization of Candida cells. The peptide was also found to possess anti-inflammatory properties, by virtue of its ability to inhibit cyclooxygenase-2 (COX-2). L10 therefore emerges as a potential therapeutic remedial solution for infections caused by ESBL positive, gram-negative bacteria and multidrug-resistant (MDR) fungal strains, on account of its multifunctional activities. This study may open up new approach to develop and design novel antimicrobials. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis and Antibacterial Activities of Antibacterial Peptides with a Spiropyran Fluorescence Probe

PubMed Central

Chen, Lei; Zhu, Yu; Yang, Danling; Zou, Rongfeng; Wu, Junchen; Tian, He

2014-01-01

In this report, antibacterial peptides1-3 were prepared with a spiropyran fluorescence probe. The probe exhibits a change in fluorescence when isomerized from a colorless spiro-form (spiropyran, Sp) to a colored open-form (merocyanine, Mc) under different chemical environments, which can be used to study the mechanism of antimicrobial activity. Peptides 1-3 exhibit a marked decrease in antimicrobial activity with increasing alkyl chain length. This is likely due to the Sp-Mc isomers in different polar environments forming different aggregate sizes in TBS, as demonstrated by time-dependent dynamic light scattering (DLS). Moreover, peptides 1-3 exhibited low cytotoxicity and hemolytic activity. These probe-modified peptides may provide a novel approach to study the effect of structural changes on antibacterial activity, thus facilitating the design of new antimicrobial agents to combat bacterial infection. PMID:25358905

Prediction of Antibacterial Activity from Physicochemical Properties of Antimicrobial Peptides

PubMed Central

Melo, Manuel N.; Ferre, Rafael; Feliu, Lídia; Bardají, Eduard; Planas, Marta; Castanho, Miguel A. R. B.

2011-01-01

Consensus is gathering that antimicrobial peptides that exert their antibacterial action at the membrane level must reach a local concentration threshold to become active. Studies of peptide interaction with model membranes do identify such disruptive thresholds but demonstrations of the possible correlation of these with the in vivo onset of activity have only recently been proposed. In addition, such thresholds observed in model membranes occur at local peptide concentrations close to full membrane coverage. In this work we fully develop an interaction model of antimicrobial peptides with biological membranes; by exploring the consequences of the underlying partition formalism we arrive at a relationship that provides antibacterial activity prediction from two biophysical parameters: the affinity of the peptide to the membrane and the critical bound peptide to lipid ratio. A straightforward and robust method to implement this relationship, with potential application to high-throughput screening approaches, is presented and tested. In addition, disruptive thresholds in model membranes and the onset of antibacterial peptide activity are shown to occur over the same range of locally bound peptide concentrations (10 to 100 mM), which conciliates the two types of observations. PMID:22194847

Synthetic Peptides Derived from Bovine Lactoferricin Exhibit Antimicrobial Activity against E. coli ATCC 11775, S. maltophilia ATCC 13636 and S. enteritidis ATCC 13076.

PubMed

Huertas Méndez, Nataly De Jesús; Vargas Casanova, Yerly; Gómez Chimbi, Anyelith Katherine; Hernández, Edith; Leal Castro, Aura Lucia; Melo Diaz, Javier Mauricio; Rivera Monroy, Zuly Jenny; García Castañeda, Javier Eduardo

2017-03-12

Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B-containing non-natural amino acids and the RWQWR motif were synthesized, purified, and characterized using RP-HPLC, MALDI-TOF mass spectrometry, and circular dichroism. The antibacterial activity of peptides against Escherichia coli ATCC 11775, Stenotrophomonas maltophilia ATCC 13636, and Salmonella enteritidis ATCC 13076 was evaluated. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. The synthetic bovine lactoferricin exhibited antibacterial activity against E. coli ATCC 11775 and S. enteritidis ATCC 13076. The dimeric peptide (RRWQWR)₂K-Ahx exhibited the highest antibacterial activity against the tested bacterial strain. The monomeric, cyclic, tetrameric, and palindromic peptides containing the RWQWR motif exhibited high and specific activity against E. coli ATCC 11775. The results suggest that short peptides derived from lactoferricin B could be considered as potential candidates for the development of antibacterial agents against infections caused by E. coli .

PGLa-H tandem-repeat peptides active against multidrug resistant clinical bacterial isolates.

PubMed

Rončević, Tomislav; Gajski, Goran; Ilić, Nada; Goić-Barišić, Ivana; Tonkić, Marija; Zoranić, Larisa; Simunić, Juraj; Benincasa, Monica; Mijaković, Marijana; Tossi, Alessandro; Juretić, Davor

2017-02-01

Antimicrobial peptides (AMPs) are promising candidates for new antibiotic classes but often display an unacceptably high toxicity towards human cells. A naturally produced C-terminal fragment of PGLa, named PGLa-H, has been reported to have a very low haemolytic activity while maintaining a moderate antibacterial activity. A sequential tandem repeat of this fragment, diPGLa-H, was designed, as well as an analogue with a Val to Gly substitution at a key position. These peptides showed markedly improved in vitro bacteriostatic and bactericidal activity against both reference strains and multidrug resistant clinical isolates of Gram-negative and Gram-positive pathogens, with generally low toxicity for human cells as assessed by haemolysis, cell viability, and DNA damage assays. The glycine substitution analogue, kiadin, had a slightly better antibacterial activity and reduced haemolytic activity, which may correlate with an increased flexibility of its helical structure, as deduced using molecular dynamics simulations. These peptides may serve as useful lead compounds for developing anti-infective agents against resistant Gram-negative and Gram-positive species. Copyright © 2016 Elsevier B.V. All rights reserved.

Production of Hypoallergenic Antibacterial Peptides from Defatted Soybean Meal in Membrane Bioreactor: A Bioprocess Engineering Study with Comprehensive Product Characterization

PubMed Central

2017-01-01

Summary Hypoallergenic antibacterial low-molecular-mass peptides were produced from defatted soybean meal in a membrane bioreactor. In the first step, soybean meal proteins were digested with trypsin in the bioreactor, operated in batch mode. For the tryptic digestion of soybean meal protein, optimum initial soybean meal concentration of 75 g/L, temperature of 40 °C and pH=9.0 were determined. After enzymatic digestion, low-molecular-mass peptides were purified with cross-flow flat sheet membrane (pore size 100 µm) and then with tubular ceramic ultrafiltration membrane (molecular mass cut-off 5 kDa). Effects of transmembrane pressure and the use of a static turbulence promoter to reduce the concentration polarization near the ultrafiltration membrane surface were examined and their positive effects were proven. For the filtration with ultrafiltration membrane, transmembrane pressure of 3·105 Pa with 3-stage discontinuous diafiltration was found optimal. The molecular mass distribution of purified peptides using ultrafiltration membrane was determined by a liquid chromatography–electrospray ionization quadrupole time-of-flight mass spectrometry setup. More than 96% of the peptides (calculated as relative frequency) from the ultrafiltration membrane permeate had the molecular mass M≤1.7 kDa and the highest molecular mass was found to be 3.1 kDa. The decrease of allergenic property due to the tryptic digestion and membrane filtration was determined by an enzyme-linked immunosorbent assay and it was found to exceed 99.9%. It was also found that the peptides purified in the ultrafiltration membrane promoted the growth of Pediococcus acidilactici HA6111-2 and they possessed antibacterial activity against Bacillus cereus. PMID:29089846

Amylocyclicin, a Novel Circular Bacteriocin Produced by Bacillus amyloliquefaciens FZB42

PubMed Central

Scholz, Romy; Vater, Joachim; Budiharjo, Anto; Wang, Zhiyuan; He, Yueqiu; Dietel, Kristin; Schwecke, Torsten; Herfort, Stefanie; Lasch, Peter

2014-01-01

Bacillus amyloliquefaciens FZB42 is a Gram-positive plant growth-promoting bacterium with an impressive capacity to synthesize nonribosomal secondary metabolites with antimicrobial activity. Here we report on a novel circular bacteriocin which is ribosomally synthesized by FZB42. The compound displayed high antibacterial activity against closely related Gram-positive bacteria. Transposon mutagenesis and subsequent site-specific mutagenesis combined with matrix-assisted laser desorption ionization–time of flight mass spectroscopy revealed that a cluster of six genes covering 4,490 bp was responsible for the production, modification, and export of and immunity to an antibacterial compound, here designated amylocyclicin, with a molecular mass of 6,381 Da. Peptide sequencing of the fragments obtained after tryptic digestion of the purified peptide revealed posttranslational cleavage of an N-terminal extension and head-to-tail circularization of the novel bacteriocin. Homology to other putative circular bacteriocins in related bacteria let us assume that this type of peptide is widespread among the Bacillus/Paenibacillus taxon. PMID:24610713

[Study on antibacterial properties and osteoblast activity of antimicrobial peptide coatings on titanium implants].

PubMed

Sun, F Q; Li, M Q; Peng, S H; Zhang, H M; Liu, M; Qu, X Y

2018-06-09

Objective: To investigate the antibacterial property and biological activity of Ti dental implant with antimicrobial peptide Pac-525 coatings, and to study the effect of peptide Pac-525 coatings on Porphyromonas gingivalis 's antibacterial performance and osteoblast proliferation and adhesion. Methods: After ultrasonic micro arc oxidation, alkali treatment and silane treatment, forty-five pure titanium specimens were exposed to antibacterial peptide Pac-525 in different concentration (0.25, 0.50, 0.75 g/L). The titanium specimens in the control group were only treated with ultrasonic micro arc oxidation, alkali treatment and silane treatment. The morphologies of coatings were observed by scanning electron microscope (SEM), and the element changes were detected by energy spectrum analyzer. Orange acridine-ethidium bromide double staining was used to detect the average percentage of live bacteria and biofilm thickness, after the specimens in each group and Porphyromonas gingivalis were co-cultured for 72 hours. Cell counting Kit-8 method and immunofluorescence staining were used to test the proliferation of osteoblasts, the number and growth morphologies of adherent cells, respectively. Results: SEM and energy spectrum analysis showed that the Pac-525 particles loaded on the surface of the coating, and the C and N elements in the Pac-525 coating group were significantly more than those in the control group. The average percentage of living bacteria in the control group, 0.25, 0.50 and 0.75 g/L antimicrobial peptides were 0.58%, 0.45%, 0.34% and 0.28%, respectively, and the difference between each group was statistically significant ( P< 0.05). The biofilm thickness of Porphyromonas gingivalis in 0.50 and 0.75 g/L antibacterial peptide group were (98.3±1.2) and (94.5±2.5) μm respectively, which were significantly less than those in control group and 0.25 g/L antibacterial peptide group [(117.6±1.5) and (118.0±1.3) μm] ( P< 0.05), respectively. The number of bone cell adhesion and proliferation of all antimicrobial peptides were significantly greater than those in the control group ( P< 0.05), and the cells stretched better. Conclusions: The antibacterial peptide coating of titanium implants could inhibit the formation of bacterial biofilm. It had good antibacterial properties and could promote the adhesion and proliferation of osteoblasts.

Antibacterial Activity of a Novel Peptide-Modified Lysin Against Acinetobacter baumannii and Pseudomonas aeruginosa

PubMed Central

Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

2015-01-01

The global emergence of multidrug-resistant (MDR) bacteria is a growing threat to public health worldwide. Natural bacteriophage lysins are promising alternatives in the treatment of infections caused by Gram-positive pathogens, but not Gram-negative ones, like Acinetobacter baumannii and Pseudomonas aeruginosa, due to the barriers posed by their outer membranes. Recently, modifying a natural lysin with an antimicrobial peptide was found able to break the barriers, and to kill Gram-negative pathogens. Herein, a new peptide-modified lysin (PlyA) was constructed by fusing the cecropin A peptide residues 1–8 (KWKLFKKI) with the OBPgp279 lysin and its antibacterial activity was studied. PlyA showed good and broad antibacterial activities against logarithmic phase A. baumannii and P. aeruginosa, but much reduced activities against the cells in stationary phase. Addition of outer membrane permeabilizers (EDTA and citric acid) could enhance the antibacterial activity of PlyA against stationary phase cells. Finally, no antibacterial activity of PlyA could be observed in some bio-matrices, such as culture media, milk, and sera. In conclusion, we reported here a novel peptide-modified lysin with significant antibacterial activity against both logarithmic (without OMPs) and stationary phase (with OMPs) A. baumannii and P. aeruginosa cells in buffer, but further optimization is needed to achieve broad activity in diverse bio-matrices. PMID:26733995

Coiled-coil forming peptides for the induction of silver nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Božič Abram, Sabina; Graduate School of Biomedicine, University of Ljubljana, Ljubljana 1000; Aupič, Jana

Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at aroundmore » 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.« less

[Cloning, prokaryotic expression and antibacterial assay of Tenecin gene encoding an antibacterial peptide from Tenebrio molitor].

PubMed

Liu, Ying; Jiang, Yu-xin; Li, Chao-pin

2011-12-01

To clone tenecin gene, an antibacterial peptide gene, from Tenebrio molitor for its prokaryotic expression and explore the molecular mechanism for regulating the expression of antibacterial peptide in Tenebrio molitor larvae. The antibacterial peptide was induced from the larvae of Tenebrio molitor by intraperitoneal injection of Escherichia coli DH-5α (1×10(8)/ml). RT-PCR was performed 72 h after the injection to clone Tenecin gene followed by sequencing and bioinformatic analysis. The recombinant expression vector pET-28a(+)-Tenecin was constructed and transformed into E. coli BL21(DE3) cells and the expression of tenecin protein was observed after IPTG induction. Tenecin expression was detected in transformed E.coli using SDS-PAGE after 1 mmol/L IPTG induction. Tenecin gene, which was about 255 bp in length, encoded Tenecin protein with a relative molecular mass of 9 kD. Incubation of E.coli with 80, 60, 40, and 20 µg/ml tenecin for 18 h resulted in a diameter of the inhibition zone of 25.1∓0.03, 20.7∓0.06, 17.2∓0.11 and 9.3∓0.04 mm, respectively. Tenecin protein possesses strong antibacterial activity against E. coli DH-5α, which warrants further study of this protein for its potential as an antibacterial agent in clinical application.

Designer antibacterial peptides kill fluoroquinolone-resistant clinical isolates.

PubMed

Otvos, Laszlo; Wade, John D; Lin, Feng; Condie, Barry A; Hanrieder, Joerg; Hoffmann, Ralf

2005-08-11

A significant number of Escherichia coli and Klebsiella pneumoniae bacterial strains in urinary tract infections are resistant to fluoroquinolones. Peptide antibiotics are viable alternatives although these are usually either toxic or insufficiently active. By applying multiple alignment and sequence optimization steps, we designed multifunctional proline-rich antibacterial peptides that maintained their DnaK-binding ability in bacteria and low toxicity in eukaryotes, but entered bacterial cells much more avidly than earlier peptide derivatives. The resulting chimeric and statistical analogues exhibited 8-32 microg/mL minimal inhibitory concentration efficacies in Muller-Hinton broth against a series of clinical pathogens. Significantly, the best peptide, compound 5, A3-APO, retained full antibacterial activity in the presence of mouse serum. Across a set of eight fluoroquinolone-resistant clinical isolates, peptide 5 was 4 times more potent than ciprofloxacin. On the basis of the in vitro efficacy, toxicity, and pharmacokinetics data, we estimate that peptide 5 will be suitable for treating infections in the 3-5 mg/kg dose range.

Chicken cathelicidin-2-derived peptides with enhanced immunomodulatory and antibacterial activities against biological warfare agents.

PubMed

Molhoek, E Margo; van Dijk, Albert; Veldhuizen, Edwin J A; Dijk-Knijnenburg, Helma; Mars-Groenendijk, Roos H; Boele, Linda C L; Kaman-van Zanten, Wendy E; Haagsman, Henk P; Bikker, Floris J

2010-09-01

Host defence peptides (HDPs) are considered to be excellent candidates for the development of novel therapeutic agents. Recently, it was demonstrated that the peptide C1-15, an N-terminal segment of chicken HDP cathelicidin-2, exhibits potent antibacterial activity while lacking cytotoxicity towards eukaryotic cells. In the present study, we report that C1-15 is active against bacteria such as Bacillus anthracis and Yersinia pestis that may potentially be used by bioterrorists. Substitution of single and multiple phenylalanine (Phe) residues to tryptophan (Trp) in C1-15 resulted in variants with improved antibacterial activity against B. anthracis and Y. pestis as well as decreased salt sensitivity. In addition, these peptides exhibited enhanced neutralisation of lipopolysaccharide (LPS)-induced release of pro-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs). The antibacterial and LPS-neutralising activities of these C1-15-derived peptides are exerted at concentrations far below the concentrations that are toxic to human PBMCs. Taken together, we show that Phe-->Trp substitutions in C1-15 variants enhances the antibacterial and LPS-neutralising activities against pathogenic bacteria, including those that may potentially be used as biological warfare agents. Copyright (c) 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Mechanism of action of recombinant Acc-royalisin from royal jelly of Chinese honeybee against gram-positive bacteria

USDA-ARS?s Scientific Manuscript database

The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Chinese honeybee Apis cerana...

Functional gold nanoparticle-based antibacterial agents for nosocomial and antibiotic-resistant bacteria.

PubMed

Kuo, Yen-Ling; Wang, Sin-Ge; Wu, Ching-Yi; Lee, Kai-Chieh; Jao, Chan-Jung; Chou, Shiu-Huey; Chen, Yu-Chie

2016-10-01

Medical treatments for bacterial-infections have become challenging because of the emergence of antibiotic-resistant bacterial strains. Thus, new therapeutics and antibiotics must be developed. Arginine and tryptophan can target negatively-charged bacteria and penetrate bacterial cell membrane, respectively. Synthetic-peptides containing arginine, tryptophan and cysteine termini, in other words, (DVFLG)2REEW4C and (DVFLG)2REEW2C, as starting materials were mixed with aqueous tetrachloroauric acid to generate peptide-immobilized gold nanoparticles (i.e., [DVFLG]2REEW4C-AuNPs and [DVFLG]2REEW2C-AuNPs) through one-pot reactions. The peptide immobilized AuNPs exhibit targeting capacity and antibacterial activity. Furthermore, (DVFLG)2REEW4C-AuNPs immobilized with a higher number of tryptophan molecules possess more effective antibacterial capacity than (DVFLG)2REEW2C-AuNPs. Nevertheless, they are not harmful for animal cells. The feasibility of using the peptide-AuNPs to inhibit the cell growth of bacterium-infected macrophages was demonstrated. These results suggested that the proposed antibacterial AuNPs are effective antibacterial agents for Staphylococci, Enterococci and antibiotic-resistant bacterial strains. [Formula: see text].

Dendropsophin 1, a novel antimicrobial peptide from the skin secretion of the endemic Colombian frog Dendropsophus columbianus.

PubMed

Triana-Vidal, Luz Elena; Castro, Mariana Souza; Pires Júnior, Osmindo Rodrigues; Álvares, Alice Cunha Morales; de Freitas, Sonia Maria; Fontes, Wagner; Vargas, Jimmy Alexander Guerrero; Zúñiga-Baos, Jorge Alberto; Correia Batista, Isabel de Fátima; Grellier, Philippe; Charneau, Sébastien

2018-06-01

In efforts to find new antimicrobial peptides (AMPs), we studied the skin secretion of the endemic Colombian frog Dendropsophus columbianus belonging to a genus that has not been investigated previously. From HPLC-fractionated secretion, we identified one peptide with slightly antibacterial activity. Its peptide sequence showed no sequence similarity to current annotated peptides. We named this novel peptide dendropsophin 1 (Dc1). Afterward, two analogues were designed (Dc1.1 and Dc1.2) to improve the cationic and amphipathic features. Then, their antiproliferative and cytotoxic properties were evaluated against several pathogens including bacteria, fungi, protozoa and also mammalian cells. Dc1 and its two analogues exhibited moderate antibacterial activities and no hemolytic and cytotoxic effects on mammalian cells. Analogue Dc1.2 showed slightly improved antibacterial properties. Their secondary structures were characterised using CD spectroscopy and Dc1.2 displayed a higher α-helix content and thermal stability compared to Dc1 and Dc1.1 in hydrophobic experimental conditions.

Class I Microcins: Their Structures, Activities, and Mechanisms of Resistance

NASA Astrophysics Data System (ADS)

Severinov, Konstantin; Semenova, Ekaterina; Kazakov, Teymur

Microcin J25, microcin B17, and microcin C7-C51 are the three known members of class I posttranslationally modified microcins (heavily posttranslationally modified antibacterial peptides produced by Enterobacteriaceae with molecular weights of less than 5 kDa). The three microcins are unrelated to each other; they have structures that are highly atypical for ribosomally synthesized peptides and target essential molecular machines that are validated drug targets. In this chapter, available data on mechanisms of action, structure-activity relationships, and immunity mechanisms for class I microcins and related compounds are discussed.

Structure-function characterization and optimization of a plant-derived antibacterial peptide.

PubMed

Suarez, Mougli; Haenni, Marisa; Canarelli, Stéphane; Fisch, Florian; Chodanowski, Pierre; Servis, Catherine; Michielin, Olivier; Freitag, Ruth; Moreillon, Philippe; Mermod, Nicolas

2005-09-01

Crushed seeds of the Moringa oleifera tree have been used traditionally as natural flocculants to clarify drinking water. We previously showed that one of the seed peptides mediates both the sedimentation of suspended particles such as bacterial cells and a direct bactericidal activity, raising the possibility that the two activities might be related. In this study, the conformational modeling of the peptide was coupled to a functional analysis of synthetic derivatives. This indicated that partly overlapping structural determinants mediate the sedimentation and antibacterial activities. Sedimentation requires a positively charged, glutamine-rich portion of the peptide that aggregates bacterial cells. The bactericidal activity was localized to a sequence prone to form a helix-loop-helix structural motif. Amino acid substitution showed that the bactericidal activity requires hydrophobic proline residues within the protruding loop. Vital dye staining indicated that treatment with peptides containing this motif results in bacterial membrane damage. Assembly of multiple copies of this structural motif into a branched peptide enhanced antibacterial activity, since low concentrations effectively kill bacteria such as Pseudomonas aeruginosa and Streptococcus pyogenes without displaying a toxic effect on human red blood cells. This study thus identifies a synthetic peptide with potent antibacterial activity against specific human pathogens. It also suggests partly distinct molecular mechanisms for each activity. Sedimentation may result from coupled flocculation and coagulation effects, while the bactericidal activity would require bacterial membrane destabilization by a hydrophobic loop.

Structure-Function Characterization and Optimization of a Plant-Derived Antibacterial Peptide

PubMed Central

Suarez, Mougli; Haenni, Marisa; Canarelli, Stéphane; Fisch, Florian; Chodanowski, Pierre; Servis, Catherine; Michielin, Olivier; Freitag, Ruth; Moreillon, Philippe; Mermod, Nicolas

2005-01-01

Crushed seeds of the Moringa oleifera tree have been used traditionally as natural flocculants to clarify drinking water. We previously showed that one of the seed peptides mediates both the sedimentation of suspended particles such as bacterial cells and a direct bactericidal activity, raising the possibility that the two activities might be related. In this study, the conformational modeling of the peptide was coupled to a functional analysis of synthetic derivatives. This indicated that partly overlapping structural determinants mediate the sedimentation and antibacterial activities. Sedimentation requires a positively charged, glutamine-rich portion of the peptide that aggregates bacterial cells. The bactericidal activity was localized to a sequence prone to form a helix-loop-helix structural motif. Amino acid substitution showed that the bactericidal activity requires hydrophobic proline residues within the protruding loop. Vital dye staining indicated that treatment with peptides containing this motif results in bacterial membrane damage. Assembly of multiple copies of this structural motif into a branched peptide enhanced antibacterial activity, since low concentrations effectively kill bacteria such as Pseudomonas aeruginosa and Streptococcus pyogenes without displaying a toxic effect on human red blood cells. This study thus identifies a synthetic peptide with potent antibacterial activity against specific human pathogens. It also suggests partly distinct molecular mechanisms for each activity. Sedimentation may result from coupled flocculation and coagulation effects, while the bactericidal activity would require bacterial membrane destabilization by a hydrophobic loop. PMID:16127062

Synergistic Antibacterial Effect of the Combination of ε-Polylysine and Nisin against Enterococcus faecalis.

PubMed

Liu, Fang; Liu, Mei; Du, Lihui; Wang, Daoying; Geng, Zhiming; Zhang, Muhan; Sun, Chong; Xu, Xiaoxi; Zhu, Yongzhi; Xu, Weimin

2015-12-01

This study evaluated the antibacterial effect of the combination of ε-polylysine (ε-PL) and nisin against Enterococcus faecalis strains. The combination of ε-PL and nisin showed synergistic antibacterial activity against three Enterococcus strains. Scanning electron microscopy and a membrane permeability assay revealed that the combined treatment with ε-PL and nisin synergistically damaged the cell morphology of E. faecalis strain R612Z1 cells. Both ε-PL and nisin can dissipate the transmembrane electric potential of E. faecalis R612Z1 cells, but these peptides did not affect the transmembrane pH gradient. The combination of ε-PL and nisin can produce a high reactive oxygen species level in E. faecalis R612Z1 cells. The results indicated that the uptake of ε-PL into cells was promoted through nisin and that the combination of ε-PL and nisin could produce a high reactive oxygen species level in E. faecalis R612Z1 cells, leading to cell growth inhibition.

Synthesis, anti-MRSA, and anti-VRE activity of hemin conjugates with amino acids and branched peptides.

PubMed

Okorochenkov, Sergei A; Zheltukhina, Galina A; Mirchink, Elena P; Isakova, Elena B; Feofanov, Alexey V; Nebolsin, Vladimir E

2013-10-01

The increasing prevalence of antibiotic-resistant bacterial strains has necessitated the synthesis of novel antibacterial agents. It was previously shown that naturally occurring metalloporphyrin hemin possesses dark antibacterial activity against Gram-positive bacteria. To improve hemin antibacterial activity, we synthesized a number of hemin conjugates with amino acids and branched peptides. Arginine-containing hemin conjugates demonstrated high antibacterial activity against Gram-positive bacteria including methicillin- and vancomycin-resistant strains in vitro. Most of the synthesized conjugates showed low toxicity against human erythrocytes and leukocytes. © 2013 John Wiley & Sons A/S.

Cyclic Lipopeptide Biosynthetic Genes and Products, and Inhibitory Activity of Plant-Associated Bacillus against Phytopathogenic Bacteria

PubMed Central

Mora, Isabel; Cabrefiga, Jordi; Montesinos, Emilio

2015-01-01

The antibacterial activity against bacterial plant pathogens and its relationships with the presence of the cyclic lipopeptide (cLP) biosynthetic genes ituC (iturin), bmyB (bacillomycin), fenD (fengycin) and srfAA (surfactin), and their corresponding antimicrobial peptide products have been studied in a collection of 64 strains of Bacillus spp. isolated from plant environments. The most frequent antimicrobial peptide (AMP) genes were bmyB, srfAA and fenD (34-50% of isolates). Most isolates (98.4%) produced surfactin isoforms, 90.6% iturins and 79.7% fengycins. The antibacterial activity was very frequent and generally intense among the collection of strains because 75% of the isolates were active against at least 6 of the 8 bacterial plant pathogens tested. Hierarchical and correspondence analysis confirmed the presence of two clearly differentiated groups. One group consisted of Bacillus strains that showed a strong antibacterial activity, presented several cLPs genes and produced several isoforms of cLPs simultaneously, mainly composed of B. subtilis and B. amyloliquefaciens, although the last one was exclusive to this group. Another group was characterized by strains with very low or none antibacterial activity, that showed one or none of the cLP genes and produced a few or none of the corresponding cLPs, and was the most heterogenous group including B. subtilis, B. licheniformis, B. megaterium, B. pumilus, B. cereus and B. thuringiensis, although the last two were exclusive to this group. This work demonstrated that the antagonistic capacity of plant-associated Bacillus against plant pathogenic bacteria is related to the presence of cLP genes and to the production of the corresponding cLPs, and it is mainly associated to the species B. subtilis and B. amyloliquefaciens. Our findings would help to increase the yield and efficiency of screening methods to obtain candidate strains to biocontrol agents with a mechanism of action relaying on the production of antimicrobial cLPs. PMID:26024374

Design of a potent antibiotic peptide based on the active region of human defensin 5.

PubMed

Wang, Cheng; Shen, Mingqiang; Gohain, Neelakshi; Tolbert, William D; Chen, Fang; Zhang, Naixin; Yang, Ke; Wang, Aiping; Su, Yongping; Cheng, Tianmin; Zhao, Jinghong; Pazgier, Marzena; Wang, Junping

2015-04-09

Human defensin 5 (HD5) is a broad-spectrum antibacterial peptide with a C-terminal active region. To promote the development of this peptide into an antibiotic, we initially substituted Glu21 with Arg because it is an electronegative residue located around the active region. Although detrimental to dimer formation, the E21R substitution markedly enhanced the antibacterial activity of HD5 and increased its ability to penetrate cell membranes, demonstrating that increasing the electropositive charge compensated for the effect of dimer disruption. Subsequently, a partial Arg scanning mutagenesis was performed, and Thr7 was selected for replacement with Arg to further strengthen the antibacterial activity. The newly designed peptide, T7E21R-HD5, exhibited potent antibacterial activity, even in saline and serum solutions. In contrast to monomeric E21R-HD5, T7E21R-HD5 assembled into an atypical dimer with parallel β strands, thus expanding the role of increasing electropositive charge in bactericidal activity and providing a useful guide for further defensin-derived antibiotic design.

Nanotechnology: A Valuable Strategy to Improve Bacteriocin Formulations

PubMed Central

Fahim, Hazem A.; Khairalla, Ahmed S.; El-Gendy, Ahmed O.

2016-01-01

Bacteriocins are proteinaceous antibacterial compounds, produced by diverse bacteria, which have been successfully used as: (i) food biopreservative; (ii) anti-biofilm agents; and (iii) additives or alternatives to the currently existing antibiotics, to minimize the risk of emergence of resistant strains. However, there are several limitations that challenge the use of bacteriocins as biopreservatives/antibacterial agents. One of the most promising avenues to overcome these limitations is the use of nanoformulations. This review highlights the practical difficulties with using bacteriocins to control pathogenic microorganisms, and provides an overview on the role of nanotechnology in improving the antimicrobial activity and the physicochemical properties of these peptides. PMID:27695440

Antibacterial and cell penetrating effects of LFcin17-30, LFampin265-284, and LF chimera on enteroaggregative Escherichia coli.

PubMed

Reyes-Cortes, Ruth; Acosta-Smith, Erika; Mondragón-Flores, Ricardo; Nazmi, Kamran; Bolscher, Jan G M; Canizalez-Roman, Adrian; Leon-Sicairos, Nidia

2017-02-01

Lactoferrin (LF) is a protein with antimicrobial activity, which is conferred in part by 2 regions contained in its N-terminal lobe. These regions have been used to develop the following synthetic peptides: lactoferricin17-30, lactoferrampin265-284, and LF chimera (a fusion of lactoferricin17-30 and lactoferrampin265-284). We have reported that these LF peptides have antibacterial activity against several pathogenic bacteria; however, the exact mechanism of action has not been established. Here, we report the effects of LF peptides on the viability of enteroaggregative Escherichia coli (EAEC) and the ability of these peptides to penetrate into the bacteria cytoplasm. The viability of EAEC treated with LF peptides was determined via enumeration of colony-forming units, and the binding and internalization of the LF peptides was followed via immunogold labeling and electron microscopy. Treatment of EAEC with 20 and 40 μmol/L LF peptides reduced bacterial growth compared with untreated bacteria. Initially the peptides associated with the plasma membrane, but after 5 to 30 min of incubation, the peptides were found in the cytoplasm. Remarkably, bacteria treated with LF chimera developed cytosolic electron-dense structures that contained the antimicrobial peptide. Our results suggest that the antibacterial mechanism of LF peptides on EAEC involves their interaction with and penetration into the bacteria.

Collagencin, an antibacterial peptide from fish collagen: Activity, structure and interaction dynamics with membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ennaas, Nadia; Hammami, Riadh, E-mail: riadh.hammami@fsaa.ulaval.ca; Gomaa, Ahmed

In this study, we first report characterization of collagencin, an antimicrobial peptide identified from fish collagen hydrolysate. The peptide completely inhibited the growth of Staphylococcus aureus at 1.88 mM. Although non-toxic up to 470 μM, collagencin was hemolytic at higher concentrations. The secondary structure of collagencin was mainly composed by β-sheet and β-turn as determined by CD measurements and molecular dynamics. The peptide is likely to form β-sheet structure under hydrophobic environments and interacts with both anionic (phosphatidylglycerol) and zwitterionic (phosphoethanolamine and phosphatidylcholine) lipids as shown with CD spectroscopy and molecular dynamics. The peptide formed several hydrogen bonds with both POPG andmore » POPE lipids and remained at membrane–water interface, suggesting that collagencin antibacterial action follows a carpet mechanism. Collagenous fish wastes could be processed by enzymatic hydrolysis and transformed into products of high value having functional or biological properties. Marine collagens are a promising source of antimicrobial peptides with new implications in food safety and human health. - Highlights: • Collagencin, an antibacterial (G+ & G-) peptide identified from fish collagen hydrolysate. • The peptide completely inhibited the growth of S. aureus at 1.88 mM and non-toxic at 470 μM. • The secondary structure was mainly composed by β-sheet and turn as determined by CD and MD. • Collagencin interacts with both anionic and zwitterionic lipids as shown with CD and MD. • Collagencin antibacterial action probably follows a carpet mechanism.« less

Identification, Purification and Characterization of Laterosporulin, a Novel Bacteriocin Produced by Brevibacillus sp. Strain GI-9

PubMed Central

Singh, Pradip Kumar; Chittpurna; Ashish; Sharma, Vikas; Patil, Prabhu B.; Korpole, Suresh

2012-01-01

Background Bacteriocins are antimicrobial peptides that are produced by bacteria as a defense mechanism in complex environments. Identification and characterization of novel bacteriocins in novel strains of bacteria is one of the important fields in bacteriology. Methodology/Findings The strain GI-9 was identified as Brevibacillus sp. by 16 S rRNA gene sequence analysis. The bacteriocin produced by strain GI-9, namely, laterosporulin was purified from supernatant of the culture grown under optimal conditions using hydrophobic interaction chromatography and reverse-phase HPLC. The bacteriocin was active against a wide range of Gram-positive and Gram-negative bacteria. MALDI-TOF experiments determined the precise molecular mass of the peptide to be of 5.6 kDa and N-terminal sequencing of the thermo-stable peptide revealed low similarity with existing antimicrobial peptides. The putative open reading frame (ORF) encoding laterosporulin and its surrounding genomic region was fished out from the draft genome sequence of GI-9. Sequence analysis of the putative bacteriocin gene did not show significant similarity to any reported bacteriocin producing genes in database. Conclusions We have identified a bacteriocin producing strain GI-9, belonging to the genus Brevibacillus sp. Biochemical and genomic characterization of laterosporulin suggests it as a novel bacteriocin with broad spectrum antibacterial activity. PMID:22403615

Identification, purification and characterization of laterosporulin, a novel bacteriocin produced by Brevibacillus sp. strain GI-9.

PubMed

Singh, Pradip Kumar; Chittpurna; Ashish; Sharma, Vikas; Patil, Prabhu B; Korpole, Suresh

2012-01-01

Bacteriocins are antimicrobial peptides that are produced by bacteria as a defense mechanism in complex environments. Identification and characterization of novel bacteriocins in novel strains of bacteria is one of the important fields in bacteriology. The strain GI-9 was identified as Brevibacillus sp. by 16 S rRNA gene sequence analysis. The bacteriocin produced by strain GI-9, namely, laterosporulin was purified from supernatant of the culture grown under optimal conditions using hydrophobic interaction chromatography and reverse-phase HPLC. The bacteriocin was active against a wide range of Gram-positive and Gram-negative bacteria. MALDI-TOF experiments determined the precise molecular mass of the peptide to be of 5.6 kDa and N-terminal sequencing of the thermo-stable peptide revealed low similarity with existing antimicrobial peptides. The putative open reading frame (ORF) encoding laterosporulin and its surrounding genomic region was fished out from the draft genome sequence of GI-9. Sequence analysis of the putative bacteriocin gene did not show significant similarity to any reported bacteriocin producing genes in database. We have identified a bacteriocin producing strain GI-9, belonging to the genus Brevibacillus sp. Biochemical and genomic characterization of laterosporulin suggests it as a novel bacteriocin with broad spectrum antibacterial activity.

Synthesis and characterization of bactericidal oligopeptides designed on the basis of an insect anti-bacterial peptide.

PubMed Central

Saido-Sakanaka, H; Ishibashi, J; Sagisaka, A; Momotani, E; Yamakawa, M

1999-01-01

Defensin from a beetle, Allomyrina dichotoma, is known to have anti-bacterial activity against Gram-positive bacteria. This peptide, which comprises 43 amino acid residues, was effective against methicillin-resistant Staphylococcus aureus. We identified the active site of beetle defensin by measuring anti-bacterial activity against S. aureus of 64 overlapping 12-mer peptides with either a free carboxylate or a free amide group at their C-termini. An LCAAHCLAIGRR-NH2 (19L-30R-NH2) fragment showed the greatest activity of the synthetic oligopeptides. The 19L-30R-NH2 fragment was effective against both Gram-positive and Gram-negative bacteria. CD spectra showed that the 19L-30R-NH2 fragment formed an alpha-helical structure in the lipidic environment. The anti-bacterial effect of the 19L-30R-NH2 fragment was due to its interaction with bacterial membranes, judging from the leakage of liposome-entrapped glucose. Its anti-bacterial activity was increased when certain amino acid residues were replaced. Truncated peptides having had some amino acids removed from the N-terminus of the 19L-30R-NH2 fragment (8-10-mer peptides) still had strong anti-bacterial activity. Deleting some amino acids from the C-terminal region of the fragment dramatically reduced activity, indicating that the C-terminal region of the 19L-30R-NH2 fragment, i.e. RR-NH2, is important for exerting anti-bacterial activity. The AHCLAIGRR-NH2 (22A-30R-NH2) fragment and its analogues exhibited about 3-fold and 9-12-fold higher activity against S. aureus than did the 19L-30R-NH2 fragment, and these analogues were effective against methicillin-resistant S. aureus and Pseudomonas aeruginosa isolated from patients. These oligopeptides showed no haemolytic activity and did not inhibit the growth of murine fibroblast cells. PMID:9931294

Production of antibacterial Bombyx mori cecropin A in mealworm-pathogenic Beauveria bassiana ERL1170.

PubMed

Lee, Se Jin; Yu, Jeong Seon; Parker, Bruce L; Skinner, Margaret; Je, Yeon Ho; Kim, Jae Su

2015-01-01

Efforts are underway to produce antimicrobial peptides in yellow mealworms (Tenebrio molitor), which can be developed as more effective and safer animal feed additives. In this work, we expressed Bombyx mori (Bm) cecropin-A in mealworms by the infection of transformed entomopathogenic Beauveria bassiana ERL1170. The active domain of Bm cecropin A gene was tagged with a signal sequence of B. bassiana for extracellular secretion, and the fragment was inserted into ERL1170 by the restriction enzyme-mediated integration method. Transformant D-6 showed antibacterial activity against Bacillus subtilis and Listeria monocytogenes. Against T. molitor larvae, D-6 had similar mortality to wild-type, and D6-infected mealworm suspension showed strong antibacterial activity against the two bacteria, but not in the wild-type-infected mealworms, thereby increasing the value of mealworms as animal feed additives.

Environmental monitoring and assessment of antibacterial metabolite producing actinobacteria screened from marine sediments in south coastal regions of Karnataka, India.

PubMed

Skariyachan, Sinosh; Garka, Shruthi; Puttaswamy, Sushmitha; Shanbhogue, Shobitha; Devaraju, Raksha; Narayanappa, Rajeswari

2017-06-01

Assessment of the therapeutic potential of secondary metabolite producing microorganisms from the marine coastal areas imparts scope and application in the field of environmental monitoring. The present study aims to screen metabolites with antibacterial potential from actionbacteria associated with marine sediments collected from south coastal regions of Karnataka, India. The actinobacteria were isolated and characterized from marine sediments by standard protocol. The metabolites were extracted, and antibacterial potential was analyzed against eight hospital associated bacteria. The selected metabolites were partially characterized by proximate analysis, SDS-PAGE, and FTIR-spectroscopy. The antibiogram of the test clinical isolates revealed that they were emerged as multidrug-resistant strains (P ≤ 0.05). Among six actinobacteria (IS1-1S6) screened, 100 μl -1 metabolite from IS1 showed significant antibacterial activities against all the clinical isolates except Pseudomonas aeruginosa. IS2 demonstrated antimicrobial potential towards Proteus mirabilis, Streptococcus pyogenes, and Escherichia coli. The metabolite from IS3 showed activity against Strep. pyogenes and E. coli. The metabolites from IS4, IS5, and IS6 exhibited antimicrobial activities against Ps. aeruginosa (P ≤ 0.05). The two metabolites that depicted highest antibacterial activities against the test strains were suggested to be antimicrobial peptides with low molecular weight. These isolates were characterized and designated as Streptomyces sp. strain mangaluru01 and Streptomyces sp. mangaloreK01 by 16S ribosomal DNA (rDNA) sequencing. This study suggests that south coastal regions of Karnataka, India, are one of the richest sources of antibacterial metabolites producing actinobacteria and monitoring of these regions for therapeutic intervention plays profound role in healthcare management.

Virtual Screening Approach of Bacterial Peptide Deformylase Inhibitors Results in New Antibiotics.

PubMed

Merzoug, Amina; Chikhi, Abdelouahab; Bensegueni, Abderrahmane; Boucherit, Hanane; Okay, Sezer

2018-03-01

The increasing resistance of bacteria to antibacterial therapy poses an enormous health problem, it renders the development of new antibacterial agents with novel mechanism of action an urgent need. Peptide deformylase, a metalloenzyme which catalytically removes N-formyl group from N-terminal methionine of newly synthesized polypeptides, is an important target in antibacterial drug discovery. In this study, we report the structure-based virtual screening of ZINC database in order to discover potential hits as bacterial peptide deformylase enzyme inhibitors with more affinity as compared to GSK1322322, previously known inhibitor. After virtual screening, fifteen compounds of the top hits predicted were purchased and evaluated in vitro for their antibacterial activities against one Gram positive (Staphylococcus aureus) and three Gram negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella. pneumoniae) bacteria in different concentrations by disc diffusion method. Out of these, three compounds, ZINC00039650, ZINC03872971 and ZINC00126407, exhibited significant zone of inhibition. The results obtained were confirmed using the dilution method. Thus, these proposed compounds may aid the development of more efficient antibacterial agents. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synergy of antibacterial and antioxidant activities from crude extracts and peptides of selected plant mixture

PubMed Central

2013-01-01

Background A plant mixture containing indigenous Australian plants was examined for synergistic antimicrobial activity using selected test microorganisms. This study aims to investigate antibacterial activities, antioxidant potential and the content of phenolic compounds in aqueous, ethanolic and peptide extracts of plant mixture. Methods Well diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays were used to test antibacterial activity against four pathogenic bacteria namely Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Pseudomonas aeruginosa. DPPH (2, 2-diphenyl-1- picrylhydrazyl) and superoxide dismutase (SOD) assays were used to evaluate antioxidant activity. HPLC and gel filtration were used for purification of the peptides. Scanning electron microscope was applied to investigate the mode of attachment of the peptides on target microbial membranes. Results Aqueous extraction of the mixture showed no inhibition zones against all the test bacteria. Mean diameter of inhibition zones for ethanol extraction of this mixture attained 8.33 mm, 7.33 mm, and 6.33 mm against S. aureus at corresponding concentrations of 500, 250 and 125 mg/ml while E .coli showed inhibition zones of 9.33 mm, 8.00 mm and 6.66 mm at the same concentrations. B. cereus exhibited inhibition zones of 11.33 mm, 10.33 mm and 10.00 mm at concentrations of 500, 250 and 125 mg/ml respectively. The peptide extract demonstrated antibacterial activity against S. aureus, E. coli and B. cereus. The MIC and MBC values for ethanol extracts were determined at 125 mg/ml concentration against S. aureus and E. coli and B. cereus value was 31.5 mg/ml. MIC and MBC values showed that the peptide extract was significantly effective at low concentration of the Australian plant mixture (APM). Phenolic compounds were detected in hot aqueous and ethanolic extracts of the plant mixture. Hot aqueous, ethanol and peptides extracts also exhibited antioxidant activities. Conclusions It was concluded that APM possessed good antibacterial and antioxidant activities following extraction with different solvents. The results suggest that APM provide a new source with antibacterial agents and antioxidant activity for nutraceutical or medical applications. PMID:24330547

Cell Penetrating Peptides and Cationic Antibacterial Peptides

PubMed Central

Rodriguez Plaza, Jonathan G.; Morales-Nava, Rosmarbel; Diener, Christian; Schreiber, Gabriele; Gonzalez, Zyanya D.; Lara Ortiz, Maria Teresa; Ortega Blake, Ivan; Pantoja, Omar; Volkmer, Rudolf; Klipp, Edda; Herrmann, Andreas; Del Rio, Gabriel

2014-01-01

Cell penetrating peptides (CPP) and cationic antibacterial peptides (CAP) have similar physicochemical properties and yet it is not understood how such similar peptides display different activities. To address this question, we used Iztli peptide 1 (IP-1) because it has both CPP and CAP activities. Combining experimental and computational modeling of the internalization of IP-1, we show it is not internalized by receptor-mediated endocytosis, yet it permeates into many different cell types, including fungi and human cells. We also show that IP-1 makes pores in the presence of high electrical potential at the membrane, such as those found in bacteria and mitochondria. These results provide the basis to understand the functional redundancy of CPPs and CAPs. PMID:24706763

Probiotic Properties of Lactobacillus fermentum Strains Isolated from Human Oral Samples and Description of their Antibacterial Activity.

PubMed

Fuochi, Virginia; Volti, Giovanni Li; Furneri, Pio M

2017-01-01

Gram positive bacteria produce peptides, defined bacteriocins which exhibit good antibacterial activity. We evaluated the ability of L. fermentum to produce bacteriocins having therefore, good probiotic features and finally, be safe towards microglial cells. Eight wild strains, identified using molecular techniques, were investigated for the evaluation of resistance to bile salts, low pH, H2O2 production, biofilm formation, antibacterial activity and safety on microglia cells (BV2). The determination of the susceptibility/resistance profile showed that the strains are sensitive to the antibiotics tested. All strains showed a good tolerability to extremely low pH as well as resisting in presence of bile salts. In addition, the strains showed excellent activity against pathogens and one of them (LAC 42) showed activity also against Pseudomonas aeruginosa and Klebsiella pneumoniae. Finally, LAC 42 and its active compound did not change microglia cell viability following 24h exposure. Our data on this antibacterial molecule suggest that it is a compound with low molecular weight and with highly hydrophilic component. These results describe the characteristics of Lactobacillus strains and provide evidences for their possible use as new potential probiotic. In addition, other studies are now warranted to exploit the antibacterial activity of the supernatant LAC 42 and for its complete chemical characterization. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Janthinocins A, B and C, novel peptide lactone antibiotics produced by Janthinobacterium lividum. I. Taxonomy, fermentation, isolation, physico-chemical and biological characterization.

PubMed

O'Sullivan, J; McCullough, J; Johnson, J H; Bonner, D P; Clark, J C; Dean, L; Trejo, W H

1990-08-01

Janthinocins A, B and C are novel antibacterial agents produced by Janthinobacterium lividum. They were isolated from fermentation broths and characterized by UV, IR, NMR and mass spectroscopy. They are cyclic decapeptide lactones with marked activity against aerobic and anaerobic Gram-positive bacteria and are 2 to 4 times more potent in vitro than vancomycin. Janthinocins A and B were also found to be effective in a Staphylococcus aureus systemic infection in mice.

Antibacterial Activity of Synthetic Peptides Derived from Lactoferricin against Escherichia coli ATCC 25922 and Enterococcus faecalis ATCC 29212

PubMed Central

León-Calvijo, María A.; Leal-Castro, Aura L.; Almanzar-Reina, Giovanni A.; Rosas-Pérez, Jaiver E.; García-Castañeda, Javier E.; Rivera-Monroy, Zuly J.

2015-01-01

Peptides derived from human and bovine lactoferricin were designed, synthesized, purified, and characterized using RP-HPLC and MALDI-TOF-MS. Specific changes in the sequences were designed as (i) the incorporation of unnatural amino acids in the sequence, the (ii) reduction or (iii) elongation of the peptide chain length, and (iv) synthesis of molecules with different number of branches containing the same sequence. For each peptide, the antibacterial activity against Escherichia coli ATCC 25922 and Enterococcus faecalis ATCC 29212 was evaluated. Our results showed that Peptides I.2 (RWQWRWQWR) and I.4 ((RRWQWR)4K2 Ahx 2C2) exhibit bigger or similar activity against E. coli (MIC 4–33 μM) and E. faecalis (MIC 10–33 μM) when they were compared with lactoferricin protein (LF) and some of its derivate peptides as II.1 (FKCRRWQWRMKKLGA) and IV.1 (FKCRRWQWRMKKLGAPSITCVRRAE). It should be pointed out that Peptides I.2 and I.4, containing the RWQWR motif, are short and easy to synthesize; our results demonstrate that it is possible to design and obtain synthetic peptides that exhibit enhanced antibacterial activity using a methodology that is fast and low-cost and that allows obtaining products with a high degree of purity and high yield. PMID:25815317

Antibacterial activity of synthetic peptides derived from lactoferricin against Escherichia coli ATCC 25922 and Enterococcus faecalis ATCC 29212.

PubMed

León-Calvijo, María A; Leal-Castro, Aura L; Almanzar-Reina, Giovanni A; Rosas-Pérez, Jaiver E; García-Castañeda, Javier E; Rivera-Monroy, Zuly J

2015-01-01

Peptides derived from human and bovine lactoferricin were designed, synthesized, purified, and characterized using RP-HPLC and MALDI-TOF-MS. Specific changes in the sequences were designed as (i) the incorporation of unnatural amino acids in the sequence, the (ii) reduction or (iii) elongation of the peptide chain length, and (iv) synthesis of molecules with different number of branches containing the same sequence. For each peptide, the antibacterial activity against Escherichia coli ATCC 25922 and Enterococcus faecalis ATCC 29212 was evaluated. Our results showed that Peptides I.2 (RWQWRWQWR) and I.4 ((RRWQWR)4K2Ahx2C2) exhibit bigger or similar activity against E. coli (MIC 4-33 μM) and E. faecalis (MIC 10-33 μM) when they were compared with lactoferricin protein (LF) and some of its derivate peptides as II.1 (FKCRRWQWRMKKLGA) and IV.1 (FKCRRWQWRMKKLGAPSITCVRRAE). It should be pointed out that Peptides I.2 and I.4, containing the RWQWR motif, are short and easy to synthesize; our results demonstrate that it is possible to design and obtain synthetic peptides that exhibit enhanced antibacterial activity using a methodology that is fast and low-cost and that allows obtaining products with a high degree of purity and high yield.

Antimicrobial Activity of Novel Synthetic Peptides Derived from Indolicidin and Ranalexin against Streptococcus pneumoniae

PubMed Central

Jindal, Hassan Mahmood; Le, Cheng Foh; Mohd Yusof, Mohd Yasim; Velayuthan, Rukumani Devi; Lee, Vannajan Sanghiran; Zain, Sharifuddin Md; Isa, Diyana Mohd; Sekaran, Shamala Devi

2015-01-01

Antimicrobial peptides (AMPs) represent promising alternatives to conventional antibiotics in order to defeat multidrug-resistant bacteria such as Streptococcus pneumoniae. In this study, thirteen antimicrobial peptides were designed based on two natural peptides indolicidin and ranalexin. Our results revealed that four hybrid peptides RN7-IN10, RN7-IN9, RN7-IN8, and RN7-IN6 possess potent antibacterial activity against 30 pneumococcal clinical isolates (MIC 7.81-15.62µg/ml). These four hybrid peptides also showed broad spectrum antibacterial activity (7.81µg/ml) against S. aureus, methicillin resistant S. aureus (MRSA), and E. coli. Furthermore, the time killing assay results showed that the hybrid peptides were able to eliminate S. pneumoniae within less than one hour which is faster than the standard drugs erythromycin and ceftriaxone. The cytotoxic effects of peptides were tested against human erythrocytes, WRL-68 normal liver cell line, and NL-20 normal lung cell line. The results revealed that none of the thirteen peptides have cytotoxic or hemolytic effects at their MIC values. The in silico molecular docking study was carried out to investigate the binding properties of peptides with three pneumococcal virulent targets by Autodock Vina. RN7IN6 showed a strong affinity to target proteins; autolysin, pneumolysin, and pneumococcal surface protein A (PspA) based on rigid docking studies. Our results suggest that the hybrid peptides could be suitable candidates for antibacterial drug development. PMID:26046345

Anhydrous polymer-based coating with sustainable controlled release functionality for facile, efficacious impregnation, and delivery of antimicrobial peptides.

PubMed

Lim, Kaiyang; Saravanan, Rathi; Chong, Kelvin K L; Goh, Sharon H M; Chua, Ray R Y; Tambyah, Paul A; Chang, Matthew W; Kline, Kimberly A; Leong, Susanna S J

2018-04-17

Anhydrous polymers are actively explored as alternative materials to overcome limitations of conventional hydrogel-based antibacterial coating. However, the requirement for strong organic solvent in polymerization reactions often necessitates extra protection steps for encapsulation of target biomolecules, lowering encapsulation efficiency, and increasing process complexity. This study reports a novel coating strategy that allows direct solvation and encapsulation of antimicrobial peptides (HHC36) into anhydrous polycaprolactone (PCL) polymer-based dual layer coating. A thin 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) film is layered onto the peptide-impregnated PCL as a diffusion barrier, to modulate and enhance release kinetics. The impregnated peptides are eventually released in a controlled fashion. The use of 2,2,2-trifluoroethanol (TFE), as polymerization and solvation medium, induces the impregnated peptides to adopt highly stable turned conformation, conserving peptide integrity, and functionality during both encapsulation and subsequent release processes. The dual layer coating showed sustained antibacterial functionality, lasting for 14 days. In vivo assessment using an experimental mouse wounding model demonstrated good biocompatibility and significant antimicrobial efficacy of the coating under physiological conditions. The coating was translated onto silicone urinary catheters and showed promising antibacterial efficacy, even outperforming commercial silver-based Dover cather. This anhydrous polymer-based platform holds immense potential as an effective antibacterial coating to prevent clinical device-associated infections. The simplicity of the coating process enhances its industrial viability. © 2018 Wiley Periodicals, Inc.

Synthesis and antibacterial evaluation of novel cationic chalcone derivatives possessing broad spectrum antibacterial activity.

PubMed

Chu, Wen-Chao; Bai, Peng-Yan; Yang, Zhao-Qing; Cui, De-Yun; Hua, Yong-Gang; Yang, Yi; Yang, Qian-Qian; Zhang, En; Qin, Shangshang

2018-01-01

There is an urgent need to identify new antibiotics with novel mechanisms that combat antibiotic resistant bacteria. Herein, a series of chalcone derivatives that mimic the essential properties of cationic antimicrobial peptides were designed and synthesized. Antibacterial activities against drug-sensitive bacteria, including Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Salmonella enterica, as well as clinical multiple drug resistant isolates of methicillin-resistant S. aureus (MRSA), KPC-2-producing and NDM-1-producing Carbapenem-resistant Enterobacteriaceae were evaluated. Representative compounds 5a (MIC: 1 μg/mL against S. aureus, 0.5 μg/mL against MRSA) and 5g (MIC: 0.5 μg/mL against S. aureus, 0.25 μg/mL against MRSA) showed good bactericidal activity against both Gram-positive and Gram-negative bacteria, including the drug-resistant species MRSA, KPC and NDM. These membrane-active antibacterial compounds were demonstrated to reduce the viable cell counts in bacterial biofilms effectively and do not induce the development of resistance in bacteria. Additionally, these representative molecules exhibited negligible toxicity toward mammalian cells at a suitable concentration. The combined results indicate that this series of cationic chalcone derivatives have potential therapeutic effects against bacterial infections. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

A novel insect defensin mediates the inducible antibacterial activity in larvae of the dragonfly Aeschna cyanea (Paleoptera, Odonata).

PubMed

Bulet, P; Cociancich, S; Reuland, M; Sauber, F; Bischoff, R; Hegy, G; Van Dorsselaer, A; Hetru, C; Hoffmann, J A

1992-11-01

The injection of low doses of bacteria into the aquatic larvae of dragonflies (Aeschna cyanea, Odonata, Paleoptera) induces the appearance in their hemolymph of a potent antibacterial activity. We have isolated a 38-residue peptide from this hemolymph which is strongly active against Gram-positive bacteria and also shows activity against one of the Gram-negative bacteria which was tested. The peptide is a novel member of the insect defensin family of inducible antibacterial peptides, which had so far only been reported from the higher insect orders believed to have evolved 100 million years after the Paleoptera. Aeschna defensin is more potent than defensin from the dipteran Phormia, from which its structure differs in several interesting aspects, which are discussed in the paper.

An FPGA Implementation to Detect Selective Cationic Antibacterial Peptides

PubMed Central

Polanco González, Carlos; Nuño Maganda, Marco Aurelio; Arias-Estrada, Miguel; del Rio, Gabriel

2011-01-01

Exhaustive prediction of physicochemical properties of peptide sequences is used in different areas of biological research. One example is the identification of selective cationic antibacterial peptides (SCAPs), which may be used in the treatment of different diseases. Due to the discrete nature of peptide sequences, the physicochemical properties calculation is considered a high-performance computing problem. A competitive solution for this class of problems is to embed algorithms into dedicated hardware. In the present work we present the adaptation, design and implementation of an algorithm for SCAPs prediction into a Field Programmable Gate Array (FPGA) platform. Four physicochemical properties codes useful in the identification of peptide sequences with potential selective antibacterial activity were implemented into an FPGA board. The speed-up gained in a single-copy implementation was up to 108 times compared with a single Intel processor cycle for cycle. The inherent scalability of our design allows for replication of this code into multiple FPGA cards and consequently improvements in speed are possible. Our results show the first embedded SCAPs prediction solution described and constitutes the grounds to efficiently perform the exhaustive analysis of the sequence-physicochemical properties relationship of peptides. PMID:21738652

Targeted separation of antibacterial peptide from protein hydrolysate of anchovy cooking wastewater by equilibrium dialysis.

PubMed

Tang, Wenting; Zhang, Hui; Wang, Li; Qian, Haifeng; Qi, Xiguang

2015-02-01

Anchovy (Engraulis japonicus) cooking wastewater (ACWW) is a by-product resulted from the production of boiled-dried anchovies in the seafood processing industry. In this study, the protein hydrolysate of ACWW (ACWWPH) was found to have antimicrobial activity after enzymatic hydrolysis with Protamex. For the targeted screening of antibacterial peptides, liposomes constructed from Staphylococcus aureus membrane lipids were used in an equilibrium dialysis system. The hydrolysate was further purified by liposome equilibrium dialysis combined with high performance liquid chromatography. The purified antimicrobial peptide (ACWWP1) was determined to be GLSRLFTALK, with a molecular weight of 1104.6622Da. The peptide exhibited no haemolytic activity up to a concentration of 512μg/ml. It displayed a dose-dependent bactericidal effect in reconstituted milk. The change in cell surface hydrophobicity and membrane-permeable action of the purified ACWWP1 may have contributed to the antibacterial effect. This study suggests that liposome equilibrium dialysis can be used for the targeted screening of antimicrobial peptides. Copyright © 2014 Elsevier Ltd. All rights reserved.

Covalent modification of a ten-residue cationic antimicrobial peptide with levofloxacin

NASA Astrophysics Data System (ADS)

Rodriguez, Carlos; Papanastasiou, Emilios; Juba, Melanie; Bishop, Barney

2014-09-01

The rampant spread of antibiotic resistant bacteria has spurred interest in alternative strategies for developing next-generation antibacterial therapies. As such, there has been growing interest in cationic antimicrobial peptides (CAMPs) and their therapeutic applications. Modification of CAMPs via conjugation to auxiliary compounds, including small molecule drugs, is a new approach to developing effective, broad-spectrum antibacterial agents with novel physicochemical properties and versatile antibacterial mechanisms. Here, we’ve explored design parameters for engineering CAMPs conjugated to small molecules with favorable physicochemical and antibacterial properties by covalently affixing a fluoroquinolone antibiotic, levofloxacin, to the ten-residue CAMP Pep-4. Relative to the unmodified Pep-4, the conjugate was found to demonstrate substantially increased antibacterial potency under high salt concentrations. Historically, it has been observed that most CAMPs lose antibacterial effectiveness in such high ionic strength environments, a fact that has presented a challenge to their development as therapeutics. Physicochemical studies revealed that P4LC was more hydrophobic than Pep-4, while mechanistic findings indicated that the conjugate was more effective at disrupting bacterial membrane integrity. Although the inherent antibacterial effect of the incorporated levofloxacin molecules did not appear to be substantially realized in this conjugate, these findings nevertheless suggest that covalent attachment of small molecule antibiotics with favorable physicochemical properties to CAMPs could be a promising strategy for enhancing peptide performance and overall therapeutic potential. These results have broader applicability to the development of future CAMP-antibiotic conjugates for potential therapeutic applications.

Screening and characterization of novel bacteriocins from lactic acid bacteria.

PubMed

Zendo, Takeshi

2013-01-01

Bacteriocins produced by lactic acid bacteria (LAB) are expected to be safe antimicrobial agents. While the best studied LAB bacteriocin, nisin A, is widely utilized as a food preservative, various novel ones are required to control undesirable bacteria more effectively. To discover novel bacteriocins at the early step of the screening process, we developed a rapid screening system that evaluates bacteriocins produced by newly isolated LAB based on their antibacterial spectra and molecular masses. By means of this system, various novel bacteriocins were identified, including a nisin variant, nisin Q, a two-peptide bacteriocin, lactococcin Q, a leaderless bacteriocin, lacticin Q, and a circular bacteriocin, lactocyclicin Q. Moreover, some LAB isolates were found to produce multiple bacteriocins. They were characterized as to their structures, mechanisms of action, and biosynthetic mechanisms. Novel LAB bacteriocins and their biosynthetic mechanisms are expected for applications such as food preservation and peptide engineering.

Antibacterial function of the human cathelicidin-18 peptide (LL-37) between theory and practice.

PubMed

Iacob, Simona A; Iacob, Diana G

2014-01-01

The human cathelicidin-18 is an antimicrobial, immunomodulatory and tissue repair peptide. The LL-37 fragment of this peptide which is in fact the active domain of the cathelicidin-18 is critical for the human antibacterial defense and epithelial integrity. It's activity against resistant pathogens, the potential of epithelial healing after microbial injury and the neutralization of bacterial endotoxin underlie the most important benefits of this peptide. However, there are still a number of questions that remain to be answered regarding the precise interactions of cathelicidin-18 within the immune system, the exact tissue concentrations or its possible pro-tumoral activity. In this respect, the therapeutic potential of cathelicidin-18 in various infections has been proved by in vitro experiments, but additional detailed clinical studies are still required to ascertain its antimicrobial role in vivo. We present a short review on the antibacterial activity of human cathelicidin-18 (LL-37) according to in vitro experiments while discussing its potential use in the clinical practice.

Structural diversity of marine cyclic peptides and their molecular mechanisms for anticancer, antibacterial, antifungal, and other clinical applications.

PubMed

Lee, Yeji; Phat, Chanvorleak; Hong, Soon-Cheol

2017-09-01

Many cyclic peptides and analogues derived from marine sources are known to possess biological properties, including anticancer, antitumor, antibacterial, antifungal, antiparasitic, anti-inflammation, anti-proliferative, anti-hypertensive, cytotoxic, and antibiotic properties. These compounds demonstrate different activities and modes of action according to their structure such as cyclic oligopeptide, cyclic lipopeptide, cyclic glycopeptide and cyclic depsipeptide. The recent advances in application of the above-mentioned cyclic peptides were reported in dolastatins, soblidotin, didemnin B, aplidine, salinosporamide A, kahalalide F and bryostatin 1 and they are currently in clinical trials. These cyclic peptides are possible novel drugs discovered and developed from marine origin. Literature data concerning the potential properties of marine cyclic peptides were reviewed here, and the structural diversity and biological activities of marine cyclic peptides are discussed in relation to the molecular mechanisms of these marine cyclic peptides. Copyright © 2017 Elsevier Inc. All rights reserved.

Antimicrobial Activity of Lactoferrin-Related Peptides and Applications in Human and Veterinary Medicine.

PubMed

Bruni, Natascia; Capucchio, Maria Teresa; Biasibetti, Elena; Pessione, Enrica; Cirrincione, Simona; Giraudo, Leonardo; Corona, Antonio; Dosio, Franco

2016-06-11

Antimicrobial peptides (AMPs) represent a vast array of molecules produced by virtually all living organisms as natural barriers against infection. Among AMP sources, an interesting class regards the food-derived bioactive agents. The whey protein lactoferrin (Lf) is an iron-binding glycoprotein that plays a significant role in the innate immune system, and is considered as an important host defense molecule. In search for novel antimicrobial agents, Lf offers a new source with potential pharmaceutical applications. The Lf-derived peptides Lf(1-11), lactoferricin (Lfcin) and lactoferrampin exhibit interesting and more potent antimicrobial actions than intact protein. Particularly, Lfcin has demonstrated strong antibacterial, anti-fungal and antiparasitic activity with promising applications both in human and veterinary diseases (from ocular infections to osteo-articular, gastrointestinal and dermatological diseases).

Paenibacillus polymyxa PKB1 produces variants of polymyxin B-type antibiotics.

PubMed

Shaheen, Mohamed; Li, Jingru; Ross, Avena C; Vederas, John C; Jensen, Susan E

2011-12-23

Polymyxins are cationic lipopeptide antibiotics active against many species of Gram-negative bacteria. We sequenced the gene cluster for polymyxin biosynthesis from Paenibacillus polymyxa PKB1. The 40.8 kb gene cluster comprises three nonribosomal peptide synthetase-encoding genes and two ABC transporter-like genes. Disruption of a peptide synthetase gene abolished all antibiotic production, whereas deletion of one or both transporter genes only reduced antibiotic production. Computational analysis of the peptide synthetase modules suggested that the enzyme system produces variant forms of polymyxin B (1 and 2), with D-2,4-diaminobutyrate instead of L-2,4-diaminobutyrate in amino acid position 3. Two antibacterial metabolites were resolved by HPLC and identified by high-resolution mass spectrometry and MS/MS sequencing as the expected variants 3 and 4 of polymyxin B(1) (1) and B(2) (2). Stereochemical analysis confirmed the presence of both D-2,4-diaminobutyrate and L-2,4-diaminobutyrate residues. Copyright © 2011 Elsevier Ltd. All rights reserved.

Discovery of an ultra-short linear antibacterial tetrapeptide with anti-MRSA activity from a structure-activity relationship study.

PubMed

Lau, Qiu Ying; Ng, Fui Mee; Cheong, Jin Wei Darryl; Yap, Yi Yong Alvin; Tan, Yoke Yan Fion; Jureen, Roland; Hill, Jeffrey; Chia, Cheng San Brian

2015-11-13

The overuse and misuse of antibiotics has resulted in the emergence of drug-resistant pathogenic bacteria, including meticillin-resistant Staphylococcus aureus (MRSA), the primary pathogen responsible for human skin and soft-tissue infections. Antibacterial peptides are known to kill bacteria by rapidly disrupting their membranes and are deemed plausible alternatives to conventional antibiotics. One advantage of their membrane-targeting mode of action is that bacteria are unlikely to develop resistance as changing their cell membrane structure and morphology would likely involve extensive genetic mutations. However, major concerns in using peptides as antibacterial drugs include their instability towards plasma proteases, toxicity towards human cells due to their membrane-targeting mode of action and high manufacturing cost. These concerns can be mitigated by developing peptides as topical agents, by the judicial selection of amino acids and developing very short peptides respectively. In this preliminary report, we reveal a linear, non-hemolytic tetrapeptide with rapid bactericidal activity against MRSA developed from a structure-activity relationship study based on the antimicrobial hexapeptide WRWRWR-NH2. Our finding opens promising avenues for the development of ultra-short antibacterials to treat multidrug-resistant MRSA skin and soft tissue infections. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Antibacterial peptides from plants: what they are and how they probably work.

PubMed

Barbosa Pelegrini, Patrícia; Del Sarto, Rafael Perseghini; Silva, Osmar Nascimento; Franco, Octávio Luiz; Grossi-de-Sa, Maria Fátima

2011-01-01

Plant antibacterial peptides have been isolated from a wide variety of species. They consist of several protein groups with different features, such as the overall charge of the molecule, the content of disulphide bonds, and structural stability under environmental stress. Although the three-dimensional structures of several classes of plant peptides are well determined, the mechanism of action of some of these molecules is still not well defined. However, further studies may provide new evidences for their function on bacterial cell wall. Therefore, this paper focuses on plant peptides that show activity against plant-pathogenic and human-pathogenic bacteria. Furthermore, we describe the folding of several peptides and similarities among their three-dimensional structures. Some hypotheses for their mechanisms of action and attack on the bacterial membrane surface are also proposed.

Development and application of active films for food packaging using antibacterial peptide of Bacillus licheniformis Me1.

PubMed

Nithya, V; Murthy, P S K; Halami, P M

2013-08-01

An attempt was made to evaluate the effectiveness of partially purified antibacterial peptide (ppABP) produced by Bacillus licheniformis Me1 for food preservation by means of active packaging. The active packaging films containing ppABP were developed using two different packing materials [low-density polyethylene (LDPE) and cellulose films] by two different methods: soaking and spread coating. The activated films showed antibacterial activity against pathogens. The release study of ppABP from coated film showed that the LDPE films liberated ppABP as soon as it comes in contact with water, while gradual release of coated ppABP was observed in case of cellulose films. The activated films showed residual activity in different simulating conditions, such as pH of food and storage temperatures. The activated films demonstrated its biopreservative efficacy in controlling the growth of pathogens in cheese and paneer. The ppABP-activated films were found to be effective for biopreservation. The ppABP from active films got diffused into the food matrix and reduced the growth rate and maximum growth population of the target micro-organism. Both types of ppABP-activated films can be used as a packaging material to control spoilage and pathogenic organisms in food, thereby extending the shelf life of foods. © 2013 The Society for Applied Microbiology.

Purification, cDNA cloning and modification of a defensin from the coconut rhinoceros beetle, Oryctes rhinoceros.

PubMed

Ishibashi, J; Saido-Sakanaka, H; Yang, J; Sagisaka, A; Yamakawa, M

1999-12-01

A novel member of the insect defensins, a family of antibacterial peptides, was purified from larvae of the coconut rhinoceros beetle, Oryctes rhinoceros, immunized with Escherichia coli. A full-size cDNA was cloned by combining reverse-transcription PCR (RT-PCR), and 5'- and 3'-rapid amplification of cDNA ends (RACE). Analysis of the O. rhinoceros defensin gene expression showed it to be expressed in the fat body and hemocyte, midgut and Malpighian tubules. O. rhinoceros defensin showed strong antibacterial activity against Staphylococcus aureus. A 9-mer peptide amidated at its C-terminus, AHCLAICRK-NH2 (Ala22-Lys30-NH2), was synthesized based on the deduced amino-acid sequence, assumed to be an active site sequence by analogy with the sequence of a defensin isolated from larvae of the beetle Allomyrina dichotoma. This peptide showed antibacterial activity against S. aureus, methicillin-resistant S. aureus, E. coli and Pseudomonas aeruginosa. We further modified this oligopeptide and synthesized five 9-mer peptides, ALRLAIRKR-NH2, ALLLAIRKR-NH2, AWLLAIRKR-NH2, ALYLAIRKR-NH2 and ALWLAIRKR-NH2. These oligopeptides showed strong antibacterial activity against Gram-negative and Gram-positive bacteria. The antibacterial effect of Ala22-Lys30-NH2 analogues was due to its interaction with bacterial membranes, judging from the leakage of liposome-entrapped glucose. These Ala22-Lys30-NH2 analogues did not show haemolytic activity and did not inhibit the growth of murine fibroblast cells or macrophages, except for AWLLAIRKR-NH2.

Alanine scan of the peptide antibiotic feglymycin: assessment of amino acid side chains contributing to antimicrobial activity.

PubMed

Hänchen, Anne; Rausch, Saskia; Landmann, Benjamin; Toti, Luigi; Nusser, Antje; Süssmuth, Roderich D

2013-03-18

The antibiotic feglymycin is a linear 13-mer peptide synthesized by the bacterium Streptomyces sp. DSM 11171. It mainly consists of the nonproteinogenic amino acids 4-hydroxyphenylglycine and 3,5-dihydroxyphenylglycine. An alanine scan of feglymycin was performed by solution-phase peptide synthesis in order to assess the significance of individual amino acid side chains for biological activity. Hence, 13 peptides were synthesized from di- and tripeptide building blocks, and subsequently tested for antibacterial activity against Staphylococcus aureus strains. Furthermore we tested the inhibition of peptidoglycan biosynthesis enzymes MurA and MurC, which are inhibited by feglymycin. Whereas the antibacterial activity is significantly based on the three amino acids D-Hpg1, L-Hpg5, and L-Phe12, the inhibitory activity against MurA and MurC depends mainly on L-Asp13. The difference in the position dependence for antibacterial activity and enzyme inhibition suggests multiple molecular targets in the modes of action of feglymycin. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recombinant production of a chimeric antimicrobial peptide in E. coli and assessment of its activity against some avian clinically isolated pathogens.

PubMed

Tanhaiean, Abass; Azghandi, Marjan; Razmyar, Jamshid; Mohammadi, Elyas; Sekhavati, Mohammad Hadi

2018-06-08

Over the last decades, poultry industry faced to the rapid emergence of multidrug-resistant bacteria as a global concern. Antimicrobial peptide (AMPs) known as potential antibiotic alternative and were considered as a new antimicrobial agent. Current methods of production and purification of AMPs have several limitations such as: costly, time-consuming and killing the producing host cells in recombinant form. In the present study, a chimeric peptide derived from camel lactoferrin was produced in Escherichia coli periplasmic space using a pET-based expression system and its antibacterial activity was determined on some avian pathogens in vitro. A carboxy-terminal polyhistidine tag was used for purification by Ni 2+ affinity chromatography with an average yield of 0.42 g/L. The His-tagged chimeric peptide showed different range of antimicrobial activity against clinically isolated avian pathogens with low chicken blood hemolysis activity and high serum stability. Overall, the results of this investigation showed the recombinant chimeric peptide was successfully expressed in pET-based expression system and could be considered as a proper alternative for some currently used antibiotics in poultry industry and drugs veterinary medicine. Copyright © 2018 Elsevier Ltd. All rights reserved.

Characterization of an antimicrobial peptide produced by Bacillus subtilis subsp. spizezinii showing inhibitory activity towards Haemophilus parasuis.

PubMed

Teixeira, Mário Lettieri; Dalla Rosa, Andréia; Brandelli, Adriano

2013-05-01

Haemophilus parasuis is the pathogen that causes Glässer's disease, a major illness affecting young pigs. The aim of this work was to investigate the antagonistic activity of antimicrobial substances produced by Bacillus species against H. parasuis. Among the tested strains, only Bacillus subtilis ATCC 6633 inhibited H. parasuis growth. The antibacterial substance was purified by ammonium sulfate precipitation, gel filtration chromatography on Sephadex G-50 and ion-exchange chromatography on DEAE-cellulose. The purification was about 100-fold with a yield of 0.33 %. The purified substance was resistant up to 80 °C and pH ranging 3-7, but the substance lost its activity when it was treated with proteases. The peptide had a molecular mass of 1083 Da and its sequence was determined by MS as NRWCFAGDD, which showed no homology with other known antimicrobial peptides. The complete inhibition of H. parasuis growth was observed at 20 µg peptide ml(-1) after 20 min of exposure. The peptide obtained by chemical synthesis also showed antimicrobial activity on H. parasuis. The identification of antimicrobial substances that can be effective against H. parasuis is very relevant to combat this pathogen that causes important losses in swine production.

Synthetic Mimic of Antimicrobial Peptide with Nonmembrane-Disrupting Antibacterial Properties

PubMed Central

2008-01-01

Polyguanidinium oxanorbornene (PGON) was synthesized from norbornene monomers via ring-opening metathesis polymerization. This polymer was observed to be strongly antibacterial against Gram-negative and Gram-positive bacteria as well as nonhemolytic against human red blood cells. Time-kill studies indicated that this polymer is lethal and not just bacteriostatic. In sharp contrast to previously reported SMAMPs (synthetic mimics of antimicrobial peptides), PGON did not disrupt membranes in vesicle-dye leakage assays and microscopy experiments. The unique biological properties of PGON, in same ways similar to cell-penetrating peptides, strongly encourage the examination of other novel guanidino containing macromolecules as powerful and selective antimicrobial agents. PMID:18850741

Mechanisms of action and in vivo antibacterial efficacy assessment of five novel hybrid peptides derived from Indolicidin and Ranalexin against Streptococcus pneumoniae

PubMed Central

Jindal, Hassan Mahmood; Zandi, Keivan; Ong, Kien Chai; Velayuthan, Rukumani Devi; Rasid, Sara Maisha; Samudi Raju, Chandramathi

2017-01-01

Background Antimicrobial peptides (AMPs) are of great potential as novel antibiotics for the treatment of broad spectrum of pathogenic microorganisms including resistant bacteria. In this study, the mechanisms of action and the therapeutic efficacy of the hybrid peptides were examined. Methods TEM, SEM and ATP efflux assay were used to evaluate the effect of hybrid peptides on the integrity of the pneumococcal cell wall/membrane. DNA retardation assay was assessed to measure the impact of hybrid peptides on the migration of genomic DNA through the agarose gel. In vitro synergistic effect was checked using the chequerboard assay. ICR male mice were used to evaluate the in vivo toxicity and antibacterial activity of the hybrid peptides in a standalone form and in combination with ceftriaxone. Results The results obtained from TEM and SEM indicated that the hybrid peptides caused significant morphological alterations in Streptococcus pneumoniae and disrupting the integrity of the cell wall/membrane. The rapid release of ATP from pneumococcal cells after one hour of incubation proposing that the antibacterial action for the hybrid peptides is based on membrane permeabilization and damage. The DNA retardation assay revealed that at 62.5 µg/ml all the hybrid peptides were capable of binding and preventing the pneumococcal genomic DNA from migrating through the agarose gel. In vitro synergy was observed when pneumococcal cells treated with combinations of hybrid peptides with each other and with conventional drugs erythromycin and ceftriaxone. The in vivo therapeutic efficacy results revealed that the hybrid peptide RN7-IN8 at 20 mg/kg could improve the survival rate of pneumococcal bacteremia infected mice, as 50% of the infected mice survived up to seven days post-infection. In vivo antibacterial efficacy of the hybrid peptide RN7-IN8 was signficantly improved when combined with the standard antibiotic ceftriaxone at (20 mg/kg + 20 mg/kg) as 100% of the infected mice survived up to seven days post-infection. Discussion Our results suggest that attacking and breaching the cell wall/membrane is most probably the principal mechanism for the hybrid peptides. In addition, the hybrid peptides could possess another mechanism of action by inhibiting intracellular functions such as DNA synthesis. AMPs could play a great role in combating antibiotic resistance as they can reduce the therapeutic concentrations of standard drugs. PMID:29018620

Conformational flexibility determines selectivity and antibacterial, antiplasmodial, and anticancer potency of cationic α-helical peptides.

PubMed

Vermeer, Louic S; Lan, Yun; Abbate, Vincenzo; Ruh, Emrah; Bui, Tam T; Wilkinson, Louise J; Kanno, Tokuwa; Jumagulova, Elmira; Kozlowska, Justyna; Patel, Jayneil; McIntyre, Caitlin A; Yam, W C; Siu, Gilman; Atkinson, R Andrew; Lam, Jenny K W; Bansal, Sukhvinder S; Drake, Alex F; Mitchell, Graham H; Mason, A James

2012-10-05

We used a combination of fluorescence, circular dichroism (CD), and NMR spectroscopies in conjunction with size exclusion chromatography to help rationalize the relative antibacterial, antiplasmodial, and cytotoxic activities of a series of proline-free and proline-containing model antimicrobial peptides (AMPs) in terms of their structural properties. When compared with proline-free analogs, proline-containing peptides had greater activity against Gram-negative bacteria, two mammalian cancer cell lines, and intraerythrocytic Plasmodium falciparum, which they were capable of killing without causing hemolysis. In contrast, incorporation of proline did not have a consistent effect on peptide activity against Mycobacterium tuberculosis. In membrane-mimicking environments, structures with high α-helix content were adopted by both proline-free and proline-containing peptides. In solution, AMPs generally adopted disordered structures unless their sequences comprised more hydrophobic amino acids or until coordinating phosphate ions were added. Proline-containing peptides resisted ordering induced by either method. The roles of the angle subtended by positively charged amino acids and the positioning of the proline residues were also investigated. Careful positioning of proline residues in AMP sequences is required to enable the peptide to resist ordering and maintain optimal antibacterial activity, whereas varying the angle subtended by positively charged amino acids can attenuate hemolytic potential albeit with a modest reduction in potency. Maintaining conformational flexibility improves AMP potency and selectivity toward bacterial, plasmodial, and cancerous cells while enabling the targeting of intracellular pathogens.

The Human Antimicrobial Protein Bactericidal/Permeability-Increasing Protein (BPI) Inhibits the Infectivity of Influenza A Virus

PubMed Central

Pinkenburg, Olaf; Meyer, Torben; Bannert, Norbert; Norley, Steven; Bolte, Kathrin; Czudai-Matwich, Volker; Herold, Susanne; Gessner, André; Schnare, Markus

2016-01-01

In addition to their well-known antibacterial activity some antimicrobial peptides and proteins (AMPs) display also antiviral effects. A 27 aa peptide from the N-terminal part of human bactericidal/permeability-increasing protein (BPI) previously shown to harbour antibacterial activity inhibits the infectivity of multiple Influenza A virus strains (H1N1, H3N2 and H5N1) the causing agent of the Influenza pneumonia. In contrast, the homologous murine BPI-peptide did not show activity against Influenza A virus. In addition human BPI-peptide inhibits the activation of immune cells mediated by Influenza A virus. By changing the human BPI-peptide to the sequence of the mouse homologous peptide the antiviral activity was completely abolished. Furthermore, the human BPI-peptide also inhibited the pathogenicity of the Vesicular Stomatitis Virus but failed to interfere with HIV and measles virus. Electron microscopy indicate that the human BPI-peptide interferes with the virus envelope and at high concentrations was able to destroy the particles completely. PMID:27273104

Metabolic fate of lactoferricin-based antimicrobial peptides: effect of truncation and incorporation of amino acid analogs on the in vitro metabolic stability.

PubMed

Svenson, Johan; Vergote, Valentijn; Karstad, Rasmus; Burvenich, Christian; Svendsen, John S; De Spiegeleer, Bart

2010-03-01

A series of promising truncated antibacterial tripeptides derived from lactoferricin has been prepared, and their in vitro metabolic stability in the main metabolic compartments, plasma, liver, kidney, stomach, duodenum, and brain, has been investigated for the first time. The potential stabilizing effect of truncation, C-terminal capping, and introduction of the bulky synthetic amino acid biphenylalanine is also investigated. The drug-like peptides displayed large differences in half-lives in the different matrixes ranging from 4.2 min in stomach and duodenum to 355.9 min in liver. Kinetic analysis of the metabolites revealed that several different degrading enzymes simultaneously target the different peptide bonds and that the outcome of the tested strategies to increase the stability is clearly enzyme-specific. Some of the metabolic enzymes even prefer the synthetic modifications incorporated over the natural counterparts. Collectively, it is shown that the necessary antibacterial pharmacophore generates compounds that are not only potent antibacterial peptides, but excellent substrates for the main degrading enzymes. All the amide bonds are thus rapidly targeted by different enzymes despite the short peptidic sequences of the tested compounds. Hence, our results illustrate that several structural changes are needed before these compounds can be considered for oral administration. Strategies to overcome such metabolic challenges are discussed.

Purification and characterization of four antibacterial peptides from protamex hydrolysate of Atlantic mackerel (Scomber scombrus) by-products.

PubMed

Ennaas, Nadia; Hammami, Riadh; Beaulieu, Lucie; Fliss, Ismail

2015-07-03

Proteins from fish by-product sources are valuable source of bioactive peptides and show promise as functional foods ingredients. The objective of the present study was to isolate and characterize antibacterial peptides from protamex hydrolysates of Atlantic mackerel (Scomber scombrus) by-products. Four sequences SIFIQRFTT (P4), RKSGDPLGR (P8.1), AKPGDGAGSGPR (P8.2) and GLPGPLGPAGPK (P11) were identified in peptide fractions separated using RP-HPLC. At 200 μg mL(-1), while peptides P8.1, P8.2 and P11 exhibited partial inhibition, P4 totally inhibited tested Gram-positive (Listeria innocua) and Gram-negative (Escherichia coli) bacterial strains. These results suggest that the protein hydrolysate derived from mackerel by-products could be used as an antimicrobial ingredient in both functional food and nutraceutical applications. Copyright © 2015 Elsevier Inc. All rights reserved.

Production, purification, sequencing and activity spectra of mutacins D-123.1 and F-59.1

PubMed Central

2011-01-01

Background The increase in bacterial resistance to antibiotics impels the development of new anti-bacterial substances. Mutacins (bacteriocins) are small antibacterial peptides produced by Streptococcus mutans showing activity against bacterial pathogens. The objective of the study was to produce and characterise additional mutacins in order to find new useful antibacterial substances. Results Mutacin F-59.1 was produced in liquid media by S. mutans 59.1 while production of mutacin D-123.1 by S. mutans 123.1 was obtained in semi-solid media. Mutacins were purified by hydrophobic chromatography. The amino acid sequences of the mutacins were obtained by Edman degradation and their molecular mass was determined by mass spectrometry. Mutacin F-59.1 consists of 25 amino acids, containing the YGNGV consensus sequence of pediocin-like bacteriocins with a molecular mass calculated at 2719 Da. Mutacin D-123.1 has an identical molecular mass (2364 Da) with the same first 9 amino acids as mutacin I. Mutacins D-123.1 and F-59.1 have wide activity spectra inhibiting human and food-borne pathogens. The lantibiotic mutacin D-123.1 possesses a broader activity spectrum than mutacin F-59.1 against the bacterial strains tested. Conclusion Mutacin F-59.1 is the first pediocin-like bacteriocin identified and characterised that is produced by Streptococcus mutans. Mutacin D-123.1 appears to be identical to mutacin I previously identified in different strains of S. mutans. PMID:21477375

Production, purification, sequencing and activity spectra of mutacins D-123.1 and F-59.1.

PubMed

Nicolas, Guillaume G; LaPointe, Gisèle; Lavoie, Marc C

2011-04-10

The increase in bacterial resistance to antibiotics impels the development of new anti-bacterial substances. Mutacins (bacteriocins) are small antibacterial peptides produced by Streptococcus mutans showing activity against bacterial pathogens. The objective of the study was to produce and characterise additional mutacins in order to find new useful antibacterial substances. Mutacin F-59.1 was produced in liquid media by S. mutans 59.1 while production of mutacin D-123.1 by S. mutans 123.1 was obtained in semi-solid media. Mutacins were purified by hydrophobic chromatography. The amino acid sequences of the mutacins were obtained by Edman degradation and their molecular mass was determined by mass spectrometry. Mutacin F-59.1 consists of 25 amino acids, containing the YGNGV consensus sequence of pediocin-like bacteriocins with a molecular mass calculated at 2719 Da. Mutacin D-123.1 has an identical molecular mass (2364 Da) with the same first 9 amino acids as mutacin I. Mutacins D-123.1 and F-59.1 have wide activity spectra inhibiting human and food-borne pathogens. The lantibiotic mutacin D-123.1 possesses a broader activity spectrum than mutacin F-59.1 against the bacterial strains tested. Mutacin F-59.1 is the first pediocin-like bacteriocin identified and characterised that is produced by Streptococcus mutans. Mutacin D-123.1 appears to be identical to mutacin I previously identified in different strains of S. mutans.

Antibacterial and anti-inflammatory activity of a temporin B peptide analogue on an in vitro model of cystic fibrosis.

PubMed

Bezzerri, Valentino; Avitabile, Concetta; Dechecchi, Maria Cristina; Lampronti, Ilaria; Borgatti, Monica; Montagner, Giulia; Cabrini, Giulio; Gambari, Roberto; Romanelli, Alessandra

2014-10-01

Natural peptides with antimicrobial properties are deeply investigated as tools to fight bacteria resistant to common antibiotics. Small peptides, as those belonging to the temporin family, are very attractive because their activity can easily be tuned after small modification to their primary sequence. Structure-activity studies previously reported by us allowed the identification of one peptide, analogue of temporin B, TB_KKG6A, showing, unlike temporin B, antimicrobial activity against both Gram-positive and Gram-negative bacteria. In this paper, we investigated the antimicrobial and anti-inflammatory activity of the peptide TB_KKG6A against Pseudomonas aeruginosa. Interestingly, we found that the peptide exhibits antimicrobial activity at low concentrations, being able to downregulate the pro-inflammatory chemokines and cytokines interleukin (IL)-8, IL-1β, IL-6 and tumor necrosis factor-α produced downstream infected human bronchial epithelial cells. Experiments were carried out also with temporin B, which was found to show pro-inflammatory activity. Details on the interaction between TB_KKG6A and the P. aeruginosa LPS were obtained by circular dichroism and fluorescence studies. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.

Antibacterial Activity of AI-Hemocidin 2, a Novel N-Terminal Peptide of Hemoglobin Purified from Arca inflata.

PubMed

Li, Chunlei; Zhu, Jianhua; Wang, Yanqing; Chen, Yuyan; Song, Liyan; Zheng, Weiming; Li, Jingjing; Yu, Rongmin

2017-06-29

The continued emergence of antibiotic resistant bacteria in recent years is of great concern. The search for new classes of antibacterial agents has expanded to non-traditional sources such as shellfish. An antibacterial subunit of hemoglobin (Hb-I) was purified from the mantle of Arca inflata by phosphate extraction and ion exchange chromatography. A novel antibacterial peptide, AI-hemocidin 2, derived from Hb-I, was discovered using bioinformatics analysis. It displayed antibacterial activity across a broad spectrum of microorganisms, including several Gram-positive and Gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 37.5 to 300 μg/mL, and it exhibited minimal hemolytic or cytotoxic activities. The antibacterial activity of AI-hemocidin 2 was thermostable (25-100 °C) and pH resistant (pH 3-10). The cellular integrity was determined by flow cytometry. AI-hemocidin 2 was capable of permeating the cellular membrane. Changes in the cell morphology were observed with a scanning electron microscope. Circular dichroism spectra suggested that AI-hemocidin 2 formed an α-helix structure in the membrane mimetic environment. The results indicated that the anti-bacterial mechanism for AI-hemocidin 2 occurred through disrupting the cell membrane. AI-hemocidin 2 might be a potential candidate for tackling antibiotic resistant bacteria.

Extensive in vivo human milk peptidomics reveals specific proteolysis yielding protective antimicrobial peptides

PubMed Central

Dallas, David C.; Guerrero, Andres; Khaldi, Nora; Castillo, Patricia A.; Martin, William F.; Smilowitz, Jennifer T.; Bevins, Charles L.; Barile, Daniela; German, J. Bruce; Lebrilla, Carlito B.

2013-01-01

Milk is traditionally considered an ideal source of the basic elemental nutrients required by infants. More detailed examination is revealing that milk represents a more functional ensemble of components with benefits to both infants and mothers. A comprehensive peptidomics method was developed and used to analyze human milk yielding an extensive array of protein products present in the fluid. Over 300 milk peptides were identified originating from major and many minor protein components of milk. As expected, the majority of peptides derived from β-casein, however no peptide fragments from the major milk proteins lactoferrin, α-lactalbumin and secretory immunoglobulin A were identified. Proteolysis in the mammary gland is selective—released peptides were drawn only from specific proteins and typically from only select parts of the parent sequence. A large number of the peptides showed significant sequence overlap with peptides with known antimicrobial or immunomodulatory functions. Antibacterial assays showed the milk peptide mixtures inhibited the growth of Escherichia coli and Staphylococcus aureus. The pre-digestion of milk proteins and the consequent release antibacterial peptides may provide a selective advantage through evolution by protecting both the mother's mammary gland and her nursing offspring from infection. PMID:23586814

Periodontal disease in patients from the original Kostmann family with severe congenital neutropenia.

PubMed

Carlsson, Göran; Wahlin, Ylva-Britt; Johansson, Anders; Olsson, Anders; Eriksson, Torbjörn; Claesson, Rolf; Hänström, Lennart; Henter, Jan-Inge

2006-04-01

Patients with Kostmann syndrome (severe congenital neutropenia [SCN]) typically normalize their absolute neutrophil count (ANC) upon granulocyte colony-stimulating factor (G-CSF) therapy. However, although they no longer experience life-threatening bacterial infections, they frequently still have recurrent gingivitis and even severe periodontitis, often starting in early childhood. We studied the periodontal disease in the four surviving patients belonging to the family originally described by Kostmann. Their odontological records, x-rays, color photos, bacterial cultures, serum antibodies to oral bacteria, and histopathological examinations were reviewed. The data were also correlated to previous investigations on their antibacterial peptides and molecular biology. Three patients had periodontal disease, despite normal ANC and professional dental care, and had neutrophils deficient in antibacterial peptides. One of these patients also had a heterozygous mutation in the neutrophil elastase gene, had severe periodontal disease and overgrowth of the periodontal pathogen Actinobacillus actinomycetemcomitans in the dental flora, and 15 permanent teeth had been extracted by the age of 27. One bone marrow-transplanted patient had no periodontal disease. Normalized ANC levels are not sufficient to maintain normal oral health in SCN patients, and because neutrophils are important for first-line defense and innate immunity, the deficiency of the antibacterial peptide LL-37 probably explains their chronic periodontal disease. Professional dental care is still important for SCN patients, despite treatment with G-CSF and normal ANC levels. Whether antibacterial peptides play a role in the pathogenesis of periodontitis in other patients remains to be elucidated.

Novel chimeric peptide with enhanced cell specificity and anti-inflammatory activity.

PubMed

Kim, Young-Min; Kim, Nam-Hong; Lee, Jong-Wan; Jang, Jin-Sun; Park, Yung-Hoon; Park, Seong-Cheol; Jang, Mi-Kyeong

2015-07-31

An antimicrobial peptide (AMP), Hn-Mc, was designed by combining the N-terminus of HPA3NT3 and the C-terminus of melittin. This chimeric AMP exhibited potent antibacterial activity with low minimal inhibitory concentrations (MICs), ranging from 1 to 2 μM against four drug-susceptible bacteria and ten drug-resistant bacteria. Moreover, the hemolysis and cytotoxicity was reduced significantly compared to those of the parent peptides, highlighting its high cell selectivity. The morphological changes in the giant unilamellar vesicles and bacterial cell surfaces caused by the Hn-Mc peptide suggested that it killed the microbial cells by damaging the membrane envelope. An in vivo study also demonstrated the antibacterial activity of the Hn-Mc peptide in a mouse model infected with drug-resistant bacteria. In addition, the chimeric peptide inhibited the expression of lipopolysaccharide (LPS)-induced cytokines in RAW 264.7 cells by preventing the interaction between LPS and Toll-like receptors. These results suggest that this chimeric peptide is an antimicrobial and anti-inflammatory candidate as a pharmaceutic agent. Copyright © 2015 Elsevier Inc. All rights reserved.

The fabrication and in vitro properties of antibacterial polydopamine-LL-37-POPC coatings on micro-arc oxidized titanium.

PubMed

He, Ye; Zhang, Yangyang; Shen, Xinkun; Tao, Bailong; Liu, Ju; Yuan, Zhang; Cai, Kaiyong

2018-05-31

Bacterial infection commonly occurs in clinical settings when the procedure involves a medical implant. Thus, the fabrication of antimicrobial medical materials has attracted much attention in recent years. To improve the antibacterial properties of titanium (Ti)-based biomedical materials, surface microporous structures, with antimicrobial peptide coatings, were employed in this study. Native Ti substrates were endowed with a certain level of antibacterial activity after treatment with the micro-arc oxidation (MAO). A multilayer consisting of polydopamine, cationic antimicrobial peptides LL-37, and phospholipid (POPC) was coated onto MAO substrates, leading to antibacterial activity against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. The combination of polydopamine-LL-37-POPC was found to alleviate the burst release of LL-37 in the initial phase. This multilayer coated onto microporous Ti substrates also showed favorable cytocompatibility to both mesenchymal stem cells (MSCs) and osteoblasts. These findings illustrate a novel strategy for the development of antibacterial Ti-based implants. Copyright © 2018 Elsevier B.V. All rights reserved.

Antibacterial activity in bovine lactoferrin-derived peptides.

PubMed Central

Hoek, K S; Milne, J M; Grieve, P A; Dionysius, D A; Smith, R

1997-01-01

Several peptides sharing high sequence homology with lactoferricin B (Lf-cin B) were generated from bovine lactoferrin (Lf) with recombinant chymosin. Two peptides were copurified, one identical to Lf-cin B and another differing from Lf-cin B by the inclusion of a C-terminal alanine (lactoferricin). Two other peptides were copurified from chymosin-hydrolyzed Lf, one differing from Lf-cin B by the inclusion of C-terminal alanyl-leucine and the other being a heterodimer linked by a disulfide bond. These peptides were isolated in a single step from chymosin-hydrolyzed Lf by membrane ion-exchange chromatography and were purified by reverse-phase high-pressure liquid chromatography (HPLC). They were characterized by N-terminal Edman sequencing, mass spectrometry, and antibacterial activity determination. Pure lactoferricin, prepared from pepsin-hydrolyzed Lf, was purified by standard chromatography techniques. This peptide was analyzed against a number of gram-positive and gram-negative bacteria before and after reduction of its disulfide bond or cleavage after its single methionine residue and was found to inhibit the growth of all the test bacteria at a concentration of 8 microM or less. Subfragments of lactoferricin were isolated from reduced and cleaved peptide by reverse-phase HPLC. Subfragment 1 (residues 1 to 10) was active against most of the test microorganisms at concentrations of 10 to 50 microM. Subfragment 2 (residues 11 to 26) was active against only a few microorganisms at concentrations up to 100 microM. These antibacterial studies indicate that the activity of lactoferricin is mainly, but not wholly, due to its N-terminal region. PMID:8980754

Antibacterial activities of peptides from the water-soluble extracts of Italian cheese varieties.

PubMed

Rizzello, C G; Losito, I; Gobbetti, M; Carbonara, T; De Bari, M D; Zambonin, P G

2005-07-01

Water-soluble extracts of 9 Italian cheese varieties that differed mainly for type of cheese milk, starter, technology, and time of ripening were fractionated by reversed-phase fast protein liquid chromatography, and the antimicrobial activity of each fraction was first assayed toward Lactobacillus sakei A15 by well-diffusion assay. Active fractions were further analyzed by HPLC coupled to electrospray ionization-ion trap mass spectrometry, and peptide sequences were identified by comparison with a proteomic database. Parmigiano Reggiano, Fossa, and Gorgonzola water-soluble extracts did not show antibacterial peptides. Fractions of Pecorino Romano, Canestrato Pugliese, Crescenza, and Caprino del Piemonte contained a mixture of peptides with a high degree of homology. Pasta filata cheeses (Caciocavallo and Mozzarella) also had antibacterial peptides. Peptides showed high levels of homology with N-terminal, C-terminal, or whole fragments of well known antimicrobial or multifunctional peptides reported in the literature: alphaS1-casokinin (e.g., sheep alphaS1-casein (CN) f22-30 of Pecorino Romano and cow alphaS1-CN f24-33 of Canestrato Pugliese); isracidin (e.g., sheep alphaS1-CN f10-21 of Pecorino Romano); kappacin and casoplatelin (e.g., cow kappa-CN f106-115 of Canestrato Pugliese and Crescenza); and beta-casomorphin-11 (e.g., goat beta-CN f60-68 of Caprino del Piemonte). As shown by the broth microdilution technique, most of the water-soluble fractions had a large spectrum of inhibition (minimal inhibitory concentration of 20 to 200 microg/mL) toward gram-positive and gram-negative bacterial species, including potentially pathogenic bacteria of clinical interest. Cheeses manufactured from different types of cheese milk (cow, sheep, and goat) have the potential to generate similar peptides with antimicrobial activity.

Bu-2470, a new peptide antibiotic complex. I. Production, isolation and properties of Bu-2470 A, B1 and B2.

PubMed

Konishi, M; Sugawara, K; Tomita, K; Matsumoto, K; Miyaki, T; Fujisawa, K; Tsukiura, H; Kawaguchi, H

1983-06-01

A strain of Bacillus circulans produced a complex of basic peptide antibiotics designated Bu-2470, which was found to contain four active components, A, B1, B2a and B2b. Bu-2470 A specifically inhibited various Pseudomonas species including P. aeruginosa, P. maltophilia and P. putida, but otherwise its antibacterial spectrum was limited to certain Gram-negative organisms. Bu-2470 B1 and B2 (B2a + B2b) showed broad antibiotic activity against Gram-positive and Gram-negative bacteria including Pseudomonas species. The physicochemical and biological properties of Bu-2470 B1 and B2 are very similar to those of the octapeptin group of antibiotics.

Synthesis and in vitro antibacterial activity of oxazolidine LBM-415 analogs as peptide deformylase inhibitors.

PubMed

Yu, Linliang; Zhou, Weicheng; Wang, Zhenyu

2011-03-01

The drug resistant bacteria pose a severe threat to human health. The increasing resistance of those pathogens to traditional antibacterial therapy renders the identification of new antibacterial agents with novel antibacterial mechanisms an urgent need. In this study, a series of (2S)-N-substituted-1-[(formyhydroxyamino)methyl]-1-oxohexyl]-2-oxazolidinecarboxamides were designed, synthesized and evaluated for in vitro antibacterial activity. Most of these compounds displayed good activities against Gram-positive organisms comparable to reference agent LBM-415. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

The effect of selective D- or N(alpha)-methyl arginine substitution on the activity of the proline-rich antimicrobial peptide, Chex1-Arg20.

NASA Astrophysics Data System (ADS)

Li, Wenyi; Sun, Zhe; O'Brien-Simpson, Neil M.; Otvos, Laszlo; Reynolds, Eric C.; Hossain, Mohammed A.; Separovic, Frances; Wade, John D.

2017-01-01

In vivo pharmacokinetics studies have shown that the proline-rich antimicrobial peptide, A3-APO, which is a discontinuous dimer of the peptide, Chex1-Arg20, undergoes degradation to small fragments at positions Pro6-Arg7 and Val19-Arg20. With the aim of minimizing or abolishing this degradation, a series of Chex1-Arg20 analogues were prepared via Fmoc/tBu solid phase peptide synthesis with D-arginine or, in some cases, peptide backbone N-methylated arginine, substitution at these sites. All the peptides were tested for antibacterial activity against the Gram-negative bacterium Klebsiella pneumoniae. The resulting activity of position-7 substitution of Chex1-Arg20 analogues showed that arginine-7 is a crucial residue for maintaining activity against K. pneumoniae. However, arginine-20 substitution had a much less deleterious effect on the antibacterial activity of the peptide. Moreover, none of these peptides displayed any cytotoxicity to HEK and H-4-II-E mammalian cells. These results will aid the development of more effective and stable PrAMPs via judicious amino acid substitutions.

Heterologous expression of bovine lactoferricin in Pichia methanolica.

PubMed

Wang, Haikuan; Zhao, Xinhuai; Lu, Fuping

2007-06-01

According to the bias of codon utilization of Pichia methanolica, a fragment encoding bovine lactoferricin has been cloned and expressed in the P. methanolica under the control of the alcohol oxidase promoter, which was followed by the Saccharomyces cerevisiae alpha-factor signal peptide. The alpha-factor signal peptide efficiently directed the secretion of bovine lactoferricin from the recombinant yeast cell. The recombinant bovine lactoferricin appears to be successfully expressed, as it displays antibacterial activity (antibacterial assay). Moreover, the identity of the recombinant product was estimated by Tricine-SDS-PAGE.

Antibacterial Activity of AI-Hemocidin 2, a Novel N-Terminal Peptide of Hemoglobin Purified from Arca inflata

PubMed Central

Li, Chunlei; Zhu, Jianhua; Wang, Yanqing; Chen, Yuyan; Song, Liyan; Zheng, Weiming; Li, Jingjing; Yu, Rongmin

2017-01-01

The continued emergence of antibiotic resistant bacteria in recent years is of great concern. The search for new classes of antibacterial agents has expanded to non-traditional sources such as shellfish. An antibacterial subunit of hemoglobin (Hb-I) was purified from the mantle of Arca inflata by phosphate extraction and ion exchange chromatography. A novel antibacterial peptide, AI-hemocidin 2, derived from Hb-I, was discovered using bioinformatics analysis. It displayed antibacterial activity across a broad spectrum of microorganisms, including several Gram-positive and Gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 37.5 to 300 μg/mL, and it exhibited minimal hemolytic or cytotoxic activities. The antibacterial activity of AI-hemocidin 2 was thermostable (25–100 °C) and pH resistant (pH 3–10). The cellular integrity was determined by flow cytometry. AI-hemocidin 2 was capable of permeating the cellular membrane. Changes in the cell morphology were observed with a scanning electron microscope. Circular dichroism spectra suggested that AI-hemocidin 2 formed an α-helix structure in the membrane mimetic environment. The results indicated that the anti-bacterial mechanism for AI-hemocidin 2 occurred through disrupting the cell membrane. AI-hemocidin 2 might be a potential candidate for tackling antibiotic resistant bacteria. PMID:28661457

Antimicrobial peptides of the genus Bacillus: a new era for antibiotics.

PubMed

Sumi, Chandra Datta; Yang, Byung Wook; Yeo, In-Cheol; Hahm, Young Tae

2015-02-01

The rapid onset of resistance reduces the efficacy of most conventional antimicrobial drugs and is a general cause of concern for human well-being. Thus, there is great demand for a continuous supply of novel antibiotics to combat this problem. Bacteria-derived antimicrobial peptides (AMPs) have long been used as food preservatives; moreover, prior to the development of conventional antibiotics, these AMPs served as an efficient source of antibiotics. Recently, peptides produced by members of the genus Bacillus were shown to have a broad spectrum of antimicrobial activity against pathogenic microbes. Bacillus-derived AMPs can be synthesized both ribosomally and nonribosomally and can be classified according to peptide biosynthesis, structure, and molecular weight. The precise mechanism of action of these AMPs is not yet clear; however, one proposed mechanism is that these AMPs kill bacteria by forming channels in and (or) disrupting the bacterial cell wall. Bacillus-derived AMPs have potential in the pharmaceutical industry, as well as the food and agricultural sectors. Here, we focus on Bacillus-derived AMPs as a novel alternative approach to antibacterial drug development. We also provide an overview of the biosynthesis, mechanisms of action, applications, and effectiveness of different AMPs produced by members of the Bacillus genus, including several recently identified novel AMPs.

Surface-independent antibacterial coating using silver nanoparticle-generating engineered mussel glue.

PubMed

Jo, Yun Kee; Seo, Jeong Hyun; Choi, Bong-Hyuk; Kim, Bum Jin; Shin, Hwa Hui; Hwang, Byeong Hee; Cha, Hyung Joon

2014-11-26

During implant surgeries, antibacterial agents are needed to prevent bacterial infections, which can cause the formation of biofilms between implanted materials and tissue. Mussel adhesive proteins (MAPs) derived from marine mussels are bioadhesives that show strong adhesion and coating ability on various surfaces even in wet environment. Here, we proposed a novel surface-independent antibacterial coating strategy based on the fusion of MAP to a silver-binding peptide, which can synthesize silver nanoparticles having broad antibacterial activity. This sticky recombinant fusion protein enabled the efficient coating on target surface and the easy generation of silver nanoparticles on the coated-surface under mild condition. The biosynthesized silver nanoparticles showed excellent antibacterial efficacy against both Gram-positive and Gram-negative bacteria and also revealed good cytocompatibility with mammalian cells. In this coating strategy, MAP-silver binding peptide fusion proteins provide hybrid environment incorporating inorganic silver nanoparticle and simultaneously mediate the interaction of silver nanoparticle with surroundings. Moreover, the silver nanoparticles were fully synthesized on various surfaces including metal, plastic, and glass by a simple, surface-independent coating manner, and they were also successfully synthesized on a nanofiber surface fabricated by electrospinning of the fusion protein. Thus, this facile surface-independent silver nanoparticle-generating antibacterial coating has great potential to be used for the prevention of bacterial infection in diverse biomedical fields.

[Application on food preservative of antimicrobial peptides].

PubMed

Zhao, Hongyan; Mu, Yu; Zhao, Baohua

2009-07-01

Antimicrobial peptides are an integral component of the innate immune system, it can counteract outer membrane pathogen such as bacteria, fungi, viruses, protozoan and so on. Owing to the sterilization and innocuity, it has the potential to be crude food preservative. In this paper the uses of antibacterial peptides in the food preservative were analyzed.

A novel antibacterial peptide derived from Crocodylus siamensis haemoglobin hydrolysate induces membrane permeabilization causing iron dysregulation, oxidative stress and bacterial death.

PubMed

Lueangsakulthai, J; Jangpromma, N; Temsiripong, T; McKendrick, J E; Khunkitti, W; Maddocks, S E; Klaynongsruang, S

2017-10-01

A novel antibacterial peptide from Crocodylus siamensis haemoglobin hydrolysate (CHH) was characterized for antimicrobial activity. CHHs were hydrolysed for 2 h (2 h-CHH), 4 h (4h-CHH), 6 h (6 h-CHH) and 8 h (8 h-CHH). The 8 h-CHH showed antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa at concentrations of 20, 20, 20 and 10 mg ml -1 (w/v) respectively. Fluorescent microscopy revealed that the 8 h-CHH had bactericidal activity against E. coli and P. aeruginosa. β-galactosidase assay supported by RT-qPCR demonstrated that the 8 h-CHH resulted in differential expression of genes involved in iron homeostasis (ftnA and bfd) and oxidative stress (sodA, soxR and oxyR). Siderophore assay indicated that the 8 h-CHH also impaired siderophore production with diminished expression of pvdF. This pattern of gene expression suggests that the 8 h-CHH triggers the release of free ferric ions in the cytoplasm. However, decreased expression of genes associated with the SOS response (recA and lexA) in combination with neutral comet revealed that no DNA damage was caused by 8 h-CHH. Membrane permeabilization assay indicated that 8 h-CHH caused membrane leakage thought to mediate the antibacterial and iron-stress responses observed, due to loss of regulated iron transport. The novel active peptide from 8 h-CHH was determined as QAIIHNEKVQAHGKKVL (QL17), with 41% hydrophobicity and +2 net charge. The QAIIHNEKVQAHGKKVL fragment of C. siamensis haemoglobin is antibacterial via a mechanism that likely relies on iron dysregulation and oxidative stress which results in bacterial death. We have described for the first time, a novel peptide derived from C. siamensis haemoglobin hydrolysate that has the potential to be developed as a novel antimicrobial peptide. © 2017 The Society for Applied Microbiology.

Novel haemoglobin-derived antimicrobial peptides from chicken (Gallus gallus) blood: purification, structural aspects and biological activity.

PubMed

Vasilchenko, A S; Rogozhin, E A; Vasilchenko, A V; Kartashova, O L; Sycheva, M V

2016-12-01

To purify and characterize antimicrobial peptides derived from the acid extract of Gallus gallus blood cells. Two polypeptides (i.e. CHb-1 and CHb-2) with antibacterial activity were detected in the acidic extract of blood cells from chicken (G. gallus). The isolated peptides that possessed a potent antibacterial activity were purified using a two-step chromatography procedure that involved solid-phase extraction of a total protein/peptide extract followed by thin fractionation by reversed-phase high performance liquid chromatography (RP-HPLC). The molecular masses of the purified peptides were similar and were 4824·4 and 4825·2 Da, which have been measured by matrix-assisted laser desorption/ionization mass spectrometry (MALDI TOF MS). Their amino acid sequences were determined by Edman degradation and showed that the peptides were fully identical to the two fragments of G. gallus α-haemoglobin localized into different subunits (A and D respectively). The peptides were active in micromolar concentrations against Gram-negative Escherichia coli K12 TG1. Using the 1-N-phenylnaphthylamine, the FITC-dextran labelled probes and the live/dead staining allowed to show the hemocidin mode of action and estimate the pore size. In this study, for the first time, α-haemoglobin from chicken (G. gallus) has been investigated as a donor of the two high homologous native peptide fragments that possess potent antibacterial activity in vitro. These are membrane-active peptides and their mechanism of action against E. coli involves a toroidal pore formation. The obtained results expand the perception of the role of haemoglobin in a living system, describing it as a source of multifunction substances. Additionally, the data presented in this paper may contribute to the development of new, cost-effective, antimicrobial agents. © 2016 The Society for Applied Microbiology.

Engineered chimeric peptides with antimicrobial and titanium-binding functions to inhibit biofilm formation on Ti implants.

PubMed

Geng, Hongjuan; Yuan, Yang; Adayi, Aidina; Zhang, Xu; Song, Xin; Gong, Lei; Zhang, Xi; Gao, Ping

2018-01-01

Titanium (Ti) implants have been commonly used in oral medicine. However, despite their widespread clinical application, these implants are susceptible to failure induced by microbial infection due to bacterial biofilm formation. Immobilization of chimeric peptides with antibacterial properties on the Ti surface may be a promising antimicrobial approach to inhibit biofilm formation. Here, chimeric peptides were designed by connecting three sequences (hBD-3-1/2/3) derived from human β-defensin-3 (hBD-3) with Ti-binding peptide-l (TBP-l: RKLPDAGPMHTW) via a triple glycine (G) linker to modify Ti surfaces. Using X-ray photoelectron spectroscopy (XPS), the properties of individual domains of the chimeric peptides were evaluated for their binding activity toward the Ti surface. The antimicrobial and anti-biofilm efficacy of the peptides against initial settlers, Streptococcus oralis (S. oralis), Streptococcus gordonii (S. gordonii) and Streptococcus sanguinis (S. sanguinis), was evaluated with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Transmission electron microscopy (TEM) and real-time quantitative PCR (qRT-PCR) were used to study cell membrane changes and the underlying antimicrobial mechanism. Compared with the other two peptides, TBP-1-GGG-hBD3-3 presented stronger antibacterial activity and remained stable in saliva and serum. Therefore, it was chosen as the best candidate to modify Ti surfaces in this study. This peptide inhibited the growth of initial streptococci and biofilm formation on Ti surfaces with no cytotoxicity to MC3T3-E1 cells. Disruption of the integrity of bacterial membranes and decreased expression of adhesion protein genes from S. gordonii revealed aspects of the antibacterial mechanism of TBP-1-GGG-hBD3-3. We conclude that engineered chimeric peptides with antimicrobial activity provide a potential solution for inhibiting biofilm formation on Ti surfaces to reduce or prevent the occurrence of peri-implant diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Antibacterial activity inducible in the haemolymph of the silkworm, Bombyx mori, by injection of formalin-treated Escherichia coli K-12 during the fifth larval instar and pharate adult development.

PubMed

Sumida, M; Ichimori, H; Johchi, S; Takaoka, A; Yuhki, T; Mori, H; Matsubara, F

1992-01-01

1. Antibacterial activity inducible in the haemolymph of the silkworm, Bombyx mori, by immunization, i.e. by injection of formalin-treated Escherichia coli (E. coli) K-12 during the fifth larval instar and pharate adult development that was reared aseptically on an artificial diet was determined by inhibition zone assay using the same bacterium as a test organism. 2. A peak of antibacterial activity was observed in each development stage; approximately 8 mm in diameter of a clear zone at days 3 or 4 in the fifth larval instar and approximately 5 mm at day 1 in the pharate adults. 3. Acid polyacrylamide gel electrophoresis of immunized haemolymph followed by overlay assay showed that an activity band was associated with two peptide bands that were similar to the cecropin-like peptides A and B that were reported in the silkworm (Morishima et al., 1988, Agri. Biol. Chem. 52, 929-934). Any other activity bands were not observed. No activity band was detectable from the haemolymph of non-immunized insects. 4. Fractionation of antibacterial peptides in immunized haemolymph on a CM-cellulose column resulted in separation of two groups of activity, both in the fifth instar larvae and in the pharate adults with a slight difference in elution conditions. 5. Duration of high antibacterial activity induced by a single immunization was approximately 12 hr in the fifth instar day 3 larvae and 48 hr in the day 2 pharate adults.

Production of Bioactive Secondary Metabolites by Marine Vibrionaceae

PubMed Central

Mansson, Maria; Gram, Lone; Larsen, Thomas O.

2011-01-01

Bacteria belonging to the Vibrionaceae family are widespread in the marine environment. Today, 128 species of vibrios are known. Several of them are infamous for their pathogenicity or symbiotic relationships. Despite their ability to interact with eukaryotes, the vibrios are greatly underexplored for their ability to produce bioactive secondary metabolites and studies have been limited to only a few species. Most of the compounds isolated from vibrios so far are non-ribosomal peptides or hybrids thereof, with examples of N-containing compounds produced independent of nonribosomal peptide synthetases (NRPS). Though covering a limited chemical space, vibrios produce compounds with attractive biological activities, including antibacterial, anticancer, and antivirulence activities. This review highlights some of the most interesting structures from this group of bacteria. Many compounds found in vibrios have also been isolated from other distantly related bacteria. This cosmopolitan occurrence of metabolites indicates a high incidence of horizontal gene transfer, which raises interesting questions concerning the ecological function of some of these molecules. This account underlines the pending potential for exploring new bacterial sources of bioactive compounds and the challenges related to their investigation. PMID:22131950

The functional interaction between abaecin and pore-forming peptides indicates a general mechanism of antibacterial potentiation.

PubMed

Rahnamaeian, Mohammad; Cytryńska, Małgorzata; Zdybicka-Barabas, Agnieszka; Vilcinskas, Andreas

2016-04-01

Long-chain proline-rich antimicrobial peptides such as bumblebee abaecin show minimal activity against Gram-negative bacteria despite binding efficiently to specific intracellular targets. We recently reported that bumblebee abaecin interacts with Escherichia coli DnaK but shows negligible antibacterial activity unless it is combined with sublethal doses of the pore-forming peptide hymenoptaecin. These two bumblebee peptides are co-expressed in vivo in response to a bacterial challenge. Here we investigated whether abaecin interacts similarly with pore-forming peptides from other organisms by replacing hymenoptaecin with sublethal concentrations of cecropin A (0.3 μM) or stomoxyn (0.05 μM). We found that abaecin increased the membrane permeabilization effects of both peptides, confirming that it can reduce the minimal inhibitory concentrations of pore-forming peptides from other species. We also used atomic force microscopy to show that 20 μM abaecin combined with sublethal concentrations of cecropin A or stomoxyn causes profound structural changes to the bacterial cell surface. Our data indicate that the potentiating functional interaction between abaecin and pore-forming peptides is not restricted to specific co-expressed peptides from the same species but is likely to be a general mechanism. Combination therapies based on diverse insect-derived peptides could therefore be used to tackle bacteria that are recalcitrant to current antibiotics. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Valorization of cruor slaughterhouse by-product by enzymatic hydrolysis for the production of antibacterial peptides: focus on α 1-32 family peptides mechanism and kinetics modeling.

PubMed

Hedhili, K; Dimitrov, K; Vauchel, P; Sila, A; Chataigné, G; Dhulster, P; Nedjar, N

2015-10-01

Bovine hemoglobin is the major component of the cruor (slaughterhouse by-product) and can be considered as an important source of active peptides that could be obtained by pepsic hydrolysis. The kinetics of appearance and disappearance of several antibacterial peptides from α 1-32 family during hydrolysis of synthesized α 1-32 peptide, of purified bovine hemoglobin and of cruor was studied, and reaction scheme for the hydrolysis of α 1-32 family peptides from these three sources was determined. On this basis, a mathematical model was proposed to predict the concentration of each peptide of interest of this family depending on hydrolysis time, and also on temperature (in the range 15-37 °C), pH (in the range 3.5-5.5) and enzyme to substrate ratio (in the range 1/50-1/200 for the synthesized peptide and 1/5-1/20 for purified bovine hemoglobin and cruor). Apparent rate constants of reactions were determined by applying the model on a set of experimental data and it was shown that they depended on the temperature according to Arrhenius's law, that their dependence on the pH was linear, and that enzyme to substrate ratio influence was limited (in the studied range).

Biological effects of paenilamicin, a secondary metabolite antibiotic produced by the honey bee pathogenic bacterium Paenibacillus larvae.

PubMed

Garcia-Gonzalez, Eva; Müller, Sebastian; Hertlein, Gillian; Heid, Nina; Süssmuth, Roderich D; Genersch, Elke

2014-10-01

Paenibacillus larvae is the etiological agent of American Foulbrood (AFB) a world-wide distributed devastating disease of the honey bee brood. Previous comparative genome analysis and more recently, the elucidation of the bacterial genome, provided evidence that this bacterium harbors putative functional nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) and therefore, might produce nonribosomal peptides (NRPs) and polyketides (PKs). Such biosynthesis products have been shown to display a wide-range of biological activities such as antibacterial, antifungal or cytotoxic activity. Herein we present an in silico analysis of the first NRPS/PKS hybrid of P. larvae and we show the involvement of this cluster in the production of a compound named paenilamicin (Pam). For the characterization of its in vitro and in vivo bioactivity, a knock-out mutant strain lacking the production of Pam was constructed and subsequently compared to wild-type species. This led to the identification of Pam by mass spectrometry. Purified Pam-fractions showed not only antibacterial but also antifungal and cytotoxic activities. The latter suggested a direct effect of Pam on honey bee larval death which could, however, not be corroborated in laboratory infection assays. Bee larvae infected with the non-producing Pam strain showed no decrease in larval mortality, but a delay in the onset of larval death. We propose that Pam, although not essential for larval mortality, is a virulence factor of P. larvae influencing the time course of disease. These findings are not only of significance in elucidating and understanding host-pathogen interactions but also within the context of the quest for new compounds with antibiotic activity for drug development. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Purification and antibacterial activity of recombinant warnericin RK expressed in Escherichia coli.

PubMed

Verdon, Julien; Girardin, Nicolas; Marchand, Adrienne; Héchard, Yann; Berjeaud, Jean-Marc

2013-06-01

Warnericin RK is a small cationic peptide produced by Staphylococcus warneri RK. This peptide has an antimicrobial spectrum of activity almost restricted to the Legionella genus. It is a membrane-active peptide with a proposed detergent-like mechanism of action at high concentration. Moreover, the fatty acids content of Legionella was shown to modulate the peptide activity. In order to decipher the mode of action in details using solid-state NMR spectroscopy, large amount of an isotopic labeled peptide is required. Since it is less expensive to obtain such a peptide biologically, we report here methods to express warnericin RK in Escherichia coli with or without a fusion partner and to purify resulting recombinant peptides. The cDNA fragment encoding warnericin RK was synthesized and ligated into three expression vectors. Two fusion peptides, carrying polyhistidine tag in N- or C-terminal and a native peptide, without tag, were expressed in E. coli cells. Fusion peptides were purified, with a yield of 3 mg/l, by affinity chromatography and reverse-phase HPLC. The recombinant native peptide was purified using a two-step purification method consisting of a hydrophobic chromatography followed by a reverse-phase HPLC step with a yield of 1.4 mg/l. However, the anti-Legionella activity was lower for both tagged peptide probably because of structural modifications. So, the native recombinant peptide was preferentially chosen for (15)N-labeling experiments. Our results suggest that the developed production and purification procedures will be useful in obtaining a large quantity of recombinant isotope-labeled warnericin RK for further studies.

Bioactive Secondary Metabolites from a Thai Collection of Soil and Marine-Derived Fungi of the Genera Neosartorya and Aspergillus.

PubMed

Zin, War War May; Prompanya, Chadaporn; Buttachon, Suradet; Kijjoa, Anake

2016-01-01

Fungi are microorganisms which can produce interesting secondary metabolites with structural diversity. Although terrestrial fungi have been extensively investigated for their bioactive secondary metabolites such as antibiotics, marine-derived fungi have only recently attracted attention of Natural Products chemists. Our group has been working on the secondary metabolites produced by the cultures of the fungi of the genera Neosartorya and Aspergillus, collected from soil and marine environments from the tropical region for the purpose of finding new leads for anticancer and antibacterial drugs. This review covers only the secondary metabolites of four soil and six marine-derived species of Neosarorya as well as a new species of marine-derived Aspergillus, investigated by our group. In total, we have isolated fifty three secondary metabolites which can be categorized as polyketides (two), isocoumarins (six), terpenoids (two), meroterpenes (fourteen), alkaloids (twenty eight) and cyclic peptide (one). The anticancer and antibacterial activities of these fungal metabolites are also discussed. Among fifty three secondary metabolites isolated, only the alkaloid eurochevalierine and the cadinene sesquiterpene, isolated from the soil fungus N. pseudofisheri, showed relevant in vitro cytostatic activity against glioblastoma (U373) and non-small cell lung cancer (A549) cell lines while the meroditerpene aszonapyrone A exhibited strong antibacterial activity against multidrug-resistant Gram-positive bacteria and also strong antibiofilm activity in these isolates.

Angiotensin I-converting-enzyme-inhibitory and antibacterial peptides from Lactobacillus helveticus PR4 proteinase-hydrolyzed caseins of milk from six species.

PubMed

Minervini, F; Algaron, F; Rizzello, C G; Fox, P F; Monnet, V; Gobbetti, M

2003-09-01

Sodium caseinates prepared from bovine, sheep, goat, pig, buffalo or human milk were hydrolyzed by a partially purified proteinase of Lactobacillus helveticus PR4. Peptides in each hydrolysate were fractionated by reversed-phase fast-protein liquid chromatography. The fractions which showed the highest angiotensin I-converting-enzyme (ACE)-inhibitory or antibacterial activity were sequenced by mass spectrum and Edman degradation analyses. Various ACE-inhibitory peptides were found in the hydrolysates: the bovine alpha(S1)-casein (alpha(S1)-CN) 24-47 fragment (f24-47), f169-193, and beta-CN f58-76; ovine alpha(S1)-CN f1-6 and alpha(S2)-CN f182-185 and f186-188; caprine beta-CN f58-65 and alpha(S2)-CN f182-187; buffalo beta-CN f58-66; and a mixture of three tripeptides originating from human beta-CN. A mixture of peptides with a C-terminal sequence, Pro-Gly-Pro, was found in the most active fraction of the pig sodium caseinate hydrolysate. The highest ACE-inhibitory activity of some peptides corresponded to the concentration of the ACE inhibitor (S)-N-(1-[ethoxycarbonyl]-3-phenylpropyl)-ala-pro maleate (enalapril) of 49.253 micro g/ml (100 micro mol/liter). Several of the above sequences had features in common with other ACE-inhibitory peptides reported in the literature. The 50% inhibitory concentration (IC(50)) of some of the crude peptide fractions was very low (16 to 100 micro g/ml). Some identified peptides were chemically synthesized, and the ACE-inhibitory activity and IC(50)s were confirmed. An antibacterial peptide corresponding to beta-CN f184-210 was identified in human sodium caseinate hydrolysate. It showed a very large spectrum of inhibition against gram-positive and -negative bacteria, including species of potential clinical interest, such as Enterococcus faecium, Bacillus megaterium, Escherichia coli, Listeria innocua, Salmonella spp., Yersinia enterocolitica, and Staphylococcus aureus. The MIC for E. coli F19 was ca. 50 micro g/ml. Once generated, the bioactive peptides were resistant to further degradation by proteinase of L. helveticus PR4 or by trypsin and chymotrypsin.

Antimicrobial Peptides as Potential Alternatives to Antibiotics in Food Animal Industry.

PubMed

Wang, Shuai; Zeng, Xiangfang; Yang, Qing; Qiao, Shiyan

2016-05-03

Over the last decade, the rapid emergence of multidrug-resistant pathogens has become a global concern, which has prompted the search for alternative antibacterial agents for use in food animals. Antimicrobial peptides (AMPs), produced by bacteria, insects, amphibians and mammals, as well as by chemical synthesis, are possible candidates for the design of new antimicrobial agents because of their natural antimicrobial properties and a low propensity for development of resistance by microorganisms. This manuscript reviews the current knowledge of the basic biology of AMPs and their applications in non-ruminant nutrition. Antimicrobial peptides not only have broad-spectrum activity against bacteria, fungi, and viruses but also have the ability to bypass the common resistance mechanisms that are placing standard antibiotics in jeopardy. In addition, AMPs have beneficial effects on growth performance, nutrient digestibility, intestinal morphology and gut microbiota in pigs and broilers. Therefore, AMPs have good potential as suitable alternatives to conventional antibiotics used in swine and poultry industries.

Antimicrobial Peptides Derived from Fusion Peptides of Influenza A Viruses, a Promising Approach to Designing Potent Antimicrobial Agents.

PubMed

Wang, Jingyu; Zhong, Wenjing; Lin, Dongguo; Xia, Fan; Wu, Wenjiao; Zhang, Heyuan; Lv, Lin; Liu, Shuwen; He, Jian

2015-10-01

The emergence and dissemination of antibiotic-resistant bacterial pathogens have spurred the urgent need to develop novel antimicrobial agents with different mode of action. In this respect, we turned several fusogenic peptides (FPs) derived from the hemagglutinin glycoproteins (HAs) of IAV into potent antibacterials by replacing the negatively or neutrally charged residues of FPs with positively charged lysines. Their antibacterial activities were evaluated by testing the MICs against a panel of bacterial strains including S. aureus, S. mutans, P. aeruginosa, and E. coli. The results showed that peptides HA-FP-1, HA-FP-2-1, and HA-FP-3-1 were effective against both Gram-positive and Gram-negative bacteria with MICs ranging from 1.9 to 16.0 μm, while the toxicities toward mammalian cells were low. In addition, the mode of action and the secondary structure of these peptides were also discussed. These data not only provide several potent peptides displaying promising potential in development as broad antimicrobial agents, but also present a useful strategy in designing new antimicrobial agents. © 2015 John Wiley & Sons A/S.

Cytocompatibility, antibacterial activity and biodegradability of self-assembling beta-hairpin peptide-based hydrogels for tissue regenerative applications

NASA Astrophysics Data System (ADS)

Salick, Daphne Ann

Every year, millions of people suffer from tissue loss or failure. One approach to repair damaged or diseased tissue is through tissue/organ transplantation. However, one of the major problems which exist with this approach is that there are more people in need of a transplant than there are donors. Over the past several decades, scientists and doctors have come together to find a way to overcome this challenge. This collaboration has led to the development of biomimetic scaffolds, which closely mimic the desired tissue of interest to act as a substitute for the unfunctional tissue, with hopes to improve the quality of life. The Schneider and Pochan labs have developed a biomimetic scaffold using self-assembling beta-hairpin peptides. The self-assembly event can be triggered in response to physiological conditions, which is dictated by the monomer, to form non covalently crosslinked mechanically rigid hydrogels. In vitro studies showed that hydrogels were cytocompatible and may not elicit a pro-inflammatory response from murine macrophages. These material properties show promise for the use of these hydrogels in tissue engineering. When implanting a material into a host, a major concern is the introduction of infection. Infection, if not prevented or halted, results in poor tissue integration and function, ultimately leading to implant removal from the host. Interestingly, the beta-hairpin hydrogels were shown to exhibit antibacterial properties against pathogens commonly found in hospital environments. This inherently antibacterial hydrogel is advantageous because it may help decrease or diminish bacterial contamination when implanted in vivo, which may help to increase the success of implants. Also, a unique and exciting feature of these peptide-based hydrogels is their ability to shear-thin and self-heal. Hydrogels can be directly formed in a syringe and be subsequently delivered to a tissue defect in a minimally invasive manner where they will recover to their original mechanical rigidity. The resultant syringe-delivered gel was also shown to possess antibacterial properties. Aside from the material's inherent antibacterial activity, these peptide-based scaffolds display degradation that can be controlled using an exogenously added enzyme. This suggests that by using peptide design, the gel network degradation can be controlled to allow for the proper formation of functional tissue. The work described in this thesis shows these described attributes, as well as, the potential of these peptide-based gels for use as tissue substitutes.

Nanobiostructure of fibrous-like alumina functionalized with an analog of the BP100 peptide: Synthesis, characterization and biological applications.

PubMed

Torres, L M F C; Braga, N A; Gomes, I P; Almeida, M T; Santos, T L; de Mesquita, J P; da Silva, L M; Martins, H R; Kato, K C; Dos Santos, W T P; Resende, J M; Pereira, M C; Bemquerer, M P; Rodrigues, M A; Verly, R M

2018-03-01

The functionalization of alumina nanoparticles of specific morphology with antimicrobial peptides (AMP) can be a promising strategy for modeling medical devices and packaging materials for cosmetics, medicines or food, since the contamination by pathogens could be reduced. In this paper, we show the synthesis of a fibrous-like alumina nanobiostructure, as well as its functionalization with the peptide EAAA-BP100, an analog of the antimicrobial peptide BP100. The antibacterial activity of the obtained material against some bacterial strains is also investigated. The covalent binding of the peptide to the nanoparticles was promoted by a reaction between the carboxyl group of the glutamate side chain (E1) of the peptide and the amino groups of the alumina nanoparticles, previously modified by reaction with 3-aminopropyltrietoxysilane (APTES). The functionalized nanoparticles were characterized by zeta potential measurements, Fourier transform infrared spectroscopy, and other physicochemical techniques. Although the obtained alumina nanobiostructure shows a relatively low degree of substitution with EAAA-BP100, antibacterial activities against Escherichia coli and Salmonella typhimurium strains are appreciably higher than the activities of the free peptide. The obtained results can affect the design of new hybrid nanobiomaterials based on nanoparticles functionalized with AMP. Copyright © 2018. Published by Elsevier B.V.

Expression, purification, and antibacterial activity of bovine lactoferrampin-lactoferricin in Pichia pastoris.

PubMed

Tang, Xiang-Shan; Tang, Zhi-Ru; Wang, Sheng-Ping; Feng, Ze-Meng; Zhou, Dong; Li, Tie-Jun; Yin, Yu-Long

2012-02-01

Bovine lactoferrampin (LFA) and bovine lactoferricin (LFC) are two antimicrobial peptides located in the N(1) domain of bovine lactoferrin. The bactericidal activity of the fused peptide LFA-LFC is stronger than that of either LFA or LFC. The high cost of peptide production from either native digestion or chemical synthesis limits the clinical application of antimicrobial peptides. The expression of recombinant peptides in yeast may be an effective alternative. In the current study, the expression, purification, and antibacterial activity of LFA-LFC using the Pichia pastoris expression system are reported. The linearized expression vector pPICZaA-LFA-LFC was transformed into P. pastoris KM71 by electroporation, and positive colonies harboring the target genes were screened out and used for fermentation. The recombinant LFA-LFC peptide was purified via two-step column chromatography and identified by tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results indicate that P. pastoris is a suitable system for secreting LFA-LFC. The fermentation supernate and the purified LFA-LFC show high antimicrobial activities. The current study is the first to report on the expression and purification of LFA-LFC in P. pastoris and may have potential practical applications in microbial peptide production.

Expression in Escherichia coli and purification of bioactive antibacterial peptide ABP-CM4 from the Chinese silk worm, Bombyx mori.

PubMed

Li, Bao-Cun; Zhang, Shuang-Quan; Dan, Wen-Bing; Chen, Yu-Qing; Cao, Peng

2007-07-01

The antibacterial peptide CM4 (ABP-CM4), isolated from Chinese Bombys mori, is a 35-residue cationic, amphipathic alpha-helical peptide that exhibits a broad range of antimicrobial activity. To explore a new approach for the expression of ABP-CM4 in E. coli, the gene ABP-CM4, obtained by recursive PCR (rPCR), was cloned into the vector pET32a to construct a fusion expression plasmid. The fusion protein Trx-CM4 was expressed in soluble form, purified by Ni(2+)-chelating chromatography, and cleaved by formic acid to release recombinant CM4. Purification of rCM4 was achieved by affinity chromatography and reverse-phase HPLC. The purified of recombinant peptide showed antimicrobial activities against E. coli K(12)D(31), Penicillium chrysogenum, Aspergillus niger and Gibberella saubinetii. According to the antimicrobial peptide database (http://aps.unmc.edu/AP/main.html), 116 peptides contain a Met residue, but only 5 peptides contain the AspPro site, indicating a broader application of formic acid than CNBr in cleaving fusion protein. The successful application to the expression of the ABP-CM4 indicates that the system is a low-cost, efficient way of producting milligram quantities of ABP-CM4 that is biologically active.

Effect of Antimicrobial Peptide KSL-W on Human Gingival Tissue and C. albicans Growth, Transition and Secreted Aspartyl Proteinase (SAPS) 2, 4, 5 and 6 Expressions

DTIC Science & Technology

2016-07-01

broad range of antibacterial activity and could play a role in preventing microbial infections(Decanis et al., 2009), (Zaslof, 2002). These antimicrobial...range of antibacterial activity and could play a role in preventing microbial infections(Decanis et al., 2009),(Zaslof, 2002). These antimicrobial...KSL- W (KKVVFWVKFK)(Na et al., 2007), which possess a broad range of antibacterial activity . It killed selected strains of non-oral and oral

Novel Group of Leaderless Multipeptide Bacteriocins from Gram-Positive Bacteria.

PubMed

Ovchinnikov, Kirill V; Chi, Hai; Mehmeti, Ibrahim; Holo, Helge; Nes, Ingolf F; Diep, Dzung B

2016-09-01

From raw milk we found 10 Lactococcus garvieae isolates that produce a new broad-spectrum bacteriocin. Though the isolates were obtained from different farms, they turned out to possess identical inhibitory spectra, fermentation profiles of sugars, and repetitive sequence-based PCR (rep-PCR) DNA patterns, indicating that they produce the same bacteriocin. One of the isolates (L. garvieae KS1546) was chosen for further assessment. Purification and peptide sequencing combined with genome sequencing revealed that the antimicrobial activity was due to a bacteriocin unit composed of three similar peptides of 32 to 34 amino acids. The three peptides are produced without leader sequences, and their genes are located next to each other in an operon-like structure, adjacent to the genes normally involved in bacteriocin transport (ABC transporter) and self-immunity. The bacteriocin, termed garvicin KS (GarKS), showed sequence homology to four multipeptide bacteriocins in databases: the known staphylococcal aureocin A70, consisting of four peptides, and three unannotated putative multipeptide bacteriocins produced by Bacillus cereus All these multipeptide bacteriocin loci show conserved genetic organization, including being located adjacent to conserved genetic determinants (Cro/cI and integrase) which are normally associated with mobile genetic elements or genome rearrangements. The antimicrobial activity of all multipeptide bacteriocins was confirmed with synthetic peptides, and all were shown to have broad antimicrobial spectra, with GarKS being the most active of them. The inhibitory spectrum of GarKS includes important pathogens belonging to the genera Staphylococcus, Bacillus, Listeria, and Enterococcus Bacterial resistance to antibiotics is a very serious global problem. There are no new antibiotics with novel antimicrobial mechanisms in clinical trials. Bacteriocins use antimicrobial mechanisms different from those of antibiotics and can kill antibiotic-resistant bacteria, but the number of bacteriocins with very broad antimicrobial spectra is very small. In this study, we have found and purified a novel three-peptide bacteriocin, garvicin KS. By homology search, we were able to find one known and three novel sequence-related bacteriocins consisting of 3 or 4 peptides. None of the peptides has modified amino acids in its sequence. Thus, the activity of all bacteriocins was confirmed with chemically synthesized peptides. All of them, especially garvicin KS, have very broad antibacterial spectra, thus representing a great potential in antimicrobial applications in the food industry and medicine. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Novel Group of Leaderless Multipeptide Bacteriocins from Gram-Positive Bacteria

PubMed Central

Chi, Hai; Mehmeti, Ibrahim; Holo, Helge; Nes, Ingolf F.

2016-01-01

ABSTRACT From raw milk we found 10 Lactococcus garvieae isolates that produce a new broad-spectrum bacteriocin. Though the isolates were obtained from different farms, they turned out to possess identical inhibitory spectra, fermentation profiles of sugars, and repetitive sequence-based PCR (rep-PCR) DNA patterns, indicating that they produce the same bacteriocin. One of the isolates (L. garvieae KS1546) was chosen for further assessment. Purification and peptide sequencing combined with genome sequencing revealed that the antimicrobial activity was due to a bacteriocin unit composed of three similar peptides of 32 to 34 amino acids. The three peptides are produced without leader sequences, and their genes are located next to each other in an operon-like structure, adjacent to the genes normally involved in bacteriocin transport (ABC transporter) and self-immunity. The bacteriocin, termed garvicin KS (GarKS), showed sequence homology to four multipeptide bacteriocins in databases: the known staphylococcal aureocin A70, consisting of four peptides, and three unannotated putative multipeptide bacteriocins produced by Bacillus cereus. All these multipeptide bacteriocin loci show conserved genetic organization, including being located adjacent to conserved genetic determinants (Cro/cI and integrase) which are normally associated with mobile genetic elements or genome rearrangements. The antimicrobial activity of all multipeptide bacteriocins was confirmed with synthetic peptides, and all were shown to have broad antimicrobial spectra, with GarKS being the most active of them. The inhibitory spectrum of GarKS includes important pathogens belonging to the genera Staphylococcus, Bacillus, Listeria, and Enterococcus. IMPORTANCE Bacterial resistance to antibiotics is a very serious global problem. There are no new antibiotics with novel antimicrobial mechanisms in clinical trials. Bacteriocins use antimicrobial mechanisms different from those of antibiotics and can kill antibiotic-resistant bacteria, but the number of bacteriocins with very broad antimicrobial spectra is very small. In this study, we have found and purified a novel three-peptide bacteriocin, garvicin KS. By homology search, we were able to find one known and three novel sequence-related bacteriocins consisting of 3 or 4 peptides. None of the peptides has modified amino acids in its sequence. Thus, the activity of all bacteriocins was confirmed with chemically synthesized peptides. All of them, especially garvicin KS, have very broad antibacterial spectra, thus representing a great potential in antimicrobial applications in the food industry and medicine. PMID:27316965

Antimicrobial peptides expressed in medicinal maggots of the blow fly Lucilia sericata show combinatorial activity against bacteria.

PubMed

Pöppel, Anne-Kathrin; Vogel, Heiko; Wiesner, Jochen; Vilcinskas, Andreas

2015-05-01

The larvae of the common green bottle fly (Lucilia sericata) produce antibacterial secretions that have a therapeutic effect on chronic and nonhealing wounds. Recent developments in insect biotechnology have made it possible to use these larvae as a source of novel anti-infectives. Here, we report the application of next-generation RNA sequencing (RNA-Seq) to characterize the transcriptomes of the larval glands, crop, and gut, which contribute to the synthesis of antimicrobial peptides (AMPs) and proteins secreted into wounds. Our data confirm that L. sericata larvae have adapted in order to colonize microbially contaminated habitats, such as carrion and necrotic wounds, and are protected against infection by a diverse spectrum of AMPs. L. sericata AMPs include not only lucifensin and lucimycin but also novel attacins, cecropins, diptericins, proline-rich peptides, and sarcotoxins. We identified 47 genes encoding putative AMPs and produced 23 as synthetic analogs, among which some displayed activities against a broad spectrum of microbial pathogens, including Pseudomonas aeruginosa, Proteus vulgaris, and Enterococcus faecalis. Against Escherichia coli (Gram negative) and Micrococcus luteus (Gram positive), we found mostly additive effects but also synergistic activity when selected AMPs were tested in combination. The AMPs that are easy to synthesize are currently being produced in bulk to allow their evaluation as novel anti-infectives that can be formulated in hydrogels to produce therapeutic wound dressings and adhesive bandages. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Virtual Screening of Peptide and Peptidomimetic Fragments Targeted to Inhibit Bacterial Dithiol Oxidase DsbA.

PubMed

Duprez, Wilko; Bachu, Prabhakar; Stoermer, Martin J; Tay, Stephanie; McMahon, Róisín M; Fairlie, David P; Martin, Jennifer L

2015-01-01

Antibacterial drugs with novel scaffolds and new mechanisms of action are desperately needed to address the growing problem of antibiotic resistance. The periplasmic oxidative folding system in Gram-negative bacteria represents a possible target for anti-virulence antibacterials. By targeting virulence rather than viability, development of resistance and side effects (through killing host native microbiota) might be minimized. Here, we undertook the design of peptidomimetic inhibitors targeting the interaction between the two key enzymes of oxidative folding, DsbA and DsbB, with the ultimate goal of preventing virulence factor assembly. Structures of DsbB--or peptides--complexed with DsbA revealed key interactions with the DsbA active site cysteine, and with a hydrophobic groove adjacent to the active site. The present work aimed to discover peptidomimetics that target the hydrophobic groove to generate non-covalent DsbA inhibitors. The previously reported structure of a Proteus mirabilis DsbA active site cysteine mutant, in a non-covalent complex with the heptapeptide PWATCDS, was used as an in silico template for virtual screening of a peptidomimetic fragment library. The highest scoring fragment compound and nine derivatives were synthesized and evaluated for DsbA binding and inhibition. These experiments discovered peptidomimetic fragments with inhibitory activity at millimolar concentrations. Although only weakly potent relative to larger covalent peptide inhibitors that interact through the active site cysteine, these fragments offer new opportunities as templates to build non-covalent inhibitors. The results suggest that non-covalent peptidomimetics may need to interact with sites beyond the hydrophobic groove in order to produce potent DsbA inhibitors.

Synergistic activity of synthetic N-terminal peptide of human lactoferrin in combination with various antibiotics against carbapenem-resistant Klebsiella pneumoniae strains.

PubMed

Morici, P; Florio, W; Rizzato, C; Ghelardi, E; Tavanti, A; Rossolini, G M; Lupetti, A

2017-10-01

The spread of multi-drug resistant (MDR) Klebsiella pneumoniae strains producing carbapenemases points to a pressing need for new antibacterial agents. To this end, the in-vitro antibacterial activity of a synthetic N-terminal peptide of human lactoferrin, further referred to as hLF1-11, was evaluated against K. pneumoniae strains harboring different carbapenemase genes (i.e. OXA-48, KPC-2, KPC-3, VIM-1), with different susceptibility to colistin and other antibiotics, alone or in combination with conventional antibiotics (gentamicin, tigecycline, rifampicin, clindamycin, and clarithromycin). An antimicrobial peptide susceptibility assay was used to assess the bactericidal activity of hLF1-11 against the different K. pneumoniae strains tested. The synergistic activity was evaluated by a checkerboard titration method, and the fractional inhibitory concentration (FIC) index was calculated for the various combinations. hLF1-11 was more efficient in killing a K. pneumoniae strain susceptible to most antimicrobials (including colistin) than a colistin-susceptible strain and a colistin-resistant MDR K. pneumoniae strain. In addition, hLF1-11 exhibited a synergistic effect with the tested antibiotics against MDR K. pneumoniae strains. The results of this study indicate that resistance to hLF1-11 and colistin are not strictly associated, and suggest an hLF1-11-induced sensitizing effect of K. pneumoniae to antibiotics, especially to hydrophobic antibiotics, which are normally not effective on Gram-negative bacteria. Altogether, these data indicate that hLF1-11 in combination with antibiotics is a promising candidate to treat infections caused by MDR-K. pneumoniae strains.

Antimicrobial properties of analgesic kyotorphin peptides unraveled through atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ribeiro, Marta M.B.; Franquelim, Henri G.; Torcato, Ines M.

Highlights: Black-Right-Pointing-Pointer New kyotorphin derivatives have antimicrobial properties against S. aureus. Black-Right-Pointing-Pointer Atomic force microscopy show membrane disturbing effects of KTP-NH{sub 2} and IbKTP-NH{sub 2}. Black-Right-Pointing-Pointer None of the KTP derivatives are hemolytic. Black-Right-Pointing-Pointer The minimal peptidic sequence with antimicrobial activity is Tyr-Arg, if amidated. -- Abstract: Antimicrobial peptides (AMPs) are promising candidates as alternatives to conventional antibiotics for the treatment of resistant pathogens. In the last decades, new AMPs have been found from the cleavage of intact proteins with no antibacterial activity themselves. Bovine hemoglobin hydrolysis, for instance, results in AMPs and the minimal antimicrobial peptide sequence was definedmore » as Tyr-Arg plus a positively charged amino acid residue. The Tyr-Arg dipeptide alone, known as kyotorphin (KTP), is an endogenous analgesic neuropeptide but has no antimicrobial activity itself. In previous studies new KTP derivatives combining C-terminal amidation and Ibuprofen (Ib) - KTP-NH{sub 2}, IbKTP, IbKTP-NH{sub 2} - were designed in order to improve KTP brain targeting. Those modifications succeeded in enhancing peptide-cell membrane affinity towards fluid anionic lipids and higher analgesic activity after systemic injection resulted therefrom. Here, we investigated if this affinity for anionic lipid membranes also translates into antimicrobial activity because bacteria have anionic membranes. Atomic force microscopy revealed that KTP derivatives perturbed Staphylococcus aureus membrane structure by inducing membrane blebbing, disruption and lysis. In addition, these peptides bind to red blood cells but are non-hemolytic. From the KTP derivatives tested, amidated KTP proves to be the most active antibacterial agent. The combination of analgesia and antibacterial activities with absence of toxicity is highly appealing from the clinical point of view and broadens the therapeutic potential and application of kyotorphin peptides.« less

Antibacterial activity and genotypic-phenotypic characteristics of bacteriocin-producing Bacillus subtilis KKU213: potential as a probiotic strain.

PubMed

Khochamit, Nalisa; Siripornadulsil, Surasak; Sukon, Peerapol; Siripornadulsil, Wilailak

2015-01-01

The antimicrobial activity and probiotic properties of Bacillus subtilis strain KKU213, isolated from local soil, were investigated. The cell-free supernatant (CFS) of a KKU213 culture containing crude bacteriocins exhibited inhibitory effects on Gram-positive bacteria, including Bacillus cereus, Listeria monocytogenes, Micrococcus luteus, and Staphylococcus aureus. The antibacterial activity of the CFS precipitated with 40% ammonium sulfate (AS) remained even after treatment at 60 and 100 °C, at pH 4 and 10 and with proteolytic enzymes, detergents and heavy metals. When analyzed by SDS-PAGE and overlaid with the indicator strains B. cereus and S. aureus, the 40% AS precipitate exhibited inhibitory activity on proteins smaller than 10 kDa. However, proteins larger than 25 kDa and smaller than 10 kDa were still observed on a native protein gel. Purified subtilosin A was prepared by Amberlite XAD-16 bead extraction and HPLC and analyzed by Nano-LC-QTOF-MS. Its molecular mass was found to be 3.4 kDa, and it retained its antibacterial activity. These results are consistent with the detection of the anti-listerial subtilosin A gene of the sbo/alb cluster in the KKU213 strain, which is 100% identical to that of B. subtilis subsp. subtilis 168. In addition to stable and cyclic subtilosin A, a mixture of many extracellular antibacterial peptides was also detected in the KKU213 culture. The KKU213 strain produced extracellular amylase, cellulase, lipase and protease, is highly acid-resistant (pH 2) when cultured in inulin and promotes health and reduces infection of intestinally colonized broiler chickens. Therefore, we propose that bacteriocin-producing B. subtilis KKU213 could be used as a potential probiotic strain or protective culture. Copyright © 2014 Elsevier GmbH. All rights reserved.

Nature's Way to Make the Lantibiotics

ERIC Educational Resources Information Center

Relyea, Heather A.; van der Donk, Wilfred A.

2006-01-01

The biosynthesis and mode of action of a class of compounds called lantibiotics, a peptide with antibacterial activity against multi-drug resistant bacteria as well as food-borne pathogens like Listeria monocytogenes and Clostridium botulinum is described. These peptide-derived compounds are especially interesting because they could be used as…

Expression of recombinant antibacterial lactoferricin-related peptides from Pichia pastoris expression system.

PubMed

Chen, Gen-Hung; Chen, Wei-Ming; Huang, Guo-Ting; Chen, Yu-Wen; Jiang, Shann-Tzong

2009-10-28

Four recombinant antimicrobial peptide (rAMP) cDNAs, constructed from two goat lactoferricin-related peptide cDNAs (GLFcin and GLFcin II) with/without (His)(6)-Tag, were cloned into pPICZalphaC and transformed into Pichia pastoris SMD1168H. After methanol induction, these rAMPs were expressed and secreted into broth. They were purified after CM-Sepharose (without His-tg), HisTrap (with His-tg) and Sephadex G-25 chromatographies. The yield of purified rAMP was 0.15 mg/mL of broth. These 4 rAMPs were thermal-stable and with high antibacterial activity against Escherichia coli BCRC 11549, Pseudomonas aeruginosa BCRC 12450, Bacillus cereus BCRC 10603, Staphylococcus aureus BCRC 25923, Propioni bacterium acnes BCRC 10723, and Listera monocytogenes BCRC 14845. The minimum inhibitory concentration (MIC) of rAMPs against these indicators ranged from 4.07 to 16.00 mg/mL.

Biohybrid Polymer-Antimicrobial Peptide Medium against Enterococcus faecalis

PubMed Central

Eckhard, Lea H.; Sol, Asaf; Abtew, Ester; Shai, Yechiel; Domb, Abraham J.

2014-01-01

Antimicrobial peptides (AMPs) are conserved evolutionary components of the innate immune system that are being tested as alternatives to antibiotics. Slow release of AMPs using biodegradable polymers can be advantageous in maintaining high peptide levels for topical treatment, especially in the oral environment in which dosage retention is challenged by drug dilution with saliva flow and by drug inactivation by salivary enzymatic activity. Enterococcus faecalis is a multidrug resistant nosocomial pathogen and a persistent pathogen in root canal infections. In this study, four ultra-short lipopeptides (C16-KGGK, C16-KLLK, C16-KAAK and C16-KKK) and an amphipathic α-helical antimicrobial peptide (Amp-1D) were tested against E. faecalis. The antibacterial effect was determined against planktonic bacteria and bacteria grown in biofilm. Of the five tested AMPs, C16-KGGK was the most effective. Next C16-KGGK was formulated with one of two polymers poly (lactic acid co castor oil) (DLLA) or ricinoleic acid-based poly (ester-anhydride) P(SA-RA). Peptide-synthetic polymer conjugates, also referred to as biohybrid mediums were tested for antibacterial activity against E. faecalis grown in suspension and in biofilms. The new formulations exhibited strong and improved anti- E. faecalis activity. PMID:25279943

Molecular structure, chemical synthesis, and antibacterial activity of ABP-dHC-cecropin A from drury (Hyphantria cunea).

PubMed

Zhang, Jiaxin; Movahedi, Ali; Wang, Xiaoli; Wu, Xiaolong; Yin, Tongming; Zhuge, Qiang

2015-06-01

The increasing resistance of bacteria and fungi to currently available antibiotics is a major concern worldwide, leading to enormous efforts to develop new antibiotics with new modes of actions. In this paper, cDNA encoding cecropin A was amplified from drury (Hyphantria cunea) (dHC) pupa fatbody total RNA using RT-PCR. The full-length dHC-cecropin A cDNA encoded a protein of 63 amino acids with a predicted 26-amino acid signal peptide and a 37-amino acid functional domain. We synthesized the antibacterial peptide (ABP) from the 37-amino acid functional domain (ABP-dHC-cecropin A), and amidated it via the C-terminus. Time-of-flight mass spectrometry showed its molecular weight to be 4058.94. The ABP-dHC-cecropin A was assessed in terms of its protein structure using bioinformatics and CD spectroscopy. The protein's secondary structure was predicted to be α-helical. In an antibacterial activity analysis, the ABP-dHC-cecropin A exhibited strong antibacterial activity against E. coli K12D31 and Agrobacterium EHA105. Copyright © 2014 Elsevier Inc. All rights reserved.

Angiotensin I-Converting-Enzyme-Inhibitory and Antibacterial Peptides from Lactobacillus helveticus PR4 Proteinase-Hydrolyzed Caseins of Milk from Six Species

PubMed Central

Minervini, F.; Algaron, F.; Rizzello, C. G.; Fox, P. F.; Monnet, V.; Gobbetti, M.

2003-01-01

Sodium caseinates prepared from bovine, sheep, goat, pig, buffalo or human milk were hydrolyzed by a partially purified proteinase of Lactobacillus helveticus PR4. Peptides in each hydrolysate were fractionated by reversed-phase fast-protein liquid chromatography. The fractions which showed the highest angiotensin I-converting-enzyme (ACE)-inhibitory or antibacterial activity were sequenced by mass spectrum and Edman degradation analyses. Various ACE-inhibitory peptides were found in the hydrolysates: the bovine αS1-casein (αS1-CN) 24-47 fragment (f24-47), f169-193, and β-CN f58-76; ovine αS1-CN f1-6 and αS2-CN f182-185 and f186-188; caprine β-CN f58-65 and αS2-CN f182-187; buffalo β-CN f58-66; and a mixture of three tripeptides originating from human β-CN. A mixture of peptides with a C-terminal sequence, Pro-Gly-Pro, was found in the most active fraction of the pig sodium caseinate hydrolysate. The highest ACE-inhibitory activity of some peptides corresponded to the concentration of the ACE inhibitor (S)-N-(1-[ethoxycarbonyl]-3-phenylpropyl)-ala-pro maleate (enalapril) of 49.253 μg/ml (100 μmol/liter). Several of the above sequences had features in common with other ACE-inhibitory peptides reported in the literature. The 50% inhibitory concentration (IC50) of some of the crude peptide fractions was very low (16 to 100 μg/ml). Some identified peptides were chemically synthesized, and the ACE-inhibitory activity and IC50s were confirmed. An antibacterial peptide corresponding to β-CN f184-210 was identified in human sodium caseinate hydrolysate. It showed a very large spectrum of inhibition against gram-positive and -negative bacteria, including species of potential clinical interest, such as Enterococcus faecium, Bacillus megaterium, Escherichia coli, Listeria innocua, Salmonella spp., Yersinia enterocolitica, and Staphylococcus aureus. The MIC for E. coli F19 was ca. 50 μg/ml. Once generated, the bioactive peptides were resistant to further degradation by proteinase of L. helveticus PR4 or by trypsin and chymotrypsin. PMID:12957917

Protein-only, antimicrobial peptide-containing recombinant nanoparticles with inherent built-in antibacterial activity.

PubMed

Serna, Naroa; Sánchez-García, Laura; Sánchez-Chardi, Alejandro; Unzueta, Ugutz; Roldán, Mónica; Mangues, Ramón; Vázquez, Esther; Villaverde, Antonio

2017-09-15

The emergence of bacterial antibiotic resistances is a serious concern in human and animal health. In this context, naturally occurring cationic antimicrobial peptides (AMPs) might play a main role in a next generation of drugs against bacterial infections. Taking an innovative approach to design self-organizing functional proteins, we have generated here protein-only nanoparticles with intrinsic AMP microbicide activity. Using a recombinant version of the GWH1 antimicrobial peptide as building block, these materials show a wide antibacterial activity spectrum in absence of detectable toxicity on mammalian cells. The GWH1-based nanoparticles combine clinically appealing properties of nanoscale materials with full biocompatibility, structural and functional plasticity and biological efficacy exhibited by proteins. Because of the largely implemented biological fabrication of recombinant protein drugs, the protein-based platform presented here represents a novel and scalable strategy in antimicrobial drug design, that by solving some of the limitations of AMPs offers a promising alternative to conventional antibiotics. The low molecular weight antimicrobial peptide GWH1 has been engineered to oligomerize as self-assembling protein-only nanoparticles of around 50nm. In this form, the peptide exhibits potent and broad antibacterial activities against both Gram-positive and Gram-negative bacteria, without any harmful effect over mammalian cells. As a solid proof-of-concept, this finding strongly supports the design and biofabrication of nanoscale antimicrobial materials with in-built functionalities. The protein-based homogeneous composition offer advantages over alternative materials explored as antimicrobial agents, regarding biocompatibility, biodegradability and environmental suitability. Beyond the described prototype, this transversal engineering concept has wide applicability in the design of novel nanomedicines for advanced treatments of bacterial infections. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Screening And Optimizing Antimicrobial Peptides By Using SPOT-Synthesis

NASA Astrophysics Data System (ADS)

López-Pérez, Paula M.; Grimsey, Elizabeth; Bourne, Luc; Mikut, Ralf; Hilpert, Kai

2017-04-01

Peptide arrays on cellulose are a powerful tool to investigate peptide interactions with a number of different molecules, for examples antibodies, receptors or enzymes. Such peptide arrays can also be used to study interactions with whole cells. In this review, we focus on the interaction of small antimicrobial peptides with bacteria. Antimicrobial peptides (AMPs) can kill multidrug-resistant (MDR) human pathogenic bacteria and therefore could be next generation antibiotics targeting MDR bacteria. We describe the screen and the result of different optimization strategies of peptides cleaved from the membrane. In addition, screening of antibacterial activity of peptides that are tethered to the surface is discussed. Surface-active peptides can be used to protect surfaces from bacterial infections, for example implants.

The Central Hinge Link Truncation of the Antimicrobial Peptide Fowlicidin-3 Enhances Its Cell Selectivity without Antibacterial Activity Loss

PubMed Central

Qu, Pei; Gao, Wei; Chen, Huixian; Li, Dan; Yang, Na; Zhu, Jian; Li, Zhongqiu

2016-01-01

Antimicrobial peptides (AMPs) have been paid considerable attention because of their broad-spectrum antimicrobial activity and a reduced possibility of the development of bacterial drug resistance. Fowlicidin-3 (Fow-3) is an identified type of chicken cathelicidin AMP that has exhibited considerable antimicrobial activity and cytotoxicity. To reduce cell toxicity and improve cell selectivity, several truncated peptides of fowlicidin-3, Fow-3(1-15), Fow-3(1-19), Fow-3(1-15-20-27), and Fow-3(20-27), were synthesized. Our results indicated that neither the N- nor C-terminal segment alone [Fow-3(1-15), Fow-3(1-19), Fow-3(20-27)] was sufficient to confer antibacterial activity. However, Fow-3(1-19) with the inclusion of the central hinge link (-AGIN-) retained substantial cell toxicity, which other analogs lost. Fow-3(1-15-20-27) displayed potent antimicrobial activity for a wide range of Gram-negative and Gram-positive bacteria and no obvious hemolytic activity or cytotoxicity. The central link region was shown to be critically important in the function of cell toxicity but was not relevant to antibacterial activity. Fow-3(1-15-20-27) maintained antibacterial activity in the presence of physiological concentrations of salts. The results from fluorescence spectroscopy, scanning electron microcopy, and transmission electron microcopy showed that Fow-3(1-15-20-27) as well as fowlicidin-3 killed bacterial cells by increasing membrane permeability and damaging the membrane envelope integrity. Fow-3(1-15-20-27) could be a promising antimicrobial agent for clinical application. PMID:26902768

Antibacterial activity and cytocompatibility of an implant coating consisting of TiO2 nanotubes combined with a GL13K antimicrobial peptide.

PubMed

Li, Tao; Wang, Na; Chen, Su; Lu, Ran; Li, Hongyi; Zhang, Zhenting

2017-01-01

Prevention of implant-associated infections at an early stage of surgery is highly desirable for the long-term efficacy of implants in dentistry and orthopedics. Infection prophylaxis using conventional antibiotics is becoming less effective due to the development of bacteria resistant to multiple antibiotics. An ideal strategy to conquer bacterial infections is the local delivery of antibacterial agents. Therefore, antimicrobial peptide (AMP) eluting coatings on implant surfaces is a promising alternative. In this study, the feasibility of utilizing TiO 2 nanotubes (TNTs), processed using anodization, as carriers to deliver a candidate AMP on titanium surfaces for the prevention of implant-associated infections is assessed. The broad-spectrum GL13K (GKIIKLKASLKLL-CONH2) AMP derived from human parotid secretory protein was selected and immobilized to TNTs using a simple soaking technique. Field emission scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectrometry analyses confirmed the successful immobilization of GL13K to anatase TNTs. The drug-loaded coatings demonstrated a sustained and slow drug release profile in vitro and eradicated the growth of Fusobacterium nucleatum and Porphyromonas gingivalis within 5 days of culture, as assessed by disk-diffusion assay. The GL13K-immobilized TNT (GL13K-TNT) coating demonstrated greater biocompatibility, compared with a coating produced by incubating TNTs with equimolar concentrations of metronidazole. GL13K-TNTs produced no observable cytotoxicity to preosteoblastic cells (MC3T3-E1). The coating may also have an immune regulatory effect, in support of rapid osseointegration around implants. Therefore, the combination of TNTs and AMP GL13K may achieve simultaneous antimicrobial and osteoconductive activities.

Identification and Characterization of the Anti-Methicillin-Resistant Staphylococcus aureus WAP-8294A2 Biosynthetic Gene Cluster from Lysobacter enzymogenes OH11 ▿ †

PubMed Central

Zhang, Wei; Li, Yaoyao; Qian, Guoliang; Wang, Yan; Chen, Haotong; Li, Yue-Zhong; Liu, Fengquan; Shen, Yuemao; Du, Liangcheng

2011-01-01

Lysobactor enzymogenes strain OH11 is an emerging biological control agent of fungal and bacterial diseases. We recently completed its genome sequence and found it contains a large number of gene clusters putatively responsible for the biosynthesis of nonribosomal peptides and polyketides, including the previously identified antifungal dihydromaltophilin (HSAF). One of the gene clusters contains two huge open reading frames, together encoding 12 modules of nonribosomal peptide synthetases (NRPS). Gene disruption of one of the NRPS led to the disappearance of a metabolite produced in the wild type and the elimination of its antibacterial activity. The metabolite and antibacterial activity were also affected by the disruption of some of the flanking genes. We subsequently isolated this metabolite and subjected it to spectroscopic analysis. The mass spectrometry and nuclear magnetic resonance data showed that its chemical structure is identical to WAP-8294A2, a cyclic lipodepsipeptide with potent anti-methicillin-resistant Staphylococcus aureus (MRSA) activity and currently in phase I/II clinical trials. The WAP-8294A2 biosynthetic genes had not been described previously. So far, the Gram-positive Streptomyces have been the primary source of anti-infectives. Lysobacter are Gram-negative soil/water bacteria that are genetically amendable and have not been well exploited. The WAP-8294A2 synthetase represents one of the largest NRPS complexes, consisting of 45 functional domains. The identification of these genes sets the foundation for the study of the WAP-8294A2 biosynthetic mechanism and opens the door for producing new anti-MRSA antibiotics through biosynthetic engineering in this new source of Lysobacter. PMID:21930890

Bactericidal activity of tracheal antimicrobial peptide against respiratory pathogens of cattle.

PubMed

Taha-Abdelaziz, Khaled; Perez-Casal, José; Schott, Courtney; Hsiao, Jason; Attah-Poku, Samuel; Slavić, Durđa; Caswell, Jeff L

2013-04-15

Tracheal antimicrobial peptide (TAP) is a β-defensin produced by mucosal epithelial cells of cattle. Although effective against several human pathogens, the activity of this bovine peptide against the bacterial pathogens that cause bovine respiratory disease have not been reported. This study compared the antibacterial effects of synthetic TAP against Mannheimia haemolytica, Histophilus somni, Pasteurella multocida, and Mycoplasma bovis. Bactericidal activity against M. bovis was not detected. In contrast, the Pasteurellaceae bacteria showed similar levels of susceptibility to that of Escherichia coli, with 0.125μg TAP inhibiting growth in a radial diffusion assay and minimum inhibitory concentrations of 1.56-6.25μg/ml in a bactericidal assay. Significant differences among isolates were not observed. Sequencing of exon 2 of the TAP gene from 23 cattle revealed a prevalent non-synonymous single nucleotide polymorphism (SNP) A137G, encoding either serine or asparagine at residue 20 of the mature peptide. The functional effect of this SNP was tested against M. haemolytica using synthetic peptides. The bactericidal effect of the asparagine-containing peptide was consistently higher than the serine-containing peptide. Bactericidal activities were similar for an acapsular mutant of M. haemolytica compared to the wild type. These findings indicate that the Pasteurellaceae bacteria that cause bovine respiratory disease are susceptible to killing by bovine TAP and appear not to have evolved resistance, whereas M. bovis appears to be resistant. A non-synonymous SNP was identified in the coding region of the TAP gene, and the corresponding peptides vary in their bactericidal activity against M. haemolytica. Copyright © 2013 Elsevier B.V. All rights reserved.

Microcins from Enterobacteria: On the Edge Between Gram-Positive Bacteriocins and Colicins

NASA Astrophysics Data System (ADS)

Rebuffat, Sylvie

Most bacteria and archaea produce gene-encoded antimicrobial peptides/proteins called bacteriocins, which are secreted by the producing bacteria to compete against other microorganisms in a given niche. They are considered important mediators of intra- and interspecies interactions and therefore a factor in ­maintaining the microbial diversity and stability. They are ribosomally synthesized, and most of them are produced as inactive precursor proteins, which in some cases are further enzymatically modified. Bacteriocins generally exert potent antibacterial activities directed against bacterial species closely related to the producing bacteria. Bacteriocins are abundant and diverse in Gram-negative and Gram-positive bacteria. This chapter focuses on colicins and microcins from enterobacteria (mainly Escherichia coli) and on bacteriocins from lactic acid bacteria (LAB). Microcins are the lower-molecular-mass bacteriocins produced by Gram-negative bacteria with a repertoire of only 14 representatives. They form a very restricted family of bacteriocins, compared to the huge family of LAB bacteriocins that is constituted of several hundreds of peptides, with which microcins share common characteristics. Nevertheless, microcins also show similarities, particularly in their uptake mechanisms, with the higher-molecular-mass colicins, also produced by E. coli strains. On the edge between LAB bacteriocins and colicins, microcins appear to combine highly efficient strategies developed by both Gram-positive and Gram-negative bacteria at different levels, including uptake, translocation, killing of target cells, and immunity of the producing bacteria, making them important actors of bacterial competitions and fascinating models for novel concepts toward antimicrobial strategies and against resistance mechanisms.

Electrostatic immobilization of antimicrobial peptides on polyethylenimine and their antibacterial effect against Staphylococcus epidermidis.

PubMed

Hernandez-Montelongo, J; Corrales Ureña, Y R; Machado, D; Lancelloti, M; Pinheiro, M P; Rischka, K; Lisboa-Filho, P N; Cotta, M A

2018-04-01

Staphylococcus epidermidis is a gram-positive bacterium, and one of the most prevalent causes of nosocomial infections due to its strong ability to form biofilms on catheters and surgical implants. Here we explore the antimicrobial properties of Tet-124 peptides, which are part of the innate defense against different multicellular organisms in nature. Two different Tet-124 peptides were immobilized on a polyethylenimine (PEI) film to determine their impact on the antimicrobial properties: KLWWMIRRW (Tet-124), which contains only natural amino acids, and KLWWMIRRWG-(F-Br)-G (F-Br = 4-Bromophenylalanine), a modified Tet-124 sequence with the addition of an unnatural amino acid. The immobilization was obtained as a result of the electrostatic interaction between PEI amino groups and the C-terminal carboxylic groups of tryptophan and glycine amino acids of Tet-124 and Tet-124-Br peptides, respectively. The process was monitored and studied by water contact angle, Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Quartz Crystal Microbalance with Dissipation (QCM-D) measurements. The antibacterial effect of our samples against S. epidermis was evaluated by the spread plate counting method, and cytotoxicity was tested using fibroblast cultures. Our results indicate the feasibility to immobilize electrostatically both Tet-124 peptides for biomedical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Lysozyme enhances the bactericidal effect of BP100 peptide against Erwinia amylovora, the causal agent of fire blight of rosaceous plants.

PubMed

Cabrefiga, Jordi; Montesinos, Emilio

2017-02-17

Fire blight is an important disease affecting rosaceous plants. The causal agent is the bacteria Erwinia amylovora which is poorly controlled with the use of conventional bactericides and biopesticides. Antimicrobial peptides (AMPs) have been proposed as a new compounds suitable for plant disease control. BP100, a synthetic linear undecapeptide (KKLFKKILKYL-NH 2 ), has been reported to be effective against E. amylovora infections. Moreover, BP100 showed bacteriolytic activity, moderate susceptibility to protease degradation and low toxicity. However, the peptide concentration required for an effective control of infections in planta is too high due to some inactivation by tissue components. This is a limitation beause of the high cost of synthesis of this compound. We expected that the combination of BP100 with lysozyme may produce a synergistic effect, enhancing its activity and reducing the effective concentration needed for fire blight control. The combination of a synhetic multifunctional undecapeptide (BP100) with lysozyme produces a synergistic effect. We showed a significant increase of the antimicrobial activity against E. amylovora that was associated to the increase of cell membrane damage and to the reduction of cell metabolism. Combination of BP100 with lysozyme reduced the time required to achieve cell death and the minimal inhibitory concentration (MIC), and increased the activity of BP100 in the presence of leaf extracts even when the peptide was applied at low doses. The results obtained in vitro were confirmed in leaf infection bioassays. The combination of BP100 with lysozyme showed synergism on the bactericidal activity against E. amylovora and provide the basis for developing better formulations of antibacterial peptides for plant protection.

Sustained Release of Antibacterial Lipopeptides from Biodegradable Polymers against Oral Pathogens

PubMed Central

Eckhard, Lea H.; Houri-Haddad, Yael; Sol, Asaf; Zeharia, Rotem; Shai, Yechiel; Beyth, Shaul; Domb, Abraham J.

2016-01-01

The development of antibacterial drugs to overcome various pathogenic species, which inhabit the oral cavity, faces several challenges, such as salivary flow and enzymatic activity that restrict dosage retention. Owing to their amphipathic nature, antimicrobial peptides (AMPs) serve as the first line of defense of the innate immune system. The ability to synthesize different types of AMPs enables exploitation of their advantages as alternatives to antibiotics. Sustained release of AMPs incorporated in biodegradable polymers can be advantageous in maintaining high levels of the peptides. In this study, four potent ultra-short lipopeptides, conjugated to an aliphatic acid chain (16C) were incorporated in two different biodegradable polymers: poly (lactic acid co castor oil) (PLACO) and ricinoleic acid-based poly (ester-anhydride) (P(SA-RA)) for sustained release. The lipopeptide and polymer formulations were tested for antibacterial activity during one week, by turbidometric measurements of bacterial outgrowth, anti-biofilm activity by live/dead staining, biocompatibility by hemolysis and XTT colorimetric assays, mode of action by fluorescence-activated cell sorting (FACS) and release profile by a fluorometric assay. The results show that an antibacterial and anti-biofilm effect, as well as membrane disruption, can be achieved by the use of a formulation of lipopeptide incorporated in biodegradable polymer. PMID:27606830

Cloning and expression of antibacterial goat lactoferricin from Escherichia coli AD494(DE3)pLysS expression system.

PubMed

Chen, Gen-Hung; Yin, Li-Jung; Chiang, I-Hua; Jiang, Shann-Tzong

2008-12-01

Goat lactoferricin (GLfcin), an antibacterial peptide, is released from the N terminus of goat lactoferrin by pepsin digestion. Two GLfcin-related cDNAs, GLfcin L and GLfcin S, encoding Ala20-Ser60 and Ser36-Ser60 of goat lactoferrin, respectively, were cloned into the pET-23a(+) expression vector upstream from (His)6-Tag gene and transformed into Escherichia coli AD494(DE3)pLysS expression host. After being induced by isopropyl-beta-D-thiogalactopyranoside (IPTG), two (His)6-Tag fused recombinant lactoferricins, GLfcin L-His*Tag and GLfcin S-His*Tag, were expressed in soluble form within the E. coli cytoplasm. The GLfcin L-His*Tag and GLfcin S-His*Tag were purified using HisTrap affinity chromatography. According to an antibacterial activity assay using the agar diffusion method, GLfcin L-His*Tag had antibacterial activity against E. coli BCRC 11549, Staphylococcus aureus BCRC 25923, and Propionibacterium acnes BCRC 10723, while GLfcin S-His*Tag was able to inhibit the growth of E. coli BCRC 11549 and P. acnes BCRC 10723. These two recombinant lactoferricins behaved as thermostable peptides, which could retain their activity for up to 30 min of exposure at 100 degrees C.

Transition metal ions mediated tyrosine based short peptide amphiphile nanostructures inhibit bacterial growth.

PubMed

Joshi, Khashti Ballabh; Singh, Ramesh; Mishra, Narendra Kumar; Kumar, Vikas; Vinayak, Vandana

2018-05-17

We report the design and synthesis of biocompatible small peptide based molecule for the controlled and targeted delivery of the encapsulated bioactive metal ions via transforming their internal nanostructures. Tyrosine based short peptide amphiphile (sPA) was synthesized which self-assembled into β-sheet like secondary structures. The self assembly of the designed sPA was modulated by using different bioactive transition metal ions which is confirmed by spectroscopic and microscopic techniques. These bioactive metal ions conjugated sPA hybrid structures are further used to develop antibacterial materials. It is due to the excellent antibacterial activity of zinc ions that the growth of clinically relevant bacteria such as E. Coli was inhibited in the presence of zinc-sPA conjugate. The bacterial test demonstrated that owing to high biocompatibility with bacterial cell, the designed sPA worked as metal ions delivery agent and therefore it can show great potential in locally addressing bacterial infections. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of short peptides containing lysine and epsilon-aminocaproic acid on fibrinolytic activity of plasmin and topoisomerase II action on supercoiled DNA.

PubMed

Midura-Nowaczek, Krystyna; Purwin, Maciej; Markowska, Agnieszka; Drozdowska, Danuta; Bruzgo, Magdalena

2013-01-01

Effects of eight short peptides containing lysine and epsilon-aminocaproic acid (EACA) on prolongation of the clot lysis time, as well as hemolytic and antibacterial activities were investigated. Interaction with plasmids pBR322 and pUC19 with the use of ethidium bromide assay and determination of influence on the activity of topoisomerase I and II were also tested. Examined compounds inhibited fibrinolytic activity of plasmin and five of them were more active than EACA. Amides of dipeptides were most active antifibrinolytics (IC50 < 0.2 mM). According to the obtained data, the significant inhibition of fibrinolytic activity of plasmin was not associated with hemolytic effects. Examined compounds did not show antibacterial activity (MIC > 512 mg/L). DNA binding effects determined with the use of ethidium bromide were weak for all peptides and similar to those observed with EACA. Six compounds inhibited topoisomerase II action on supercoiled DNA.

Characterization of antimicrobial substances produced by Enterococcus faecalis MRR 10-3, isolated from the uropygial gland of the hoopoe (Upupa epops).

PubMed

Martín-Platero, Antonio M; Valdivia, Eva; Ruíz-Rodríguez, Magdalena; Soler, Juan J; Martín-Vivaldi, Manuel; Maqueda, Mercedes; Martínez-Bueno, Manuel

2006-06-01

The uropygial gland (preen gland) is a holocrine secretory gland situated at the base of the tail in birds which produces a hydrophobic fatty secretion. In certain birds, such as the hoopoe, Upupa epops, the composition of this secretion is influenced by both seasonal and sexual factors, becoming darker and more malodorous in females and in their nestlings during the nesting phase. The secretion is spread throughout the plumage when the bird preens itself, leaving its feathers flexible and waterproof. It is also thought to play a role in defending the bird against predators and parasites. We have isolated from the uropygial secretion of a nestling a bacterium that grows in monospecific culture which we have identified unambiguously by phenotypic and genotypic means as Enterococcus faecalis. The strain in question produces antibacterial substances that are active against all gram-positive bacteria assayed and also against some gram-negative strains. Its peptide nature identifies it as a bacteriocin within the group known as enterocins. Two peptides were purified to homogeneity (MR10A and MR10B), and matrix-assisted laser desorption ionization-time of flight (mass spectrometry) analysis showed masses of 5201.58 and 5207.7 Da, respectively. Amino acid sequencing of both peptides revealed high similarity with enterocin L50A and L50B (L. M. Cintas, P. Casaus, H. Holo, P. E. Hernández, I. F. Nes, and L. S. Håvarstein, J. Bacteriol. 180:1988-1994, 1998). PCR amplification of total DNA from strain MRR10-3 with primers for the L50A/B structural genes and sequencing of the amplified fragment revealed almost identical sequences, except for a single conservative change in residue 38 (Glu-->Asp) in MR10A and two changes in residues 9 (Thr-->Ala) and 15 (Leu-->Phe) in MR10B. This is the first time that the production of bacteriocins by a bacterium isolated from the uropygial gland has been described. The production of these broad-spectrum antibacterial substances by an enterococcal strain living in the uropygial gland may be important to the hygiene of the nest and thus to the health of the eggs and chicks.

Characterization of Antimicrobial Substances Produced by Enterococcus faecalis MRR 10-3, Isolated from the Uropygial Gland of the Hoopoe (Upupa epops)

PubMed Central

Martín-Platero, Antonio M.; Valdivia, Eva; Ruíz-Rodríguez, Magdalena; Soler, Juan J.; Martín-Vivaldi, Manuel; Maqueda, Mercedes; Martínez-Bueno, Manuel

2006-01-01

The uropygial gland (preen gland) is a holocrine secretory gland situated at the base of the tail in birds which produces a hydrophobic fatty secretion. In certain birds, such as the hoopoe, Upupa epops, the composition of this secretion is influenced by both seasonal and sexual factors, becoming darker and more malodorous in females and in their nestlings during the nesting phase. The secretion is spread throughout the plumage when the bird preens itself, leaving its feathers flexible and waterproof. It is also thought to play a role in defending the bird against predators and parasites. We have isolated from the uropygial secretion of a nestling a bacterium that grows in monospecific culture which we have identified unambiguously by phenotypic and genotypic means as Enterococcus faecalis. The strain in question produces antibacterial substances that are active against all gram-positive bacteria assayed and also against some gram-negative strains. Its peptide nature identifies it as a bacteriocin within the group known as enterocins. Two peptides were purified to homogeneity (MR10A and MR10B), and matrix-assisted laser desorption ionization-time of flight (mass spectrometry) analysis showed masses of 5201.58 and 5207.7 Da, respectively. Amino acid sequencing of both peptides revealed high similarity with enterocin L50A and L50B (L. M. Cintas, P. Casaus, H. Holo, P. E. Hernández, I. F. Nes, and L. S. Håvarstein, J. Bacteriol. 180:1988-1994, 1998). PCR amplification of total DNA from strain MRR10-3 with primers for the L50A/B structural genes and sequencing of the amplified fragment revealed almost identical sequences, except for a single conservative change in residue 38 (Glu→Asp) in MR10A and two changes in residues 9 (Thr→Ala) and 15 (Leu→Phe) in MR10B. This is the first time that the production of bacteriocins by a bacterium isolated from the uropygial gland has been described. The production of these broad-spectrum antibacterial substances by an enterococcal strain living in the uropygial gland may be important to the hygiene of the nest and thus to the health of the eggs and chicks. PMID:16751538

Production of enterocin A by Enterococcus faecium MMRA isolated from 'Rayeb', a traditional Tunisian dairy beverage.

PubMed

Rehaiem, A; Martínez, B; Manai, M; Rodríguez, A

2010-05-01

Characterization and purification of a bacteriocin produced by a wild Enterococcus faecium strain, isolated from a Tunisian traditional fermented milk. Enterococcus faecium MMRA was selected on the basis of its strong anti-Listeria activity. The antibacterial activity was sensitive to proteases, confirming its proteinaceous nature. It was extremely heat stable (15 min at 121 degrees C), remained active over a wide pH range (2-12), and also after treatment with lipase, amylase, organic solvents, detergents, lyophilisation and long-term storage at -20 degrees C. Production of the bacteriocin occurred throughout the logarithmic growth phase, it did not adhere to the surface of the producer cells and the mode of action was bactericidal. After partial purification of the active supernatants, a 4-kDa band with antibacterial activity was revealed by SDS-PAGE electrophoresis and bioassay. Tryptic digestion followed by MALDI-TOF mass spectrometry identified the peptide as enterocin A. The inhibitory activity of Ent. faecium MMRA, a wild strain isolated from the artisan dairy beverage 'Rayeb', is due to the synthesis of an enterocin A. Traditional fresh Tunisian fermented dairy products are generally manufactured with raw milk that can be used as a source of uncharacterized wild lactic acid bacteria strains. To our knowledge, this is the first report on the isolation of an enterocin A producing Ent. faecium from 'Rayeb'. This bacteriocin or the producing strain might have a promising potential in biopreservation to enhance the hygienic quality of this dairy product.

The Central Hinge Link Truncation of the Antimicrobial Peptide Fowlicidin-3 Enhances Its Cell Selectivity without Antibacterial Activity Loss.

PubMed

Qu, Pei; Gao, Wei; Chen, Huixian; Li, Dan; Yang, Na; Zhu, Jian; Feng, Xingjun; Liu, Chunlong; Li, Zhongqiu

2016-05-01

Antimicrobial peptides (AMPs) have been paid considerable attention because of their broad-spectrum antimicrobial activity and a reduced possibility of the development of bacterial drug resistance. Fowlicidin-3 (Fow-3) is an identified type of chicken cathelicidin AMP that has exhibited considerable antimicrobial activity and cytotoxicity. To reduce cell toxicity and improve cell selectivity, several truncated peptides of fowlicidin-3, Fow-3(1-15), Fow-3(1-19), Fow-3(1-15-20-27), and Fow-3(20-27), were synthesized. Our results indicated that neither the N- nor C-terminal segment alone [Fow-3(1-15), Fow-3(1-19), Fow-3(20-27)] was sufficient to confer antibacterial activity. However, Fow-3(1-19) with the inclusion of the central hinge link (-AGIN-) retained substantial cell toxicity, which other analogs lost. Fow-3(1-15-20-27) displayed potent antimicrobial activity for a wide range of Gram-negative and Gram-positive bacteria and no obvious hemolytic activity or cytotoxicity. The central link region was shown to be critically important in the function of cell toxicity but was not relevant to antibacterial activity. Fow-3(1-15-20-27) maintained antibacterial activity in the presence of physiological concentrations of salts. The results from fluorescence spectroscopy, scanning electron microcopy, and transmission electron microcopy showed that Fow-3(1-15-20-27) as well as fowlicidin-3 killed bacterial cells by increasing membrane permeability and damaging the membrane envelope integrity. Fow-3(1-15-20-27) could be a promising antimicrobial agent for clinical application. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Review of new insights into antimicrobial agents.

PubMed

Dehghan Esmatabadi, M J; Bozorgmehr, A; Hajjari, S N; Sadat Sombolestani, A; Malekshahi, Z V; Sadeghizadeh, M

2017-02-28

People have known the bacteria and have used various ways to deal with them, from a long time ago. Perhaps, natural antibiotics with have been the first step in fighting against pathogens. However, several factors, such as dealing with unfamiliar bacteria or emergence of drug-resistant species, have motivated us to discover new antibiotics or  even change previous types. In this regard, a variety of natural and synthetic antibiotics with different origins, mechanism of action, structures and functional spectrum, have been developed and used. Some impact on the synthesis of nucleic acids and some affect protein synthesis so destroy bacteria. There is a ring in the structure of most of the antibiotics which gives them special properties. However, despite their numerous advantages, antibiotics also have drawbacks ehich limit their use in all situations. Therefore, other approaches such as photodynamic therapy (PDT) and antibacterial peptides were considered as alternatives. Photodynamic therapy (PDT) is a treatment that uses photosensitizing agents, along with light, to kill bacteria. The photosensitizing agents only work after they have been activated by certain kinds of light. Antibacterial peptides are a unique and diverse group of molecules which have  between 12 and 50 amino acids in general.  In this paper, will reviewt hree mentioned topics, namely antibiotics, photodynamic therapy and antibacterial peptides and will discuss the advantages and disadvantages of each approach briefly.

Biomedical Applications of Organometal-Peptide Conjugates

NASA Astrophysics Data System (ADS)

Metzler-Nolte, Nils

Peptides are well suited as targeting vectors for the directed delivery of metal-based drugs or probes for biomedical investigations. This chapter describes synthetic strategies for the preparation of conjugates of medically interesting peptides with covalently bound metal complexes. Peptides that were used include neuropeptides (enkephalin, neuropeptide Y, neurotensin), uptake peptides (TAT and poly-Arg), and intracellular localization sequences. To these peptides, a whole variety of transition metal complexes has been attached in recent years by solid-phase peptide synthesis (SPPS) techniques. The metal complex can be attached to the peptide on the resin as part of the SPPS scheme. Alternatively, the metal complex may be attached to the peptide as a postsynthetic modification. Advantages as well as disadvantages for either strategy are discussed. Biomedical applications include radiopharmaceutical applications, anticancer and antibacterial activity, metal-peptide conjugates as targeted CO-releasing molecules, and metal-peptide conjugates in biosensor applications.

Enhancement of endotoxin neutralization by coupling of a C12-alkyl chain to a lactoferricin-derived peptide

PubMed Central

2004-01-01

Antibacterial peptide acylation, which mimics the structure of the natural lipopeptide polymyxin B, increases antimicrobial and endotoxin-neutralizing activities. The interaction of the lactoferricin-derived peptide LF11 and its N-terminally acylated analogue, lauryl-LF11, with different chemotypes of bacterial lipopolysaccharide (LPS Re, Ra and smooth S form) was investigated by biophysical means and was related to the peptides' biological activities. Both peptides exhibit high antibacterial activity against the three strains of Salmonella enterica differing in the LPS chemotype. Lauryl-LF11 has one order of magnitude higher activity against Re-type, but activity against Ra- and S-type bacteria is comparable with that of LF11. The alkyl derivative peptide lauryl-LF11 shows a much stronger inhibition of the LPS-induced cytokine induction in human mononuclear cells than LF11. Although peptide–LPS interaction is essentially of electrostatic nature, the lauryl-modified peptide displays a strong hydrophobic component. Such a feature might then explain the fact that saturation of the peptide binding takes place at a much lower peptide/LPS ratio for LF11 than for lauryl-LF11, and that an overcompensation of the negative LPS backbone charges is observed for lauryl-LF11. The influence of LF11 on the gel-to-liquid-crystalline phase-transition of LPS is negligible for LPS Re, but clearly fluidizing for LPS Ra. In contrast, lauryl-LF11 causes a cholesterol-like effect in the two chemotypes, fluidizing in the gel and rigidifying of the hydrocarbon chains in the liquid-crystalline phase. Both peptides convert the mixed unilamellar/non-lamellar aggregate structure of lipid A, the ‘endotoxic principle’ of LPS, into a multilamellar one. These data contribute to the understanding of the mechanisms of the peptide-mediated neutralization of endotoxin and effect of lipid modification of peptides. PMID:15344905

Antimicrobial activity and mechanism of the human milk-sourced peptide Casein201.

PubMed

Zhang, Fan; Cui, Xianwei; Fu, Yanrong; Zhang, Jun; Zhou, Yahui; Sun, Yazhou; Wang, Xing; Li, Yun; Liu, Qianqi; Chen, Ting

2017-04-08

Casein201 is one of the human milk sourced peptides that differed significantly in preterm and full-term mothers. This study is designed to demonstrate the biological characteristics, antibacterial activity and mechanisms of Casein201 against common pathogens in neonatal infection. The analysis of biological characteristics was done by bioinformatics. Disk diffusion method and flow cytometry were used to detect the antimicrobial activity of Casein201. Killing kinetics of Casein201 was measured using microplate reader. The antimicrobial mechanism of Casein201 was studied by electron microscopy and electrophoresis. Bioinformatics analysis indicates that Casein201 derived from β-casein and showed significant sequence overlap. Antibacterial assays showed Casein201 inhibited the growth of S taphylococcus aureus and Y ersinia enterocolitica. Ultrastructural analyses revealed that the antibacterial activity of Casein201 is through cytoplasmic structures disintegration and bacterial cell envelope alterations but not combination with DNA. We conclude the antimicrobial activity and mechanism of Casein201. Our data demonstrate that Casein201 has potential therapeutic value for the prevention and treatment of pathogens in neonatal infection. Copyright © 2017 Elsevier Inc. All rights reserved.

Therapeutic options and emerging alternatives for multidrug resistant staphylococcal infections.

PubMed

Magana, Maria; Ioannidis, Anastasios; Magiorkinis, Emmanouil; Ursu, Oleg; Bologa, Cristian G; Chatzipanagiotou, Stylianos; Hamblin, Michael R; Tegos, George P

2015-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) remains the single biggest challenge in infectious disease in the civilized world. Moreover, vancomycin resistance is also spreading, leading to fears of untreatable infections as were common in ancient times. Molecular microbiology and bioinformatics have revealed many of the mechanisms involved in resistance development. Mobile genetic elements, up-regulated virulence factors and multi-drug efflux pumps have been implicated. A range of approved antibiotics from the glycopeptide, lipopeptide, pleuromutilin, macrolide, oxazolidinone, lincosamide, aminoglycoside, tetracycline, steptogramin, and cephalosporin classes has been employed to treat MRSA infections. The upcoming pipeline of drugs for MRSA includes some new compounds from the above classes, together with fluoroquinolones, antibacterial peptide mimetics, aminomethylciclines, porphyrins, peptide deformylase inhibitors, oxadiazoles, and diaminopyrimidines. A range of non-drug alternative approaches has emerged for MRSA treatment. Bacteriophage-therapy including purified lysins has made a comeback after being discovered in the 1930s. Quorum-sensing inhibitors are under investigation. Small molecule inhibitors of multi-drug efflux pumps may potentiate existing antibiotics. The relative failure of staphylococcal vaccines is being revisited by efforts with multi-valent vaccines and improved adjuvants. Photodynamic therapy uses non-toxic photosensitizers and harmless visible light to produce reactive oxygen species that can nonspecifically destroy bacteria while preserving host cells. Preparation of nanoparticles can kill bacteria themselves, as well as improve the delivery of anti-bacterial drugs. Anti-MRSA drug discovery remains an exciting field with great promise for the future.

Endogenous and Exogenous KdpF Peptide Increases Susceptibility of Mycobacterium bovis BCG to Nitrosative Stress and Reduces Intramacrophage Replication

PubMed Central

Rosas Olvera, Mariana; Vivès, Eric; Molle, Virginie; Blanc-Potard, Anne-Béatrice; Gannoun-Zaki, Laila

2017-01-01

Emerging antibiotic resistance in pathogenic bacteria like Mycobacterium sp., poses a threat to human health and therefore calls for the development of novel antibacterial strategies. We have recently discovered that bacterial membrane peptides, such as KdpF, possess anti-virulence properties when overproduced in pathogenic bacterial species. Overproduction of the KdpF peptide in Mycobacterium bovis BCG decreased bacterial replication within macrophages, without presenting antibacterial activity. We propose that KdpF functions as a regulatory molecule and interferes with bacterial virulence, potentially through interaction with the PDIM transporter MmpL7. We demonstrate here that KdpF overproduction in M. bovis BCG, increased bacterial susceptibility to nitrosative stress and thereby was responsible for lower replication rate within macrophages. Moreover, in a bacterial two-hybrid system, KdpF was able to interact not only with MmpL7 but also with two membrane proteins involved in nitrosative stress detoxification (NarI and NarK2), and a membrane protein of unknown function that is highly induced upon nitrosative stress (Rv2617c). Interestingly, we showed that the exogenous addition of KdpF synthetic peptide could affect the stability of proteins that interact with this peptide. Finally, the exogenous KdpF peptide presented similar biological effects as the endogenously expressed peptide including nitrosative stress susceptibility and reduced intramacrophage replication rate for M. bovis BCG. Taken together, our results establish a link between high levels of KdpF and nitrosative stress susceptibility to further highlight KdpF as a potent molecule with anti-virulence properties. PMID:28428950

The leader peptide of mutacin 1140 has distinct structural components compared to related class I lantibiotics

PubMed Central

Escano, Jerome; Stauffer, Byron; Brennan, Jacob; Bullock, Monica; Smith, Leif

2014-01-01

Lantibiotics are ribosomally synthesized peptide antibiotics composed of an N-terminal leader peptide that promotes the core peptide's interaction with the post translational modification (PTM) enzymes. Following PTMs, mutacin 1140 is transported out of the cell and the leader peptide is cleaved to yield the antibacterial peptide. Mutacin 1140 leader peptide is structurally unique compared to other class I lantibiotic leader peptides. Herein, we further our understanding of the structural differences of mutacin 1140 leader peptide with regard to other class I leader peptides. We have determined that the length of the leader peptide is important for the biosynthesis of mutacin 1140. We have also determined that mutacin 1140 leader peptide contains a novel four amino acid motif compared to related lantibiotics. PTM enzyme recognition of the leader peptide appears to be evolutionarily distinct from related class I lantibiotics. Our study on mutacin 1140 leader peptide provides a basis for future studies aimed at understanding its interaction with the PTM enzymes. PMID:25400246

Intestinal mucus affinity and biological activity of an orally administered antibacterial and anti-inflammatory peptide.

PubMed

Dupont, Aline; Kaconis, Yani; Yang, Ines; Albers, Thorben; Woltemate, Sabrina; Heinbockel, Lena; Andersson, Mats; Suerbaum, Sebastian; Brandenburg, Klaus; Hornef, Mathias W

2015-02-01

Antimicrobial peptides (AMP) provide protection from infection by pathogenic microorganisms and restrict bacterial growth at epithelial surfaces to maintain mucosal homeostasis. In addition, they exert a significant anti-inflammatory activity. Here we analysed the anatomical distribution and biological activity of an orally administered AMP in the context of bacterial infection and host-microbial homeostasis. The anatomical distribution as well as antibacterial and anti-inflammatory activity of the endogenous AMP cryptdin 2 and the synthetic peptide Pep19-2.5 at the enteric mucosal surface were analysed by immunostaining, functional viability and stimulation assays, an oral Salmonella enterica subsp. enterica sv. Typhimurium (S. Typhimurium) model and comparative microbiota analysis. Endogenous cryptdin 2 was found attached to bacteria of the enteric microbiota within the intestinal mucus layer. Similarly, the synthetic peptide Pep19-2.5 attached rapidly to bacterial cells, exhibited a marked affinity for the intestinal mucus layer in vivo, altered the structural organisation of endotoxin in a mucus matrix and demonstrated potent anti-inflammatory and antibacterial activity. Oral Pep19-2.5 administration induced significant changes in the composition of the enteric microbiota as determined by high-throughput 16S rDNA sequencing. This may have contributed to the only transient improvement of the clinical symptoms after oral infection with S. Typhimurium. Our findings demonstrate the anti-inflammatory activity and mucus affinity of the synthetic AMP Pep19-2.5 and characterise the influence on microbiota composition and enteropathogen infection after oral administration. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Antibacterial and leishmanicidal activities of temporin-SHd, a 17-residue long membrane-damaging peptide.

PubMed

Abbassi, Feten; Raja, Zahid; Oury, Bruno; Gazanion, Elodie; Piesse, Christophe; Sereno, Denis; Nicolas, Pierre; Foulon, Thierry; Ladram, Ali

2013-02-01

Temporins are a family of short antimicrobial peptides (8-17 residues) that mostly show potent activity against Gram-positive bacteria. Herein, we demonstrate that temporin-SHd, a 17-residue peptide with a net charge of +2 (FLPAALAGIGGILGKLF(amide)), expressed a broad spectrum of antimicrobial activity. This peptide displayed potent antibacterial activities against Gram-negative and Gram-positive bacteria, including multi-drug resistant Staphylococcus aureus strains, as well as antiparasitic activity against promastigote and the intracellular stage (amastigote) of Leishmania infantum, at concentration not toxic for the macrophages. Temporin-SHd that is structured in a non-amphipathic α-helix in anionic membrane-mimetic environments, strongly and selectively perturbs anionic bilayer membranes by interacting with the polar head groups and acyl region of the phospholipids, with formation of regions of two coexisting phases: one phase rich in peptide and the other lipid-rich. The disruption of lipid packing within the bilayer may lead to the formation of transient pores and membrane permeation/disruption once a threshold peptide accumulation is reached. To our knowledge, Temporin-SHd represents the first known 17-residue long temporin expressing such broad spectrum of antimicrobial activity including members of the trypanosomatidae family. Additionally, since only a few shorter members (13 residues) of the temporin family are known to display antileishmanial activity (temporins-TA, -TB and -SHa), SHd is an interesting tool to analyze the antiparasitic mechanism of action of temporins. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Marine-Derived Bioactive Peptides for Biomedical Sectors: A Review.

PubMed

Ruiz-Ruiz, Federico; Mancera-Andrade, Elena I; Iqbal, Hafiz M N

2017-01-01

Marine-based resources such as algae and other marine by-products have been recognized as rich sources of structurally diverse bioactive peptides. Evidently, their structural characteristics including unique amino acid residues are responsible for their biological activity. Several of the above-mentioned marine-origin species show multi-functional bioactivities that are useful for a new discovery and/or reinvention of biologically active ingredients, nutraceuticals and/or pharmaceuticals. Therefore, in recent years, marine-derived bioactive peptides have gained a considerable attention with high-value biomedical and/or pharmaceutical potentials. Furthermore, a wider spectrum of bioactive peptides can be produced through proteolytic-assisted hydrolysis of various marine resources under controlled physicochemical (pH and temperature of the reaction media) environment. Owing to their numerous health-related beneficial effects and therapeutic potential in the treatment and/or prevention of many diseases, such marine-derived bioactive peptides exhibit a wider spectrum of biological activities such as anti-cancerous, anti-proliferative, anti-coagulant, antibacterial, antifungal, and anti-tumor activities among many others. Based on emerging evidence of marine-derived peptide mining, the above-mentioned marine resources contain noteworthy levels of high-value protein. The present review article mainly summarizes the marine-derived bioactive peptides and emphasizing their potential applications in biomedical and/or pharmaceutical sectors of the modern world. In conclusion, recent literature has provided evidence that marine-derived bioactive peptides play a critical role in human health along with many possibilities of designing new functional nutraceuticals and/or pharmaceuticals to clarify potent mechanisms of action for a wider spectrum of diseases. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Antibacterial and antiproliferative peptides in synbiotic yogurt-Release and stability during refrigerated storage.

PubMed

Sah, B N P; Vasiljevic, T; McKechnie, S; Donkor, O N

2016-06-01

The search for alternative therapeutics is on the rise due to the extensive increase in bacterial resistance to various conventional antibiotics and side effects of conventional cancer therapies. Bioactive peptides released from natural sources such as dairy foods by lactic acid bacteria have received attention as a potential source of biotherapeutic peptides. However, liberation of peptides in yogurt depends on proteolytic activities of the cultures used. Thus, this research was conducted to establish generation of inhibitory peptides in yogurt against pathogenic bacteria and cancer cells during storage at 4°C for 28d. Water-soluble crude peptide extracts were prepared by high-speed centrifugation of plain and probiotic yogurts supplemented with or without pineapple peel powder (PPP). The inhibition zones against Escherichia coli and Staphylococcus aureus by PPP-fortified probiotic yogurt at 28d of storage were, respectively, 25.89 and 11.72mm in diameter, significantly higher than that of nonsupplemented control yogurts. Antiproliferative activity against HT29 colon cancer cells was also significantly higher in probiotic yogurt with PPP than in nonsupplemented probiotic yogurt. Overall, crude water-soluble peptide extracts of the probiotic yogurt with PPP possessed stronger inhibitory activities against bacteria and cancer cells than controls, and these activities were maintained during storage. However, activities were lowered substantially during in vitro gastrointestinal digestion. These findings support the possibility of utilizing dairy-derived bioactive peptides in the development of a superior alternative to the current generation of antibacterial and anticancer agents, as well as a functional ingredient in foods, nutraceuticals, and pharmaceuticals. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Lactobacillus salivarius: bacteriocin and probiotic activity.

PubMed

Messaoudi, S; Manai, M; Kergourlay, G; Prévost, H; Connil, N; Chobert, J-M; Dousset, X

2013-12-01

Lactic acid bacteria (LAB) antimicrobial peptides typically exhibit antibacterial activity against food-borne pathogens, as well as spoilage bacteria. Therefore, they have attracted the greatest attention as tools for food biopreservation. In some countries LAB are already extensively used as probiotics in food processing and preservation. LAB derived bacteriocins have been utilized as oral, topical antibiotics or disinfectants. Lactobacillus salivarius is a promising probiotic candidate commonly isolated from human, porcine, and avian gastrointestinal tracts (GIT), many of which are producers of unmodified bacteriocins of sub-classes IIa, IIb and IId. It is a well-characterized bacteriocin producer and probiotic organism. Bacteriocins may facilitate the introduction of a producer into an established niche, directly inhibit the invasion of competing strains or pathogens, or modulate the composition of the microbiota and influence the host immune system. This review gives an up-to-date overview of all L. salivarius strains, isolated from different origins, known as bacteriocin producing and/or potential probiotic. Copyright © 2013 Elsevier Ltd. All rights reserved.

Purification of bacteriocins produced by lactic acid bacteria.

PubMed

Saavedra, Lucila; Castellano, Patricia; Sesma, Fernando

2004-01-01

Bacteriocins are antibacterial substances of a proteinaceous nature that are produced by different bacterial species. Lactic acid bacteria (LAB) produce biologically active peptides or protein complexes that display a bactericidal mode of action almost exclusively toward Gram-positive bacteria and particularly toward closely related species. Generally they are active against food spoilage and foodborne pathogenic microorganisms including Bacillus cereus, Clostridium perfringens, Staphylococcus aureus, and Listeria monocytogenes. There is an increased tendency to use natural occurring metabolites to prevent the growth of undesirable flora in foodstuffs. These metabolites could replace the use of chemical additives such as sorbic acid, sulfur dioxide, nitrite, nitrate, and others. For instance, bacteriocins produced by LAB may be promising for use as bio-preservaties. Bacteriocins of lactic acid bacteria are typically cationic, hydrophobic peptides and differ widely in many characteristics including molecular weight, presence of particular groups of amino acids, pI, net positive charge, and post-translational modifications of certain amino acids. This heterogeneity within the LAB bacteriocins may explain the different procedures for isolation and purification developed so far. The methods most frequently used for isolation, concentration, and purification involve salt precipitation of bacteriocins from culture supernatants, followed by various combinations of gel filtration, ion-exchange chromatography, and reverse-phase high-performance liquid chromatography (RP-HPLC). In this chapter, a protocol is described that combines several methods used in our laboratory for the purification of two cationic bacteriocins, Lactocin 705AL and Enterocin CRL10, produced by Lactobacillus casei CRL705 and Enterococcus mundtii CRL10, respectively.

Design and activity of novel lactoferrampin analogues against O157:H7 enterohemorrhagic Escherichia coli.

PubMed

Cruz, Jenniffer; Ortiz, Claudia; Guzmán, Fanny; Cárdenas, Constanza; Fernandez-Lafuente, Roberto; Torres, Rodrigo

2014-04-01

Lactoferrampin 265-284 (LFampin 265-284) is a peptide consisting of residues 265-284 of N1-domain of bovine Lactoferrin (LF). This peptide has several cationic groups in the C-terminal lobe, exhibiting an antibacterial activity against a wide range of microorganisms. However, LFampin 265-284 exhibits low antimicrobial activity against the O157:H7 enterohaemorrhagic Escherichia coli (EHEC O157:H7) when compared with Lactoferrin chimera and Lactoferricin. Here, we have designed three analogues of LFampin 265-284 based on the distribution of cationic groups, hydrophobicity, size, and sequence. Analogues were synthesized by solid phase chemistry using Fmoc methodology obtaining peptides with 95% purity. All peptides maintain the ability to adopt helical conformations (checked by circular dichroism spectra and molecular simulations). Some of these analogues exhibited a significant increase in antimicrobial activity by counting colony forming units against EHEC O157:H7 compared to native LFampin 265-284, with MIC of 10 and 40 µM for 264G-D265K and 264G-D265K/S272R, respectively. The incorporation of a GKLI sequence in the N-terminal lobe increased dramatically its antibacterial activity, an effect which has been attributed to the addition of cationic groups in the N-terminal side that may stabilize the helical conformation of the new designed peptides. Copyright © 2013 Wiley Periodicals, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dae Hong; Lee, Ik Hwan; Nam, Seung Taek

Highlights: • 11-mer peptide Lumbricusin, a defensin like peptide, is isolated from earthworm. • We here demonstrated that Lumbricusin has neurotropic and neuroprotective effects. • p27 degradation by Lumbricusin mediates effects of Lumbricusin on neuronal cells. - Abstract: We recently isolated a polypeptide from the earthworm Lumbricus terrestris that is structurally similar to defensin, a well-known antibacterial peptide. An 11-mer antibacterial peptide (NH{sub 2}-RNRRWCIDQQA), designated Lumbricusin, was synthesized based on the amino acid sequence of the isolated polypeptide. Since we previously reported that CopA3, a dung beetle peptide, enhanced neuronal cell proliferation, we here examined whether Lumbricusin exerted neurotropic and/ormore » neuroprotective effects. Lumbricusin treatment induced a time-dependent increase (∼51%) in the proliferation of human neuroblastoma SH-SY5Y cells. Lumbricusin also significantly inhibited the apoptosis and decreased viability induced by treatment with 6-hydroxy dopamine, a Parkinson’s disease-mimicking agent. Immunoblot analyses revealed that Lumbricusin treatment increased ubiquitination of p27{sup Kip1} protein, a negative regulator of cell-cycle progression, in SH-SY5Y cells, and markedly promoted its degradation. Notably, adenoviral-mediated over-expression of p27{sup Kip1} significantly blocked the antiapoptotic effect of Lumbricusin in 6-hydroxy dopamine-treated SH-SY5Y cells. These results suggest that promotion of p27{sup Kip1} degradation may be the main mechanism underlying the neuroprotective and neurotropic effects of Lumbricusin.« less

Alkynyl-Containing Peptides of Marine Origin: A Review

PubMed Central

Chai, Qiu-Ye; Yang, Zhen; Lin, Hou-Wen; Han, Bing-Nan

2016-01-01

Since the 1990s, a number of terminal alkynyl residue-containing cyclic/acyclic peptides have been identified from marine organisms, especially cyanobacteria and marine mollusks. This review has presented 66 peptides, which covers over 90% marine peptides with terminal alkynyl fatty acyl units. In fact, more than 90% of these peptides described in the literature are of cyanobacterial origin. Interestingly, all the linear peptides featured with terminal alkyne were solely discovered from marine cyanobacteria. The objective of this article is to provide an overview on the types, structural characterization of these unusual terminal alkynyl fatty acyl units, as well as the sources and biological functions of their composed peptides. Many of these peptides have a variety of biological activities, including antitumor, antibacterial, antimalarial, etc. Further, we have also discussed the evident biosynthetic origin responsible for formation of terminal alkynes of natural PKS (polyketide synthase)/NRPS (nonribosome peptide synthetase) hybrids. PMID:27886049

Protein Hydrolysates and Biopeptides: Production, Biological Activities, and Applications in Foods and Health Benefits. A Review.

PubMed

Nasri, M

In recent years, a great deal of interest has been expressed regarding the production, characterization, and applications of protein hydrolysates and food-derived biopeptides due to their numerous beneficial health effects. In this regard, research is mainly focused on investigating the therapeutic potential of these natural compounds. Based on their amino acids composition, sequences, hydrophobicity, and length, peptides released from food proteins, beyond their nutritional properties, can exhibit various biological activities including antihypertensive, antioxidative, antithrombotic, hypoglycemic, hypocholesterolemic, and antibacterial activities among others. Protein hydrolysates are essentially produced by enzymatic hydrolysis of whole protein sources by appropriate proteolytic enzymes under controlled conditions, followed by posthydrolysis processing to isolate desired and potent bioactive peptides from a complex mixture of active and inactive peptides. Therefore, because of their human health potential and safety profiles, protein hydrolysates and biopeptides may be used as ingredients in functional foods and pharmaceuticals to improve human health and prevent diseases. In this review, we have focused on the major variables influencing the enzymatic process of protein hydrolysates production. The biological properties of protein hydrolysates will be described as well as their applications in foods and health benefits. © 2017 Elsevier Inc. All rights reserved.

Properties and applications of antimicrobial peptides in biodefense against biological warfare threat agents.

PubMed

Dawson, Raymond Murray; Liu, Chun-Qiang

2008-01-01

Recent advances in knowledge of the properties of antimicrobial peptides (AMPs) are reviewed. AMPs are typically small, positively charged, amphipathic peptides that interact electrostatically and non-stereospecifically with the bacterial cell membrane, resulting in its permeabilization and cell death. Classes of AMPs, their mechanisms of action, hemolytic activity, and cytotoxicity towards host cells are discussed. A particular focus is AMPs with potential for use in defense against biological warfare agents. Some AMPs cytotoxic to Bacillus anthracis have been described. Synthesis of these peptides in multivalent form leads to a synergistic increase in antibacterial activity. Strategies to enhance the potency, stability, and selectivity of AMPs are discussed.

Spider peptide toxin lycosin-I induces apoptosis and inhibits migration of prostate cancer cells.

PubMed

Shen, Hongwei; Xie, Yuan; Ye, Senlin; He, Kancheng; Yi, Lu; Cui, Rongrong

2018-05-01

Spider toxins are molecularly diverse and some display not only a strong antibacterial effect but also exhibit significant inhibition of tumor growth and promote tumor cell apoptosis. The aim of the present investigation was to explore different antitumor effects of the spider peptide toxin lycosin-I through different pathways at different concentrations. It was found that by inactivating STAT3 pathway, high concentrations of lycosin-I induce apoptosis in prostate cancer cells and low concentrations of lycosin-I inhibit the migration of prostate cancer cells. This finding provides favorable evidence for further study of the molecular diversity of spider toxins. Impact statement The spider peptide toxin has become an important research topic. These toxins are molecularly diverse and some display not only a strong antibacterial effect but also exhibit significant inhibition of tumor growth and promote tumor cell apoptosis. Inspired by previous studies, the present study aims to investigate the effects of different concentrations of lycosin-I on the invasiveness and apoptosis of human prostate cancer cells. The findings provide favorable evidence for further study of the molecular diversity of spider toxins.

Phylloseptins: a novel class of anti-bacterial and anti-protozoan peptides from the Phyllomedusa genus.

PubMed

Leite, José Roberto S A; Silva, Luciano P; Rodrigues, Maria Izabel S; Prates, Maura V; Brand, Guilherme D; Lacava, Bruno M; Azevedo, Ricardo B; Bocca, Anamélia L; Albuquerque, Sergio; Bloch, Carlos

2005-04-01

Six novel peptides called phylloseptins (PS-1, -2, -3, -4, -5, and -6) showing anti-bacterial (PS-1) and anti-protozoan (PS-4 and -5) activities were isolated from the skin secretion of the Brazilian tree-frogs, Phyllomedusa hypochondrialis and Phyllomedusa oreades. Phylloseptins have a primary structure consisting of 19-21 amino acid residues (1.7-2.1 kDa). They have common structural features, such as a highly conserved N-terminal region and C-terminal amidation. Phylloseptin-1 (FLSLIPHAINAVSAIAKHN-NH2) demonstrated a strong effect against gram-positive and gram-negative bacteria (MICs ranging from 3 to 7.9 microM), without showing significant hemolytic activity (<0.6% at the MIC range) towards mammalian cells. Atomic force microscopy experiments indicated that the bacteriolytic properties of these peptides might be related to their disruptive action on the cell membrane, characterized by a number of bubble-like formations, preceding every cell lysis. PS-4 and PS-5 showed anti-protozoan activity with IC50 at about 5 microM for Trypanosoma cruzi.

Design, Synthesis and Affinity Properties of Biologically Active Peptide and Protein Conjugates of Cotton Cellulose

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, J. V.; Goheen, Steven C.

The formation of peptide and protein conjugates of cellulose on cotton fabrics provides promising leads for the development of wound healing, antibacterial, and decontaminating textiles. An approach to the design, synthesis, and analysis of bioconjugates containing cellulose peptide and protein conjugates includes: 1) computer graphic modeling for a rationally designed structure; 2) attachment of the peptide or protein to cotton cellulose through a linker amino acid, and 3) characterization of the resulting bioconjugate. Computer graphic simulation of protein and peptide cellulose conjugates gives a rationally designed biopolymer to target synthetic modifications to the cotton cellulose. Techniques for preparing these typesmore » of conjugates involve both sequential assembly of the peptide on the fabric and direct crosslinking of the peptide or protein as cellulose bound esters or carboxymethylcellulose amides.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, C.; Coggill, P.; Bateman, A.

Many Gram-positive lactic acid bacteria (LAB) produce anti-bacterial peptides and small proteins called bacteriocins, which enable them to compete against other bacteria in the environment. These peptides fall structurally into three different classes, I, II, III, with class IIa being pediocin-like single entities and class IIb being two-peptide bacteriocins. Self-protective cognate immunity proteins are usually co-transcribed with these toxins. Several examples of cognates for IIa have already been solved structurally. Streptococcus pyogenes, closely related to LAB, is one of the most common human pathogens, so knowledge of how it competes against other LAB species is likely to prove invaluable. Wemore » have solved the crystal structure of the gene-product of locus Spy-2152 from S. pyogenes, (PDB: 2fu2), and found it to comprise an anti-parallel four-helix bundle that is structurally similar to other bacteriocin immunity proteins. Sequence analyses indicate this protein to be a possible immunity protein protective against class IIa or IIb bacteriocins. However, given that S. pyogenes appears to lack any IIa pediocin-like proteins but does possess class IIb bacteriocins, we suggest this protein confers immunity to IIb-like peptides. Combined structural, genomic and proteomic analyses have allowed the identification and in silico characterization of a new putative immunity protein from S. pyogenes, possibly the first structure of an immunity protein protective against potential class IIb two-peptide bacteriocins. We have named the two pairs of putative bacteriocins found in S. pyogenes pyogenecin 1, 2, 3 and 4.« less

De-Novo Design of Antimicrobial Peptides for Plant Protection

PubMed Central

Zeitler, Benjamin; Herrera Diaz, Areli; Dangel, Alexandra; Thellmann, Martha; Meyer, Helge; Sattler, Michael; Lindermayr, Christian

2013-01-01

This work describes the de-novo design of peptides that inhibit a broad range of plant pathogens. Four structurally different groups of peptides were developed that differ in size and position of their charged and hydrophobic clusters and were assayed for their ability to inhibit bacterial growth and fungal spore germination. Several peptides are highly active at concentrations between 0,1 and 1 µg/ml against plant pathogenic bacteria, such as Pseudomonas syringae, Pectobacterium carotovorum, and Xanthomonas vesicatoria. Importantly, no hemolytic activity could be detected for these peptides at concentrations up to 200 µg/ml. Moreover, the peptides are also active after spraying on the plant surface demonstrating a possible way of application. In sum, our designed peptides represent new antimicrobial agents and with the increasing demand for antimicrobial compounds for production of “healthy” food, these peptides might serve as templates for novel antibacterial and antifungal agents. PMID:23951222

De-novo design of antimicrobial peptides for plant protection.

PubMed

Zeitler, Benjamin; Herrera Diaz, Areli; Dangel, Alexandra; Thellmann, Martha; Meyer, Helge; Sattler, Michael; Lindermayr, Christian

2013-01-01

This work describes the de-novo design of peptides that inhibit a broad range of plant pathogens. Four structurally different groups of peptides were developed that differ in size and position of their charged and hydrophobic clusters and were assayed for their ability to inhibit bacterial growth and fungal spore germination. Several peptides are highly active at concentrations between 0,1 and 1 µg/ml against plant pathogenic bacteria, such as Pseudomonas syringae, Pectobacterium carotovorum, and Xanthomonas vesicatoria. Importantly, no hemolytic activity could be detected for these peptides at concentrations up to 200 µg/ml. Moreover, the peptides are also active after spraying on the plant surface demonstrating a possible way of application. In sum, our designed peptides represent new antimicrobial agents and with the increasing demand for antimicrobial compounds for production of "healthy" food, these peptides might serve as templates for novel antibacterial and antifungal agents.

A simple fragment of cyclic acyldepsipeptides is necessary and sufficient for ClpP activation and antibacterial activity.

PubMed

Carney, Daniel W; Compton, Corey L; Schmitz, Karl R; Stevens, Julia P; Sauer, Robert T; Sello, Jason K

2014-10-13

The development of new antibacterial agents, particularly those with unique biological targets, is essential to keep pace with the inevitable emergence of drug resistance in pathogenic bacteria. We identified the minimal structural component of the cyclic acyldepsipeptide (ADEP) antibiotics that exhibits antibacterial activity. We found that N-acyldifluorophenylalanine fragments function via the same mechanism of action as ADEPs, as evidenced by the requirement of ClpP for the fragments' antibacterial activity, the ability of fragments to activate Bacillus subtilis ClpP in vitro, and the capacity of an N-acyldifluorophenylalanine affinity matrix to capture ClpP from B. subtilis cell lysates. N-acyldifluorophenylalanine fragments are much simpler in structure than the full ADEPs and are also highly amenable to structural diversification. Thus, the stage has been set for the development of non-peptide activators of ClpP that can be used as antibacterial agents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fusion expression of the PGLa-AM1 with native structure and evaluation of its anti-Helicobacter pylori activity.

PubMed

Zhang, Xiaolin; Jiang, Anmin; Wang, Guisheng; Yu, Hao; Qi, Banghua; Xiong, Youyi; Zhou, Guoliang; Qin, Meisong; Dou, Jinfeng; Wang, Jianfei

2017-07-01

Helicobacter pylori (H. pylori) shows increasingly enhanced resistance to various antibiotics, and its eradication has become a major problem in medicine. The antimicrobial peptide PGLa-AM1 is a short peptide with 22 amino acids and exhibits strong antibacterial activity. In this study, we investigated whether it has anti-H. pylori activity for the further development of anti-H. pylori drugs to replace existing antibiotics. However, the natural antimicrobial peptide PGLa-AM1 shows a low yield and is difficult to separate, limiting its application. A good strategy to solve this problem is to express the antimicrobial peptide PGLa-AM1 using gene engineering at a high level and low cost. For getting PGLa-AM1 with native structure, in this study, a specific protease cleavage site of tobacco etch virus (TEV) was designed before the PGLa-AM1 peptide. For convenience to purify and identify high-efficiency expression PGLa-AM1, the PGLa-AM1 gene was fused with the polyhedrin gene of Bombyx mori (B. mori), and a 6 × His tag was designed to insert before the amino terminus of the fusion protein. The fusion antibacterial peptide PGLa-AM1 (FAMP) gene codon was optimized, and the gene was synthesized and cloned into the Escherichia coli (E. coli) pET-30a (+) expression vector. The results showed that the FAMP was successfully expressed in E. coli. Its molecular weight was approximately 34 kDa, and its expression level was approximately 30 mg/L. After the FAMP was purified, it was further digested with TEV protease. The acquired recombinant antimicrobial peptide PGLa-AM1 exerted strong anti-H. pylori activity and therapeutic effect in vitro and in vivo.

A novel synthetic peptide inspired on Lys49 phospholipase A2 from Crotalus oreganus abyssus snake venom active against multidrug-resistant clinical isolates.

PubMed

Almeida, José R; Mendes, Bruno; Lancellotti, Marcelo; Marangoni, Sergio; Vale, Nuno; Passos, Óscar; Ramos, Maria J; Fernandes, Pedro A; Gomes, Paula; Da Silva, Saulo L

2018-04-10

Currently, the evolving and complex mechanisms of bacterial resistance to conventional antibiotics are increasing, while alternative medicines are drying up, which urges the need to discover novel agents able to kill antibiotic-resistant bacteria. Lys49 phospholipase A 2 s (PLA 2 s) from snake venoms are multifunctional toxins able to induce a huge variety of therapeutic effects and consequently serve as templates for new drug leads. Hence, the present study was aimed at the synthesis of oligopeptides mimicking regions of the antibacterial Lys49 PLA 2 toxin (CoaTx-II), recently isolated from Crotalus oreganus abyssus snake venom, to identify small peptides able to reproduce the therapeutic action of the toxin. Five peptides, representing major regions of interest within CoaTx-II, were synthesized and screened for their antibacterial properties. The 13-mer peptide pC-CoaTxII, corresponding to residues 115-129 of CoaTx-II, was able to reproduce the promising bactericidal effect of the toxin against multi-resistant clinical isolates. Peptide pC-CoaTxII is mainly composed by positively charged and hydrophobic amino acids, a typical trait in most antimicrobial peptides, and presented no defined secondary structure in aqueous environment. The physicochemical properties of pC-CoaTxII are favorable towards a strong interaction with anionic lipid membranes as those in bacteria. Additional in silico studies suggest formation of a water channel across the membrane upon peptide insertion, eventually leading to bacterial cell disruption and death. Overall, our findings confirm the valuable potential of snake venom toxins towards design and synthesis of novel antimicrobials, thus representing key insights towards development of alternative efficient antimicrobials to fight bacterial resistance to current antibiotics. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Human Lactoferrin and Peptides Derived from a Surface-Exposed Helical Region Reduce Experimental Escherichia coli Urinary Tract Infection in Mice

PubMed Central

Håversen, Liliana A.; Engberg, Inga; Baltzer, Lars; Dolphin, Gunnar; Hanson, Lars Å.; Mattsby-Baltzer, Inger

2000-01-01

Lactoferrin (LF) is a multifunctional immunoregulatory protein that has been associated with host defense at mucosal surfaces through its antibacterial properties. The antibacterial and anti-inflammatory properties of LF were further explored with an animal model of experimental urinary tract infection. Bovine LF (bLF), human LF (hLF), and synthetic peptide sequences based on the antibacterial region of hLF (amino acid residues 16 to 40 [HLD1] and 18 to 40 [HLD2]) were given orally to female mice 30 min after the instillation of 108 Escherichia coli bacteria into the urinary bladder. The control groups received phosphate-buffered saline or water. C3H/Tif mice were treated with hLF or bLF, and C3H/HeN mice were treated with bLF only. The numbers of bacteria in the kidneys and bladder of C3H/Tif and C3H/HeN mice were significantly reduced 24 h later by the LF treatments compared to the findings for the control group. The hLF-treated group showed the strongest reduction compared with the vehicle-treated-group (P values were 0.009 and 0.0001 for the kidneys and bladder, respectively). The urinary leukocyte response was diminished in the hLF-treated group. The hLF treatment also significantly reduced the urinary interleukin-6 (IL-6) levels at 2 h and the systemic IL-6 levels at 24 h after infection (P values were 0.04 and < 0.002, respectively). In the bLF-treated animals, no such strong anti-inflammatory effects were obtained. In another series of experiments, C3H/Tif mice perorally treated with HLD1 or HLD2 also showed reduced numbers of bacteria in the kidneys compared with the vehicle-treated mice, although the results were significantly different only for HLD2 (P < 0.01). Analysis of urine from hLF-fed C3H/Tif mice showed that hLF was excreted into the urinary tract at 2 h after feeding. Testing of the in vitro bactericidal activity of LF (1 mg/ml) or the peptides (0.1 mg/ml) in mouse urine against the E. coli bacteria revealed moderate killing only by HLD2. In conclusion, these results demonstrate for the first time that oral administration of hLF or peptides thereof is effective in reducing infection and inflammation at a remote site, the urinary tract, possibly through transfer of hLF or its peptides to the site of infection via renal secretion. The antibacterial mechanism is suggested to involve bactericidal capacities of LF, fragments thereof, or its peptides. PMID:10992490

cDNA cloning and characterization of the antibacterial peptide cecropin 1 from the diamondback moth, Plutella xylostella L.

PubMed

Jin, Fengliang; Sun, Qiang; Xu, Xiaoxia; Li, Linmiao; Gao, Gang; Xu, Yingjie; Yu, Xiaoqiang; Ren, Shunxiang

2012-10-01

Cecropins are linear cationic antibacterial peptides that have potent activities against microorganisms. In the present study, a 480bp full-length cDNA encoding diamondback moth (Plutella xylostella) cecropin 1 (designated as Px-cec1) was obtained using RT-PCR. A Northern blot analysis showed that the Px-cec1 transcript was predominantly expressed in fat bodies, hemocytes, midgut and epidermis with the highest expression level in fat bodies. The expression of Px-cec1 mRNA in fat bodies was significantly increased 24h after microbial challenge, with the highest induced expression by Staphylococcus aureus. A circular dichroism (CD) analysis revealed that the recombinant Px-cec1 mainly contained α-helixes. Antimicrobial assays demonstrated that recombinant Px-cec1 exhibited a broad spectrum of anti-microbial properties against fungi, Gram-positive and Gram-negative bacteria, but it did not exhibit hemolytic activity against human erythrocytes. Furthermore, Px-cec1 caused significant morphological alterations of S. aureus, as shown by scanning electron microscopy and transmission electron microscopy. These results demonstrated that Px-cec1 exerts its antibacterial activity by acting on the cell membrane to disrupt bacterial cell structures. Copyright © 2012 Elsevier Inc. All rights reserved.

Production process of a new cellulosic fiber with antimicrobial properties.

PubMed

Zikeli, Stefan

2006-01-01

The Lyocell process (system: cellulose-water-N-methylmorpholine oxide) of Zimmer AG offers special advantages for the production of cellulose fibers. The process excels by dissolving the most diverse cellulose types as these are optimally adjusted to the process by applying different pretreatment methods. Based on this stable process, Zimmer AG's objective is to impart to the Lyocell fiber additional value to improve quality of life and thus to tap new markets for the product. Thanks to the specific incorporation of seaweed, the process allows to produce cellulose Lyocell fibers with additional and new features. They are activated in a further step - by specific charging with metal ions - in order to obtain antibacterial properties. The favorable textile properties of fibers produced by the Lyocell process are not adversely affected by the incorporation of seaweed material or by activation to obtain an antibacterial fiber so that current textile products can be made from the fibers thus produced. The antibacterial effect is achieved by metal ion activation of the Lyocell fibers with incorporated seaweed, which contrasts with the antibacterial fibers known so far. Antibacterial fibers produced by conventional methods are in part only surface finished with antibacterially active chemicals or else they are produced by incorporating organic substances with antibacterial and fungicidal effects. Being made from cellulose, the antibacterial Lyocell fiber Sea Cell Active as the basis for quality textiles exhibits a special wear comfort compared to synthetic fibers with antibacterial properties and effects. This justifies the conclusion that the Zimmer Lyocell process provides genuine value added and that it is a springboard for further applications.

Antifungal properties of durancins isolated from Enterococcus durans A5-11 and of its synthetic fragments.

PubMed

Belguesmia, Y; Choiset, Y; Rabesona, H; Baudy-Floc'h, M; Le Blay, G; Haertlé, T; Chobert, J-M

2013-04-01

The aim of this work was to study the antifungal properties of durancins isolated from Enterococcus durans A5-11 and of their chemically synthesized fragments. Enterococcus durans A5-11 is a lactic acid bacteria strain isolated from traditional Mongolian airag cheese. This strain inhibits the growth of several fungi including Fusarium culmorum, Penicillium roqueforti and Debaryomyces hansenii. It produces two bacteriocins: durancin A5-11a and durancin A5-11b, which have similar antimicrobial properties. The whole durancins A5-11a and A5-11b, as well as their N- and C-terminal fragments were synthesized, and their antifungal properties were studied. C-terminal fragments of both durancins showed stronger antifungal activities than other tested peptides. Treatment of D. hansenii LMSA2.11.003 strain with 2 mmol l(-1) of the synthetic peptides led to the loss of the membrane integrity and to several changes in the ultra-structure of the yeast cells. Chemically synthesized durancins and their synthetic fragments showed different antimicrobial properties from each other. N-terminal peptides show activities against both bacterial and fungal strains tested. C-terminal peptides have specific activities against tested fungal strain and do not show antibacterial activity. However, the C-terminal fragment enhances the activity of the N-terminal fragment in the whole bacteriocins against bacteria. © 2012 The Society for Applied Microbiology.

Design of bactericidal peptides against Escherichia coli O157:H7, Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus.

PubMed

Cruz, Jenniffer; Rondon, Paola; Torres, Rodrigo; Urquiza, Mauricio; Guzman, Fanny; Alvarez, Claudio; Abengozar, Maria Angeles; Sierra, Daniel A; Rivas, Luis; Fernandez-Lafuente, Roberto; Ortiz, Claudia

2018-05-08

Antimicrobial peptides are on the first line of defense against pathogenic microorganisms of many living beings. These compounds are considered natural antibiotics that can overcome bacterial resistance to conventional antibiotics. Due to this characteristic, new peptides with improved properties are quite appealing for designing new strategies for fighting pathogenic bacteria Methods: Sixteen designed peptides were synthesized using Fmoc chemistry; five of them are new cationic antimicrobial peptides (CAMPs) designed using a genetic algorithm that optimizes the antibacterial activity based on selected physicochemical descriptors and 11 analog peptides derived from these five peptides were designed and constructed by single amino acid substitutions. These 16 peptides were structurally characterized and their biological activity was determined against Escherichia coli O157:H7 (E. coli O157:H7), and methicillin-resistant strains of Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (P. aeruginosa) were determined Results: These 16 peptides were folded into an α-helix structure in membrane-mimicking environment. Among these 16 peptides, GIBIM-P5S9K (ATKKCGLFKILKGVGKI) showed the highest antimicrobial activity against E. coli O157:H7 (MIC=10µM), methicillin resistant Staphylococcus aureus (MRSA) (MIC=25µM) and Pseudomonas aeruginosa (MIC=10 µM). Peptide GIBIM-P5S9K caused permeabilization of the bacterial membrane at 25 µM as determined by the Sytox Green uptake assay and the labelling of these bacteria by using the fluoresceinated peptide. GIBIM-P5S9K seems to be specific for these bacteria because at 50 µM provoked lower than 40% of erythrocyte hemolysis. New CAMPs have been designed using a genetic algorithm based on selected physicochemical descriptors and single amino acid substitution. These CAMPs interacted quite specifically with the bacterial cell membrane, GIBIM-P5S9K exhibiting high antibacterial activity on Escherichia coli O157:H7, methicillin resistant strains of Staphylococcus aureus and P. aeruginosa. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

The leader peptide of mutacin 1140 has distinct structural components compared to related class I lantibiotics.

PubMed

Escano, Jerome; Stauffer, Byron; Brennan, Jacob; Bullock, Monica; Smith, Leif

2014-12-01

Lantibiotics are ribosomally synthesized peptide antibiotics composed of an N-terminal leader peptide that promotes the core peptide's interaction with the post translational modification (PTM) enzymes. Following PTMs, mutacin 1140 is transported out of the cell and the leader peptide is cleaved to yield the antibacterial peptide. Mutacin 1140 leader peptide is structurally unique compared to other class I lantibiotic leader peptides. Herein, we further our understanding of the structural differences of mutacin 1140 leader peptide with regard to other class I leader peptides. We have determined that the length of the leader peptide is important for the biosynthesis of mutacin 1140. We have also determined that mutacin 1140 leader peptide contains a novel four amino acid motif compared to related lantibiotics. PTM enzyme recognition of the leader peptide appears to be evolutionarily distinct from related class I lantibiotics. Our study on mutacin 1140 leader peptide provides a basis for future studies aimed at understanding its interaction with the PTM enzymes. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Peptides, Peptidomimetics, and Polypeptides from Marine Sources: A Wealth of Natural Sources for Pharmaceutical Applications

PubMed Central

Sable, Rushikesh; Parajuli, Pravin; Jois, Seetharama

2017-01-01

Nature provides a variety of peptides that are expressed in most living species. Evolutionary pressure and natural selection have created and optimized these peptides to bind to receptors with high affinity. Hence, natural resources provide an abundant chemical space to be explored in peptide-based drug discovery. Marine peptides can be extracted by simple solvent extraction techniques. The advancement of analytical techniques has made it possible to obtain pure peptides from natural resources. Extracted peptides have been evaluated as possible therapeutic agents for a wide range of diseases, including antibacterial, antifungal, antidiabetic and anticancer activity as well as cardiovascular and neurotoxin activity. Although marine resources provide thousands of possible peptides, only a few peptides derived from marine sources have reached the pharmaceutical market. This review focuses on some of the peptides derived from marine sources in the past ten years and gives a brief review of those that are currently in clinical trials or on the market. PMID:28441741

Tissue factor pathway inhibitor 2 is found in skin and its C-terminal region encodes for antibacterial activity.

PubMed

Papareddy, Praveen; Kalle, Martina; Sørensen, Ole E; Lundqvist, Katarina; Mörgelin, Matthias; Malmsten, Martin; Schmidtchen, Artur

2012-01-01

Tissue factor pathway inhibitor 2 (TFPI-2) is a matrix-associated serine protease inhibitor with an enigmatic function in vivo. Here, we describe that TFPI-2 is present in fibrin of wounds and also expressed in skin, where it is up-regulated upon wounding. Neutrophil elastase cleaved TFPI-2, and a C-terminal fragment was found to bind to bacteria. Similarly, a prototypic peptide representing this C-terminal part, EDC34, bound to bacteria and bacterial lipopolysaccharide, and induced bacterial permeabilization. The peptide also induced leakage in artificial liposomes, and displayed a random coil conformation upon interactions with liposomes as well as lipopolysaccharide. EDC34 was antibacterial against both Gram-negative and Gram-positive bacteria in physiological buffer conditions. The results demonstrate that the C-terminus of TFPI-2 encodes for antimicrobial activity, and may be released during wounding.

New peptide deformylase inhibitors design, synthesis and pharmacokinetic assessment.

PubMed

Lv, Fengping; Chen, Chen; Tang, Yang; Wei, Jianhai; Zhu, Tong; Hu, Wenhao

2016-08-01

The docking approach for the screening of designed small molecule ligands, led to the identification of a critical arginine residue in peptide deformylase for spiro cyclopropyl PDF inhibitor's extra hydrophobic binding, providing us a useful tool for searching more efficient PDF inhibitors to fight for horrifying antibiotics resistance. Further synthetic modification was undertaken to optimize the potency of amide compounds. To lower metabolic susceptibility and in turn reduce unwanted metabolic toxicity that was observed clinically, while retaining desired antibacterial activity, the use of azoles as amide bioisosteres had also been investigated. After the completion of chemical synthesis, all the compounds were evaluated through in vitro antibacterial activity assay, some of which were further subject to in vivo rat pharmacokinetic assessment. Those findings in this letter showed that spiro cyclopropyl proline N-formyl hydroxylamines, and especially the bioisosteric azoles, can represent a promising class of PDF inhibitors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Paenilamicin: structure and biosynthesis of a hybrid nonribosomal peptide/polyketide antibiotic from the bee pathogen Paenibacillus larvae.

PubMed

Müller, Sebastian; Garcia-Gonzalez, Eva; Mainz, Andi; Hertlein, Gillian; Heid, Nina C; Mösker, Eva; van den Elst, Hans; Overkleeft, Herman S; Genersch, Elke; Süssmuth, Roderich D

2014-09-26

The spore-forming bacterium Paenibacillus larvae is the causative agent of American Foulbrood (AFB), a fatal disease of honey bees that occurs worldwide. Previously, we identified a complex hybrid nonribosomal peptide/polyketide synthesis (NRPS/PKS) gene cluster in the genome of P. larvae. Herein, we present the isolation and structure elucidation of the antibacterial and antifungal products of this gene cluster, termed paenilamicins. The unique structures of the paenilamicins give deep insight into the underlying complex hybrid NRPS/PKS biosynthetic machinery. Bee larval co-infection assays reveal that the paenilamicins are employed by P. larvae in fighting ecological niche competitors and are not directly involved in killing the bee larvae. Their antibacterial and antifungal activities qualify the paenilamicins as attractive candidates for drug development. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antimicrobial Dendrimeric Peptides: Structure, Activity and New Therapeutic Applications

PubMed Central

Scorciapino, Mariano A.; Serra, Ilaria; Manzo, Giorgia; Rinaldi, Andrea C.

2017-01-01

Microbial resistance to conventional antibiotics is one of the most outstanding medical and scientific challenges of our times. Despite the recognised need for new anti-infective agents, however, very few new drugs have been brought to the market and to the clinic in the last three decades. This review highlights the properties of a new class of antibiotics, namely dendrimeric peptides. These intriguing novel compounds, generally made of multiple peptidic sequences linked to an inner branched core, display an array of antibacterial, antiviral and antifungal activities, usually coupled to low haemolytic activity. In addition, several peptides synthesized in oligobranched form proved to be promising tools for the selective treatment of cancer cells. PMID:28273806

Antimicrobial Dendrimeric Peptides: Structure, Activity and New Therapeutic Applications.

PubMed

Scorciapino, Mariano A; Serra, Ilaria; Manzo, Giorgia; Rinaldi, Andrea C

2017-03-03

Microbial resistance to conventional antibiotics is one of the most outstanding medical and scientific challenges of our times. Despite the recognised need for new anti-infective agents, however, very few new drugs have been brought to the market and to the clinic in the last three decades. This review highlights the properties of a new class of antibiotics, namely dendrimeric peptides. These intriguing novel compounds, generally made of multiple peptidic sequences linked to an inner branched core, display an array of antibacterial, antiviral and antifungal activities, usually coupled to low haemolytic activity. In addition, several peptides synthesized in oligobranched form proved to be promising tools for the selective treatment of cancer cells.

Isolation of an invertebrate-type lysozyme from the nephridia of the echiura, Urechis unicinctus, and its recombinant production and activities.

PubMed

Oh, Hye Young; Kim, Chan-Hee; Go, Hye-Jin; Park, Nam Gyu

2018-05-09

Invertebrates, unlike vertebrates which have adaptive immune system, rely heavily on the innate immune system for the defense against pathogenic bacteria. Lysozymes, along with other immune effectors, are regarded as an important group in this defense. An invertebrate-type (i-type) lysozyme, designated Urechis unicinctus invertebrate-type lysozyme, Uu-ilys, has been isolated from nephridia of Urechis unicinctus using a series of high performance liquid chromatography (HPLC), and ultrasensitive radial diffusion assay (URDA) as a bioassay system. Analyses of the primary structure and cDNA cloning revealed that Uu-ilys was approximately 14 kDa and composed of 122 amino acids (AAs) of which the precursor had a total of 160 AAs containing a signal peptide of 18 AAs and a pro-sequence of 20 AAs encoded by the nucleotide sequence of 714 bp that comprises a 5' untranslated region (UTR) of 42 bp, an open reading frame (ORF) of 483 bp, and a 3' UTR of 189 bp. Multiple sequence alignment showed Uu-ilys has high homology to i-type lysozymes from several annelids. Relatively high transcriptional expression levels of Uu-ilys was detected in nephridia, anal vesicle, and intestine. The native Uu-ilys exhibited comparable lysozyme enzymatic and antibacterial activities to hen egg white lysozyme. Collectively, these data suggest that Uu-ilys, the isolated antibacterial protein, plays a role in the immune defense mechanism of U. unicinctus. Recombinant Uu-ilys (rUu-ilys) produced in a bacterial expression system showed significantly decreased lysozyme lytic activity from that of the native while its potency on radial diffusion assay detecting antibacterial activity was retained, which may indicate the non-enzymatic antibacterial capacity of Uu-ilys. Copyright © 2018. Published by Elsevier Ltd.

Small cationic antimicrobial peptides delocalize peripheral membrane proteins

PubMed Central

Wenzel, Michaela; Chiriac, Alina Iulia; Otto, Andreas; Zweytick, Dagmar; May, Caroline; Schumacher, Catherine; Gust, Ronald; Albada, H. Bauke; Penkova, Maya; Krämer, Ute; Erdmann, Ralf; Metzler-Nolte, Nils; Straus, Suzana K.; Bremer, Erhard; Becher, Dörte; Brötz-Oesterhelt, Heike; Sahl, Hans-Georg; Bandow, Julia Elisabeth

2014-01-01

Short antimicrobial peptides rich in arginine (R) and tryptophan (W) interact with membranes. To learn how this interaction leads to bacterial death, we characterized the effects of the minimal pharmacophore RWRWRW-NH2. A ruthenium-substituted derivative of this peptide localized to the membrane in vivo, and the peptide also integrated readily into mixed phospholipid bilayers that resemble Gram-positive membranes. Proteome and Western blot analyses showed that integration of the peptide caused delocalization of peripheral membrane proteins essential for respiration and cell-wall biosynthesis, limiting cellular energy and undermining cell-wall integrity. This delocalization phenomenon also was observed with the cyclic peptide gramicidin S, indicating the generality of the mechanism. Exogenous glutamate increases tolerance to the peptide, indicating that osmotic destabilization also contributes to antibacterial efficacy. Bacillus subtilis responds to peptide stress by releasing osmoprotective amino acids, in part via mechanosensitive channels. This response is triggered by membrane-targeting bacteriolytic peptides of different structural classes as well as by hypoosmotic conditions. PMID:24706874

Novel Polymyxin Derivatives Carrying Only Three Positive Charges Are Effective Antibacterial Agents ▿

PubMed Central

Vaara, Martti; Fox, John; Loidl, Günther; Siikanen, Osmo; Apajalahti, Juha; Hansen, Frank; Frimodt-Møller, Niels; Nagai, Junya; Takano, Mikihisa; Vaara, Timo

2008-01-01

The lack of novel antibiotics against gram-negative bacteria has reinstated polymyxins as the drugs of last resort to treat serious infections caused by extremely multiresistant gram-negative organisms. However, polymyxins are nephrotoxic, and this feature may complicate therapy or even require its discontinuation. Like that of aminoglycosides, the nephrotoxicity of polymyxins might be related to the highly cationic nature of the molecule. Colistin and polymyxin B carry five positive charges. Here we show that novel polymyxin derivatives carrying only three positive charges are effective antibacterial agents. NAB739 has a cyclic peptide portion identical to that of polymyxin B, but in the linear portion of the peptide, it carries the threonyl-d-serinyl residue (no cationic charges) instead of the diaminobutyryl-threonyl-diaminobutyryl residue (two cationic charges). The MICs of NAB739 for 17 strains of Escherichia coli were identical, or very close, to those of polymyxin B. Furthermore, NAB739 was effective against other polymyxin-susceptible strains of Enterobacteriaceae and against Acinetobacter baumannii. At subinhibitory concentrations, it dramatically sensitized A. baumannii to low concentrations of antibiotics such as rifampin, clarithromycin, vancomycin, fusidic acid, and meropenem. NAB739 methanesulfonate was a prodrug analogous to colistin methanesulfonate. NAB740 was the most active derivative against Pseudomonas aeruginosa. NAB7061 (linear portion of the peptide, threonyl-aminobutyryl) lacked direct antibacterial activity but sensitized the targets to hydrophobic antibiotics by factors up to 2,000. The affinities of the NAB compounds for isolated rat kidney brush border membrane were significantly lower than that of polymyxin B. PMID:18591267

Isolation of Salmonella spp. from lettuce and evaluation of its susceptibility to novel bacteriocins of Bacillus thuringiensis and antibiotics.

PubMed

Castañeda-Ramírez, Cristobal; Cortes-Rodríguez, Viridiana; de la Fuente-Salcido, Norma; Bideshi, Dennis K; del Rincón-Castro, M Cristina; Barboza-Corona, J Eleazar

2011-02-01

In this study, 13% of fresh lettuce (Lactuca sativa) samples collected from markets and supermarkets in two cities of Mexico were contaminated with Salmonella spp. From those samples, amplicons of ∼300 base pairs (bp) were amplified, corresponding to the expected size of the invasion (invA) and internal transcribed spacer regions of the 16S and 23S rRNA genes of Salmonella spp. Additionally, Salmonella strains were isolated and harbored plasmids ranging from ∼9 to 16 kbp. From these strains, 91% were resistant to ampicillin and nitrofurantoin, whereas 55% were resistant to cephalothin and chloramphenicol. No resistance was detected to amikacin, carbenicillin, cefotaxime, gentamicin, netilmicin, norfloxacin, and sulfamethoxazole-trimethoprim. When Salmonella isolates were tested against novel bacteriocins (morricin 269, kurstacin 287, kenyacin 404, entomocin 420, and tolworthcin 524) produced by five Mexican strains of Bacillus thuringiensis, 50% were susceptible to these antimicrobial peptides. This is the first report showing that Salmonella strains isolated from lettuce are susceptible to bacteriocins produced by the most important bioinsecticide worldwide, suggesting the potential use of these antibacterial peptides as therapeutic agents or food preservatives to reduce or destroy populations of Salmonella spp. Copyright ©, International Association for Food Protection

A Diverse Family of Host-Defense Peptides (Piscidins) Exhibit Specialized Anti-Bacterial and Anti-Protozoal Activities in Fishes.

PubMed

Salger, Scott A; Cassady, Katherine R; Reading, Benjamin J; Noga, Edward J

2016-01-01

Conventional antibiotics and other chemical-based drugs are currently one of the most common methods used to control disease-related mortality in animal agriculture. Use of the innate immune system to decrease disease related mortalities is a novel alternative to conventional drugs. One component of the innate immune system is the host-defense peptides, also known as antimicrobial peptides. Host-defense peptides are typically small, amphipathic, α-helical peptides with a broad-spectrum of action against viral, bacterial, fungal, and/or protozoal pathogens. Piscidins are host-defense peptides first discovered in the hybrid striped bass (white bass, Morone chrysops, x striped bass, M. saxatilis). In this paper we identify four new piscidin isoforms in the hybrid striped bass and describe their tissue distributions. We also determine the progenitor species of origin of each piscidin (orthology) and propose a revised nomenclature for this newly described piscidin family based on a three class system. The Class I piscidins (22 amino acids in length; striped bass and white bass piscidin 1 and piscidin 3) show broad-spectrum activity against bacteria and ciliated protozoans, while the Class III piscidins (55 amino acids in length; striped bass and white bass piscidin 6 and striped bass piscidin 7) primarily show anti-protozoal activity. The Class II piscidins (44-46 amino acids in length; striped bass and white bass piscidin 4 and white bass piscidin 5) have a level of activity against bacteria and protozoans intermediate to Classes I and III. Knowledge of piscidin function and activity may help in the future development of disease-resistant lines of striped bass and white bass that could be used to produce superior hybrids for aquaculture.

Helical 1:1 α/Sulfono-γ-AA Heterogeneous Peptides with Antibacterial Activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

She, Fengyu; Nimmagadda, Alekhya; Teng, Peng

As one of the greatest threats facing in 21st century, antibiotic resistance is now a major public health concern. Host-defense peptides (HDPs) offer an alternative approach to combat emerging multidrug-resistant bacteria. It is known that helical HDPs such as magainin 2 and its analogs adopt cationic amphipathic conformations upon interaction with bacterial membranes, leading to membrane disruption and subsequent bacterial cell death. We have previously shown that amphipathic sulfono-γ-AApeptides could mimic magainin 2 and exhibit bactericidal activity. In this article, we demonstrate for the first time that amphipathic helical 1:1 α/sulfono-γ-AA heterogeneous peptides, in which regular amino acids and sulfono-γ-AApeptidemore » building blocks are alternatively present in a 1:1 pattern, display potent antibacterial activity against both Gram-positive and Gram-negative bacterial pathogens. Small Angle X-ray Scattering (SAXS) suggests that the lead sequences adopt defined helical structures. The subsequent studies including 2 fluorescence microscopy and time-kill experiments indicate that these hybrid peptides exert antimicrobial activity by mimicking the mechanism of HDPs. Our findings may lead to the development of HDP-mimicking antimicrobial peptidomimetics that combat drug-resistant bacterial pathogens. In addition, our results also demonstrate the effective design of a new class of helical foldamer, which could be employed to interrogate other important biological targets such as protein-protein interactions in the future.« less

Selectivity in the potentiation of antibacterial activity of α-peptide/β-peptoid peptidomimetics and antimicrobial peptides by human blood plasma.

PubMed

Hein-Kristensen, Line; Knapp, Kolja M; Franzyk, Henrik; Gram, Lone

2013-11-01

Antimicrobial peptides (AMPs) are promising leads for novel antibiotics; however, their activity is often compromised under physiological conditions. The purpose of this study was to determine the activity of α-peptide/β-peptoid peptidomimetics and AMPs against Escherichia coli and Staphylococcus aureus in the presence of human blood-derived matrices and immune effectors. The minimum inhibitory concentration (MIC) of two peptidomimetics against E. coli decreased by up to one order of magnitude when determined in 50% blood plasma as compared to MHB media. The MIC of a membrane-active AMP, LL-I/3, also decreased, whereas two intracellularly acting AMPs were not potentiated by plasma. Blood serum had no effect on activity against E. coli and neither matrix had an effect on activity against S. aureus. Unexpectedly, physiological concentrations of human serum albumin did not influence activity. Plasma potentiation was not mediated by an LL-37 analogue, lysozyme or hydrogen peroxide; however, plasma potentiation of activity was abolished when the complement system was heat-inactivated. Time-course experiments indicated that potentiation was due to plasma-mediated effects on bacterial cells prior to activities of peptidomimetics. The unexpected enhancement of antibacterial activity of peptidomimetics and AMPs under physiological conditions significantly increases the therapeutic potential of these compounds. Copyright © 2013 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Antibacterial activity and phospholipid recognition of the recombinant defensin J1-1 from Capsicum genus.

PubMed

Guillén-Chable, Francisco; Arenas-Sosa, Iván; Islas-Flores, Ignacio; Corzo, Gerardo; Martinez-Liu, Cynthia; Estrada, Georgina

2017-08-01

The gene of the four disulfide-bridged defensin J1-1 from Capsicum was cloned into the expression vector pQE30 containing a 6His-tag as fusion protein. This construct was transfected into Origami strain of Escherichia coli and expressed after induction with isopropyl thiogalactoside (IPTG). The level of expression was 4 mg/L of culture medium, and the His-tagged recombinant defensin (HisXarJ1-1) was expressed exclusively into inclusion bodies. After solubilization, HisXarJ1-1 was purified by affinity and hydrophobic interaction chromatography. The reverse-phase HPLC profile of the HisXarJ1-1 product obtained from the affinity chromatography step showed single main peptide fraction of molecular masses of 7050.6 Da and after treatment with DTT a single fraction of 7, 042.6 Da corresponding to the reduced peptide was observed. An in vitro folding step of the HisXarJ1-1 generated a distinct profile of oxidized forms of the peptide this oxidized peptide was capable of binding phosphatidic acid in vitro. Possible dimer and oligomer of HisXarJ1-1 were visible in gel electrophoresis and immunodetected with anti-His antibodies. Pure recombinant defensin HisXarJ1-1 exhibited antibacterial activity against Pseudomonas aeruginosa. Copyright © 2017 Elsevier Inc. All rights reserved.

King cobra peptide OH-CATH30 as a potential candidate drug through clinic drug-resistant isolates.

PubMed

Zhao, Feng; Lan, Xin-Qiang; Du, Yan; Chen, Pei-Yi; Zhao, Jiao; Zhao, Fang; Lee, Wen-Hui; Zhang, Yun

2018-03-18

Cationic antimicrobial peptides (AMPs) are considered as important candidate therapeutic agents, which exert potent microbicidal properties against bacteria, fungi and some viruses. Based on our previous findings king cobra cathelicidin (OH-CATH) is a 34-amino acid peptide that exerts strong antibacterial and weak hemolytic activity. The aim of this research is to evaluate the efficacy of both OH-CATH30 and its analog D-OH-CATH30 against clinical isolates comparing with routinely utilized antibiotics in vitro. In this study, 584 clinical isolates were tested (spanning 2013-2016) and the efficacy of the candidate peptides and antibiotics were determined by a broth microdilution method according to the CLSI guidelines. Among the 584 clinical isolates, 85% were susceptible to OH-CATH30 and its analogs. Both L- and D-OH-CATH30 showed higher efficacy against (toward) Gram-positive bacteria and stronger antibacterial activity against nearly all Gram-negative bacteria tested compare with antibiotics. The highest bactericidal activity was detected against Acinetobacter spp., including multi-drug-resistant Acinetobacter baumannii (MRAB) and methicillin-resistant Staphylococcus aureus (MRSA). The overall efficacy of OH-CATH30 and its analogs was higher than that of the 9 routinely used antibiotics. OH-CATH30 is a promising candidate drug for the treatment of a wide variety of bacterial infections which are resistant to many routinely used antimicrobial agents.

Synthesis, antimicrobial activity and toxicity of analogs of the scorpion venom BmKn peptides.

PubMed

Bea, Roberto de la Salud; Petraglia, Adam Fine; Johnson, Laura Elena Luque de

2015-07-01

Two analogs of the natural peptide BmKn1 and four of BmKn2 found in the venom of the scorpion Buthus martensii Karsh have been synthesized and tested to compare their antimicrobial and hemolytic activity with the natural ones. Modifications of the natural sequence were done on the hydrophobic side of the alpha helix by increasing the size and hydrophobicity of the residues with alanine (BmKn2A1), valine (BmKn2V1) and leucine (BmKn2L1) respectively, and on the hydrophilic side by increasing the charge from +2 to +3 with two lysines (BmKn2K7). In order to study observed peptide aggregation, two peptides with one (BmKn1-6Lys) and two (BmKn1L2K2) positive charges respectively in the hydrophobic side have been also designed. Results show that the valine substituted analog BmKn2V1 and lysine substituted analog BmKn2K7 have in general, the highest antibiotic and hemolytic activity of the group. Introduction of one positive charge on the hydrophobic side shows a significant increase in antibacterial activity compared with the original sequence except for Bacillus and Enterobacter where, unexpectedly, the activity flats-off. In contrast, the analog with two positive charges has minimal antibacterial or hemolytic activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antifungal mechanism of antibacterial peptide, ABP-CM4, from Bombyx mori against Aspergillus niger.

PubMed

Zhang, Jie; Wu, Xi; Zhang, Shuang-Quan

2008-12-01

Antibacterial peptide, CM4 (ABP-CM4), a 35 amino acid peptide from Chinese silkworm-Bombyx mori, displayed a strong antifungal activity against Aspergillus niger, Trichoderma viride and Gibberella saubinetii. Scanning electron microcopy showed that the morphology of conidia became more irregular and swelled when treated with ABP-CM4 at its minimal inhibitory concentration (MIC) of 8 muM. A cell wall regeneration assay indicated that the plasma membrane was the prime target of ABP-CM4 action. Confocal laser scanning microscopy showed that the cytoskeleton of A. niger was destroyed when treated with ABP-CM4 at 8 muM. Furthermore, transmission electron microscopy showed that the membrane and the cellular organelles of fungus were disrupted and there were many vacuoles in the fungal cellular space after the treatment with ABP-CM4. A gel-retardation assay showed that ABP-CM4 bound the DNA of A. niger. Our results suggest that ABP-CM4 exerts its antifungal activity by disrupting the structure of cell membranes and the cytoskeleton and interacts with the organelles, such as the mitochondrion and with the DNA in the fungal cell, subsequently resulting in cell death.

Potential Applications of the Cyclic Peptide Enterocin AS-48 in the Preservation of Vegetable Foods and Beverages.

PubMed

Abriouel, Hikmate; Lucas, Rosario; Omar, Nabil Ben; Valdivia, Eva; Gálvez, Antonio

2010-06-01

Bacteriocins are antimicrobial peptides produced by bacteria. Among them, the enterococcal bacteriocin (enterocin) AS-48 stands for its peculiar characteristics and broad-spectrum antimicrobial activity. AS-48 belongs to the class of circular bacteriocins and has been studied in depth in several aspects: peptide structure, genetic determinants, and mode of action. Recently, a wealth of knowledge has accumulated on the antibacterial activity of this bacteriocin against foodborne pathogenic and spoilage bacteria in food systems, especially in vegetable foods and drinks. This work provides a general overview on the results from tests carried out with AS-48 in different vegetable food categories (such as fruit juices, ciders, sport and energy drinks, fresh fruits and vegetables, pre-cooked ready to eat foods, canned vegetables, and bakery products). Depending on the food substrate, the bacteriocin has been tested alone or as part of hurdle technology, in combination with physico-chemical treatments (such as mild heat treatments or high-intensity pulsed electric fields) and other antimicrobial substances (such as essential oils, phenolic compounds, and chemical preservatives). Since the work carried out on bacteriocins in preservation of vegetable foods and drinks is much more limited compared to meat and dairy products, the results reported for AS-48 may open new possibilities in the field of bacteriocin applications.

Antimicrobial peptides containing unnatural amino acid exhibit potent bactericidal activity against ESKAPE pathogens.

PubMed

Hicks, R P; Abercrombie, J J; Wong, R K; Leung, K P

2013-01-01

A series of 36 synthetic antimicrobial peptides containing unnatural amino acids were screened to determine their effectiveness to treat Enterococcus faecium, Staphylococcus aureus, Klebsiella pnemoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species (ESKAPE) pathogens, which are known to commonly infect chronic wounds. The primary amino acid sequences of these peptides incorporate either three or six dipeptide units consisting of the unnatural amino acids Tetrahydroisoquinolinecarboxylic acid (Tic) and Octahydroindolecarboxylic acid (Oic). The Tic-Oic dipeptide units are separated by SPACER amino acids with specific physicochemical properties that control how these peptides interact with bacterial cell membranes of different chemical compositions. These peptides exhibited minimum inhibitory concentrations (MIC) against these pathogens in the range from >100 to 6.25 μg/mL. The observed diversity of MIC values for these peptides against the various bacterial strains are consistent with our hypothesis that the complementarity of the physicochemical properties of the peptide and the lipid of the bacteria's cell membrane determines the resulting antibacterial activity of the peptide. Published by Elsevier Ltd.

Natural antimicrobial peptides as promising anti-HIV candidates

PubMed Central

Wang, Guangshun

2015-01-01

Human immunodeficiency virus type 1 (HIV-1) infection remains to be one of the major global health problems. It is thus necessary to identify novel therapeutic molecules to combat HIV-1. Natural antimicrobial peptides (AMPs) have been recognized as promising templates for developing topical microbicides. This review systematically discusses over 80 anti-HIV peptides annotated in the antimicrobial peptide database (http://aps.unmc.edu/AP). Such peptides have been discovered from bacteria, plants, and animals. Examples include gramicidin and bacteriocins from bacteria, cyclotides from plants, melittins and cecropins from insects, piscidins from fish, ascaphins, caerins, dermaseptins, esculentins, and maximins from amphibians, and cathelicidins and defensins from vertebrates. These peptides appear to work by different mechanisms and could block viral entry in multiple ways. As additional advantages, such anti-HIV peptides may possess other desired features such as antibacterial, antiparasital, spermicidal, and anticancer activity. With continued optimization of peptide stability, production, formulation and delivery methods, it is anticipated that some of these compounds may eventually become new anti-HIV drugs. PMID:26834391

Purification and characterization of the bacteriocin Thuricin Bn1 produced by Bacillus thuringiensis subsp. kurstaki Bn1 isolated from a hazelnut pest.

PubMed

Ugras, Serpil; Sezen, Kazim; Kati, Hatice; Demirbag, Zihni

2013-02-01

A novel bioactive molecule produced by Bacillus thuringiensis subsp. kurstaki Bn1 (Bt-Bn1), isolated from a common pest of hazelnut, Balaninus nucum L. (Coleoptera: Curculionidae), was determined, purified, and characterized in this study. The Bt-Bn1 strain was investigated for antibacterial activity with an agar spot assay and well diffusion assay against B. cereus, B. weinhenstephenensis, L. monocytogenes, P. savastanoi, P. syringae, P. lemoignei, and many other B. thuringiensis strains. The production of bioactive molecule was determined at the early logarithmic phase in the growth cycle of strain Bt-Bn1 and its production continued until the beginning of the stationary phase. The mode of action of this molecule displayed bacteriocidal or bacteriolytic effect depending on the concentration. The bioactive molecule was purified 78-fold from the bacteria supernatant with ammonium sulfate precipitation, dialysis, ultrafiltration, gel filtration chromatography, and HPLC, respectively. The molecular mass of this molecule was estimated via SDS-PAGE and confirmed by the ESI-TOFMS as 3,139 Da. The bioactive molecule was also determined to be a heat-stable, pH-stable (range 6-8), and proteinase K sensitive antibacterial peptide, similar to bacteriocins. Based on all characteristics determined in this study, the purified bacteriocin was named as thuricin Bn1 because of the similarities to the previously identified thuricin-like bacteriocin produced by the various B. thuringiensis strains. Plasmid elution studies showed that gene responsible for the production of thuricin Bn1 is located on the chromosome of Bt-Bn1. Therefore, it is a novel bacteriocin and the first recorded one produced by an insect originated bacterium. It has potential usage for the control of many different pathogenic and spoilage bacteria in the food industry, agriculture, and various other areas.

An iterative glycosyltransferase EntS catalyzes transfer and extension of O- and S-linked monosaccharide in enterocin 96

PubMed Central

Nagar, Rupa; Rao, Alka

2017-01-01

Abstract Glycosyltransferases are essential tools for in vitro glycoengineering. Bacteria harbor an unexplored variety of protein glycosyltransferases. Here, we describe a peptide glycosyltransferase (EntS) encoded by ORF0417 of Enterococcus faecalis TX0104. EntS di-glycosylates linear peptide of enterocin 96 – a known antibacterial, in vitro. It is capable of transferring as well as extending the glycan onto the peptide in an iterative sequential dissociative manner. It can catalyze multiple linkages: Glc/Gal(-O)Ser/Thr, Glc/Gal(-S)Cys and Glc/Gal(β)Glc/Gal(-O/S)Ser/Thr/Cys, in one pot. Using EntS generated glycovariants of enterocin 96 peptide, size and identity of the glycan are found to influence bioactivity of the peptide. The study identifies EntS as an enzyme worth pursuing, for in vitro peptide glycoengineering. PMID:28498962

HYDROLYTIC BREAKDOWN OF LACTOFERRICIN BY LACTIC ACID BACTERIA

USDA-ARS?s Scientific Manuscript database

Lactoferricin is a 25 amino acid antimicrobial peptide domain that is liberated by pepsin digestion of lactoferrin in bovine milk. Along with its antibacterial properties, lactoferricin has also been reported to have immunostimulatory, antiviral, and anticarcinogenic effects. There is substantial ...

Antibacterial Titanium Produced Using Selective Laser Melting

NASA Astrophysics Data System (ADS)

Macpherson, Andrew; Li, Xiaopeng; McCormick, Paul; Ren, Ling; Yang, Ke; Sercombe, Timothy B.

2017-12-01

Titanium and titanium alloys used in current medical and dental applications do not possess antibacterial properties, and therefore, postoperative infection remains a significant risk. Recently, the addition of silver and copper to conventional biomaterials has been shown to produce a material with good antibacterial properties. In this article, we investigate selective laser melting as a method of producing antibacterial Ti-6Al-4V containing elemental additions of Cu or Ag. The addition of Ag had no effect on the microstructure or strength, but it did result in a 300% increase in the ductility of the alloy. In contrast, the addition of Cu resulted in an increase in strength but in a decrease in ductility, along with a change in the structure of the material. The Cu-containing alloy also showed moderate antibacterial properties and was superior to the Ag-containing alloy.

Recent studies on the antimicrobial peptides lactoferricin and lactoferrampin.

PubMed

Yin, C; Wong, J H; Ng, T B

2014-01-01

Lactoferricin and lactoferrampin, peptides derived from the whey protein lactoferrin, are antimicrobial agents with a promising prospect and are currently one of the research focuses. In this review, a basic introduction including location and solution structures of these two peptides is given. Their biological activities encompassing antiviral, antibacterial, antifungal and anti-inflammatory activities with possible mechanisms are mentioned. In terms of modification studies, research about identification of their active derivatives and crucial amino acid residues is also discussed. Various attempts at modification of lactoferricin and lactoferrampin such as introducing big hydrophobic side-chains; employing special amino acids for synthesis; N-acetylization, amidation, cyclization and peptide chimera are summarized. The studies on lactoferricin-lactoferrampin chimera are discussed in detail. Future prospects of lactoferricin and lactoferrampin are covered.

Presence of chromogranin-derived antimicrobial peptides in plasma during coronary artery bypass surgery and evidence of an immune origin of these peptides.

PubMed

Tasiemski, Aurélie; Hammad, Hamida; Vandenbulcke, Franck; Breton, Christophe; Bilfinger, Thomas J; Pestel, Joel; Salzet, Michel

2002-07-15

Chromogranin A (CGA) and chromogranin B (CGB) are acidic proteins stored in secretory organelles of endocrine cells and neurons. In addition to their roles as helper proteins in the packaging of peptides, they may serve as prohormones to generate biologically active peptides such as vasostatin-1 and secretolytin. These molecules derived from CGA and CGB, respectively, possess antimicrobial properties. The present study demonstrates that plasmatic levels of both vasostatin-1 and secretolytin increase during surgery in patients undergoing cardiopulmonary bypass (CPB). Vasostatin-1 and secretolytin, initially present in plasma at low levels, are released just after skin incision. Consequently, they can be added to enkelytin, an antibacterial peptide derived from proenkephalin A, for the panoply of components acting as a first protective barrier against hypothetical invasion of pathogens, which may occur during surgery. CGA and CGB, more commonly viewed as markers for endocrine and neuronal cells, were also found to have an immune origin. RNA messengers coding for CGB were amplified by reverse transcription-polymerase chain reaction in human monocytes, and immunocytochemical analysis by confocal microscopy revealed the presence of CGA or CGB or both in monocytes and neutrophils. A combination of techniques including confocal microscopic analysis, mass spectrometry measurement, and antibacterial tests allowed for the identification of the positive role of interleukin 6 (IL-6) in the secretolytin release from monocytes in vitro. Because IL-6 release is known to be strongly enhanced during CPB, we suggest a possible relationship between IL-6 and the increased level of secretolytin in patients undergoing CPB.

Computational study of solution behavior of magainin 2 monomers.

PubMed

Petkov, P; Marinova, R; Kochev, V; Ilieva, N; Lilkova, E; Litov, L

2018-03-27

Antimicrobial peptides (AMPs) play crucial role as mediators of the primary host defense against microbial invasion. They are considered a promising alternative to antibiotics for multidrug resistant bacterial strains. For complete understanding of the antimicrobial defense mechanism, a detailed knowledge of the dynamics of peptide-membrane interactions, including atomistic studies on AMPs geometry and both peptide and membrane structural changes during the whole process is a prerequisite. We aim at clarifying the conformation dynamics of small linear AMPs in solution as a first step of in silico protocol for establishing a correspondence between certain amino-acid sequence motifs, secondary-structure elements, conformational dynamics in solution and the intensity and mode of interaction with the bacterial membrane. To this end, we use molecular dynamics simulations augmented by well-tempered metadynamics to study the free-energy landscape of two AMPs with close primary structure and different antibacterial activity - the native magainin 2 (MG2) and an analog (MG2m, with substitutions F5Y and F16W) in aqueous solution. We observe that upon solvation, the initial α-helical structures change differently. The native form remains structured, with three shorter α-helical motifs, connected by random coils, while the synthetic analog tends predominantly to a disordered conformation. Our results indicate the importance of the side-chains at positions 5 and 16 for maintaining the solvated peptide conformation. They also provide a modeling background for recent experimental observations, relating the higher α-helical content in solution (peptide pre-folding) in the case of small linear AMPs to a lower antibacterial activity.

The Potential Use of Natural and Structural Analogues of Antimicrobial Peptides in the Fight against Neglected Tropical Diseases.

PubMed

Lewies, Angélique; Wentzel, Johannes F; Jacobs, Garmi; Du Plessis, Lissinda H; Angélique, Lewies; Frederik, Wentzel Johannes; Garmi, Jacobs; Hester, Du Plessis Lissinda

2015-08-24

Recently, research into the development of new antimicrobial agents has been driven by the increase in resistance to traditional antibiotics and Emerging Infectious Diseases. Antimicrobial peptides (AMPs) are promising candidates as alternatives to current antibiotics in the treatment and prevention of microbial infections. AMPs are produced by all known living species, displaying direct antimicrobial killing activity and playing an important role in innate immunity. To date, more than 2000 AMPs have been discovered and many of these exhibit broad-spectrum antibacterial, antiviral and anti-parasitic activity. Neglected tropical diseases (NTDs) are caused by a variety of pathogens and are particularly wide-spread in low-income and developing regions of the world. Alternative, cost effective treatments are desperately needed to effectively battle these medically diverse diseases. AMPs have been shown to be effective against a variety of NTDs, including African trypanosomes, leishmaniosis and Chagas disease, trachoma and leprosy. In this review, the potential of selected AMPs to successfully treat a variety of NTD infections will be critically evaluated.

Cationic antimicrobial peptides in penaeid shrimp.

PubMed

Tassanakajon, Anchalee; Amparyup, Piti; Somboonwiwat, Kunlaya; Supungul, Premruethai

2011-08-01

Penaeid shrimp aquaculture has been consistently affected worldwide by devastating diseases that cause a severe loss in production. To fight a variety of harmful microbes in the surrounding environment, particularly at high densities (of which intensive farming represents an extreme example), shrimps have evolved and use a diverse array of antimicrobial peptides (AMPs) as part of an important first-line response of the host defense system. Cationic AMPs in penaeid shrimps composed of penaeidins, crustins, and anti-lipopolysaccharide factors are comprised of multiple classes or isoforms and possess antibacterial and antifungal activities against different strains of bacteria and fungi. Shrimp AMPs are primarily expressed in circulating hemocytes, which is the main site of the immune response, and hemocytes expressing AMPs probably migrate to infection sites to fight against pathogen invasion. Indeed, most AMPs are produced as early as the nauplii developmental stage to protect shrimp larvae from infections. In this review, we discuss the sequence diversity, expression, gene structure, and antimicrobial activities of cationic AMPs in penaeid shrimps. The information available on antimicrobial activities indicates that these shrimp AMPs have potential therapeutic applications in the control of disease problems in aquaculture.

Insect antimicrobial peptides: potential tools for the prevention of skin cancer.

PubMed

Tonk, Miray; Vilcinskas, Andreas; Rahnamaeian, Mohammad

2016-09-01

Antimicrobial peptides/proteins (AMPs) are biologically active molecules with diverse structural properties that are produced by mammals, plants, insects, ticks, and microorganisms. They have a range of antibacterial, antifungal, antiviral, and even anticancer activities, and their biological properties could therefore be exploited for therapeutic and prophylactic applications. Cancer and cancer drug resistance are significant current health challenges, so the development of innovative cancer drugs with minimal toxicity toward normal cells and novel modes of action that can evade resistance may provide a new direction for anticancer therapy. The skin is the first line of defense against heat, sunlight, injury, and infection, and skin cancer is thus the most common type of cancer. The skin that has been exposed to sunlight is particularly susceptible, but lesions can occur anywhere on the body. Skin cancer awareness and self-efficacy are necessary to improve sun protection behavior, but more effective preventative approaches are also required. AMPs may offer a new prophylactic approach against skin cancer. In this mini review, we draw attention to the potential use of insect AMPs for the prevention and treatment of skin cancer.

Budesonide suppresses pulmonary antibacterial host defense by down-regulating cathelicidin-related antimicrobial peptide in allergic inflammation mice and in lung epithelial cells

PubMed Central

2013-01-01

Background Glucocorticoids are widely regarded as the most effective treatment for asthma. However, the direct impact of glucocorticoids on the innate immune system and antibacterial host defense during asthma remain unclear. Understanding the mechanisms underlying this process is critical to the clinical application of glucocorticoids for asthma therapy. After sensitization and challenge with ovalbumin (OVA), BALB/c mice were treated with inhaled budesonide and infected with Pseudomonas aeruginosa (P. aeruginosa). The number of viable bacteria in enflamed lungs was evaluated, and levels of interleukin-4 (IL-4) and interferon-γ (IFN-γ) in serum were measured. A lung epithelial cell line was pretreated with budesonide. Levels of cathelicidin-related antimicrobial peptide (CRAMP) were measured by immunohistochemistry and western blot analysis. Intracellular bacteria were observed in lung epithelial cells. Results Inhaled budesonide enhanced lung infection in allergic mice exposed to P. aeruginosa and increased the number of viable bacteria in lung tissue. Higher levels of IL-4 and lower levels of IFN-γ were observed in the serum. Budesonide decreased the expression of CRAMP, increased the number of internalized P. aeruginosa in OVA-challenged mice and in lung epithelial cell lines. These data indicate that inhaled budesonide can suppress pulmonary antibacterial host defense by down-regulating CRAMP in allergic inflammation mice and in cells in vitro. Conclusions Inhaled budesonide suppressed pulmonary antibacterial host defense in an asthmatic mouse model and in lung epithelium cells in vitro. This effect was dependent on the down-regulation of CRAMP. PMID:23387852

Synthesis and biological evaluation of asymmetric gramicidin S analogues containing modified D-phenylalanine residues.

PubMed

van der Knaap, Matthijs; Engels, Eefje; Busscher, Henk J; Otero, José M; Llamas-Saiz, Antonio L; van Raaij, Mark J; Mars-Groenendijk, Roos H; Noort, Daan; van der Marel, Gijsbert A; Overkleeft, Herman S; Overhand, Mark

2009-09-01

The synthesis of new analogues of the cationic antimicrobial peptide gramicidin S, having a modified D-phenylalanine residue, their antibacterial properties against several gram positive and negative strains, as well as their hemolytic activity is reported.

Nonribosomal peptide synthetase biosynthetic clusters of ESKAPE pathogens.

PubMed

Gulick, Andrew M

2017-08-02

Covering: up to 2017.Natural products are important secondary metabolites produced by bacterial and fungal species that play important roles in cellular growth and signaling, nutrient acquisition, intra- and interspecies communication, and virulence. A subset of natural products is produced by nonribosomal peptide synthetases (NRPSs), a family of large, modular enzymes that function in an assembly line fashion. Because of the pharmaceutical activity of many NRPS products, much effort has gone into the exploration of their biosynthetic pathways and the diverse products they make. Many interesting NRPS pathways have been identified and characterized from both terrestrial and marine bacterial sources. Recently, several NRPS pathways in human commensal bacterial species have been identified that produce molecules with antibiotic activity, suggesting another source of interesting NRPS pathways may be the commensal and pathogenic bacteria that live on the human body. The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) have been identified as a significant cause of human bacterial infections that are frequently multidrug resistant. The emerging resistance profile of these organisms has prompted calls from multiple international agencies to identify novel antibacterial targets and develop new approaches to treat infections from ESKAPE pathogens. Each of these species contains several NRPS biosynthetic gene clusters. While some have been well characterized and produce known natural products with important biological roles in microbial physiology, others have yet to be investigated. This review catalogs the NRPS pathways of ESKAPE pathogens. The exploration of novel NRPS products may lead to a better understanding of the chemical communication used by human pathogens and potentially to the discovery of novel therapeutic approaches.

Dynamic membrane interactions of antibacterial and antifungal biomolecules, and amyloid peptides, revealed by solid-state NMR spectroscopy.

PubMed

Naito, Akira; Matsumori, Nobuaki; Ramamoorthy, Ayyalusamy

2018-02-01

A variety of biomolecules acting on the cell membrane folds into a biologically active structure in the membrane environment. It is, therefore, important to determine the structures and dynamics of such biomolecules in a membrane environment. While several biophysical techniques are used to obtain low-resolution information, solid-state NMR spectroscopy is one of the most powerful means for determining the structure and dynamics of membrane bound biomolecules such as antibacterial biomolecules and amyloidogenic proteins; unlike X-ray crystallography and solution NMR spectroscopy, applications of solid-state NMR spectroscopy are not limited by non-crystalline, non-soluble nature or molecular size of membrane-associated biomolecules. This review article focuses on the applications of solid-state NMR techniques to study a few selected antibacterial and amyloid peptides. Solid-state NMR studies revealing the membrane inserted bent α-helical structure associated with the hemolytic activity of bee venom melittin and the chemical shift oscillation analysis used to determine the transmembrane structure (with α-helix and 3 10 -helix in the N- and C-termini, respectively) of antibiotic peptide alamethicin are discussed in detail. Oligomerization of an amyloidogenic islet amyloid polypeptide (IAPP, or also known as amylin) resulting from its aggregation in a membrane environment, molecular interactions of the antifungal natural product amphotericin B with ergosterol in lipid bilayers, and the mechanism of lipid raft formation by sphingomyelin studied using solid state NMR methods are also discussed in this review article. This article is part of a Special Issue entitled "Biophysical Exploration of Dynamical Ordering of Biomolecular Systems" edited by Dr. Koichi Kato. Copyright © 2017 Elsevier B.V. All rights reserved.

Combined antioxidant effects of Neem extract, bacteria, red blood cells and Lysozyme: possible relation to periodontal disease.

PubMed

Heyman, Leali; Houri-Haddad, Yael; Heyman, Samuel N; Ginsburg, Isaac; Gleitman, Yossi; Feuerstein, Osnat

2017-08-10

The common usage of chewing sticks prepared from Neem tree (Azadirachta indica) in India suggests its potential efficacy in periodontal diseases. The objective of this study is to explore the antibacterial effects of Neem leaf extract on the periodontophatic bacteria Porphyromonas gingivalis and Fusobacterium nucleatum, and its antioxidant capacities alone and in combination with bacteria and polycationic peptides that may be at the site of inflammation. Neem leaf extract was prepared by ethanol extraction. The growth kinetics of P. gingivalis and F. nucleatum under anaerobic conditions in the presence of Neem leaf extract were measured. Broth microdilution test was used to determine the Minimal Inhibitory Concentration (MIC) of Neem leaf extract against each bacterial strain. The effect of Neem leaf extract on the coaggregation of the bacteria was assessed by a visual semi-quantitative assay. The antioxidant capacities of Neem leaf extract alone and in combination with bacteria, with the addition of red blood cells or the polycationic peptides chlorhexidine and lisozyme, were determined using a chemiluminescence assay. Neem leaf extract showed prominent dose-dependent antibacterial activity against P. gingivalis, however, had no effect on the growth of F. nucleatum nor on the coaggregation of the two bacteria. Yet, it showed intense antioxidant activity, which was amplified following adherence to bacteria and with the addition of red blood cells or the polycationic peptides. Neem leaf extract, containing polyphenols that adhere to oral surfaces, have the potential to provide long-lasting antibacterial as well as synergic antioxidant activities when in complex with bacteria, red blood cells and lisozyme. Thus, it might be especially effective in periodontal diseases.

Antibacterial and anticancer activity of a series of novel peptides incorporating cyclic tetra-substituted C(α) amino acids.

PubMed

Hicks, Rickey P

2016-09-15

Eleven antimicrobial peptides (AMP) based on the incorporation of cyclic tetra substituted C(α) amino acids, as well as other unnatural amino acids were designed, synthesized and screened for in vitro activity against 18 strains of bacteria as well as 12 cancer cell lines. The AMPs discussed herein are derived from the following peptide sequence: Ac-GF(X)G(X)B(X)G(X)F(X)G(X)GB(X)BBBB-amide, X=any one of the following residues, A5c, A6c, Tic or Oic and B=any one of the following residues, Arg, Lys, Orn, Dpr or Dab. A diversity of in vitro inhibitory activity was observed for these AMPs. Several analogs exhibited single digit μM activity against drug resistant bacteria including; multiple drug resistant Mycobacterium tuberculosis, extremely drug resistant Mycobacterium tuberculosis and MRSA. The physicochemical properties of the basic amino acid residues incorporated into these AMPs seem to play a major role in defining antibacterial activity. Overall hydrophobicity seems to play a limited role in defining antibacterial activity. The ESKAPE pathogens were used to compare the activity of these AMPs to another family of synthetic AMPs incorporating the unnatural amino acids Tic and Oic. In most cases similarly substituted members of both families exhibited similar inhibitory activity against the ESKAPE pathogens. In specific cases differences in activity as high as 15 fold were observed between analogs. In addition four of these AMPs exhibited promising IC50 (<7.5μM) values against 12 different and diverse cancer cell lines. Five other AMPs exhibited promising IC50 (<7.5μM) values against selected cancer cell lines. Copyright © 2016 Elsevier Ltd. All rights reserved.

Selective cytotoxicity of the antibacterial peptide ABP-dHC-Cecropin A and its analog towards leukemia cells.

PubMed

Sang, Ming; Zhang, Jiaxin; Zhuge, Qiang

2017-05-15

Some cationic antibacterial peptides, with typical amphiphilic α-helical conformations in a membrane-mimicking environment, exhibit anticancer properties as a result of a similar mechanism of action towards both bacteria and cancer cells. We previously reported the cDNA sequence of the antimicrobial peptide ABP-dHC-Cecropin A precursor cloned from drury (Hyphantria cunea) (dHC). In the present study, we synthesized and structurally characterized ABP-dHC-Cecropin A and its analog, ABP-dHC-Cecropin A-K(24). Circular dichroism spectroscopy showed that ABP-dHC-Cecropin A and its analog adopt a well-defined α-helical structure in a 50% trifluorethanol solution. The cytotoxicity and cell selectivity of these peptides were further examined in three leukemia cell lines and two non-cancerous cell lines. The MTT assay indicated both of these peptides have a concentration-dependent cytotoxic effect in leukemia cells, although the observed cytotoxicity was greater with ABP-dHC-Cecropin A-K(24) treatment, whereas they were not cytotoxic towards the non-cancerous cell lines. Moreover, ABP-dHC-Cecropin A and its analog had a lower hemolytic effect in human red blood cells. Together, these results suggest the peptides are selectively cytotoxic towards leukemia cells. Confocal laser scanning microscopy determined that the peptides were concentrated at the surface of the leukemia cells, and changes in the cell membrane were determined with a permeability assay, which suggested that the anticancer activity of ABP-dHC-Cecropin A and its analog is a result of its presence at the leukemia cell membrane. ABP-dHC-Cecropin A and its analog may represent a novel anticancer agent for leukemia therapy, considering its cancer cell selectivity and relatively low cytotoxicity in normal cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Constitutive expression of transgenes encoding derivatives of the synthetic antimicrobial peptide BP100: impact on rice host plant fitness

PubMed Central

2012-01-01

Background The Biopeptide BP100 is a synthetic and strongly cationic α-helical undecapeptide with high, specific antibacterial activity against economically important plant-pathogenic bacteria, and very low toxicity. It was selected from a library of synthetic peptides, along with other peptides with activities against relevant bacterial and fungal species. Expression of the BP100 series of peptides in plants is of major interest to establish disease-resistant plants and facilitate molecular farming. Specific challenges were the small length, peptide degradation by plant proteases and toxicity to the host plant. Here we approached the expression of the BP100 peptide series in plants using BP100 as a proof-of-concept. Results Our design considered up to three tandemly arranged BP100 units and peptide accumulation in the endoplasmic reticulum (ER), analyzing five BP100 derivatives. The ER retention sequence did not reduce the antimicrobial activity of chemically synthesized BP100 derivatives, making this strategy possible. Transformation with sequences encoding BP100 derivatives (bp100der) was over ten-fold less efficient than that of the hygromycin phosphotransferase (hptII) transgene. The BP100 direct tandems did not show higher antimicrobial activity than BP100, and genetically modified (GM) plants constitutively expressing them were not viable. In contrast, inverted repeats of BP100, whether or not elongated with a portion of a natural antimicrobial peptide (AMP), had higher antimicrobial activity, and fertile GM rice lines constitutively expressing bp100der were produced. These GM lines had increased resistance to the pathogens Dickeya chrysanthemi and Fusarium verticillioides, and tolerance to oxidative stress, with agronomic performance comparable to untransformed lines. Conclusions Constitutive expression of transgenes encoding short cationic α-helical synthetic peptides can have a strong negative impact on rice fitness. However, GM plants expressing, for example, BP100 based on inverted repeats, have adequate agronomic performance and resistant phenotypes as a result of a complex equilibrium between bp100der toxicity to plant cells, antimicrobial activity and transgene-derived plant stress response. It is likely that these results can be extended to other peptides with similar characteristics. PMID:22947243

Constitutive expression of transgenes encoding derivatives of the synthetic antimicrobial peptide BP100: impact on rice host plant fitness.

PubMed

Nadal, Anna; Montero, Maria; Company, Nuri; Badosa, Esther; Messeguer, Joaquima; Montesinos, Laura; Montesinos, Emilio; Pla, Maria

2012-09-04

The Biopeptide BP100 is a synthetic and strongly cationic α-helical undecapeptide with high, specific antibacterial activity against economically important plant-pathogenic bacteria, and very low toxicity. It was selected from a library of synthetic peptides, along with other peptides with activities against relevant bacterial and fungal species. Expression of the BP100 series of peptides in plants is of major interest to establish disease-resistant plants and facilitate molecular farming. Specific challenges were the small length, peptide degradation by plant proteases and toxicity to the host plant. Here we approached the expression of the BP100 peptide series in plants using BP100 as a proof-of-concept. Our design considered up to three tandemly arranged BP100 units and peptide accumulation in the endoplasmic reticulum (ER), analyzing five BP100 derivatives. The ER retention sequence did not reduce the antimicrobial activity of chemically synthesized BP100 derivatives, making this strategy possible. Transformation with sequences encoding BP100 derivatives (bp100der) was over ten-fold less efficient than that of the hygromycin phosphotransferase (hptII) transgene. The BP100 direct tandems did not show higher antimicrobial activity than BP100, and genetically modified (GM) plants constitutively expressing them were not viable. In contrast, inverted repeats of BP100, whether or not elongated with a portion of a natural antimicrobial peptide (AMP), had higher antimicrobial activity, and fertile GM rice lines constitutively expressing bp100der were produced. These GM lines had increased resistance to the pathogens Dickeya chrysanthemi and Fusarium verticillioides, and tolerance to oxidative stress, with agronomic performance comparable to untransformed lines. Constitutive expression of transgenes encoding short cationic α-helical synthetic peptides can have a strong negative impact on rice fitness. However, GM plants expressing, for example, BP100 based on inverted repeats, have adequate agronomic performance and resistant phenotypes as a result of a complex equilibrium between bp100der toxicity to plant cells, antimicrobial activity and transgene-derived plant stress response. It is likely that these results can be extended to other peptides with similar characteristics.

[Characteristics and identification of bacteriocins produced by Lactococcus lactis subsp. lactis 194-K].

PubMed

Ustiugova, E A; Timofeeva, A V; Stoianova, L G; Netrusov, A I; Katrukha, G S

2012-01-01

The Lactococcus lactis subsp. lactis 194-K strain has been established to be able to produce two bacteriocins, one of which was identified as the known lantibiotic nisin A, and the other 194-D bacteriocin represents a polypeptide with a 2589-Da molecular mass and comprises 20 amino acid residues. Both bacteriocins were produced in varying proportions in all of the studied nutrient media, which support the growth of the producer. Depending on the cultivation medium, the nisin A content was 380- to 1123-fold lower in the 194-K stain culture fluid than that of the 194-D peptide. In comparision to to nisin A Bacteriocin 194-D possessed a wide range of antibacterial activity and suppressed the growth of both Gram-positive and Gram-negative bacteria. An optimal medium for 194-D bacteriocin synthesis was shown to be a fermentation medium which contained yeast extract, casein hydrolysate, and potassium phosphate. The biosynthesis ofbacteriocin 194-D by the 194-K strain in these media occurred parallel to producer growth, and its maximal accumulation in the culture fluid was observed at 14-20 h of the strain's growth.

Antibacterials in Household Products

MedlinePlus

... it irritates their skin. ♦ Build-up in the environment: Triclosan is slow to degrade and residue build-up ... plasma. ♦ Antibacterial resistance: Residue-producing antibacterials, most ... Some bacteria are naturally resistant to triclosan. ♦ Immune ...

Antibacterial liamocins with alternative carbohydrate headgroups

USDA-ARS?s Scientific Manuscript database

Liamocins are unique polyol lipids with biosurfactant, anticancer, and antibacterial properties, produced by certain strains of the fungus Aureobasidium pullulans. Liamocins have potential agricultural and pharmaceutical applications as antibacterials with specificity against Streptococcus sp. There...

In Vitro Study of Bacteriophage AB3 Endolysin LysAB3 Activity Against Acinetobacter baumannii Biofilm and Biofilm-Bound A. baumannii.

PubMed

Zhang, Jie; Xu, Lu-Lu; Gan, Dan; Zhang, Xingping

2018-06-01

The increase in the prevalence of drug-resistant Acinetobacter baumannii is a serious public health concern, which is closely linked to the formation of biofilm. It is reported that the bacteriophage and its endolysin have a good ability to degrade biofilms. The goals of this study were to compare the ability of A. baumannii bacteriophage AB3, its endolysin AB3, and three antibiotics to degrade A. baumannii biofilm and biofilm-bound A. baumannii and to understand the antibacterial mechanism of LysAB3. The 558-bp sequence of the LysAB3 gene was amplified by polymerase chain reaction (PCR); the fragment was cloned into pET28a (+) to construct the recombinant plasmid pET28a-LysAB3, which was then expressed in E. coli BL21 (DE3) to obtain the LysAB3. Differences in A. baumannii biofilm and biofilm-bound A. baumannii after treatment with bacteriophage AB3, LysAB3 or three antibiotics were examined using the crystal violet staining method and an MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) assay. Changes in biofilm morphology and thickness in each treatment group were observed by laser scanning confocal microscopy. In addition, a LysAB3 construct with the amphiphilic peptide structural region removed (LysAB3-D) was assessed for its antibacterial activity. After 24-hour treatment with either bacteriophage AB3 and its LysAB3, A. baumannii biofilms were significantly degraded, and the number of viable biofilm-bound A. baumannii were also significantly decreased. After removing the amphiphilic peptide structure motif from LysAB3, the antibacterial activity decreased from 95.8% to 33.3%. Thus, LysAB3 can effectively degrade A. baumannii biofilm and biofilm-bound A. baumannii in vitro. The antibacterial mechanism of LysAB3 may be associated with the ability of the amphiphilic peptide structural region to enhance the permeability of cytoplasmic membrane of A. baumannii by degradation of bacterial wall peptidoglycan.

Synthesis and Evaluation of Antimicrobial Activity of [R₄W₄K]-Levofloxacin and [R₄W₄K]-Levofloxacin-Q Conjugates.

PubMed

Riahifard, Neda; Tavakoli, Kathy; Yamaki, Jason; Parang, Keykavous; Tiwari, Rakesh

2017-06-08

The development of a new class of antibiotics to fight bacterial resistance is a time-consuming effort associated with high-cost and commercial risks. Thus, modification, conjugation or combination of existing antibiotics to enhance their efficacy is a suitable strategy. We have previously reported that the amphiphilic cyclic peptide [R₄W₄] had antibacterial activity with a minimum inhibitory concentration (MIC) of 2.97 µg/mL against Methicillin-resistant Staphylococcus aureus (MRSA). Herein, we hypothesized that conjugation or combination of the amphiphilic cyclic peptide [R₄W₄] with levofloxacin or levofloxacin-Q could improve the antibacterial activity of levofloxacin and levofloxacin-Q. Fmoc/tBu solid-phase chemistry was employed to synthesize conjugates of [R₄W₄K]-levofloxacin-Q and [R₄W₄K]-levofloxacin. The carboxylic acid group of levofloxacin or levofloxacin-Q was conjugated with the amino group of β-alanine attached to lysine in the presence of 2-(1 H -benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU) and N , N -diisopropylethylamine (DIPEA) for 3 h to afford the products. Antibacterial assays were conducted to determine the potency of conjugates [R₄W₄K]-levofloxacin-Q and [R₄W₄K]-levofloxacin against MRSA and Klebsiella pneumoniae . Although levofloxacin-Q was inactive even at a concentration of 128 µg/mL, [R₄W₄K]-levofloxacin-Q conjugate and the corresponding physical mixture showed MIC values of 8 µg/mL and 32 µg/mL against MRSA and Klebsiella pneumonia , respectively, possibly due to the activity of the peptide. On the other hand, [R₄W₄K]-levofloxacin conjugate (MIC = 32 µg/mL and MIC = 128 µg/mL) and the physical mixture (MIC = 8 µg/mL and 32 µg/mL) was less active than levofloxacin (MIC = 2 µg/mL and 4 = µg/mL) against MRSA and Klebsiella pneumoniae , respectively. The data showed that the conjugation of levofloxacin with [R₄W₄K] significantly reduced the antibacterial activity compared to the parent analogs, while [R₄W₄K]-levofloxacin-Q conjugate was more significantly potent than levofloxacin-Q alone.

Recombinant Scorpine Produced Using SUMO Fusion Partner in Escherichia coli Has the Activities against Clinically Isolated Bacteria and Inhibits the Plasmodium falciparum Parasitemia In Vitro

PubMed Central

Gu, Yaping; Zhou, Huayun; Cao, Jun; Gao, Qi

2014-01-01

Scorpine, a small cationic peptide from the venom of Pandinus imperator, which has been shown to have anti-bacterial and anti-plasmodial activities, has potential important applications in the pharmaceutical industries. However, the isolation of scorpine from natural sources is inefficient and time-consuming. Here, we first report the expression and purification of recombinant scorpine in Escherichia coli, using small ubiquitin-related modifier (SUMO) fusion partner. The fusion protein was expressed in soluble form in E. coli, and expression was verified by SDS-PAGE and western blotting analysis. The fusion protein was purified to 90% purity by nickel–nitrilotriacetic acid (Ni2+–NTA) resin chromatography. After the SUMO-scorpine fusion protein was cleaved by the SUMO protease, the cleaved sample was reapplied to a Ni2+–NTA column. Tricine/SDS-PAGE gel results indicated that Scorpine had been purified successfully to more than 95% purity. The recombinantly expressed Scorpine showed anti-bacterial activity against two standard bacteria including Staphylococcus aureus ATCC 29213 and Acinetobacter baumannii ATCC 19606, and clinically isolated bacteria including S. aureus S, S. aureus R, A. baumannii S, and A. baumannii R. It also produced 100% reduction in Plasmodium falciparum parasitemia in vitro. Thus, the expression strategy presented in this study allowed convenient high yield and easy purification of recombinant Scorpine for pharmaceutical applications in the future. PMID:25068263

High-Throughput Fabrication Method for Producing a Silver-Nanoparticles-Doped Nanoclay Polymer Composite with Novel Synergistic Antibacterial Effects at the Material Interface.

PubMed

Cai, Shaobo; Pourdeyhimi, Behnam; Loboa, Elizabeth G

2017-06-28

In this study, we report a high-throughput fabrication method at industrial pilot scale to produce a silver-nanoparticles-doped nanoclay-polylactic acid composite with a novel synergistic antibacterial effect. The obtained nanocomposite has a significantly lower affinity for bacterial adhesion, allowing the loading amount of silver nanoparticles to be tremendously reduced while maintaining satisfactory antibacterial efficacy at the material interface. This is a great advantage for many antibacterial applications in which cost is a consideration. Furthermore, unlike previously reported methods that require additional chemical reduction processes to produce the silver-nanoparticles-doped nanoclay, an in situ preparation method was developed in which silver nanoparticles were created simultaneously during the composite fabrication process by thermal reduction. This is the first report to show that altered material surface submicron structures created with the loading of nanoclay enables the creation of a nanocomposite with significantly lower affinity for bacterial adhesion. This study provides a promising scalable approach to produce antibacterial polymeric products with minimal changes to industry standard equipment, fabrication processes, or raw material input cost.

Antibacterial Activity Affected by the Conformational Flexibility in Glycine-Lysine Based α-Helical Antimicrobial Peptides.

PubMed

Rončević, Tomislav; Vukičević, Damir; Ilić, Nada; Krce, Lucija; Gajski, Goran; Tonkić, Marija; Goić-Barišić, Ivana; Zoranić, Larisa; Sonavane, Yogesh; Benincasa, Monica; Juretić, Davor; Maravić, Ana; Tossi, Alessandro

2018-04-12

Antimicrobial peptides often show broad-spectrum activity due to a mechanism based on bacterial membrane disruption, which also reduces development of permanent resistance, a desirable characteristic in view of the escalating multidrug resistance problem. Host cell toxicity however requires design of artificial variants of natural AMPs to increase selectivity and reduce side effects. Kiadins were designed using rules obtained from natural peptides active against E. coli and a validated computational algorithm based on a training set of such peptides, followed by rational conformational alterations. In vitro activity, tested against ESKAPE strains (ATCC and clinical isolates), revealed a varied activity spectrum and cytotoxicity that only in part correlated with conformational flexibility. Peptides with a higher proportion of Gly were generally less potent and caused less bacterial membrane alteration, as observed by flow cytometry and AFM, which correlate to structural characteristics as observed by circular dichroism spectroscopy and predicted by molecular dynamics calculations.

Lacrain: the first antimicrobial peptide from the body extract of the Brazilian centipede Scolopendra viridicornis.

PubMed

Chaparro, E; da Silva, P I

2016-09-01

Antimicrobial activities have previously been described by traditional Eastern medicine in Chilopoda body extracts, but until now no bioactive peptides have been described. In this study, a novel antimicrobial peptide, lacrain, was isolated from the body extract of the Brazilian Chilopoda Scolopendra viridicornis. The peptide was isolated by reverse-phase high-performance liquid chromatography (RP-HPLC). Its activity was tested using a liquid growth inhibition assay and the peptide was characterised using mass spectrometry. Lacrain has a sequence composed of eight amino acid residues and a molecular mass of 925.5 Da. A synthetic peptide of the native lacrain had identical characteristics to those of the isolated material, confirming its sequence. The synthetic peptide was active only against Gram-negative bacteria, showing strong bactericidal activity. Moreover, the peptide did not present haemolytic activity against human erythrocytes. Lacrain represents a novel molecule with powerful antibacterial activity that could be used as a new template for the development of drugs against clinically resistant bacterial strains. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Antimicrobial Peptide Potency is Facilitated by Greater Conformational Flexibility when Binding to Gram-negative Bacterial Inner Membranes

NASA Astrophysics Data System (ADS)

Amos, Sarah-Beth T. A.; Vermeer, Louic S.; Ferguson, Philip M.; Kozlowska, Justyna; Davy, Matthew; Bui, Tam T.; Drake, Alex F.; Lorenz, Christian D.; Mason, A. James

2016-11-01

The interaction of antimicrobial peptides (AMPs) with the inner membrane of Gram-negative bacteria is a key determinant of their abilities to exert diverse bactericidal effects. Here we present a molecular level understanding of the initial target membrane interaction for two cationic α-helical AMPs that share structural similarities but have a ten-fold difference in antibacterial potency towards Gram-negative bacteria. The binding and insertion from solution of pleurocidin or magainin 2 to membranes representing the inner membrane of Gram-negative bacteria, comprising a mixture of 128 anionic and 384 zwitterionic lipids, is monitored over 100 ns in all atom molecular dynamics simulations. The effects of the membrane interaction on both the peptide and lipid constituents are considered and compared with new and published experimental data obtained in the steady state. While both magainin 2 and pleurocidin are capable of disrupting bacterial membranes, the greater potency of pleurocidin is linked to its ability to penetrate within the bacterial cell. We show that pleurocidin displays much greater conformational flexibility when compared with magainin 2, resists self-association at the membrane surface and penetrates further into the hydrophobic core of the lipid bilayer. Conformational flexibility is therefore revealed as a key feature required of apparently α-helical cationic AMPs for enhanced antibacterial potency.

Mechanism of action and in vitro activity of short hybrid antimicrobial peptide PV3 against Pseudomonas aeruginosa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Memariani, Hamed; Shahbazzadeh, Delavar; Sabatier, Jean-Marc

Antimicrobial peptides are attractive candidates for developing novel therapeutic agents, since they are lethal to a broad spectrum of pathogens and have a unique low tendency for resistance development. In this study, mechanism of action and in vitro anti-pseudomonal activity of previously designed short hybrid antimicrobial peptide PV3 were investigated. Compared to ceftazidime, PV3 had not only higher antibacterial activity but also faster bactericidal activity. PV3 reduced biofilm biomass and viability of biofilm embedded bacteria in a concentration-dependent manner. Although the antimicrobial activity of PV3 was reduced in Mueller-Hinton broth (MHB) containing human serum, it was still active enough to eradicationmore » of bacteria at low concentrations. Compared with standard condition (MHB only), there was no significant decrease in antibacterial activity of PV3 against P. aeruginosa strains under 150 mM NaCl (p = 0.615) and 1 mM MgCl{sub 2} (p = 0.3466). Fluorescence microscopy and field emission scanning electron microscopy further indicated that PV3 killed bacteria by disrupting the cell membrane. Since PV3 has potent anti-pseudomonal activity and has little cytotoxicity in vitro, it seems plausible that the peptide should be further investigated with animal studies to support future pharmacological formulations and potential topical applications. - Highlights: • PV3 killed Pseudomonas aeruginosa by membrane-disrupting mechanism. • PV3 reduced biofilm biomass and viability of biofilm embedded bacteria in a concentration-dependent manner. • Short hybrid antimicrobial peptide PV3 exhibited higher and faster bactericidal activity comparing to ceftazidime.« less

A study on the interactions of Aurein 2.5 with bacterial membranes.

PubMed

Dennison, Sarah R; Morton, Leslie H G; Shorrocks, Andrea J; Harris, Frederick; Phoenix, David A

2009-02-01

Aurein 2.5 (GLFDIVKKVVGAFGSL-NH(2)) is an uncharacterised antimicrobial peptide. At an air/water interface, it exhibited strong surface activity (maximal surface pressure 25mNm(-1)) and molecular areas consistent with the adoption of alpha-helical structure orientated either perpendicular (1.72nm(2)molecule(-1)) or parallel (3.6nm(2)molecule(-1)) to the interface. Aurein 2.5 was strongly antibacterial, exhibiting a minimum inhibitory concentration (MIC) of 30microM against Bacillus subtilis and Escherichia coli. The peptide induced maximal surface pressure changes of 9mNm(-1) and 5mNm(-1), respectively, in monolayers mimicking membranes of these organisms whilst compression isotherm analysis of these monolayers showed DeltaG(Mix)>0, indicating destabilisation by Aurein 2.5. These combined data suggested that toxicity of the peptide to these organisms may involve membrane invasion via the use of oblique orientated alpha-helical structure. The peptide induced strong, comparable maximal surface changes in monolayers of DOPG (7.5mNm(-1)) and DOPE monolayers (6mNm(-1)) suggesting that the membrane interactions of Aurein 2.5 were driven by amphiphilicity rather than electrostatic interaction. Based on these data, it was suggested that the differing ability of Aurein 2.5 to insert into membranes of B. subtilis and E. coli was probably related to membrane-based factors such as differences in lipid packing characteristics. The peptide was active against both sessile E. coli and Staphylococcus aureus with an MIC of 125microM. The broad-spectrum antibacterial activity and non-specific modes of membrane action used by Aurein 2.5 suggested use as an anti-biofilm agent such as in the decontamination of medical devices.

Antimicrobial Peptides in Reptiles

PubMed Central

van Hoek, Monique L.

2014-01-01

Reptiles are among the oldest known amniotes and are highly diverse in their morphology and ecological niches. These animals have an evolutionarily ancient innate-immune system that is of great interest to scientists trying to identify new and useful antimicrobial peptides. Significant work in the last decade in the fields of biochemistry, proteomics and genomics has begun to reveal the complexity of reptilian antimicrobial peptides. Here, the current knowledge about antimicrobial peptides in reptiles is reviewed, with specific examples in each of the four orders: Testudines (turtles and tortosises), Sphenodontia (tuataras), Squamata (snakes and lizards), and Crocodilia (crocodilans). Examples are presented of the major classes of antimicrobial peptides expressed by reptiles including defensins, cathelicidins, liver-expressed peptides (hepcidin and LEAP-2), lysozyme, crotamine, and others. Some of these peptides have been identified and tested for their antibacterial or antiviral activity; others are only predicted as possible genes from genomic sequencing. Bioinformatic analysis of the reptile genomes is presented, revealing many predicted candidate antimicrobial peptides genes across this diverse class. The study of how these ancient creatures use antimicrobial peptides within their innate immune systems may reveal new understandings of our mammalian innate immune system and may also provide new and powerful antimicrobial peptides as scaffolds for potential therapeutic development. PMID:24918867

Lactoferricin B causes depolarization of the cytoplasmic membrane of Escherichia coli ATCC 25922 and fusion of negatively charged liposomes.

PubMed

Ulvatne, H; Haukland, H H; Olsvik, O; Vorland, L H

2001-03-09

Antimicrobial peptides have been extensively studied in order to elucidate their mode of action. Most of these peptides have been shown to exert a bactericidal effect on the cytoplasmic membrane of bacteria. Lactoferricin is an antimicrobial peptide with a net positive charge and an amphipatic structure. In this study we examine the effect of bovine lactoferricin (lactoferricin B; Lfcin B) on bacterial membranes. We show that Lfcin B neither lyses bacteria, nor causes a major leakage from liposomes. Lfcin B depolarizes the membrane of susceptible bacteria, and induces fusion of negatively charged liposomes. Hence, Lfcin B may have additional targets responsible for the antibacterial effect.

Combined genetic and bioactivity-based prioritization leads to the isolation of an endophyte-derived antimycobacterial compound.

PubMed

Alvin, A; Kalaitzis, J A; Sasia, B; Neilan, B A

2016-05-01

To initiate a genetic and bioactivity-based screening programme of culturable endophytes to identify micro-organisms capable of producing bioactive polyketides and peptides. Fungal endophytes were isolated from flowers, leaves and roots of Rhoeo spathacea, revealing a community consisting of Colletotrichum sp., Fusarium sp., Guignardia sp., Phomopsis sp., Phoma sp. and Microdochium sp. Genetic screening showed that all isolates had polyketide synthase (PKS) genes and most had nonribosomal peptide synthetase (NRPS) genes. Ethyl acetate extracts of the fungal isolates exhibited antiproliferative activity against at least one of the seven bacterial and mycobacterial test strains. Nuclear Magnetic Resonance -guided fractionation of the crude extract from a Fusarium sp. strain which exhibited strong antiproliferative activity against Mycobacterium tuberculosis resulted in the isolation of the polyketide javanicin. This compound was active against Myco. tuberculosis (MIC = 25 μg ml(-1)) and Mycobacterium phlei (MIC = 50 μg ml(-1)). The medicinal plant R. spathacea hosts a variety of fungal endophytes capable of producing antibacterial and antimycobacterial compounds. There is a positive correlation between the presence of PKS and/or NRPS encoding genes in endophytes and the bioactivity of their respective organic extracts. This is the first report on the fungal endophytic diversity of R. spathacea, and the isolation of an antimycobacterial compound from the plant which has been traditionally used for the treatment of tuberculosis symptoms. © 2016 The Society for Applied Microbiology.

Identification of the Zinc Finger Protein ZRANB2 as a Novel Maternal Lipopolysaccharide-binding Protein That Protects Embryos of Zebrafish against Gram-negative Bacterial Infections*

PubMed Central

Wang, Xia; Du, Xiaoyuan; Li, Hongyan; Zhang, Shicui

2016-01-01

Zinc finger ZRANB2 proteins are widespread in animals, but their functions and mechanisms remain poorly defined. Here we clearly demonstrate that ZRANB2 is a newly identified LPS-binding protein present abundantly in the eggs/embryos of zebrafish. We also show that recombinant ZRANB2 (rZRANB2) acts as a pattern recognition receptor capable of identifying the bacterial signature molecule LPS as well as binding the Gram-negative bacteria Escherichia coli, Vibrio anguilarum, and Aeromonas hydrophila and functions as an antibacterial effector molecule capable of directly killing the bacteria. Furthermore, we reveal that N-terminal residues 11–37 consisting of the first ZnF_RBZ domain are indispensable for ZRANB2 antimicrobial activity. Importantly, microinjection of rZRANB2 into early embryos significantly enhanced the resistance of the embryos against pathogenic A. hydrophila challenge, and this enhanced bacterial resistance was markedly reduced by co-injection of anti-ZRANB2 antibody. Moreover, precipitation of ZRANB2 in the embryo extracts by preincubation with anti-ZRANB2 antibody caused a marked decrease in the antibacterial activity of the extracts against the bacteria tested. In addition, the N-terminal peptide Z1/37 or Z11/37 with in vitro antibacterial activity also promoted the resistance of embryos against A. hydrophila, but the peptide Z38/198 without in vitro antibacterial activity did not. Collectively, these results indicate that ZRANB2 is a maternal LPS-binding protein that can protect the early embryos of zebrafish against pathogenic attacks, a novel role ever assigned to ZRANB2 proteins. This work also provides new insights into the immunological function of the zinc finger proteins that are widely distributed in various animals. PMID:26740623

In vitro antimicrobial activity of natural toxins and animal venoms tested against Burkholderia pseudomallei

PubMed Central

Perumal Samy, R; Pachiappan, A; Gopalakrishnakone, P; Thwin, Maung M; Hian, Yap E; Chow, Vincent TK; Bow, Ho; Weng, Joseph T

2006-01-01

Background Burkholderia pseudomallei are the causative agent of melioidosis. Increasing resistance of the disease to antibiotics is a severe problem in treatment regime and has led to intensification of the search for new drugs. Antimicrobial peptides are the most ubiquitous in nature as part of the innate immune system and host defense mechanism. Methods Here, we investigated a group of venoms (snakes, scorpions and honey bee venoms) for antimicrobial properties against two strains of Gram-negative bacteria Burkholderia pseudomallei by using disc-diffusion assay for in vitro susceptibility testing. The antibacterial activities of the venoms were compared with that of the isolated L-amino acid oxidase (LAAO) and phospholipase A2 (PLA2s) enzymes. MICs were determined using broth dilution method. Bacterial growth was assessed by measurement of optical density at the lowest dilutions (MIC 0.25 mg/ml). The cell viability was measured using tetrazolium salts (XTT) based cytotoxic assay. Results The studied venoms showed high antimicrobial activity. The venoms of C. adamanteus, Daboia russelli russelli, A. halys, P. australis, B. candidus and P. guttata were equally as effective as Chloramphenicol and Ceftazidime (30 μg/disc). Among those tested, phospholipase A2 enzymes (crotoxin B and daboiatoxin) showed the most potent antibacterial activity against Gram-negative (TES) bacteria. Naturally occurring venom peptides and phospholipase A2 proved to possess highly potent antimicrobial activity against Burkholderia pseudomallei. The XTT-assay results showed that the cell survival decreased with increasing concentrations (0.05–10 mg/mL) of Crotalus adamanteus venom, with no effect on the cell viability evident at 0.5 mg/mL. Conclusion This antibacterial profile of snake venoms reported herein will be useful in the search for potential antibacterial agents against drug resistant microorganisms like B. pseudomallei. PMID:16784542

[Expression optimization and characterization of Tenebrio molitor antimicrobiol peptides TmAMP1m in Escherichia coli].

PubMed

Alimu, Reyihanguli; Mao, Xinfang; Liu, Zhongyuan

2013-06-01

To improve the expression level of tmAMP1m gene from Tenebrio molitor in Escherichia coli, we studied the effects of expression level and activity of the fusion protein HIS-TmAMP1m by conditions, such as culture temperature, inducing time and the final concentration of inductor Isopropyl beta-D-thiogalactopyranoside (IPTG). We analyzed the optimum expression conditions by Tricine-SDS-PAGE electrophoresis, meanwhile, detected its antibacterial activity by using agarose cavity diffusion method. The results suggest that when inducing the recombinant plasmid with a final IPTG concentration of 0.1 mmol/L at 37 degrees C for 4 h, there was the highest expression level of fusion protein HIS-TmAMP1m in Escherichia coli. Under these conditions, the expression of fusion protein accounted for 40% of the total cell lysate with the best antibacterial activity. We purified the fusion protein HIS-TmAMPlm with nickel-nitrilotriacetic acid (Ni-NTA) metal-affinity chromatography matrices. Western blotting analysis indicates that the His monoclonal antibody could be specifically bound to fusion protein HIS-TmAMPlm. After expression by inducing, the fusion protein could inhibit the growth of host cell transformed by pET30a-tmAMP1m. The fusion protein HIS-TmAMP1m had better stability and remained higher antibacterial activities when incubated at 100 degrees C for 10 h, repeated freeze thawing at -20 degrees C, dissolved in strong acid and alkali, or treated by organic solvents and protease. Moreover, the minimum inhibitory concentration results demonstrated that the fusion protein HIS-TmAMP1m has a good antibacterial activity against Staphylococcus aureus, Staphylococcus sp., Corynebacterium glutamicum, Bacillus thuringiensis, Corynebacterium sp. This study laid the foundation to promote the application of insect antimicrobial peptides and further research.

An iterative glycosyltransferase EntS catalyzes transfer and extension of O- and S-linked monosaccharide in enterocin 96.

PubMed

Nagar, Rupa; Rao, Alka

2017-05-12

Glycosyltransferases are essential tools for in vitro-glycoengineering. Bacteria harbor an unexplored variety of protein glycosyltransferases. Here, we describe a peptide glycosyltransferase (EntS) encoded by ORF0417 of Enterococcus faecalis TX0104. EntS di-glycosylates linear peptide of enterocin 96- a known antibacterial, in vitro. It is capable of transferring as well as extending the glycan onto the peptide in an iterative sequential dissociative manner. It can catalyze multiple linkages: Glc/Gal(-O)Ser/Thr, Glc/Gal(-S)Cys and Glc/Gal(β)Glc/Gal(-O/S)Ser/Thr/Cys, in one pot. Using EntS generated glycovariants of enterocin 96 peptide, size and identity of the glycan are found to influence bioactivity of the peptide. The study identifies EntS as an enzyme worth pursuing, for in vitro peptide glycoengineering. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Antibacterial Effects of a Cell-Penetrating Peptide Isolated from Kefir.

PubMed

Miao, Jianyin; Guo, Haoxian; Chen, Feilong; Zhao, Lichao; He, Liping; Ou, Yangwen; Huang, Manman; Zhang, Yi; Guo, Baoyan; Cao, Yong; Huang, Qingrong

2016-04-27

Kefir is a traditional fermented milk beverage used throughout the world for centuries. A cell-penetrating peptide, F3, was isolated from kefir by Sephadex G-50 gel filtration, DEAE-52 ion exchange, and reverse-phase high-performance liquid chromatography. F3 was determined to be a low molecular weight peptide containing one leucine and one tyrosine with two phosphate radicals. This peptide displayed antimicrobial activity across a broad spectrum of organisms including several Gram-positive and Gram-negative bacteria as well as fungi, with minimal inhibitory concentration (MIC) values ranging from 125 to 500 μg/mL. Cellular penetration and accumulation of F3 were determined by confocal laser scanning microscopy. The peptide was able to penetrate the cellular membrane of Escherichia coli and Staphylococcus aureus. Changes in cell morphology were observed by scanning electron microscopy (SEM). The results indicate that peptide F3 may be a good candidate for use as an effective biological preservative in agriculture and the food industry.

[Antimicrobial Activity of Substances Produced by Trichoderma citrinoviride Strain VKPM F-1228: Optimization of Cultivation and Assessment of Spectrum of Individual Peptaibols].

PubMed

Sadykova, V S; Kurakov, A V; Korshun, V A; Rogozhin, E A; Gromovykh, T I; Kuvarina, A E; Baranova, A A

2015-01-01

The Trichoderma citrinoviride VKPM F-1228 strain produces a complex of peptide-based antibiotics with antibacterial and antimycotic action. Synthesis of peptaibols is closely related to the conidiogenesis in the culture. The optimal procedure of the strain cultivation for production of peptaibols is stationary growing for 14 days at a temperature of 28 degrees C and pH 7.5 followed by formation of a dense mycelium film on the modified Saburo medium containing 30 gr/l of glucose and 12.5 gr/l of peptone. Eight individual peptaibols were extracted. The spectrum of their activity was estimated with the use of opportunistic bacteria and micromycetes as well as pathogenic clinical aspergilli. Compounds 9, 13, 14, 15 and 16 were shown active against opportunistic fungi and bacteria including methicillin resistant S. aureus, whereas compounds 9, 13 and 14 in addition showed antimycotic activity against clinical aspergilli.

The Cyclic Antibacterial Peptide Enterocin AS-48: Isolation, Mode of Action, and Possible Food Applications.

PubMed

Grande Burgos, María José; Pulido, Rubén Pérez; Del Carmen López Aguayo, María; Gálvez, Antonio; Lucas, Rosario

2014-12-08

Enterocin AS-48 is a circular bacteriocin produced by Enterococcus. It contains a 70 amino acid-residue chain circularized by a head-to-tail peptide bond. The conformation of enterocin AS-48 is arranged into five alpha-helices with a compact globular structure. Enterocin AS-48 has a wide inhibitory spectrum on Gram-positive bacteria. Sensitivity of Gram-negative bacteria increases in combination with outer-membrane permeabilizing treatments. Eukaryotic cells are bacteriocin-resistant. This cationic peptide inserts into bacterial membranes and causes membrane permeabilization, leading ultimately to cell death. Microarray analysis revealed sets of up-regulated and down-regulated genes in Bacillus cereus cells treated with sublethal bacteriocin concentration. Enterocin AS-48 can be purified in two steps or prepared as lyophilized powder from cultures in whey-based substrates. The potential applications of enterocin AS-48 as a food biopreservative have been corroborated against foodborne pathogens and/or toxigenic bacteria (Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Salmonella enterica) and spoilage bacteria (Alicyclobacillus acidoterrestris, Bacillus spp., Paenibacillus spp., Geobacillus stearothermophilus, Brochothrix thermosphacta, Staphylococcus carnosus, Lactobacillus sakei and other spoilage lactic acid bacteria). The efficacy of enterocin AS-48 in food systems increases greatly in combination with chemical preservatives, essential oils, phenolic compounds, and physico-chemical treatments such as sublethal heat, high-intensity pulsed-electric fields or high hydrostatic pressure.

The Cyclic Antibacterial Peptide Enterocin AS-48: Isolation, Mode of Action, and Possible Food Applications

PubMed Central

Grande Burgos, María José; Pérez Pulido, Rubén; López Aguayo, María del Carmen; Gálvez, Antonio; Lucas, Rosario

2014-01-01

Enterocin AS-48 is a circular bacteriocin produced by Enterococcus. It contains a 70 amino acid-residue chain circularized by a head-to-tail peptide bond. The conformation of enterocin AS-48 is arranged into five alpha-helices with a compact globular structure. Enterocin AS-48 has a wide inhibitory spectrum on Gram-positive bacteria. Sensitivity of Gram-negative bacteria increases in combination with outer-membrane permeabilizing treatments. Eukaryotic cells are bacteriocin-resistant. This cationic peptide inserts into bacterial membranes and causes membrane permeabilization, leading ultimately to cell death. Microarray analysis revealed sets of up-regulated and down-regulated genes in Bacillus cereus cells treated with sublethal bacteriocin concentration. Enterocin AS-48 can be purified in two steps or prepared as lyophilized powder from cultures in whey-based substrates. The potential applications of enterocin AS-48 as a food biopreservative have been corroborated against foodborne pathogens and/or toxigenic bacteria (Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Salmonella enterica) and spoilage bacteria (Alicyclobacillus acidoterrestris, Bacillus spp., Paenibacillus spp., Geobacillus stearothermophilus, Brochothrix thermosphacta, Staphylococcus carnosus, Lactobacillus sakei and other spoilage lactic acid bacteria). The efficacy of enterocin AS-48 in food systems increases greatly in combination with chemical preservatives, essential oils, phenolic compounds, and physico-chemical treatments such as sublethal heat, high-intensity pulsed-electric fields or high hydrostatic pressure. PMID:25493478

Actinopyga lecanora Hydrolysates as Natural Antibacterial Agents

PubMed Central

Ghanbari, Raheleh; Ebrahimpour, Afshin; Abdul-Hamid, Azizah; Ismail, Amin; Saari, Nazamid

2012-01-01

Actinopyga lecanora, a type of sea cucumber commonly known as stone fish with relatively high protein content, was explored as raw material for bioactive peptides production. Six proteolytic enzymes, namely alcalase, papain, pepsin, trypsin, bromelain and flavourzyme were used to hydrolyze A. lecanora at different times and their respective degrees of hydrolysis (DH) were calculated. Subsequently, antibacterial activity of the A. lecanora hydrolysates, against some common pathogenic Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas sp.) were evaluated. Papain hydrolysis showed the highest DH value (89.44%), followed by alcalase hydrolysis (83.35%). Bromelain hydrolysate after one and seven hours of hydrolysis exhibited the highest antibacterial activities against Pseudomonas sp., P. aeruginosa and E. coli at 51.85%, 30.07% and 30.45%, respectively compared to the other hydrolysates. Protein hydrolysate generated by papain after 8 h hydrolysis showed maximum antibacterial activity against S. aureus at 20.19%. The potent hydrolysates were further fractionated using RP-HPLC and antibacterial activity of the collected fractions from each hydrolysate were evaluated, wherein among them only three fractions from the bromelain hydrolysates exhibited inhibitory activities against Pseudomonas sp., P. aeruginosa and E. coli at 24%, 25.5% and 27.1%, respectively and one fraction of papain hydrolysate showed antibacterial activity of 33.1% against S. aureus. The evaluation of the relationship between DH and antibacterial activities of papain and bromelain hydrolysates revealed a meaningful correlation of four and six order functions. PMID:23222684

Enhanced membrane disruption and antibiotic action against pathogenic bacteria by designed histidine-rich peptides at acidic pH.

PubMed

Mason, A James; Gasnier, Claire; Kichler, Antoine; Prévost, Gilles; Aunis, Dominique; Metz-Boutigue, Marie-Hélène; Bechinger, Burkhard

2006-10-01

The histidine-rich amphipathic cationic peptide LAH4 has antibiotic and DNA delivery capabilities. Here, we explore the interaction of peptides from this family with model membranes as monitored by solid-state (2)H nuclear magnetic resonance and their antibiotic activities against a range of bacteria. At neutral pH, the membrane disruption is weak, but at acidic pH, the peptides strongly disturb the anionic lipid component of bacterial membranes and cause bacterial lysis. The peptides are effective antibiotics at both pH 7.2 and pH 5.5, although the antibacterial activity is strongly affected by the change in pH. At neutral pH, the LAH peptides were active against both methicillin-resistant and -sensitive Staphylococcus aureus strains but ineffective against Pseudomonas aeruginosa. In contrast, the LAH peptides were highly active against P. aeruginosa in an acidic environment, as is found in the epithelial-lining fluid of cystic fibrosis patients. Our results show that modest antibiotic activity of histidine-rich peptides can be dramatically enhanced by inducing membrane disruption, in this case by lowering the pH, and that histidine-rich peptides have potential as future antibiotic agents.

Structural characterization of a novel peptide with antimicrobial activity from the venom gland of the scorpion Tityus stigmurus: Stigmurin.

PubMed

de Melo, Edinara Targino; Estrela, Andréia Bergamo; Santos, Elizabeth Cristina Gomes; Machado, Paula Renata Lima; Farias, Kleber Juvenal Silva; Torres, Taffarel Melo; Carvalho, Enéas; Lima, João Paulo Matos Santos; Silva-Júnior, Arnóbio Antonio; Barbosa, Euzébio Guimarães; Fernandes-Pedrosa, Matheus de Freitas

2015-06-01

A new antimicrobial peptide, herein named Stigmurin, was selected based on a transcriptomic analysis of the Brazilian yellow scorpion Tityus stigmurus venom gland, an underexplored source for toxic peptides with possible biotechnological applications. Stigmurin was investigated in silico, by circular dichroism (CD) spectroscopy, and in vitro. The CD spectra suggested that this peptide interacts with membranes, changing its conformation in the presence of an amphipathic environment, with predominance of random coil and beta-sheet structures. Stigmurin exhibited antibacterial and antifungal activity, with minimal inhibitory concentrations ranging from 8.7 to 69.5μM. It was also showed that Stigmurin is toxic against SiHa and Vero E6 cell lines. The results suggest that Stigmurin can be considered a potential anti-infective drug. Copyright © 2015 Elsevier Inc. All rights reserved.

Ternary nylon-3 copolymers as host-defense peptide mimics: beyond hydrophobic and cationic subunits.

PubMed

Chakraborty, Saswata; Liu, Runhui; Hayouka, Zvi; Chen, Xinyu; Ehrhardt, Jeffrey; Lu, Qin; Burke, Eileen; Yang, Yiqing; Weisblum, Bernard; Wong, Gerard C L; Masters, Kristyn S; Gellman, Samuel H

2014-10-15

Host-defense peptides (HDPs) are produced by eukaryotes to defend against bacterial infection, and diverse synthetic polymers have recently been explored as mimics of these natural peptides. HDPs are rich in both hydrophobic and cationic amino acid residues, and most HDP-mimetic polymers have therefore contained binary combinations of hydrophobic and cationic subunits. However, HDP-mimetic polymers rarely duplicate the hydrophobic surface and cationic charge density found among HDPs ( Hu , K. ; et al. Macromolecules 2013 , 46 , 1908 ); the charge and hydrophobicity are generally higher among the polymers. Statistical analysis of HDP sequences ( Wang , G. ; et al. Nucleic Acids Res. 2009 , 37 , D933 ) has revealed that serine (polar but uncharged) is a very common HDP constituent and that glycine is more prevalent among HDPs than among proteins in general. These observations prompted us to prepare and evaluate ternary nylon-3 copolymers that contain a modestly polar but uncharged subunit, either serine-like or glycine-like, along with a hydrophobic subunit and a cationic subunit. Starting from binary hydrophobic-cationic copolymers that were previously shown to be highly active against bacteria but also highly hemolytic, we found that replacing a small proportion of the hydrophobic subunit with either of the polar, uncharged subunits can diminish the hemolytic activity with minimal impact on the antibacterial activity. These results indicate that the incorporation of polar, uncharged subunits may be generally useful for optimizing the biological activity profiles of antimicrobial polymers. In the context of HDP evolution, our findings suggest that there is a selective advantage to retaining polar, uncharged residues in natural antimicrobial peptides.

The Frog Skin-Derived Antimicrobial Peptide Esculentin-1a(1-21)NH2 Promotes the Migration of Human HaCaT Keratinocytes in an EGF Receptor-Dependent Manner: A Novel Promoter of Human Skin Wound Healing?

PubMed

Di Grazia, Antonio; Cappiello, Floriana; Imanishi, Akiko; Mastrofrancesco, Arianna; Picardo, Mauro; Paus, Ralf; Mangoni, Maria Luisa

2015-01-01

One of the many functions of skin is to protect the organism against a wide range of pathogens. Antimicrobial peptides (AMPs) produced by the skin epithelium provide an effective chemical shield against microbial pathogens. However, whereas antibacterial/antifungal activities of AMPs have been extensively characterized, much less is known regarding their wound healing-modulatory properties. By using an in vitro re-epithelialisation assay employing special cell-culture inserts, we detected that a derivative of the frog-skin AMP esculentin-1a, named esculentin-1a(1-21)NH2, significantly stimulates migration of immortalized human keratinocytes (HaCaT cells) over a wide range of peptide concentrations (0.025-4 μM), and this notably more efficiently than human cathelicidin (LL-37). This activity is preserved in primary human epidermal keratinocytes. By using appropriate inhibitors and an enzyme-linked immunosorbent assay we found that the peptide-induced cell migration involves activation of the epidermal growth factor receptor and STAT3 protein. These results suggest that esculentin-1a(1-21)NH2 now deserves to be tested in standard wound healing assays as a novel candidate promoter of skin re-epithelialisation. The established ability of esculentin-1a(1-21)NH2 to kill microbes without harming mammalian cells, namely its high anti-Pseudomonal activity, makes this AMP a particularly attractive candidate wound healing promoter, especially in the management of chronic, often Pseudomonas-infected, skin ulcers.

Characterization and antimicrobial spectrum of bacteriocins produced by lactic acid bacteria isolated from traditional Bulgarian dairy products.

PubMed

Simova, E D; Beshkova, D B; Dimitrov, Zh P

2009-02-01

To isolate bacteriocin-producing lactic acid bacteria (LAB) with high wide spectrum antibacterial activity and to characterize their inhibitory peptides. Seven LAB strains [Lactobacillus casei ssp. rhamnosus (PC5), Lactobacillus delbrueckii ssp. bulgaricus (BB18), Lactococcus lactis ssp. lactis (BCM5, BK15), Enterococcus faecium (MH3), Lactobacillus plantarum (BR12), Lactobacillus casei ssp. casei (BCZ2)], isolated from authentic Bulgarian dairy products were capable of producing bacteriocins, inhibiting the widest range of pathogenic bacteria. The bacteriocins were resistant to heating at 121 degrees C for 15 min, stable at pH 2-10, sensitive to protease, insensitive to alpha-amylase and lipase. Two of bacteriocins produced by Lact. bulgaricus BB18 (bulgaricin BB18) and E. faecium MH3 (enterocin MH3) were purified and the molecular masses were determined. The N-terminal amino acid sequence of bulgaricin BB18 did not show strong homology to other known bacteriocins. Lactobacillus bulgaricus BB18 and E. faecium MH3 produce two novel bacteriocins highly similar to the pediocin-like nonlantibiotics. The two bacteriocins are potential antimicrobial agents and, in conjunction with their producers, may have use in applications to contribute a positive effect on the balance of intestinal microflora. Furthermore, bulgaricin BB18 strongly inhibits Helicobacter pylori.

Design and Solution-Phase Synthesis of Membrane-Targeting Lipopeptides with Selective Antibacterial Activity.

PubMed

Konai, Mohini M; Adhikary, Utsarga; Haldar, Jayanta

2017-09-18

Designing selective antibacterial molecules remains an unmet goal in the field of membrane-targeting agents. Herein, we report the rational design and synthesis of a new class of lipopeptides, which possess highly selective bacterial killing over mammalian cells. The selective interaction with bacterial over mammalian membranes was established through various spectroscopic, as well as microscopic experiments, including biophysical studies with the model membranes. A detailed antibacterial structure-activity relationship was delineated after preparing a series of molecules consisting of the peptide moieties with varied sequence of amino acids, such as d-phenylalanine, d-leucine, and d-lysine. Antibacterial activity was found to vary with the nature and positioning of hydrophobicity in the molecules, as well as number of positive charges. Optimized lipopeptide 9 did not show any hemolytic activity even at 1000 μg mL -1 and displayed >200-fold and >100-fold selectivity towards S. aureus and E. coli, respectively. More importantly, compound 9 was found to display good antibacterial activity (MIC 6.3-12.5 μg mL -1 ) against the five top most critical bacteria according to World Health Organization (WHO) priority pathogens list. Therefore, the results suggested that this new class of lipopeptides bear real promises for the development as future antibacterial agents. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antibacterial surface design - Contact kill

NASA Astrophysics Data System (ADS)

Kaur, Rajbir; Liu, Song

2016-08-01

Designing antibacterial surfaces has become extremely important to minimize Healthcare Associated Infections which are a major cause of mortality worldwide. A previous biocide-releasing approach is based on leaching of encapsulated biocides such as silver and triclosan which exerts negative impacts on the environment and potentially contributes to the development of bacterial resistance. This drawback of leachable compounds led to the shift of interest towards a more sustainable and environmentally friendly approach: contact-killing surfaces. Biocides that can be bound onto surfaces to give the substrates contact-active antibacterial activity include quaternary ammonium compounds (QACs), quaternary phosphoniums (QPs), carbon nanotubes, antibacterial peptides, and N-chloramines. Among the above, QACs and N-chloramines are the most researched contact-active biocides. We review the engineering of contact-active surfaces using QACs or N-chloramines, the modes of actions as well as the test methods. The charge-density threshold of cationic surfaces for desired antibacterial efficacy and attempts to combine various biocides for the generation of new contact-active surfaces are discussed in detail. Surface positive charge density is identified as a key parameter to define antibacterial efficacy. We expect that this research field will continue to attract more research interest in view of the potential impact of self-disinfective surfaces on healthcare-associated infections, food safety and corrosion/fouling resistance required on industrial surfaces such as oil pipes and ship hulls.

Improving short antimicrobial peptides despite elusive rules for activity.

PubMed

Mikut, Ralf; Ruden, Serge; Reischl, Markus; Breitling, Frank; Volkmer, Rudolf; Hilpert, Kai

2016-05-01

Antimicrobial peptides (AMPs) can effectively kill a broad range of life threatening multidrug-resistant bacteria, a serious threat to public health worldwide. However, despite great hopes novel drugs based on AMPs are still rare. To accelerate drug development we studied different approaches to improve the antibacterial activity of short antimicrobial peptides. Short antimicrobial peptides seem to be ideal drug candidates since they can be synthesized quickly and easily, modified and optimized. In addition, manufacturing a short peptide drug will be more cost efficient than long and structured ones. In contrast to longer and structured peptides short AMPs seem hard to design and predict. Here, we designed, synthesized and screened five different peptide libraries, each consisting of 600 9-mer peptides, against Pseudomonas aeruginosa. Each library is presenting a different approach to investigate effectiveness of an optimization strategy. The data for the 3000 peptides were analyzed using models based on fuzzy logic bioinformatics and plausible descriptors. The rate of active or superior active peptides was improved from 31.0% in a semi-random library from a previous study to 97.8% in the best new designed library. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert. Copyright © 2015 Elsevier B.V. All rights reserved.

Bioactive peptides released from in vitro digestion of human milk with or without pasteurization.

PubMed

Wada, Yasuaki; Lönnerdal, Bo

2015-04-01

Pasteurized donor human milk (HM) serves as the best alternative for breast-feeding when availability of mother's milk is limited. Pasteurization is also applied to mother's own milk for very low birth weight infants, who are vulnerable to microbial infection. Whether pasteurization affects protein digestibility and therefore modulates the profile of bioactive peptides released from HM proteins by gastrointestinal digestion, has not been examined to date. HM with and without pasteurization (62.5 °C for 30 min) were subjected to in vitro gastrointestinal digestion, followed by peptidomic analysis to compare the formation of bioactive peptides. Some of the bioactive peptides, such as caseinophosphopeptide homologues, a possible opioid peptide (or propeptide), and an antibacterial peptide, were present in undigested HM and showed resistance to in vitro digestion, suggesting that these peptides are likely to exert their bioactivities in the gastrointestinal lumen, or be stably transported to target organs. In vitro digestion of HM released a large variety of bioactive peptides such as angiotensin I-converting enzyme-inhibitory, antioxidative, and immunomodulatory peptides. Bioactive peptides were released largely in the same manner with and without pasteurization. Provision of pasteurized HM may be as beneficial as breast-feeding in terms of milk protein-derived bioactive peptides.

Amphibian antimicrobial peptide fallaxin analogue FL9 affects virulence gene expression and DNA replication in Staphylococcus aureus.

PubMed

Gottschalk, Sanne; Gottlieb, Caroline T; Vestergaard, Martin; Hansen, Paul R; Gram, Lone; Ingmer, Hanne; Thomsen, Line E

2015-12-01

The rapid rise in antibiotic-resistant pathogens is causing increased health concerns, and consequently there is an urgent need for novel antimicrobial agents. Antimicrobial peptides (AMPs), which have been isolated from a wide range of organisms, represent a very promising class of novel antimicrobials. In the present study, the analogue FL9, based on the amphibian AMP fallaxin, was studied to elucidate its mode of action and antibacterial activity against the human pathogen Staphylococcus aureus. Our data showed that FL9 may have a dual mode of action against S. aureus. At concentrations around the MIC, FL9 bound DNA, inhibited DNA synthesis and induced the SOS DNA damage response, whereas at concentrations above the MIC the interaction between S. aureus and FL9 led to membrane disruption. The antibacterial activity of the peptide was maintained over a wide range of NaCl and MgCl(2) concentrations and at alkaline pH, while it was compromised by acidic pH and exposure to serum. Furthermore, at subinhibitory concentrations of FL9, S. aureus responded by increasing the expression of two major virulence factor genes, namely the regulatory rnaIII and hla, encoding α-haemolysin. In addition, the S. aureus-encoded natural tolerance mechanisms included peptide cleavage and the addition of positive charge to the cell surface, both of which minimized the antimicrobial activity of FL9. Our results add new information about FL9 and its effect on S. aureus, which may aid in the future development of analogues with improved therapeutic potential.

Reclaiming hijacked phagosomes: Hybrid nano-in-micro encapsulated MIAP peptide ensures host directed therapy by specifically augmenting phagosome-maturation and apoptosis in TB infected macrophage cells.

PubMed

Sharma, Ankur; Vaghasiya, Kalpesh; Gupta, Pushpa; Gupta, Umesh Datta; Verma, Rahul Kumar

2018-01-30

TB-Superbugs have emerged as one of the most challenging global health threat due to the decrease in effectiveness of conventional antibiotics. Meanwhile, Host defense peptides (HDP) have evolved as an alternative to classical therapeutics with lesser susceptibility of resistance. We describe the potential of nano-encapsulated synthetic Magainin-I analog peptide (MIAP) as Host Directed Therapy against TB. Micron-sized inhalable platform "Porous Nanoparticle Aggregates Particles (PNAP)" with nano-scale physiognomies were developed to improve the delivery of MIAP-peptide to the lungs and enhance its stability. This particle engineering enabled more control over aerodynamic characteristics and bioactive release. Antimicrobial and mechanistic studies were carried out against virulent H37Rv TB bacteria. These MIAP-PNAP nano-assemblies demonstrated dose and time dependent antibacterial action against virulent M.tb for at least 96 h, with up to ∼3.03-log CFU reduction in numbers of viable bacteria compared to untreated group. These MIAP-PNAP at concentration of 50 μM and above showed significant antibacterial effects on M.tb after 48-96 h of incubation. Mechanistically, MIAP nano-formulation enhanced host defense mechanism by averting bacteria-induced inhibition of phagosomal-lysosome fusion (Lysostracker) and apoptosis (Annexin-FITC) as shown by confocal microscopy and flow-cytometry. Encapsulated MIAP may serve for adjunctive host-directed TB therapy which may also synergizes the efficacy of standard anti-TB drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

Interactions of protamine with the marine bacterium, Pseudoalteromonas sp. NCIMB 2021.

PubMed

Pustam, A; Smith, C; Deering, C; Grosicki, K M T; Leng, T Y; Lin, S; Yang, J; Pink, D; Gill, T; Graham, L; Derksen, D; Bishop, C; Demont, M E; Wyeth, R C; Smith-Palmer, T

2014-03-01

Pseudoalteromonas sp. NCIMB 2021 (NCIMB 2021) was grown in synthetic seawater (SSW) containing pyruvate, in the presence (SSW(++) ) and absence (SSW(-) ) of divalent cations. Cultures contained single cells. Addition of the cationic antibacterial peptide (CAP), protamine, did not inhibit, but rather increased, the growth of NCIMB 2021 in SSW(++) and caused the bacteria to grow in chains. Bacterial growth was assessed using turbidity, cell counts and the sodium salt of resazurin. In SSW(-) , NCIMB 2021 was no longer resistant to protamine. The minimum inhibitory concentration (MIC) was 5 mg ml(-1) . Protamine is a cationic antimicrobial peptide (CAP), which is active against a variety of bacteria. This is the first in-depth study of the interaction of protamine with a marine bacterium, Pseudoalteromonas sp. NCIMB 2021. Our results show that protamine is only active in seawater in the absence of divalent cations. In the presence of the divalent cations, Mg(2+) and Ca(2+) , protamine enhances the growth of Pseudoalteromonas sp. NCIMB 2021 and produces chains rather than individual cells. These are important considerations when deciding on applications for protamine and in terms of understanding its mechanism of action. © 2013 The Society for Applied Microbiology.

Novel antibacterial polypeptide produced by Lactobacillus paracasei strain NRRL B-50314

USDA-ARS?s Scientific Manuscript database

This study reports the production and characterization of a novel antibacterial polypeptide, designated as laparaxin, which is secreted by Lactobacillus paracasei NRRL B-50314. The crude laparaxin has antibacterial activity against a range of Gram-positive bacteria including the following: lactic a...

Identification of the antibacterial compound produced by the marine epiphytic bacterium Pseudovibrio sp. D323 and related sponge-associated bacteria.

PubMed

Penesyan, Anahit; Tebben, Jan; Lee, Matthew; Thomas, Torsten; Kjelleberg, Staffan; Harder, Tilmann; Egan, Suhelen

2011-01-01

Surface-associated marine bacteria often produce secondary metabolites with antagonistic activities. In this study, tropodithietic acid (TDA) was identified to be responsible for the antibacterial activity of the marine epiphytic bacterium Pseudovibrio sp. D323 and related strains. Phenol was also produced by these bacteria but was not directly related to the antibacterial activity. TDA was shown to effectively inhibit a range of marine bacteria from various phylogenetic groups. However TDA-producers themselves were resistant and are likely to possess resistance mechanism preventing autoinhibition. We propose that TDA in isolate D323 and related eukaryote-associated bacteria plays a role in defending the host organism against unwanted microbial colonisation and, possibly, bacterial pathogens.

Production of novel types of antibacterial liamocins by diverse strains of Aureobasidium pullulans grown on different culture media.

PubMed

Leathers, Timothy D; Price, Neil P J; Bischoff, Kenneth M; Manitchotpisit, Pennapa; Skory, Christopher D

2015-10-01

To compare production of antibacterial liamocins (polyol lipids) by diverse strains of Aureobasidium pullulans grown on different culture media. Liamocins produced by strains of A. pullulans have potential agricultural and pharmaceutical applications as antibacterials with specificity against Streptococcus spp. Six strains of A. pullulans were characterized for liamocin production on four different culture media. The choice of strain and culture medium affected growth, liamocin yields, and production of contaminating pigments. Best growth and highest liamocin yields were obtained using A. pullulans strain NRRL 50384 grown on a sucrose basal medium. Unexpectedly, the choice of strain and culture medium also affected the structure of liamocins produced, providing novel types of liamocins. Liamocins varied not only in the ratios of trimer and tetramer polyester tail groups, but also in the nature of the polyol headgroup, which could include mannitol, arabitol, or glycerol. The ability to conveniently produce novel types of liamocins in good yields will provide novel antibacterials for applied uses, and facilitate structure-function studies on the mechanism of antibacterial activity.

Antimicrobial activity and mechanism of the human milk-sourced peptide Casein201

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fan; Department of Endocrinology, Children's Hospital of Nanjing Medical University, Nanjing; Cui, Xianwei

Introduction: Casein201 is one of the human milk sourced peptides that differed significantly in preterm and full-term mothers. This study is designed to demonstrate the biological characteristics, antibacterial activity and mechanisms of Casein201 against common pathogens in neonatal infection. Methodology: The analysis of biological characteristics was done by bioinformatics. Disk diffusion method and flow cytometry were used to detect the antimicrobial activity of Casein201. Killing kinetics of Casein201 was measured using microplate reader. The antimicrobial mechanism of Casein201 was studied by electron microscopy and electrophoresis. Results: Bioinformatics analysis indicates that Casein201 derived from β-casein and showed significant sequence overlap. Antibacterialmore » assays showed Casein201 inhibited the growth of S taphylococcus aureus and Y ersinia enterocolitica. Ultrastructural analyses revealed that the antibacterial activity of Casein201 is through cytoplasmic structures disintegration and bacterial cell envelope alterations but not combination with DNA. Conclusion: We conclude the antimicrobial activity and mechanism of Casein201. Our data demonstrate that Casein201 has potential therapeutic value for the prevention and treatment of pathogens in neonatal infection.« less

Cleavage Specificity of Mycobacterium tuberculosis ClpP1P2 Protease and Identification of Novel Peptide Substrates and Boronate Inhibitors with Anti-bacterial Activity*

PubMed Central

Akopian, Tatos; Kandror, Olga; Tsu, Christopher; Lai, Jack H.; Wu, Wengen; Liu, Yuxin; Zhao, Peng; Park, Annie; Wolf, Lisa; Dick, Lawrence R.; Rubin, Eric J.; Bachovchin, William; Goldberg, Alfred L.

2015-01-01

The ClpP1P2 protease complex is essential for viability in Mycobacteria tuberculosis and is an attractive drug target. Using a fluorogenic tripeptide library (Ac-X3X2X1-aminomethylcoumarin) and by determining specificity constants (kcat/Km), we show that ClpP1P2 prefers Met ≫ Leu > Phe > Ala in the X1 position, basic residues or Trp in the X2 position, and Pro ≫ Ala > Trp in the X3 position. We identified peptide substrates that are hydrolyzed up to 1000 times faster than the standard ClpP substrate. These positional preferences were consistent with cleavage sites in the protein GFPssrA by ClpXP1P2. Studies of ClpP1P2 with inactive ClpP1 or ClpP2 indicated that ClpP1 was responsible for nearly all the peptidase activity, whereas both ClpP1 and ClpP2 contributed to protein degradation. Substrate-based peptide boronates were synthesized that inhibit ClpP1P2 peptidase activity in the submicromolar range. Some of them inhibited the growth of Mtb cells in the low micromolar range indicating that cleavage specificity of Mtb ClpP1P2 can be used to design novel anti-bacterial agents. PMID:25759383

Antibacterial Peptidomimetics: Polymeric Synthetic Mimics of Antimicrobial Peptides

NASA Astrophysics Data System (ADS)

Lienkamp, Karen; Madkour, Ahmad E.; Tew, Gregory N.

Polymer-based peptidomimetics, or proteinomimetics, are a relatively young and dynamic field of research. The ability to successfully mimic the biochemical activity of antimicrobial peptides (AMPs) has been demonstrated by several groups. This has been accomplished by careful tuning of the molecule's hydrophobicity and charge density. At the same time, many important questions remain to be answered, including the role of backbone rigidity, details of membrane insertion, and the role of curvature in the self-assemblies between these novel peptidemimetics and phospholipids. As the biological properties of polymeric synthetic mimics of AMPs (SMAMPs) result from the interplay of many parameters, it is not yet possible to predict the exact properties of such molecules from their mere chemical structure. However, as demonstrated here, the effect of certain design features such as charge and hydrophobicity on the properties across a polymer series is understood. Compared to the mechanistic specifics that are known about the interactions of AMPs or small antibacterial molecules with membranes and cells, relatively little is known concerning the interaction of polymeric SMAMPs with membranes. Beyond SMAMPs, numerous opportunities exist and protein transduction domain mimics are an active area of research in the Tew laboratory. These two examples, one quite new and the other studied for almost a decade, demonstrate that it is possible to teach synthetic polymers to behave like peptides, despite their lack of sequence specificity and secondary structure.

Novel antibacterial polypeptide laparaxin produced by Lactobacillus paracasei strain NRRL B-50314 via fermentation

USDA-ARS?s Scientific Manuscript database

This study reports the production and characterization of a novel antibacterial polypeptide, designated laparaxin, which is secreted by Lactobacillus paracasei NRRL B-50314. Crude laparaxin has antibacterial activity against a wide variety of Gram-positive bacteria, including: lactic acid bacteria ...

Hydrogen peroxide-dependent antibacterial action of Melilotus albus honey.

PubMed

Sowa, P; Grabek-Lejko, D; Wesołowska, M; Swacha, S; Dżugan, M

2017-07-01

Honey originating from different floral sources exhibits the broad spectrum of antibacterial activity as a result of the presence of hydrogen peroxide as well as nonperoxide bioactive compounds. The mechanisms of antibacterial activity of Polish melilot honey were investigated for the first time. Polish melilot honey samples (Melilotus albus biennial = 3 and annual = 5, Melilotus officinalis = 1) were collected directly from beekeepers and analysed for pollen profile, basic physicochemical parameters, antioxidant capacity, radical scavenging activity, total phenolic contents as well as antibacterial properties against pathogenic bacteria Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Salmonella spp. The physicochemical properties of melilot honey were specific for light-coloured unifloral honey samples and were not dependent on its botanical and geographical origin (P > 0·05). All tested honey samples exhibited inhibitory activity (above 90%) against Gram-positive bacteria at the concentration of 12·5-25%. Above 30-50% of antibacterial activity of melilot honey was connected with glucose oxidase enzyme action and was destroyed in the presence of catalase. Hydrogen peroxide-dependent antibacterial activity of honey was inversely correlated with its radical scavenging activity (r = -0·67) and phenolic compounds (r = -0·61). Antibacterial action of melilot honey depends not only on hydrogen peroxide produced by glucose oxidase, but also on other nonperoxide bioactive components of honey. Melilot honey is used in traditional medicine as an anticoagulant agent due to the possibility of the presence of the coumarin compounds which are specific for Melilotus plant. Melilotus albus is rarely used to produce honey, and antibacterial properties of this variety of honey had not been studied yet. Nine samples of melilot honey produced in different regions of Poland were analysed according to their antibacterial activity which was correlated with physiochemical parameters and antioxidant activity. It was shown that antibacterial activity of melilot honey is created by hydrogen peroxide and other bioactive compounds. © 2017 The Society for Applied Microbiology.

Application of 3D-QSAR for identification of descriptors defining bioactivity of antimicrobial peptides.

PubMed

Bhonsle, Jayendra B; Venugopal, Divakaramenon; Huddler, Donald P; Magill, Alan J; Hicks, Rickey P

2007-12-27

In our laboratory, a series of antimicrobial peptides have been developed, where the resulting 3D-physicochemical properties are controlled by the placement of amino acids with well-defined properties (hydrophobicity, charge density, electrostatic potential, and so on) at specific locations along the peptide backbone. These peptides exhibited different in vitro activity against Staphylococcus aureus (SA) and Mycobacterium ranae (MR) bacteria. We hypothesized that the differences in the biological activity is a direct manifestation of different physicochemical interactions that occur between the peptides and the cell membranes of the bacteria. 3D-QSAR analysis has shown that, within this series, specific physicochemical properties are responsible for antibacterial activity and selectivity. There are five physicochemical properties specific to the SA QSAR model, while five properties are specific to the MR QSAR model. These results support the hypothesis that, for any particular AMP, organism selectivity and potency are controlled by the chemical composition of the target cell membrane.

Structure and membrane interactions of the homodimeric antibiotic peptide homotarsinin

NASA Astrophysics Data System (ADS)

Verly, Rodrigo M.; Resende, Jarbas M.; Junior, Eduardo F. C.; de Magalhães, Mariana T. Q.; Guimarães, Carlos F. C. R.; Munhoz, Victor H. O.; Bemquerer, Marcelo Porto; Almeida, Fábio C. L.; Santoro, Marcelo M.; Piló-Veloso, Dorila; Bechinger, Burkhard

2017-01-01

Antimicrobial peptides (AMPs) from amphibian skin are valuable template structures to find new treatments against bacterial infections. This work describes for the first time the structure and membrane interactions of a homodimeric AMP. Homotarsinin, which was found in Phyllomedusa tarsius anurans, consists of two identical cystine-linked polypeptide chains each of 24 amino acid residues. The high-resolution structures of the monomeric and dimeric peptides were determined in aqueous buffers. The dimer exhibits a tightly packed coiled coil three-dimensional structure, keeping the hydrophobic residues screened from the aqueous environment. An overall cationic surface of the dimer assures enhanced interactions with negatively charged membranes. An extensive set of biophysical data allowed us to establish structure-function correlations with antimicrobial assays against Gram-positive and Gram-negative bacteria. Although both peptides present considerable antimicrobial activity, the dimer is significantly more effective in both antibacterial and membrane biophysical assays.

Structure and membrane interactions of the homodimeric antibiotic peptide homotarsinin

PubMed Central

Verly, Rodrigo M.; Resende, Jarbas M.; Junior, Eduardo F. C.; de Magalhães, Mariana T. Q.; Guimarães, Carlos F. C. R.; Munhoz, Victor H. O.; Bemquerer, Marcelo Porto; Almeida, Fábio C. L.; Santoro, Marcelo M.; Piló-Veloso, Dorila; Bechinger, Burkhard

2017-01-01

Antimicrobial peptides (AMPs) from amphibian skin are valuable template structures to find new treatments against bacterial infections. This work describes for the first time the structure and membrane interactions of a homodimeric AMP. Homotarsinin, which was found in Phyllomedusa tarsius anurans, consists of two identical cystine-linked polypeptide chains each of 24 amino acid residues. The high-resolution structures of the monomeric and dimeric peptides were determined in aqueous buffers. The dimer exhibits a tightly packed coiled coil three-dimensional structure, keeping the hydrophobic residues screened from the aqueous environment. An overall cationic surface of the dimer assures enhanced interactions with negatively charged membranes. An extensive set of biophysical data allowed us to establish structure-function correlations with antimicrobial assays against Gram-positive and Gram-negative bacteria. Although both peptides present considerable antimicrobial activity, the dimer is significantly more effective in both antibacterial and membrane biophysical assays. PMID:28102305

Structure and membrane interactions of the homodimeric antibiotic peptide homotarsinin.

PubMed

Verly, Rodrigo M; Resende, Jarbas M; Junior, Eduardo F C; de Magalhães, Mariana T Q; Guimarães, Carlos F C R; Munhoz, Victor H O; Bemquerer, Marcelo Porto; Almeida, Fábio C L; Santoro, Marcelo M; Piló-Veloso, Dorila; Bechinger, Burkhard

2017-01-19

Antimicrobial peptides (AMPs) from amphibian skin are valuable template structures to find new treatments against bacterial infections. This work describes for the first time the structure and membrane interactions of a homodimeric AMP. Homotarsinin, which was found in Phyllomedusa tarsius anurans, consists of two identical cystine-linked polypeptide chains each of 24 amino acid residues. The high-resolution structures of the monomeric and dimeric peptides were determined in aqueous buffers. The dimer exhibits a tightly packed coiled coil three-dimensional structure, keeping the hydrophobic residues screened from the aqueous environment. An overall cationic surface of the dimer assures enhanced interactions with negatively charged membranes. An extensive set of biophysical data allowed us to establish structure-function correlations with antimicrobial assays against Gram-positive and Gram-negative bacteria. Although both peptides present considerable antimicrobial activity, the dimer is significantly more effective in both antibacterial and membrane biophysical assays.

An ecoimmunological approach to study evolutionary and ancient links between coagulation, complement and Innate immunity

PubMed Central

Kasetty, Gopinath; Alyafei, Saud; Smeds, Emanuel; Salo-Ahen, Outi M. H.; Hansson, Stefan R.; Egesten, Arne; Herwald, Heiko

2018-01-01

ABSTRACT Coagulation, complement, and innate immunity are tightly interwoven and form an alliance that can be traced back to early eukaryotic evolution. Here we employed an ecoimmunological approach using Tissue Factor Pathway Inhibitor (TFPI)-1-derived peptides from the different classes of vertebrates (i.e. fish, reptile, bird, and mammals) and tested whether they can boost killing of various human bacterial pathogens in plasma. We found signs of species-specific conservation and diversification during evolution in these peptides that significantly impact their antibacterial activity. Though all peptides tested executed bactericidal activity in mammalian plasma (with the exception of rodents), no killing was observed in plasma from birds, reptiles, and fish, pointing to a crucial role for the classical pathway of the complement system. We also observed an interference of these peptides with the human intrinsic pathway of coagulation though, unlike complement activation, this mechanism appears not to be evolutionary conserved. PMID:29473457

Lipopolysaccharide induces amyloid formation of antimicrobial peptide HAL-2.

PubMed

Wang, Jiarong; Li, Yan; Wang, Xiaoming; Chen, Wei; Sun, Hongbin; Wang, Junfeng

2014-11-01

Lipopolysaccharide (LPS), the important component of the outer membrane of Gram-negative bacteria, contributes to the integrity of the outer membrane and protects the cell against bactericidal agents, including antimicrobial peptides. However, the mechanisms of interaction between antimicrobial peptides and LPS are not clearly understood. Halictines-2 (HAL-2), one of the novel antimicrobial peptides, was isolated from the venom of the eusocial bee Halictus sexcinctus. HAL-2 has exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria and even against cancer cells. Here, we studied the interactions between HAL-2 and LPS to elucidate the antibacterial mechanism of HAL-2 in vitro. Our results show that HAL-2 adopts a significant degree of β-strand structure in the presence of LPS. LPS is capable of inducing HAL-2 amyloid formation, which may play a vital role in its antimicrobial activity. Copyright © 2014 Elsevier B.V. All rights reserved.

Insight into the mechanism of action of temporin-SHa, a new broad-spectrum antiparasitic and antibacterial agent

PubMed Central

Abbassi, Feten; Humblot, Vincent; Bouceba, Tahar; Correia, Isabelle; Casale, Sandra; Foulon, Thierry; Sereno, Denis; Oury, Bruno; Ladram, Ali

2017-01-01

Antimicrobial peptides (AMPs) are promising drugs to kill resistant pathogens. In contrast to bacteria, protozoan parasites, such as Leishmania, were little studied. Therefore, the antiparasitic mechanism of AMPs is still unclear. In this study, we sought to get further insight into this mechanism by focusing our attention on temporin-SHa (SHa), a small broad-spectrum AMP previously shown to be active against Leishmania infantum. To improve activity, we designed analogs of SHa and compared the antibacterial and antiparasitic mechanisms. [K3]SHa emerged as a highly potent compound active against a wide range of bacteria, yeasts/fungi, and trypanosomatids (Leishmania and Trypanosoma), with leishmanicidal intramacrophagic activity and efficiency toward antibiotic-resistant strains of S. aureus and antimony-resistant L. infantum. Multipassage resistance selection demonstrated that temporins-SH, particularly [K3]SHa, are not prone to induce resistance in Escherichia coli. Analysis of the mode of action revealed that bacterial and parasite killing occur through a similar membranolytic mechanism involving rapid membrane permeabilization and depolarization. This was confirmed by high-resolution imaging (atomic force microscopy and field emission gun-scanning electron microscopy). Multiple combined techniques (nuclear magnetic resonance, surface plasmon resonance, differential scanning calorimetry) allowed us to detail peptide-membrane interactions. [K3]SHa was shown to interact selectively with anionic model membranes with a 4-fold higher affinity (KD = 3 x 10−8 M) than SHa. The amphipathic α-helical peptide inserts in-plane in the hydrophobic lipid bilayer and disrupts the acyl chain packing via a detergent-like effect. Interestingly, cellular events, such as mitochondrial membrane depolarization or DNA fragmentation, were observed in L. infantum promastigotes after exposure to SHa and [K3]SHa at concentrations above IC50. Our results indicate that these temporins exert leishmanicidal activity via a primary membranolytic mechanism but can also trigger apoptotis-like death. The many assets demonstrated for [K3]SHa make this small analog an attractive template to develop new antibacterial/antiparasitic drugs. PMID:28319176

Production of novel types of antibacterial liamocins by diverse strains of Aureobasidium pullulans grown on different culture media

USDA-ARS?s Scientific Manuscript database

Objective: The objective was to compare production of antibacterial liamocins by diverse strains of A. pullulans grown on different culture media. Results: Liamocins produced by strains of A. pullulans have potential agricultural and pharmaceutical applications as antibacterials with specificity aga...

Antibacterial activity of extracellular compounds produced by a Pseudomonas strain against methicillin-resistant Staphylococcus aureus (MRSA) strains

PubMed Central

2013-01-01

Background The emergence of multidrug-resistant bacteria is a world health problem. Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA) strains, is one of the most important human pathogens associated with hospital and community-acquired infections. The aim of this work was to evaluate the antibacterial activity of a Pseudomonas aeruginosa-derived compound against MRSA strains. Methods Thirty clinical MRSA strains were isolated, and three standard MRSA strains were evaluated. The extracellular compounds were purified by vacuum liquid chromatography. Evaluation of antibacterial activity was performed by agar diffusion technique, determination of the minimal inhibitory concentration, curve of growth and viability and scanning electron microscopy. Interaction of an extracellular compound with silver nanoparticle was studied to evaluate antibacterial effect. Results The F3 (ethyl acetate) and F3d (dichloromethane- ethyl acetate) fractions demonstrated antibacterial activity against the MRSA strains. Phenazine-1-carboxamide was identified and purified from the F3d fraction and demonstrated slight antibacterial activity against MRSA, and synergic effect when combined with silver nanoparticles produced by Fusarium oxysporum. Organohalogen compound was purified from this fraction showing high antibacterial effect. Using scanning electron microscopy, we show that the F3d fraction caused morphological changes to the cell wall of the MRSA strains. Conclusions These results suggest that P. aeruginosa-produced compounds such as phenazines have inhibitory effects against MRSA and may be a good alternative treatment to control infections caused by MRSA. PMID:23773484

Buwchitin: a ruminal peptide with antimicrobial potential against Enterococcus faecalis

NASA Astrophysics Data System (ADS)

Oyama, Linda B.; Crochet, Jean-Adrien; Edwards, Joan E.; Girdwood, Susan E.; Cookson, Alan R.; Fernandez-Fuentes, Narcis; Hilpert, Kai; Golyshin, Peter N.; Golyshina, Olga V.; Privé, Florence; Hess, Matthias; Mantovani, Hilario C.; Creevey, Christopher J.; Huws, Sharon A.

2017-07-01

Antimicrobial peptides (AMPs) are gaining popularity as alternatives for treatment of bacterial infections and recent advances in omics technologies provide new platforms for AMP discovery. We sought to determine the antibacterial activity of a novel antimicrobial peptide, buwchitin, against Enterococcus faecalis. Buwchitin was identified from a rumen bacterial metagenome library, cloned, expressed and purified. The antimicrobial activity of the recombinant peptide was assessed using a broth microdilution susceptibility assay to determine the peptide's killing kinetics against selected bacterial strains. The killing mechanism of buwchitin was investigated further by monitoring its ability to cause membrane depolarization (diSC3(5) method) and morphological changes in E. faecalis cells. Transmission electron micrographs of buwchitin treated E. faecalis cells showed intact outer membranes with blebbing, but no major damaging effects and cell morphology changes. Buwchitin had negligible cytotoxicity against defibrinated sheep erythrocytes. Although no significant membrane leakage and depolarization was observed, buwchitin at minimum inhibitory concentration (MIC) was bacteriostatic against E. faecalis cells and inhibited growth in vitro by 70% when compared to untreated cells. These findings suggest that buwchitin, a rumen derived peptide, has potential for antimicrobial activity against E. faecalis.

Understanding the antimicrobial properties/activity of an 11-residue Lys homopeptide by alanine and proline scan.

PubMed

Carvajal-Rondanelli, P; Aróstica, M; Álvarez, C A; Ojeda, C; Albericio, F; Aguilar, L F; Marshall, S H; Guzmán, F

2018-05-01

Previous work demonstrated that lysine homopeptides adopt a polyproline II (PPII) structure. Lysine homopeptides with odd number of residues, especially with 11 residues (K11), were capable of inhibiting the growth of a broader spectrum of bacteria than those with an even number. Confocal studies also determined that K11 was able to localize exclusively in the bacterial membrane, leading to cell death. In this work, the mechanism of action of this peptide was further analyzed focused on examining the structural changes in bacterial membrane induced by K11, and in K11 itself when interacting with bacterial membrane lipids. Moreover, alanine and proline scans were performed for K11 to identify relevant positions in structure conformation and antibacterial activity. To do so, circular dichroism spectroscopy (CD) was conducted in saline phosphate buffer (PBS) and in lipidic vesicles, using large unilamellar vesicles (LUV), composed of 2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) or bacterial membrane lipid. Antimicrobial activity of K11 and their analogs was evaluated in Gram-positive and Gram-negative bacterial strains. The scanning electron microscopy (SEM) micrographs of Staphylococcus aureus ATCC 25923 exposed to the Lys homopeptide at MIC concentration showed blisters and bubbles formed on the bacterial surface, suggesting that K11 exerts its action by destabilizing the bacterial membrane. CD analysis revealed a remarkably enhanced PPII structure of K11 when replacing some of its central residues by proline in PBS. However, when such peptide analogs were confronted with either DMPG-LUV or membrane lipid extract-LUV, the tendency to form PPII structure was severely weakened. On the contrary, K11 peptide showed a remarkably enhanced PPII structure in the presence of DMPG-LUV. Antibacterial tests revealed that K11 was able to inhibit all tested bacteria with an MIC value of 5 µM, while proline and alanine analogs have a reduced activity on Listeria monocytogenes. Besides, the activity against Vibrio parahaemolyticus was affected in most of the alanine-substituted analogs. However, lysine substitutions by alanine or proline at position 7 did not alter the activity against all tested bacterial strains, suggesting that this position can be screened to find a substitute amino acid yielding a peptide with increased antibacterial activity. These results also indicate that the PPII secondary structure of K11 is stabilized by the interaction of the peptide with negatively charged phospholipids in the bacterial membrane, though not being the sole determinant for its antimicrobial activity.

Antibacterial Derivatives of Marine Algae: An Overview of Pharmacological Mechanisms and Applications

PubMed Central

Shannon, Emer; Abu-Ghannam, Nissreen

2016-01-01

The marine environment is home to a taxonomically diverse ecosystem. Organisms such as algae, molluscs, sponges, corals, and tunicates have evolved to survive the high concentrations of infectious and surface-fouling bacteria that are indigenous to ocean waters. Both macroalgae (seaweeds) and microalgae (diatoms) contain pharmacologically active compounds such as phlorotannins, fatty acids, polysaccharides, peptides, and terpenes which combat bacterial invasion. The resistance of pathogenic bacteria to existing antibiotics has become a global epidemic. Marine algae derivatives have shown promise as candidates in novel, antibacterial drug discovery. The efficacy of these compounds, their mechanism of action, applications as antibiotics, disinfectants, and inhibitors of foodborne pathogenic and spoilage bacteria are reviewed in this article. PMID:27110798

A New Method of Producing a Natural Antibacterial Peptide by Encapsulated Probiotics Internalized with Inulin Nanoparticles as Prebiotics.

PubMed

Cui, Lian-Hua; Yan, Chang-Guo; Li, Hui-Shan; Kim, Whee-Soo; Hong, Liang; Kang, Sang-Kee; Choi, Yun-Jaie; Cho, Chong-Su

2018-04-28

Synbiotics are a combination of probiotics and prebiotics, which lead to synergistic benefits in host welfare. Probiotics have been used as an alternative to antibiotics. Among the probiotics, Pediococcus acidilactici (PA) has shown excellent antimicrobial activity against Salmonella Gallinarum (SG) as a major poultry pathogen and has improved the production performances of animals. Inulin is widely used as a prebiotic for the improvement of animal health and growth. The main aim of this study is to investigate the effect of the antimicrobial activity of inulin nanoparticles (INs)-internalized PA encapsulated into alginate/chitosan/alginate (ACA) microcapsules (MCs) in future in vivo application. The prepared phthalyl INs (PINs) were characterized by DLS and FE-SEM. The contents of phthal groups in phthalyl inulin were estimated by ¹H-NMR measurement as 25.1 mol.-%. The sizes of the PINs measured by DLS were approximately 203 nm. Internalization into PA was confirmed by confocal microscopy and flow cytometry. Antimicrobial activity of PIN-internalized probiotics encapsulated into ACA MCs was measured by co-culture antimicrobial assays on SG. PIN-internalized probiotics had a higher antimicrobial ability than that of ACA MCs loaded with PA/inulin or PA. Interestingly, when PINs were treated with PA and encapsulated into ACA MCs, as a natural antimicrobial peptide, pediocin was produced much more in the culture medium compared with other groups inulin-loaded ACA MCs and PA-encapsulated into ACA MCs.

Antibacterial and Antifungal Compounds from Marine Fungi

PubMed Central

Xu, Lijian; Meng, Wei; Cao, Cong; Wang, Jian; Shan, Wenjun; Wang, Qinggui

2015-01-01

This paper reviews 116 new compounds with antifungal or antibacterial activities as well as 169 other known antimicrobial compounds, with a specific focus on January 2010 through March 2015. Furthermore, the phylogeny of the fungi producing these antibacterial or antifungal compounds was analyzed. The new methods used to isolate marine fungi that possess antibacterial or antifungal activities as well as the relationship between structure and activity are shown in this review. PMID:26042616

Insights into the mechanisms of Promysalin, a secondary metabolite with genus-specific antibacterial activity against Pseudomonas

USDA-ARS?s Scientific Manuscript database

Promysalin, a secondary metabolite produced by Pseudomonas putida RW10S1, has antibacterial activity against a wide variety of Pseudomonas sp., including both human and plant pathogens. Promysalin induces swarming and biofilm formation in the producing species, and inhibits growth of susceptible sp...

Antimicrobial peptides from the skins of North American frogs.

PubMed

Conlon, J Michael; Kolodziejek, Jolanta; Nowotny, Norbert

2009-08-01

North America is home to anuran species belonging to the families Bufonidae, Eleutherodactylidae, Hylidae, Leiopelmatidae, Ranidae, and Scaphiopodidae but antimicrobial peptides have been identified only in skin secretions and/or skin extracts of frogs belonging to the Leiopelmatidae ("tailed frogs") and Ranidae ("true frogs"). Eight structurally-related cationic alpha-helical peptides with broad-spectrum antibacterial activity, termed ascaphins, have been isolated from specimens of Ascaphus truei (Leiopelmatidae) occupying a coastal range. Characterization of orthologous antimicrobial peptides from Ascaphus specimens occupying an inland range supports the proposal that this population should be regarded as a separate species A. montanus. Ascaphin-8 shows potential for development into a therapeutically valuable anti-infective agent. Peptides belonging to the brevinin-1, esculentin-1, esculentin-2, palustrin-1, palustrin-2, ranacyclin, ranatuerin-1, ranatuerin-2, and temporin families have been isolated from North American ranids. It is proposed that "ranalexins" represent brevinin-1 peptides that have undergone a four amino acid residue internal deletion. Current taxonomic recommendations divide North American frogs from the family Ranidae into two genera: Lithobates and Rana. Cladistic analysis based upon the amino acid sequences of the brevinin-1 peptides provides strong support for this assignment.

A Therapeutic Potential of Animal β-hairpin Antimicrobial Peptides.

PubMed

Panteleev, Pavel V; Balandin, Sergey V; Ivanov, Vadim T; Ovchinnikova, Tatiana V

2017-01-01

Endogenous antimicrobial peptides (AMPs) are evolutionary ancient molecular factors of innate immunity that play the key role in host defense. Because of the low resistance rate, AMPs have caught extensive attention as possible alternatives to conventional antibiotics. Over the last years, it has become evident that biological functions of AMPs are beyond direct killing of microbial cells. This review focuses on a relatively small family of animal host defense peptides with the β-hairpin structure stabilized by disulfide bridges. Their small size, rigid structure, stability to proteases, and plethora of biological functions, including antibacterial, antifungal, antiviral, anticancer, endotoxin-binding, metabolism- and immune- modulating activities, make natural β-hairpin AMPs an attractive molecular basis for drug design. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

In vitro evaluation of the potential for resistance development to ceragenin CSA-13

PubMed Central

Pollard, Jake E.; Snarr, Jason; Chaudhary, Vinod; Jennings, Jacob D.; Shaw, Hannah; Christiansen, Bobbie; Wright, Jonathan; Jia, Wenyi; Bishop, Russell E.; Savage, Paul B.

2012-01-01

Objectives Though most bacteria remain susceptible to endogenous antimicrobial peptides, specific resistance mechanisms are known. As mimics of antimicrobial peptides, ceragenins were expected to retain antibacterial activity against Gram-positive and -negative bacteria, even after prolonged exposure. Serial passaging of bacteria to a lead ceragenin, CSA-13, was performed with representative pathogenic bacteria. Ciprofloxacin, vancomycin and colistin were used as comparators. The mechanisms of resistance in Gram-negative bacteria were elucidated. Methods Susceptible strains of Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumannii were serially exposed to CSA-13 and comparators for 30 passages. MIC values were monitored. Alterations in the Gram-negative bacterial membrane composition were characterized via mass spectrometry and the susceptibility of antimicrobial-peptide-resistant mutants to CSA-13 was evaluated. Results S. aureus became highly resistant to ciprofloxacin after <20 passages. After 30 passages, the MIC values of vancomycin and CSA-13 for S. aureus increased 9- and 3-fold, respectively. The Gram-negative organisms became highly resistant to ciprofloxacin after <20 passages. MIC values of colistin for P. aeruginosa and A. baumannii increased to ≥100 mg/L after 20 passages. MIC values of CSA-13 increased to ∼20–30 mg/L and plateaued over the course of the experiment. Bacteria resistant to CSA-13 displayed lipid A modifications that are found in organisms resistant to antimicrobial peptides. Conclusions CSA-13 retained potent antibacterial activity against S. aureus over the course of 30 serial passages. Resistance generated in Gram-negative bacteria correlates with modifications to the outer membranes of these organisms and was not stable outside of the presence of the antimicrobial. PMID:22899801

Targeting biofilms and persisters of ESKAPE pathogens with P14KanS, a kanamycin peptide conjugate.

PubMed

Mohamed, Mohamed F; Brezden, Anna; Mohammad, Haroon; Chmielewski, Jean; Seleem, Mohamed N

2017-04-01

The worldwide emergence of antibiotic resistance represents a serious medical threat. The ability of these resistant pathogens to form biofilms that are highly tolerant to antibiotics further aggravates the situation and leads to recurring infections. Thus, new therapeutic approaches that adopt novel mechanisms of action are urgently needed. To address this significant problem, we conjugated the antibiotic kanamycin with a novel antimicrobial peptide (P14LRR) to develop a kanamycin peptide conjugate (P14KanS). Antibacterial activities were evaluated in vitro and in vivo using a Caenorhabditis elegans model. Additionally, the mechanism of action, antibiofilm activity and anti-inflammatory effect of P14KanS were investigated. P14KanS exhibited potent antimicrobial activity against ESKAPE pathogens. P14KanS demonstrated a ≥128-fold improvement in MIC relative to kanamycin against kanamycin-resistant strains. Mechanistic studies confirmed that P14KanS exerts its antibacterial effect by selectively disrupting the bacterial cell membrane. Unlike many antibiotics, P14KanS demonstrated rapid bactericidal activity against stationary phases of both Gram-positive and Gram-negative pathogens. Moreover, P14KanS was superior in disrupting adherent bacterial biofilms and in killing intracellular pathogens as compared to conventional antibiotics. Furthermore, P14KanS demonstrated potent anti-inflammatory activity via the suppression of LPS-induced proinflammatory cytokines. Finally, P14KanS protected C. elegans from lethal infections of both Gram-positive and Gram-negative pathogens. The potent in vitro and in vivo activity of P14KanS warrants further investigation as a potential therapeutic agent for bacterial infections. This study demonstrates that equipping kanamycin with an antimicrobial peptide is a promising method to tackle bacterial biofilms and address bacterial resistance to aminoglycosides. Copyright © 2017 Elsevier B.V. All rights reserved.

A Rapid and Efficient Screening Method for Antibacterial Compound-Producing Bacteria.

PubMed

Hettiarachchi, Sachithra; Lee, Su-Jin; Lee, Youngdeuk; Kwon, Young-Kyung; De Zoysa, Mahanama; Moon, Song; Jo, Eunyoung; Kim, Taeho; Kang, Do-Hyung; Heo, Soo-Jin; Oh, Chulhong

2017-08-28

Antibacterial compounds are widely used in the treatment of human and animal diseases. The overuse of antibiotics has led to a rapid rise in the prevalence of drug-resistant bacteria, making the development of new antibacterial compounds essential. This study focused on developing a fast and easy method for identifying marine bacteria that produce antibiotic compounds. Eight randomly selected marine target bacterial species ( Agrococcus terreus, Bacillus algicola, Mesoflavibacter zeaxanthinifaciens, Pseudoalteromonas flavipulchra, P. peptidolytica, P. piscicida, P. rubra , and Zunongwangia atlantica ) were tested for production of antibacterial compounds against four strains of test bacteria ( B. cereus, B. subtilis, Halomonas smyrnensis , and Vibrio alginolyticus ). Colony picking was used as the primary screening method. Clear zones were observed around colonies of P. flavipulchra, P. peptidolytica, P. piscicida , and P. rubra tested against B. cereus, B. subtilis , and H. smyrnensis . The efficiency of colony scraping and broth culture methods for antimicrobial compound extraction was also compared using a disk diffusion assay. P. peptidolytica, P. piscicida , and P. rubra showed antagonistic activity against H. smyrnensis, B. cereus , and B. subtilis , respectively, only in the colony scraping method. Our results show that colony picking and colony scraping are effective, quick, and easy methods of screening for antibacterial compound-producing bacteria.

Antibacterial Efficacy of Tender Coconut Water (Cocos nucifera L) on Streptococcus mutans: An In-Vitro Study

PubMed Central

Rukmini, J. N.; Manasa, Sunkari; Rohini, Chenna; Sireesha, Lavanya Putchla; Ritu, Sachan; Umashankar, G. K.

2017-01-01

Objective: The antibacterial property of coconut, the presence of lauric acid, and the ability to extract antimicrobial peptides Cn-AMP (1, 2, and 3) from tender coconut water has drawn attention on its effectiveness in normal consumption. An in-vitro experimental study was conducted to evaluate the antimicrobial efficacy of tender coconut water in its natural state on Streptococcus mutans. Materials and Methods: Fresh tender coconut water and pasteurized tender coconut water were taken as test samples, dimethyl formamide was used as the negative control, and 0.2% chlorhexidine was used as the positive control. Pure strain of S. mutans (MTCC 890) was used for determining the antibacterial effects. The test samples along with the controls were subjected to antimicrobial sensitivity test procedure and the zone of inhibition was examined. Kruskal–Wallis test was used to check for any significant differences in the antibacterial efficacy between the samples. Result: There was no zone of inhibition with the tender coconut water, fresh and pasteurised, and negative control (dimethyl formamide). Zone of inhibition was seen in positive control (0.2% Chlorhexidine). Conclusion: No antimicrobial activity was demonstrated with tender coconut water in its normal state (in vitro). PMID:28462183

Antibacterial Efficacy of Tender Coconut Water (Cocos nucifera L) on Streptococcus mutans: An In-Vitro Study.

PubMed

Rukmini, J N; Manasa, Sunkari; Rohini, Chenna; Sireesha, Lavanya Putchla; Ritu, Sachan; Umashankar, G K

2017-01-01

The antibacterial property of coconut, the presence of lauric acid, and the ability to extract antimicrobial peptides Cn-AMP (1, 2, and 3) from tender coconut water has drawn attention on its effectiveness in normal consumption. An in-vitro experimental study was conducted to evaluate the antimicrobial efficacy of tender coconut water in its natural state on Streptococcus mutans . Fresh tender coconut water and pasteurized tender coconut water were taken as test samples, dimethyl formamide was used as the negative control, and 0.2% chlorhexidine was used as the positive control. Pure strain of S. mutans (MTCC 890) was used for determining the antibacterial effects. The test samples along with the controls were subjected to antimicrobial sensitivity test procedure and the zone of inhibition was examined. Kruskal-Wallis test was used to check for any significant differences in the antibacterial efficacy between the samples. There was no zone of inhibition with the tender coconut water, fresh and pasteurised, and negative control (dimethyl formamide). Zone of inhibition was seen in positive control (0.2% Chlorhexidine). No antimicrobial activity was demonstrated with tender coconut water in its normal state ( in vitro ).

Alteration of the mode of antibacterial action of a defensin by the amino-terminal loop substitution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Bin; Zhu, Shunyi, E-mail: Zhusy@ioz.ac.cn

Highlights: Black-Right-Pointing-Pointer Al-M is an engineered fungal defensin with the n-loop of an insect defensin. Black-Right-Pointing-Pointer Al-M adopts a native defensin-like structure with high antibacterial potency. Black-Right-Pointing-Pointer Al-M kills bacteria through a membrane disruptive mechanism. Black-Right-Pointing-Pointer This work sheds light on the functional evolution of CS{alpha}{beta}-type defensins. -- Abstract: Ancient invertebrate-type and classical insect-type defensins (AITDs and CITDs) are two groups of evolutionarily related antimicrobial peptides (AMPs) that adopt a conserved cysteine-stabilized {alpha}-helical and {beta}-sheet (CS{alpha}{beta}) fold with a different amino-terminal loop (n-loop) size and diverse modes of antibacterial action. Although they both are identified as inhibitors of cell wallmore » biosynthesis, only CITDs evolved membrane disruptive ability by peptide oligomerization to form pores. To understand how this occurred, we modified micasin, a fungus-derived AITDs with a non-membrane disruptive mechanism, by substituting its n-loop with that of an insect-derived CITDs. After air oxidization, the synthetic hybrid defensin (termed Al-M) was structurally identified by circular dichroism (CD) and functionally evaluated by antibacterial and membrane permeability assays and electronic microscopic observation. Results showed that Al-M folded into a native-like defensin structure, as determined by its CD spectrum that is similar to that of micasin. Al-M was highly efficacious against the Gram-positive bacterium Bacillus megaterium with a lethal concentration of 1.76 {mu}M. As expected, in contrast to micasin, Al-M killed the bacteria through a membrane disruptive mechanism of action. The alteration in modes of action supports a key role of the n-loop extension in assembling functional surface of CITDs for membrane disruption. Our work provides mechanical evidence for evolutionary relationship between AITDs and CITDs.« less

Synthesis, molecular docking, antimicrobial, antioxidant and toxicity assessment of quinoline peptides.

PubMed

Thangaraj, Muthu; Gengan, Robert Moonsamy; Ranjan, Bibhuti; Muthusamy, Ramesh

2018-01-01

A series of quinoline based peptides were synthesized by a one-pot reaction through Ugi-four component condensation of lipoic acid, cyclohexyl isocyanide, aniline derivatives and 2-methoxy quinoline-3-carbaldehyde derivatives under microwave irradiation. The products were obtained in excellent yields and high purity. Solvent optimization and the effect of microwave irradiation with various powers were also observed. All the synthesized compounds were characterized by FTIR, NMR spectral data and elemental analysis. A total of eight peptides were subjected to antimicrobial, antioxidant and toxicity evaluation. Among them, four peptides showed potential towards antibacterial screening with Bacillus cereus, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Candida albicans, Candida utilis and three peptides showed antioxidant test positive (DPPH). Besides, toxicity of all the peptides were evaluated by using brine shrimp and it was observed that four peptides showed mortality rate less than 50% up to 48h. Molecular docking studies revealed that the higher binding affinity of the two peptides toward DNA gyrase than ciprofloxacin based on Libdock score. The described chemistry represents a facile tool to synthesize complex heterocycles of pharmaceutical relevance in a highly efficient and one-pot fashion. The advantages of this method are its green approach, inexpensive solvent, shorter reaction times and excellent yields. Copyright © 2017 Elsevier B.V. All rights reserved.

Antimicrobial peptides: a review of how peptide structure impacts antimicrobial activity

NASA Astrophysics Data System (ADS)

Soares, Jason W.; Mello, Charlene M.

2004-03-01

Antimicrobial peptides (AMPs) have been discovered in insects, mammals, reptiles, and plants to protect against microbial infection. Many of these peptides have been isolated and studied exhaustively to decipher the molecular mechanisms that impart protection against infectious bacteria, fungi, and viruses. Unfortunately, the molecular mechanisms are still being debated within the scientific community but valuable clues have been obtained through structure/function relationship studies1. Biophysical studies have revealed that cecropins, isolated from insects and pigs, exhibit random structure in solution but undergo a conformational change to an amphipathic α-helix upon interaction with a membrane surface2. The lack of secondary structure in solution results in an extremely durable peptide able to survive exposure to high temperatures, organic solvents and incorporation into fibers and films without compromising antibacterial activity. Studies to better understand the antimicrobial action of cecropins and other AMPs have provided insight into the importance of peptide sequence and structure in antimicrobial activities. Therefore, enhancing our knowledge of how peptide structure imparts function may result in customized peptide sequences tailored for specific applications such as targeted cell delivery systems, novel antibiotics and food preservation additives. This review will summarize the current state of knowledge with respect to cell binding and antimicrobial activity of AMPs focusing primarily upon cecropins.

Bioactive peptides released by in vitro digestion of standard and hydrolyzed infant formulas.

PubMed

Wada, Yasuaki; Lönnerdal, Bo

2015-11-01

Hydrolyzed infant formulas serve as appropriate nutritional sources for infants afflicted with cow's milk allergy, and milk proteins in hydrolyzed formulas are industrially hydrolyzed extensively or partially. To investigate whether industrial hydrolysis may modulate the digestive trajectory of milk proteins, thereby releasing different profiles of bioactive peptides compared with standard formulas, both standard and hydrolyzed formulas were subjected to in vitro digestion and formation of bioactive peptides were compared. One standard, one extensively hydrolyzed, and one partially hydrolyzed infant formula were digested in vitro with pepsin and pancreatin, taking into account the higher gastric pH of infants, and the digesta were subjected to peptidomic analysis. The standard formula released a larger variety of bioactive peptides than from the hydrolyzed formulas, indicating that industrial hydrolysis of milk proteins may generally attenuate their indigenous bioactivities such as antibacterial, immuno-regulatory, and anti-oxidative activities. Conversely, industrial hydrolysis may facilitate the formation of bioactive peptides from hydrophobic proteins/regions such as β-LG and the "strategic zone" of β-CN, which encrypt bioactive peptides including a dipeptidyl dipeptidase-4-inhibitory, hypocholesterolemic, and opioid peptides. Infants fed hydrolyzed infant formulas may be influenced by milk protein-derived bioactive peptides in a manner different from those fed standard formula. Copyright © 2015 Elsevier Inc. All rights reserved.

Lanthipeptides: chemical synthesis versus in vivo biosynthesis as tools for pharmaceutical production.

PubMed

Ongey, Elvis Legala; Neubauer, Peter

2016-06-07

Lanthipeptides (also called lantibiotics for those with antibacterial activities) are ribosomally synthesized post-translationally modified peptides having thioether cross-linked amino acids, lanthionines, as a structural element. Lanthipeptides have conceivable potentials to be used as therapeutics, however, the lack of stable, high-yield, well-characterized processes for their sustainable production limit their availability for clinical studies and further pharmaceutical commercialization. Though many reviews have discussed the various techniques that are currently employed to produce lanthipeptides, a direct comparison between these methods to assess industrial applicability has not yet been described. In this review we provide a synoptic comparison of research efforts on total synthesis and in vivo biosynthesis aimed at fostering lanthipeptides production. We further examine current applications and propose measures to enhance product yields. Owing to their elaborate chemical structures, chemical synthesis of these biomolecules is economically less feasible for large-scale applications, and hence biological production seems to be the only realistic alternative.

Phosphonopeptides as Antibacterial Agents: Alaphosphin and Related Phosphonopeptides

PubMed Central

Allen, John G.; Atherton, Frank R.; Hall, Michael J.; Hassall, Cedric H.; Holmes, Simon W.; Lambert, Robert W.; Nisbet, Louis J.; Ringrose, Peter S.

1979-01-01

Alaphosphin, l-alanyl-l-1-aminoethylphosphonic acid, was selected from a range of phosphonopeptides for evaluation in humans on the basis of its antibacterial activity, pharmacokinetics, and stability to intestinal and kidney peptidases. In vitro, the antibacterial action was antagonized by small peptides, resulting in low activity on peptone media. On an antagonist-free medium alaphosphin was bactericidal and rapidly lysed most susceptible gram-negative bacteria, but it was largely bacteriostatic and essentially nonlytic against gram-positive organisms. Its spectrum included most strains normally isolated from urinary tract infections, but potency was greatly reduced by very high inoculum levels and by alkaline pH. Although strains of Proteus and Pseudomonas were less susceptible to alaphosphin than were other common gram-negative bacteria, like other species they formed spheroplasts when exposed under appropriate conditions. Alaphosphin was equally effective against penicillin-susceptible and -resistant strains and showed no cross-resistance with known antibiotics. Good synergy and increased bactericidal activity were demonstrated with combinations of alaphosphin and d-cycloserine or β-lactam antibiotics. Images PMID:43113

Advances in Bacterial Methionine Aminopeptidase Inhibition

PubMed Central

Helgren, Travis R.; Wangtrakuldee, Phumvadee; Staker, Bart L.; Hagen, Timothy J.

2016-01-01

Methionine aminopeptidases (MetAPs) are metalloenzymes that cleave the N-terminal methionine from newly synthesized peptides and proteins. These MetAP enzymes are present in bacteria, and knockout experiments have shown that MetAP activity is essential for cell life, suggesting that MetAPs are good antibacterial drug targets. MetAP enzymes are also present in the human host and selectivity is essential. There have been significant structural biology efforts and over 65 protein crystal structures of bacterial MetAPs are deposited into the PDB. This review highlights the available crystallographic data for bacterial MetAPs. Structural comparison of bacterial MetAPs with human MetAPs highlights differences that can lead to selectivity. In addition, this review includes the chemical diversity of molecules that bind and inhibit the bacterial MetAP enzymes. Analysis of the structural biology and chemical space of known bacterial MetAP inhibitors leads to a greater understanding of this antibacterial target and the likely development of potential antibacterial agents. PMID:26268344

Secretion expression of human neutrophil peptide 1 (HNP1) in Pichia pastoris and its functional analysis against antibiotic-resistant Helicobacter pylori.

PubMed

Zhang, Xiaolin; Jiang, Anmin; Qi, Banghua; Yu, Hao; Xiong, Youyi; Zhou, Guoliang; Qin, Meisong; Dou, Jinfeng; Wang, Jianfei

2018-06-01

Human neutrophil peptide 1 (HNP1) is a small (3.44 kDa) cationic peptide that is a distinct member of the defensin family. HNP1 plays a crucial role in controlling bacterial infections, particularly by antibiotic-resistant bacteria, through membrane perforation patterns. The structural characteristics of HNP1's three intramolecular disulfide bridges cause difficulty in its synthesis via chemical methods. In this study, bioactive recombinant HNP1 was produced using the Pichia pastoris (P. Pichia) expression system. HNP1 was fused with the polyhedrin of Bombyx mori and enhanced green fluorescent protein (EGFP) to prevent HNP1 toxicity in yeast host cells under direct expression. An enterokinase protease cleavage site (amino acid sequence DDDDK) was designed upstream of the HNP1 peptide to obtain the antibacterial peptide HNP1 with native structure after it was cleaved by the enterokinase. The fusion HNP1 protein (FHNP1) was successfully expressed and had a molecular mass of approximately 62.6 kDa, as determined using SDS-PAGE and Western blot. Then, the recovered FHNP1 was digested and purified; Tricine-SDS-PAGE results showed that HNP1 was successfully released from FHNP1. Functional analysis of induction against antibiotic-resistant Helicobacter pylori (H. pylori) showed that it was challenging for HNP1 to acquire resistance to the antibiotic-resistant H. pylori. Moreover, in vitro studies showed that HNP1 exerted a strong effect against antibiotic-resistant H. pylori activity. Furthermore, the animal model of H. pylori infection established in vivo showed that HNP1 significantly reduced the colonization of antibiotic-resistant H. pylori in the stomach. Our study indicated that this could be a new potential avenue for large-scale production of HNP1 for therapeutic application against the antibiotic-resistant H. pylori infection in humans.

Isolation, characterization and chromatography based purification of antibacterial compound isolated from rare endophytic actinomycetes Micrococcus yunnanensis.

PubMed

Ranjan, Ravi; Jadeja, Vasantba

2017-10-01

Endophytic actinomycetes are considered as one of the relatively unexplored potential sources in search of antibiotic producer against antibiotic resistant pathogens. A potent strain isolated from Catharanthus roseus that displays antibacterial potential against antibiotic resistant human pathogen Staphylococcus aureus was characterized and designated as Micrococcus yunnanensis strain rsk5. Rsk5 is capable of producing optimum antibacterial metabolites on starch casein medium at 30 °C, pH 5 and 2% NaCl condition. The crude antibacterial agent was extracted from fermentation broth by ethyl acetate and separated by TLC using chloroform-methanol (24:1, v/v) solvent system with R f value of 0.26. It was partially purified by flash chromatography, followed by HPLC and analyzed by ultraviolet visible spectrophotometer to get absorption maxima at 208.4 nm. The ESI-MS spectra showed molecular ion peaks at m / z 472.4 [M-H], which does not match with any known antibacterial compound.

Activating and Attenuating the Amicoumacin Antibiotics.

PubMed

Park, Hyun Bong; Perez, Corey E; Perry, Elena Kim; Crawford, Jason M

2016-06-24

The amicoumacins belong to a class of dihydroisocoumarin natural products and display antibacterial, antifungal, anticancer, and anti-inflammatory activities. Amicoumacins are the pro-drug activation products of a bacterial nonribosomal peptide-polyketide hybrid biosynthetic pathway and have been isolated from Gram-positive Bacillus and Nocardia species. Here, we report the stimulation of a "cryptic" amicoumacin pathway in the entomopathogenic Gram-negative bacterium Xenorhabdus bovienii, a strain not previously known to produce amicoumacins. X. bovienii participates in a multi-lateral symbiosis where it is pathogenic to insects and mutualistic to its Steinernema nematode host. Waxmoth larvae are common prey of the X. bovienii-Steinernema pair. Employing a medium designed to mimic the amino acid content of the waxmoth circulatory fluid led to the detection and characterization of amicoumacins in X. bovienii. The chemical structures of the amicoumacins were supported by 2D-NMR, HR-ESI-QTOF-MS, tandem MS, and polarimeter spectral data. A comparative gene cluster analysis of the identified X. bovienii amicoumacin pathway to that of the Bacillus subtilis amicoumacin pathway and the structurally-related Xenorhabdus nematophila xenocoumacin pathway is presented. The X. bovienii pathway encodes an acetyltransferase not found in the other reported pathways, which leads to a series of N-acetyl-amicoumacins that lack antibacterial activity. N-acetylation of amicoumacin was validated through in vitro protein biochemical studies, and the impact of N-acylation on amicoumacin's mode of action was examined through ribosomal structural analyses.

Antibacterial property of fabrics coated by magnesium-based brucites

NASA Astrophysics Data System (ADS)

Wang, Ying; Sha, Lin; Zhao, Jiao; Li, Qian; Zhu, Yimin; Wang, Ninghui

2017-04-01

A kind of environmental-friendly magnesium-based antibacterial agent was reported for the first time, which was composited by brucites with different particle sizes. The antibacterial fabrics were produced by coating the magnesium-based antibacterial agents on the 260T polyester pongee fabrics with waterborne polyurethane. The coating process was simple, low-cost, and harmless to human health and environment. Characteristics of the antibacterial agents and fabrics were studied by particulate size distribution analyzer (PSDA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results demonstrated that the coating layer was covered tightly on the fabrics and compositing of different particles by a certain proportion made full filling of the coating layer. Meanwhile, compositing did not change the structure of brucites. The antibacterial fabrics presented strong antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with the reduction percentage of 96.6% and 100%, respectively, and the antibacterial fabrics attained excellent washing durability.

Synthesis and evaluation of amphiphilic peptides as nanostructures and drug delivery tools

NASA Astrophysics Data System (ADS)

Sayeh, Naser Ali

Intracellular delivery of cell-impermeable compounds in a variety cells using delivery systems have been extensively studied in recent years. Obtaining desirable cellular uptake levels often requires the administration of high quantities of drugs to achieve the expected intracellular biological effect. Thus, improving the translocation process across the plasma membrane will significantly reduce the quantity of required administered drug and consequently minimize the side effects in most of the cases. Efficient delivery of these molecules to the cells and tissues is a difficult challenge. Compounds with low cellular permeability are commonly considered to be of limited therapeutic value. Over the past few decades, several biomedical carriers, such as polymers, nanospheres, nanocapsules, liposomes, micelles, peptides and dendrimers have been widely used to deliver therapeutic and diagnostic agents to the cells. Biomaterials generated from nano-scale compounds have shown some promising data for delivery of many compounds in a number of diseases, such as viral infections, cancer, and genetic disorders. Although much progress has been achieved in this field, many challenges still remain, such as toxicity and limited stability. Liposomes suffer from poor stability in the bloodstream and leakage during storage. They tend to aggregate and fuse with or leak entrapped drugs, especially highly hydrophilic small molecules. For solid lipid nanoparticles (SLNs), drug expulsion after polymorphic transition during storage, inadequate loading capacity, and relatively high water content of the dispersions have been observed. Poly(lactic-coglycolic acid (PLGA) degrades in the body producing its original monomers of lactic acid and glycolic acid, which are the by-products of various metabolic pathways. However, this acidic microenvironment that occurs during degradation could negatively affect the stability of the loaded compound. Dendrimers can carry drugs as complexes or as conjugates although one limitation lies in the effort of controlling the rate of drug release. The encapsulated or complexed drugs tend to be released rapidly (before reaching the target site) and in the dendrimer--drug conjugates, it is the chemical linkage that controls the drug release. Thus, future studies in this field are urgently required to create more efficient and stable biomaterials. Peptides are considered as efficient vectors for achieving optimal cellular uptake. The potential use of peptides as drug delivery vectors received much attention by the discovery of several cell-penetrating peptides (CPPs). The first CPPs discovered in 1988, that were sequences from HIV-1 encoded TAT protein, TAT (48--60), and penetrated very efficiently through cell membranes of cultured mammalian cells. CPPs are a class of diverse peptides, typically with 8--25 amino acids, and unlike most peptides, they can cross the cellular membrane with more efficiency. CPPs have also shown to undergo self-assembly and generate nanostructures. The generation of self-assembled peptides and nanostructures occur through various types of interactions between functional groups of amino acid residues, such as electrostatic, hydrophobic, and hydrogen bonding. Appropriate design and functionalization of peptides are critical for generating nanostructures. Chemically CPPs are classified into two major groups: linear and cyclic peptides. It has been previously reported that linear peptides containing hydrophilic and hydrophobic amino acids could act as membrane protein stabilizers. These compounds are short hydrophilic or amphiphilic peptides that have positively charged amino acids, such as arginine, lysine or histidine, which can interact with the negative charge phospholipids layer on the cell membrane and translocate the cargo into the cells. Conjugation to cationic linear CPPs, such as TAT, penetratin, or oligoarginine efficiently improves the cellular uptake of large hydrophilic molecules, but the cellular uptake is predominantly via an unproductive endosomal pathway. Therefore, the biological effect is very limited, as the compounds are trapped in these compartments and cannot reach their biological targets in the cytoplasm or the nucleus. Mechanisms that promote endosomal escape or avoid endosomal route are required for improving bioavailability. Highly cationic CPPs preferentially interact with particular cell types, have limited plasma half-life, show toxicity, do not cross multicellular barriers such as vasculature epithelia or the blood-brain barrier, and efficient cargo delivery requires 9-15 arginine residues. Highly cationic CPPs are, therefore not ideal small molecule drug delivery vehicles. Linear CPPs are susceptible to hydrolysis by endogenous peptidases. Conjugation to cationic CPPs, such as TAT, penetratin, or oligoarginine efficiently improves the cellular uptake of large hydrophilic molecules, but the cellular uptake occurs predominantly via an unproductive endosomal pathway. Therefore, the biological effect is very limited, as the compounds are trapped in these compartments and cannot reach their biological targets in the cytoplasm or the nucleus. Mechanisms that promote endosomal escape or avoid endosomal route are required for improving bioavailability. Highly cationic CPPs preferentially interact with particular cell types, have limited plasma half-life, show toxicity, do not cross multicellular barriers such as vasculature epithelia or the blood-brain barrier, and efficient cargo delivery requires 9-15 arginine residues. Highly cationic linear CPPs are, therefore, have not become optimized as small molecule drug delivery vehicles. On the other hand, cyclic peptides containing hydrophilic and hydrophobic amino acids have shown greater potential as drug delivery tools due to their enhanced chemical and enzymatic stability. Parang's laboratory has reported that Amphiphilic Cyclic Peptides (ACPs) containing positively charged arginine and hydrophobic tryptophan residues as potential candidates for drug delivery. Cyclic peptides have several benefits compared to linear peptides, such as rigidness of structure and stability against proteolytic enzymes. The rigidity of the structure can enhance the binding affinity of ligands toward receptors by reducing the freedom of possible structural conformations. Cyclic peptides are also present in nature and have been developed as therapeutics. Cyclosporine, gramicidin S, polymoxin B, and daptomycin are well-known examples of cyclic peptide drugs. Parang's laboratory designed amphiphilic cyclic CPPs containing alternative tryptophan and arginine residues as the positively charged and hydrophobic residues, respectively. The peptides were efficient in improving the cellular delivery of anticancer and antiviral drugs. The cellular uptake mechanism of CPPs into cells is still a matter of some debate. The cellular entry of CPP can be influenced by the type of CPP, the cell line, the nature of the cargo, and the conditions of incubation. As described above, linear CPPs pass through the plasma membrane mostly via an energy-independent or endocytosis pathway. Moreover, the cellular delivery of CPP-conjugated molecules also occurs through endosomal pathway and a strong enzymatic degradation and an inadequate cytoplasmic release of intact molecules from the conjugates are expected, thus leading to an inefficient transfer into the cytoplasm. The best strategy to overcome this issue is to designing CPP that by pass the endosomal uptake or by increasing the escape rate from the endosome to improve the intracellular delivery of CPP-attached molecules. Parang laboratory has reported the cellular uptake of a number of cyclic peptides independent of endocytotic pathway. The extraordinary ability of cyclic peptides containing tryptophan and arginine, [WR]4 and [WR] 5 to spontaneously translocate across bilayers independent of an energy source is distinctly different from the behavior of the well-known, highly cationic CPPs, such as TAT and Arg9, which do not translocate across phospholipid bilayers, and enter cells mostly by active endocytosis. Alternatively, researchers have found that an effective cellular delivery vector can be improved developed by conjugating a CPP with a fatty acid chain. Amphiphilic peptides have also become a subject of major interest as potent antibacterial agents. Antimicrobial peptides (AMPs) are produced naturally by bacteria and are considered as the first line of host defense protecting living organisms from microorganisms. Various types of AMPs has been discovered, such as defensins, cecropins, magainins and cathelicidins, with significant different structures and bioactivity profiles. The mechanism of actions for these peptides were reported as effectors and regulators of the innate immune system by increasing production and release of chemokine, and enhancing wound healing and angiogenesis. They were able to suppress biofilm formation and induce the dissolution of existing biofilms. Thus, design of new AMPs and more cost effective sequences with highly activity are urgently needed. Although a number of cyclic peptides were discovered and reported as efficient cellular delivery agents or antimicrobial agent, a more systematic investigation is required to identify design rules for optimal entrapment, drug loading, and stability. The balance of many small forces determines the overall morphology, size, and functionality of the structures. A deeper understanding of these factors is required for guiding future research, and for customizing cyclic peptides for drug loading and cellular delivery applications. Thus, additional amphiphilic cyclic and linear peptides were designed with variable electrostatic and hydrophobic residues to optimize drug encapsulation. The diversity in ring size, amino acid number, position and sequences, number of rings, net charge, and hydrophobicity of side chains in cyclic peptides will allow us to explore requirements for generating peptides with optimized drug encapsulation and to establish correlations between the structure of peptides with their drug entrapment properties. Thus, the general objective of this dissertation was to design and evaluate additional cyclic or amphiphilic peptides as nanostructures, compare their efficiency in delivery of small molecules with the previously reported cyclic peptides containing tryptophan and arginine residues. This dissertation consists of three chapters. Chapter 1. MANUSCRIPT (published in Current Organic Chemistry 2014). The objective of this work was to design amphiphilic linear and cyclic peptides containing hydrophobic tryptophan W residues that were linked through a triazole ring to positively charged arginine R and lysine (K) residues. The peptides were synthesized through click chemistry between hydrophobic peptides containing alkyne and positively charged peptides containing azide groups. Characterization of their structures like solubility, CD, TEM, cytotoxicity were investigated. The conjugates were showed minimal cytotoxicity at two cell lines. The secondary structures of both peptides were similar to a distorted α-helix as shown by CD spectroscopy. TEM imaging also showed that linear-linear (WG(triazole-KR-NH2))3 and cyclic-linear [WG(triazole-KR-NH2)]3 peptides formed nano-sized structures. Chapter 2. MANUSCRIPT I (Submitted to Journal of Molecular Modeling). In this work, we investigated the structural and dynamical aspects of cyclic-linear peptide ([WG(triazole-KR-NH2)] 3 and linear-linear peptide (WG(triazole-KR-NH2))3) formed nanostructures compared to a drug delivery system with [WR]4. While [WR]4 was found to be an efficient molecular transporter for small molecule drugs, such as lamivudine and dasatinib, cyclic-linear peptide ([WG(triazole-KR-NH2)]3 was inefficient. Molecular modeling was used to explain the differential behavior of these peptides. We showed how the morphology of these systems can affect the drug delivery efficiency. The result of this work provided insights about optimizing the amphiphilic cyclic-linear trizaolyl peptides can be used to design compounds with more efficient drug delivery capabilities. Chapter 3. MANUSCRIPT II. The objective of this Chapter was to synthesize a different series of amphiphilic peptides for different objectives. First, the amphiphilic trizaolyl peptides in Chapter I were systematically modified by increasing the number of arginine and tryptophan sequence in cyclic and linear peptides. The rationale for the modification was to enhance the possibility of interaction with the cell membrane and therefore improving the cellular uptake process. Moreover, a new class of amphiphilic peptides consist of tryptophan and glutamic acid were conjugated with a peptide containing arginine and lysine residues using Fmoc chemistry. These peptides have an amide bond that generates more flexibility compared to a triazole ring. The chemical and biological properties will be evaluated in future and compared with amphiphilic triazolyl peptides. Finally, additional fatty acids with different length chains were conjugated with positively charged peptides to be evaluated as antibacterial agents. Stearic acid (C16) and myristic acid (C14) were conjugated with a peptides consisting of arginine azide and lysine amino acids to enhance the antibacterial activity. In summary, the work in this dissertation provided insights about the synthesis and characterization of a new class of amphiphilic triazolyl peptides as drug delivery carriers and amphiphilic peptides as antibacterial agents. Molecular modeling was used to explain why triazolyl peptides were unable to enhance the delivery of small molecule drugs compared to the previously synthesized cyclic peptides [WR]4 (Chapter 2) Modification of synthesized peptides in Chapter 1, by addition of more positively charged amino acids or reducing the rigidity by incorporating amide bonds instead of triazoly groups can be used to improve the cell penetrating properties. Finally, we conjugated amphiphilic peptides with different fatty acids (Chapter 3) to investigate their application as antibacterial agents.

NRC/AMRMC Resident Research Associateship Program

DTIC Science & Technology

2017-03-01

tube formation in vitro. 4) Replacing amino acids in some peptides with D-amino acids leads to improved antibacterial and anti-biofilm activity . 5...period, the National Academies of Sciences, Engineering, and Medicine (the Academies) NRC conducted the following activities in support of the...of all active Research Advisers, current Adviser contact information and details of each Research Opportunity. Processing and Review of Applications

National Biocontainment Training Center

DTIC Science & Technology

2014-06-01

of novel antimicrobial compounds with antibacterial activity against TB (Vijayakumar, et al., Dec. 2013, Tuberculosis). She has also developed...Nanoluc. (a) insert the Nanoluc after the signal peptide , (b) insert the Nanoluc before the RSKR site, (c) insert the Nanoluc before the RRLL site...biological safe techniques. This training took place in Dallas, Texas. Trainers: Vickie Jones and Jason Hardcastle. Food and Drug Administration (FDA

Influence of Iron on Production of the Antibacterial Compound Tropodithietic Acid and Its Noninhibitory Analog in Phaeobacter inhibens

PubMed Central

D'Alvise, Paul W.; Phippen, Christopher B. W.; Nielsen, Kristian F.

2015-01-01

Tropodithietic acid (TDA) is an antibacterial compound produced by some Phaeobacter and Ruegeria spp. of the Roseobacter clade. TDA production is studied in marine broth or agar since antibacterial activity in other media is not observed. The purpose of this study was to determine how TDA production is influenced by substrate components. High concentrations of ferric citrate, as present in marine broth, or other iron sources were required for production of antibacterially active TDA. However, when supernatants of noninhibitory, low-iron cultures of Phaeobacter inhibens were acidified, antibacterial activity was detected in a bioassay. The absence of TDA in nonacidified cultures and the presence of TDA in acidified cultures were verified by liquid chromatography–high-resolution mass spectrometry. A noninhibitory TDA analog (pre-TDA) was produced by P. inhibens, Ruegeria mobilis F1926, and Phaeobacter sp. strain 27-4 under low-iron concentrations and was instantaneously converted to TDA when pH was lowered. Production of TDA in the presence of Fe3+ coincides with formation of a dark brown substance, which could be precipitated by acid addition. From this brown pigment TDA could be liberated slowly with aqueous ammonia, and both direct-infusion mass spectrometry and elemental analysis indicated a [FeIII(TDA)2]x complex. The pigment could also be produced by precipitation of pure TDA with FeCl3. Our results raise questions about how biologically active TDA is produced in natural marine settings where iron is typically limited and whether the affinity of TDA to iron points to a physiological or ecological function of TDA other than as an antibacterial compound. PMID:26519388

Peptidome analysis of human milk from women delivering macrosomic fetuses reveals multiple means of protection for infants

PubMed Central

Cui, Xianwei; Li, Yun; Yang, Lei; You, Lianghui; Wang, Xing; Shi, Chunmei; Ji, Chenbo; Guo, Xirong

2016-01-01

Breastfeeding is associated with a lower incidence of obesity, diabetes, and cardiovascular disease later in life. While macrosomic infants have a higher risk of developing obesity and other metabolic disorders. Breast milk may contain special nutrients to meet the different growth needs of different infants. Whether mothers make breast milk different to meet the requirement of macrosomic infants is still unknown. Here, we conducted a comparison between mothers delivering macrosomic and non-macrosomic infants in colostrum endogenous peptides. More than 400 peptides, originating from at least 34 protein precursors, were identified by Liquid Chromatography/Mass Spectrometry (LC/MS). Out of these, 29 peptides found to be significant differently expressed (|fold change| ≥ 3, P < 0.01). Blastp analysis revealed 41 peptides may have established biological activities, which exhibit immunomodulating, antibacterial action, antioxidation, opioid agonist and antihypertensive activity. Furthermore, we found that peptide located at β-Casein 24-38 AA has antimicrobial effect against E. coli, Y. enterocolitica and S. aureus. While, κ-Casein 89-109 AA-derived peptide plays as a regulator of preadipocyte proliferation. The profile of endogenous peptides from macrosomic term infants is different from non-macrosomic terms. This different peptide expression potentially has specific physiological function to benefit macrosomic infants. Finally, we believe that our research is a meaningfull finding which may add to the understanding of milk peptide physiological action. PMID:27566575

Peptidome analysis of human milk from women delivering macrosomic fetuses reveals multiple means of protection for infants.

PubMed

Cui, Xianwei; Li, Yun; Yang, Lei; You, Lianghui; Wang, Xing; Shi, Chunmei; Ji, Chenbo; Guo, Xirong

2016-09-27

Breastfeeding is associated with a lower incidence of obesity, diabetes, and cardiovascular disease later in life. While macrosomic infants have a higher risk of developing obesity and other metabolic disorders. Breast milk may contain special nutrients to meet the different growth needs of different infants. Whether mothers make breast milk different to meet the requirement of macrosomic infants is still unknown. Here, we conducted a comparison between mothers delivering macrosomic and non-macrosomic infants in colostrum endogenous peptides. More than 400 peptides, originating from at least 34 protein precursors, were identified by Liquid Chromatography/Mass Spectrometry (LC/MS). Out of these, 29 peptides found to be significant differently expressed (|fold change| ≥ 3, P < 0.01). Blastp analysis revealed 41 peptides may have established biological activities, which exhibit immunomodulating, antibacterial action, antioxidation, opioid agonist and antihypertensive activity. Furthermore, we found that peptide located at β-Casein 24-38 AA has antimicrobial effect against E. coli, Y. enterocolitica and S. aureus. While, κ-Casein 89-109 AA-derived peptide plays as a regulator of preadipocyte proliferation. The profile of endogenous peptides from macrosomic term infants is different from non-macrosomic terms. This different peptide expression potentially has specific physiological function to benefit macrosomic infants. Finally, we believe that our research is a meaningfull finding which may add to the understanding of milk peptide physiological action.

Characterization of the branched antimicrobial peptide M6 by analyzing its mechanism of action and in vivo toxicity.

PubMed

Pini, Alessandro; Giuliani, Andrea; Falciani, Chiara; Fabbrini, Monica; Pileri, Silvia; Lelli, Barbara; Bracci, Luisa

2007-06-01

We analyzed functional activity of the antimicrobial peptide M6 in vitro and in vivo. The peptide was identified by our group by phage library selection, rational modification and synthesis in a tetrabranched form (Pini et al., Antimicrob. Agents Chemother. 2005; 49: 2665-72). We found that it binds lipopolysaccharide, causes perforation of cell membranes without destroying external cell morphology and strongly binds DNA. The latter feature suggests that it could inhibit metabolic pathways, blocking DNA replication and/or transcription. We also observed that M6 does not stimulate humoral immune response when repeatedly administered to animals. We also analyzed M6 toxicity when administered to animals by intraperitoneal or by intravenous injection, determining a preliminary LD50 (125 and 37.5 mg/kg, respectively), which suggested that M6 could be used in vivo. These features make the antimicrobial branched peptide M6 a promising candidate for the development of a new antibacterial drug. Copyright (c) 2007 European Peptide Society and John Wiley & Sons, Ltd.

Inhibitory and antimicrobial activities of OGTI and HV-BBI peptides, fragments and analogs derived from amphibian skin.

PubMed

Dębowski, Dawid; Łukajtis, Rafał; Łęgowska, Anna; Karna, Natalia; Pikuła, Michał; Wysocka, Magdalena; Maliszewska, Irena; Sieńczyk, Marcin; Lesner, Adam; Rolka, Krzysztof

2012-06-01

A series of linear and cyclic fragments and analogs of two peptides (OGTI and HV-BBI) isolated from skin secretions of frogs were synthesized by the solid-phase method. Their inhibitory activity against several serine proteinases: bovine β-trypsin, bovine α-chymotypsin, human leukocyte elastase and cathepsin G from human neutrophils, was investigated together with evaluation of their antimicrobial activities against Gram-negative bacteria (Escherichia coli) and Gram-positive species isolated from patients (Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus sp., Streptococcus sp.). The cytotoxicity of the selected peptides toward an immortal human skin fibroblast cell line was also determined. Three peptides: HV-BBI, its truncated fragment HV-BBI(3-18) and its analog [Phe(8)]HV-BBI can be considered as bifunctional compounds with inhibitory as well as antibacterial properties. OGTI, although it did not display trypsin inhibitory activity as previously reported in the literature, exerted antimicrobial activity toward S. epidermidis. In addition, under our experimental conditions, this peptide did not show cytotoxicity. Copyright © 2012 Elsevier Inc. All rights reserved.

Antimicrobial Activities of Bacteria Associated with the Brown Alga Padina pavonica

PubMed Central

Ismail, Amel; Ktari, Leila; Ahmed, Mehboob; Bolhuis, Henk; Boudabbous, Abdellatif; Stal, Lucas J.; Cretoiu, Mariana Silvia; El Bour, Monia

2016-01-01

Macroalgae belonging to the genus Padina are known to produce antibacterial compounds that may inhibit growth of human- and animal pathogens. Hitherto, it was unclear whether this antibacterial activity is produced by the macroalga itself or by secondary metabolite producing epiphytic bacteria. Here we report antibacterial activities of epiphytic bacteria isolated from Padina pavonica (Peacocks tail) located on northern coast of Tunisia. Eighteen isolates were obtained in pure culture and tested for antimicrobial activities. Based on the 16S rRNA gene sequences the isolates were closely related to Proteobacteria (12 isolates; 2 Alpha- and 10 Gammaproteobacteria), Firmicutes (4 isolates) and Actinobacteria (2 isolates). The antimicrobial activity was assessed as inhibition of growth of 12 species of pathogenic bacteria (Aeromonas salmonicida, A. hydrophila, Enterobacter xiangfangensis, Enterococcus faecium, Escherichia coli, Micrococcus sp., Salmonella typhimurium, Staphylococcus aureus, Streptococcus sp., Vibrio alginoliticus, V. proteolyticus, V. vulnificus) and one pathogenic yeast (Candida albicans). Among the Firmicutes, isolate P8, which is closely related to Bacillus pumilus, displayed the largest spectrum of growth inhibition of the pathogenic bacteria tested. The results emphasize the potential use of P. pavonica associated antagonistic bacteria as producers of novel antibacterial compounds. PMID:27462308

The next generation of antimicrobial peptides (AMPs) as molecular therapeutic tools for the treatment of diseases with social and economic impacts.

PubMed

da Cunha, Nicolau B; Cobacho, Nicole B; Viana, Juliane F C; Lima, Loiane A; Sampaio, Kamila B O; Dohms, Stephan S M; Ferreira, Arthur C R; de la Fuente-Núñez, César; Costa, Fabrício F; Franco, Octávio L; Dias, Simoni C

2017-02-01

Anti-infective drugs have had a key role in the contemporary world, contributing to dramatically decrease mortality rates caused by infectious diseases worldwide. Antimicrobial peptides (AMPs) are multifunctional effectors of the innate immune system of mucosal surfaces and present antimicrobial activity against a range of pathogenic viruses, bacteria, and fungi. However, the discovery and development of new antibacterial drugs is a crucial step to overcome the great challenge posed by the emergence of antibiotic resistance. In this review, we outline recent advances in the development of novel AMPs with improved antimicrobial activities that were achieved through characteristic structural design. In addition, we describe recent progress made to overcome some of the major limitations that have hindered peptide biosynthesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Human Cathelicidin Antimicrobial Peptide LL-37 as a Potential Treatment for Polymicrobial Infected Wounds

PubMed Central

Duplantier, Allen J.; van Hoek, Monique L.

2013-01-01

Diabetic patients often have ulcers on their lower-limbs that are infected by multiple biofilm-forming genera of bacteria, and the elimination of the biofilm has proven highly successful in resolving such wounds in patients. To that end, antimicrobial peptides have shown potential as a new anti-biofilm approach. The single human cathelicidin peptide LL-37 has been shown to have antimicrobial and anti-biofilm activity against multiple Gram-positive and Gram-negative human pathogens, and have wound-healing effects on the host. The combination of the anti-biofilm effect and wound-healing properties of LL-37 may make it highly effective in resolving polymicrobially infected wounds when topically applied. Such a peptide or its derivatives could be a platform from which to develop new therapeutic strategies to treat biofilm-mediated infections of wounds. This review summarizes known mechanisms that regulate the endogenous levels of LL-37 and discusses the anti-biofilm, antibacterial, and immunological effects of deficient vs. excessive concentrations of LL-37 within the wound environment. Here, we review recent advances in understanding the therapeutic potential of this peptide and other clinically advanced peptides as a potential topical treatment for polymicrobial infected wounds. PMID:23840194

A novel antifungal peptide from leaves of the weed Stellaria media L.

PubMed

Rogozhin, Eugene A; Slezina, Marina P; Slavokhotova, Anna A; Istomina, Ekaterina A; Korostyleva, Tatyana V; Smirnov, Alexey N; Grishin, Eugene V; Egorov, Tsezi A; Odintsova, Tatyana I

2015-09-01

A novel peptide named SmAMP3 was isolated from leaves of common chickweed (Stellaria media L.) by a combination of acidic extraction and a single-step reversed-phase HPLC and sequenced. The peptide is basic and cysteine-rich, consists of 35 amino acids, and contains three disulphide bridges. Homology search revealed that SmAMP3 belongs to the family of hevein-like antimicrobial peptides carrying a conserved chitin-binding site. Efficient binding of chitin by SmAMP3 was proved by in vitro assays. Molecular modeling confirmed conservation of the chitin-binding module in SmAMP3 locating the variable amino acid residues to the solvent-exposed loops of the molecule. The peptide exhibits potent antifungal activity against important plant pathogens in the micromolar range, although it is devoid of antibacterial activity at concentrations below 10 μM. As judged by chromatographic behavior and mass spectrometric data, the peptide is constitutively expressed in above-ground organs and seeds of S. media plants, thus representing an important player in the preformed branch of the plant immune system. Copyright © 2015 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

High Specific Selectivity and Membrane-Active Mechanism of Synthetic Cationic Hybrid Antimicrobial Peptides Based on the Peptide FV7

PubMed Central

Tan, Tingting; Wu, Di; Li, Weizhong; Zheng, Xin; Li, Weifen; Shan, Anshan

2017-01-01

Hybrid peptides integrating different functional domains of peptides have many advantages, such as remarkable antimicrobial activity, lower hemolysis and ideal cell selectivity, compared with natural antimicrobial peptides. FV7 (FRIRVRV-NH2), a consensus amphiphilic sequence was identified as being analogous to host defense peptides. In this study, we designed a series of hybrid peptides FV7-LL-37 (17–29) (FV-LL), FV7-magainin 2 (9–21) (FV-MA) and FV7-cecropin A (1–8) (FV-CE) by combining the FV7 sequence with the small functional sequences LL-37 (17–29) (LL), magainin 2 (9–21) (MA) and cecropin A (1–8) (CE) which all come from well-described natural peptides. The results demonstrated that the synthetic hybrid peptides, in particular FV-LL, had potent antibacterial activities over a wide range of Gram-negative and Gram-positive bacteria with lower hemolytic activity than other peptides. Furthermore, fluorescent spectroscopy indicated that the hybrid peptide FV-LL exhibited marked membrane destruction by inducing outer and inner bacterial membrane permeabilization, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that FV-LL damaged membrane integrity by disrupting the bacterial membrane. Inhibiting biofilm formation assays also showed that FV-LL had similar anti-biofilm activity compared with the functional peptide sequence FV7. Synthetic cationic hybrid peptides based on FV7 could provide new models for combining different functional domains and demonstrate effective avenues to screen for novel antimicrobial agents. PMID:28178190

iAMP-2L: a two-level multi-label classifier for identifying antimicrobial peptides and their functional types.

PubMed

Xiao, Xuan; Wang, Pu; Lin, Wei-Zhong; Jia, Jian-Hua; Chou, Kuo-Chen

2013-05-15

Antimicrobial peptides (AMPs), also called host defense peptides, are an evolutionarily conserved component of the innate immune response and are found among all classes of life. According to their special functions, AMPs are generally classified into ten categories: Antibacterial Peptides, Anticancer/tumor Peptides, Antifungal Peptides, Anti-HIV Peptides, Antiviral Peptides, Antiparasital Peptides, Anti-protist Peptides, AMPs with Chemotactic Activity, Insecticidal Peptides, and Spermicidal Peptides. Given a query peptide, how can we identify whether it is an AMP or non-AMP? If it is, can we identify which functional type or types it belong to? Particularly, how can we deal with the multi-type problem since an AMP may belong to two or more functional types? To address these problems, which are obviously very important to both basic research and drug development, a multi-label classifier was developed based on the pseudo amino acid composition (PseAAC) and fuzzy K-nearest neighbor (FKNN) algorithm, where the components of PseAAC were featured by incorporating five physicochemical properties. The novel classifier is called iAMP-2L, where "2L" means that it is a 2-level predictor. The 1st-level is to answer the 1st question above, while the 2nd-level is to answer the 2nd and 3rd questions that are beyond the reach of any existing methods in this area. For the conveniences of users, a user-friendly web-server for iAMP-2L was established at http://www.jci-bioinfo.cn/iAMP-2L. Copyright © 2013 Elsevier Inc. All rights reserved.

A purely green synthesis of silver nanoparticles using Carica papaya, Manihot esculenta, and Morinda citrifolia: synthesis and antibacterial evaluations.

PubMed

Syafiuddin, Achmad; Salmiati; Hadibarata, Tony; Salim, Mohd Razman; Kueh, Ahmad Beng Hong; Sari, Ajeng Arum

2017-09-01

Green procedure for synthesizing silver nanoparticles (AgNPs) is currently considered due to its economy and toxic-free effects. Several existing works on synthesizing AgNPs using leaves extract still involve the use of physical or mechanical treatment such as heating or stirring, which consume a lot of energy. To extend and explore the green extraction philosophy, we report here the synthesis and antibacterial evaluations of a purely green procedure to synthesize AgNPs using Carica papaya, Manihot esculenta, and Morinda citrifolia leaves extract without the aforementioned additional treatment. The produced AgNPs were characterized using the ultraviolet-visible spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and antibacterial investigations. For antibacterial tests, two bacteria namely Escherichia coli and Bacillus cereus were selected. The presently employed method has successfully produced spherical AgNPs having sizes ranging from 9 to 69 nm, with plasmonic characteristics ranging from 356 to 485 nm, and energy-dispersive X-ray peak at approximately 3 keV. In addition, the smallest particles can be produced when Manihot esculenta leaves extract was applied. Moreover, this study also confirmed that both the leaves and synthesized AgNPs exhibit the antibacterial capability, depending on their concentration and the bacteria type.

Structure and Mode-of-Action of the Two-Peptide (Class-IIb) Bacteriocins.

PubMed

Nissen-Meyer, Jon; Oppegård, Camilla; Rogne, Per; Haugen, Helen Sophie; Kristiansen, Per Eugen

2010-03-01

This review focuses on the structure and mode-of-action of the two-peptide (class-IIb) bacteriocins that consist of two different peptides whose genes are next to each other in the same operon. Optimal antibacterial activity requires the presence of both peptides in about equal amounts. The two peptides are synthesized as preforms that contain a 15-30 residue double-glycine-type N-terminal leader sequence that is cleaved off at the C-terminal side of two glycine residues by a dedicated ABC-transporter that concomitantly transfers the bacteriocin peptides across cell membranes. Two-peptide bacteriocins render the membrane of sensitive bacteria permeable to a selected group of ions, indicating that the bacteriocins form or induce the formation of pores that display specificity with respect to the transport of molecules. Based on structure-function studies, it has been proposed that the two peptides of two-peptide bacteriocins form a membrane-penetrating helix-helix structure involving helix-helix-interacting GxxxG-motifs that are present in all characterized two-peptide bacteriocins. It has also been suggested that the membrane-penetrating helix-helix structure interacts with an integrated membrane protein, thereby triggering a conformational alteration in the protein, which in turn causes membrane-leakage. This proposed mode-of-action is similar to the mode-of-action of the pediocin-like (class-IIa) bacteriocins and lactococcin A (a class-IId bacteriocin), which bind to a membrane-embedded part of the mannose phosphotransferase permease in a manner that causes membrane-leakage and cell death.

Biosynthesis of 2-aminooctanoic acid and its use to terminally modify a lactoferricin B peptide derivative for improved antimicrobial activity.

PubMed

Almahboub, Sarah A; Narancic, Tanja; Devocelle, Marc; Kenny, Shane T; Palmer-Brown, William; Murphy, Cormac; Nikodinovic-Runic, Jasmina; O'Connor, Kevin E

2018-01-01

Terminal modification of peptides is frequently used to improve their hydrophobicity. While N-terminal modification with fatty acids (lipidation) has been reported previously, C-terminal lipidation is limited as it requires the use of linkers. Here we report the use of a biocatalyst for the production of an unnatural fatty amino acid, (S)-2-aminooctanoic acid (2-AOA) with enantiomeric excess > 98% ee and the subsequent use of 2-AOA to modify and improve the activity of an antimicrobial peptide. A transaminase originating from Chromobacterium violaceum was employed with a conversion efficiency 52-80% depending on the ratio of amino group donor to acceptor. 2-AOA is a fatty acid with amino functionality, which allowed direct C- and N-terminal conjugation respectively to an antimicrobial peptide (AMP) derived from lactoferricin B. The antibacterial activity of the modified peptides was improved by up to 16-fold. Furthermore, minimal inhibitory concentrations (MIC) of C-terminally modified peptide were always lower than N-terminally conjugated peptides. The C-terminally modified peptide exhibited MIC values of 25 μg/ml for Escherichia coli, 50 μg/ml for Bacillus subtilis, 100 μg/ml for Salmonella typhimurium, 200 μg/ml for Pseudomonas aeruginosa and 400 μg/ml for Staphylococcus aureus. The C-terminally modified peptide was the only peptide tested that showed complete inhibition of growth of S. aureus.

Antibacterial metabolites synthesized by psychrotrophic bacteria isolated from cold-freshwater environments.

PubMed

Barros, Javier; Becerra, José; González, Carlos; Martínez, Miguel

2013-03-01

The ability of three psychrotrophic Gram-negative bacilli isolated from Chilean Patagonian cold freshwater rivers to produce bioactive metabolites was evaluated. The strains were isolated from cold waters rivers and identified by their biochemical properties and 16S rRNA gene analysis. The metabolites fractions showing antibacterial activity were obtained by solvent extraction and partially characterized by gas-mass chromatography (GC-MS). Antibacterial activity of the fractions was evaluated by an agar-well diffusion test upon 14 bacterial strains, both Gram positive and Gram negative. Thermal and proteolytic resistances of the antibacterial metabolites fractions were also evaluated. Molecular analysis allows the identification of the three Patagonian strains as Pseudomonas sp. RG-6 (Pseudomonas brenneri 99.6 % identity), Pseudomonas sp. RG-8 (Pseudomonas trivialis 99.6 % identity) and Yersinia sp. RP-3 (Yersinia aldovae 99.5 % identity). These extracts were able to inhibit both Gram-positive and Gram-negative bacteria but not Listeria monocytogenes. The antibacterial activity of the filtrated supernatants was lost at temperatures ≥60 °C, and was not affected by proteinase K treatment. The chemical structure of the active molecule remains to be elucidated, although the GC-MS analysis of the filtrates suggests that compounds like sesquiterpenes derivatives from β-maaliene or δ-selinene could be responsible of this antibacterial activity. Pristine cold freshwater streams showed to be interesting sources of metabolites-producing microorganisms with antibacterial activity.

Draft Genome Sequence of Pedobacter sp. Strain NL19, a Producer of Potent Antibacterial Compounds

PubMed Central

2015-01-01

Here, we report the draft genome sequence of Pedobacter sp. strain NL19. The genome has 5.99 Mbp and a G+C content of 39.0%. NL19 was isolated from sludge from an abandoned uranium mine in the north of Portugal, and it produces potent antibacterials against Gram-positive and Gram-negative bacteria. PMID:25814603

Synergistic antibacterial activity of the essential oil of aguaribay (Schinus molle L.).

PubMed

de Mendonça Rocha, Pedro M; Rodilla, Jesus M; Díez, David; Elder, Heriberto; Guala, Maria Silvia; Silva, Lúcia A; Pombo, Eunice Baltazar

2012-10-12

Schinus molle L. (aguaribay, aroeira-falsa, "molle", family Anacardiaceae), a native of South America, produces an active antibacterial essential oil extracted from the leaves and fruits. This work reports a complete study of its chemical composition and determines the antibacterial activity of Schinus molle L. essential oil and its main components. The results showed that the crude extract essential oil has a potent antibacterial effect on Staphylococcus aureus ATCC 25923, a strong/moderate effect on Escherichia coli ATCC 25922 and moderate/weak one on Pseudomonas aeruginosa ATCC 27853.

Natural antimicrobial peptide complexes in the fighting of antibiotic resistant biofilms: Calliphora vicina medicinal maggots

PubMed Central

Gordya, Natalia; Yakovlev, Andrey; Kruglikova, Anastasia; Tulin, Dmitry; Potolitsina, Evdokia; Suborova, Tatyana; Bordo, Domenico; Rosano, Camillo; Chernysh, Sergey

2017-01-01

Biofilms, sedimented microbial communities embedded in a biopolymer matrix cause vast majority of human bacterial infections and many severe complications such as chronic inflammatory diseases and cancer. Biofilms’ resistance to the host immunity and antibiotics makes this kind of infection particularly intractable. Antimicrobial peptides (AMPs) are a ubiquitous facet of innate immunity in animals. However, AMPs activity was studied mainly on planktonic bacteria and little is known about their effects on biofilms. We studied structure and anti-biofilm activity of AMP complex produced by the maggots of blowfly Calliphora vicina living in environments extremely contaminated by biofilm-forming germs. The complex exhibits strong cell killing and matrix destroying activity against human pathogenic antibiotic resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii biofilms as well as non-toxicity to human immune cells. The complex was found to contain AMPs from defensin, cecropin, diptericin and proline-rich peptide families simultaneously expressed in response to bacterial infection and encoded by hundreds mRNA isoforms. All the families combine cell killing and matrix destruction mechanisms, but the ratio of these effects and antibacterial activity spectrum are specific to each family. These molecules dramatically extend the list of known anti-biofilm AMPs. However, pharmacological development of the complex as a whole can provide significant advantages compared with a conventional one-component approach. In particular, a similar level of activity against biofilm and planktonic bacteria (MBEC/MIC ratio) provides the complex advantage over conventional antibiotics. Available methods of the complex in situ and in vitro biosynthesis make this idea practicable. PMID:28278280

Natural antimicrobial peptide complexes in the fighting of antibiotic resistant biofilms: Calliphora vicina medicinal maggots.

PubMed

Gordya, Natalia; Yakovlev, Andrey; Kruglikova, Anastasia; Tulin, Dmitry; Potolitsina, Evdokia; Suborova, Tatyana; Bordo, Domenico; Rosano, Camillo; Chernysh, Sergey

2017-01-01

Biofilms, sedimented microbial communities embedded in a biopolymer matrix cause vast majority of human bacterial infections and many severe complications such as chronic inflammatory diseases and cancer. Biofilms' resistance to the host immunity and antibiotics makes this kind of infection particularly intractable. Antimicrobial peptides (AMPs) are a ubiquitous facet of innate immunity in animals. However, AMPs activity was studied mainly on planktonic bacteria and little is known about their effects on biofilms. We studied structure and anti-biofilm activity of AMP complex produced by the maggots of blowfly Calliphora vicina living in environments extremely contaminated by biofilm-forming germs. The complex exhibits strong cell killing and matrix destroying activity against human pathogenic antibiotic resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii biofilms as well as non-toxicity to human immune cells. The complex was found to contain AMPs from defensin, cecropin, diptericin and proline-rich peptide families simultaneously expressed in response to bacterial infection and encoded by hundreds mRNA isoforms. All the families combine cell killing and matrix destruction mechanisms, but the ratio of these effects and antibacterial activity spectrum are specific to each family. These molecules dramatically extend the list of known anti-biofilm AMPs. However, pharmacological development of the complex as a whole can provide significant advantages compared with a conventional one-component approach. In particular, a similar level of activity against biofilm and planktonic bacteria (MBEC/MIC ratio) provides the complex advantage over conventional antibiotics. Available methods of the complex in situ and in vitro biosynthesis make this idea practicable.

Designing Antibacterial Peptides with Enhanced Killing Kinetics

PubMed Central

Waghu, Faiza H.; Joseph, Shaini; Ghawali, Sanket; Martis, Elvis A.; Madan, Taruna; Venkatesh, Kareenhalli V.; Idicula-Thomas, Susan

2018-01-01

Antimicrobial peptides (AMPs) are gaining attention as substitutes for antibiotics in order to combat the risk posed by multi-drug resistant pathogens. Several research groups are engaged in design of potent anti-infective agents using natural AMPs as templates. In this study, a library of peptides with high sequence similarity to Myeloid Antimicrobial Peptide (MAP) family were screened using popular online prediction algorithms. These peptide variants were designed in a manner to retain the conserved residues within the MAP family. The prediction algorithms were found to effectively classify peptides based on their antimicrobial nature. In order to improve the activity of the identified peptides, molecular dynamics (MD) simulations, using bilayer and micellar systems could be used to design and predict effect of residue substitution on membranes of microbial and mammalian cells. The inference from MD simulation studies well corroborated with the wet-lab observations indicating that MD-guided rational design could lead to discovery of potent AMPs. The effect of the residue substitution on membrane activity was studied in greater detail using killing kinetic analysis. Killing kinetics studies on Gram-positive, negative and human erythrocytes indicated that a single residue change has a drastic effect on the potency of AMPs. An interesting outcome was a switch from monophasic to biphasic death rate constant of Staphylococcus aureus due to a single residue mutation in the peptide. PMID:29527201

Synthesis of nano silver on cellulosic denim fabric producing yellow colored garment with antibacterial properties.

PubMed

Maryan, Ali Sadeghian; Montazer, Majid; Harifi, Tina

2015-01-22

In this study, an aged-look denim fabric with antibacterial property was prepared in one single step process. For this purpose, the simultaneous antibacterial finishing and discoloration of denim fabric was carried out through reduction of indigo dye and silver nitrate by glucose in alkaline media using a conventional garment washing machine. The uniform distribution of silver nanoparticles on the fiber surface was confirmed by scanning electron microscope and energy dispersive X-ray spectroscopy. The treated fabrics were also characterized by X-ray diffraction (XRD) and Raman spectroscopy. Due to the color changes during the process, the color coordinates of the treated samples were also measured. Findings suggest the potential of the proposed method in producing old-look denim fabric with desirable yellow appearance and reasonable antibacterial activity against Staphylococcus aureus and Escherichia coli with low toxicity for human. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fabrication of biocompatible and efficient antimicrobial porous polymer surfaces by the Breath Figures approach.

PubMed

Vargas-Alfredo, Nelson; Martínez-Campos, Enrique; Santos-Coquillat, Ana; Dorronsoro, Ane; Cortajarena, Aitziber L; Del Campo, Adolfo; Rodríguez-Hernández, Juan

2018-03-01

We designed and fabricated highly efficient and selective antibacterial substrates, i.e. surface non-cytotoxic against mammalian cells but exhibiting strong antibacterial activity. For that purpose, microporous substrates (pore sizes in the range of 3-5 μm) were fabricated using the Breath Figures approach (BFs). These substrates have additionally a defined chemical composition in the pore cavity (herein either a poly(acrylic acid) or the antimicrobial peptide Nisin) while the composition of the rest of the surface is identical to the polymer matrix. As a result, considering the differences in size of bacteria (1-4 μm) in comparison to mammalian cells (above 10 µm) the bacteria were able to enter in contact with the inner part of the pores where the antimicrobial functionality has been placed. On the opposite, mammalian cells remain in contact with the top surface thus preventing cytotoxic effects and enhancing the biocompatibility of the substrates. The resulting antimicrobial surfaces were exposed to Staphylococcus aureus as a model bacteria and murine endothelial C166-GFP cells. Superior antibacterial performance while maintaining an excellent biocompatibility was obtained by those surfaces prepared using PAA while no evidence of significant antibacterial activity was observed at those surfaces prepared using Nisin. Copyright © 2017 Elsevier Inc. All rights reserved.

Isolation, purification, and characterization of avian antimicrobial glycopeptide from the posterior salivary gland of Sepia pharaonis.

PubMed

Karthik, R; Saravanan, R; Ebenezar, K Kumar; Sivamalai, T

2015-02-01

A proteinaceous glycopeptide was isolated from the posterior salivary gland (PSG) of Sepia pharaonis by gel (Sephadex G-100) filtration chromatography and purified by reversed-phase high-performance liquid chromatography (RP-HPLC). Among the collected fractions, fraction 12 showed a retention time (RT) of 31 min. The total protein and neutral sugar contents of the purified glycopeptide were recorded as 68.14 and 2.95 mg, respectively. The molecular weight of the purified glycopeptide was found to be ~50 kDa. The infrared (IR) and circular dichroism (CD) spectroscopy confirmed the presence of peptide and secondary structure in the purified glycopeptide. The antibacterial activity of the purified glycopeptide against avian bacterial strains was also determined. Gas chromatography-mass spectrometry (GC-MS) of the purified glycopeptide revealed the likely compounds for the antibacterial activity such as 22, 23-dibromostigmasterol acetate, 3-methyl 2-(2-oxypropyl) furan, and 2,4,4-trimethyl-3-hydroxymethyl-5A-(3-methyl-but-2-enyl)-cyclohexene. These three compounds found in the purified glycopeptide could be responsible for the antibacterial activity against the avian pathogens. The results of this study suggest that the purified glycopeptide from the PSG of S. pharaonis could be an antibacterial agent against avian bacterial pathogens.

National Biocontainment Training Center

DTIC Science & Technology

2015-02-01

develop novel diagnostic platforms to detect drug resistant TB and identification of novel antimicrobial compounds with antibacterial activity against...rCCHFV rescue work in BSL-4. Figure 6. Schematic of the CCHFV M segment fusion with Nanoluc. (a) insert the Nanoluc after the signal peptide , (b...in Dallas, Texas. Trainers: Vickie Jones and Jason Hardcastle. Food and Drug Administration (FDA-CBER) – BSL3 training was provided for faculty and

[Antibacterial activity of rare Streptomyces species against clinical resistant bacteria].

PubMed

Boughachiche, Faiza; Reghioua, Sihem; Zerizer, Habiba; Boulahrouf, Abderrahmane

2012-01-01

In the search for new antibiotics from Steptomyces, investigating extremes habitats enhances the probability of isolating novel producers. In this context, the antibacterial activity of four Streptomyces strains isolated from Ezzmoul saltpans was studied. Two of them showed antibacterial activity against antibiotic's resistant bacteria (Bacillus cereus: β-lactamines and sulfamides resistant, Streptococcus faecalis: penicillin, tetracycline and cotrimoxazole resistant, and Staphylococcus aureus Mu 50: vancomycine resistant). The most active Streptomyces strain produces one type of polar bioactive molecules that resists to temperature variation and light exposition. Its activity appears in the first culture day and reaches its maximal value in the fourth day. The second strain presents themoresistant activity that reaches its maximal value in the first culture day. It produces two types of bioactive molecules, one is polar and the second is non polar (according to thin layer chromatography technique results).

Bacillus spp. produce antibacterial activities against lactic acid bacteria that contaminate fuel ethanol plants.

PubMed

Manitchotpisit, Pennapa; Bischoff, Kenneth M; Price, Neil P J; Leathers, Timothy D

2013-05-01

Lactic acid bacteria (LAB) frequently contaminate commercial fuel ethanol fermentations, reducing yields and decreasing profitability of biofuel production. Microorganisms from environmental sources in different geographic regions of Thailand were tested for antibacterial activity against LAB. Four bacterial strains, designated as ALT3A, ALT3B, ALT17, and MR1, produced inhibitory effects on growth of LAB. Sequencing of rRNA identified these strains as species of Bacillus subtilis (ALT3A and ALT3B) and B. cereus (ALT17 and MR1). Cell mass from colonies and agar samples from inhibition zones were analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. The spectra of ALT3A and ALT3B showed a strong signal at m/z 1,060, similar in mass to the surfactin family of antimicrobial lipopeptides. ALT3A and ALT3B were analyzed by zymogram analysis using SDS-PAGE gels placed on agar plates inoculated with LAB. Cell lysates possessed an inhibitory protein of less than 10 kDa, consistent with the production of an antibacterial lipopeptide. Mass spectra of ALT17 and MR1 had notable signals at m/z 908 and 930 in the whole cell extracts and at m/z 687 in agar, but these masses do not correlate with those of previously reported antibacterial lipopeptides, and no antibacterial activity was detected by zymogram. The antibacterial activities produced by these strains may have application in the fuel ethanol industry as an alternative to antibiotics for prevention and control of bacterial contamination.

Thiopeptide Antibiotics: Retrospective and Recent Advances

PubMed Central

Just-Baringo, Xavier; Albericio, Fernando; Álvarez, Mercedes

2014-01-01

Thiopeptides, or thiazolyl peptides, are a relatively new family of antibiotics that already counts with more than one hundred different entities. Although they are mainly isolated from soil bacteria, during the last decade, new members have been isolated from marine samples. Far from being limited to their innate antibacterial activity, thiopeptides have been found to possess a wide range of biological properties, including anticancer, antiplasmodial, immunosuppressive, etc. In spite of their ribosomal origin, these highly posttranslationally processed peptides have posed a fascinating synthetic challenge, prompting the development of various methodologies and strategies. Regardless of their limited solubility, intensive investigations are bringing thiopeptide derivatives closer to the clinic, where they are likely to show their veritable therapeutic potential. PMID:24445304

Lights, Camera, Action! Antimicrobial Peptide Mechanisms Imaged in Space and Time

PubMed Central

Choi, Heejun; Rangarajan, Nambirajan; Weisshaar, James C.

2015-01-01

Deeper understanding of the bacteriostatic and bactericidal mechanisms of antimicrobial peptides (AMPs) should help in the design of new antibacterial agents. Over several decades, a variety of biochemical assays have been applied to bulk bacterial cultures. While some of these bulk assays provide time resolution on the order of 1 min, they do not capture faster mechanistic events. Nor can they provide subcellular spatial information or discern cell-to-cell heterogeneity within the bacterial population. Single-cell, time-resolved imaging assays bring a completely new spatiotemporal dimension to AMP mechanistic studies. We review recent work that provides new insights into the timing, sequence, and spatial distribution of AMP-induced effects on bacterial cells. PMID:26691950

Synthesis, construction, and evaluation of self-assembled nano-bacitracin A as an efficient antibacterial agent in vitro and in vivo

PubMed Central

Hong, Wei; Gao, Xiang; Qiu, Peng; Yang, Jie; Qiao, Mingxi; Shi, Hong; Zhang, Dexian; Tian, Chunlian; Niu, Shengli; Liu, Mingchun

2017-01-01

Bacitracin A (BA) is an excellent polypeptide antibiotic that is active against gram-positive bacteria without triggering multidrug resistance. However, BA is inactive against gram-negative bacteria because of its inability to cross the outer membrane of these cells, and it has strong nephrotoxicity, thus limiting its clinical applications. Nanoantibiotics can effectively localize antibiotics to the periplasmic space of bacteria while decreasing the adverse effects of antibiotics. In this study, biodegradable hydrophobic copolymers of poly (d,l-lactide-co-glycolide) (PLGA) were attached to the N-termini of BA to design a novel class of self-assembled nano-bacitracin A (nano-BAs), and their potential as antibacterial agents was evaluated in vitro and in vivo. Nano-BAs had a core-shell structure with a mean diameter <150 nm. Impressively, nano-BAs had strong antibacterial properties against both gram-positive and gram-negative bacteria, and the distribution of antibacterial activity as a function of PLGA block length was skewed toward longer PLGA chains. No cytotoxicity against HK-2 cells or human red blood cells (hRBCs) was observed in vitro, suggesting good biocompatibility. A high local density of BA mass on the surface promoted endocytotic cellular uptake, and hydrophobic interactions between the PLGA block and lipopolysaccharide (LPS) facilitated the uptake of nano-BAs, thereby leading to greater antibacterial activities. In addition, Nano-BA5K was found to be effective in vivo, and it served as an anti-infective agent for wound healing. Collectively, this study provides a cost-effective means of developing self-assembling nano-polypeptide antibiotic candidates with a broader antibacterial spectrum and a lower toxicity than commercially available peptide antibiotics, owing to their modification with biodegradable copolymers. PMID:28721045

Synthesis, construction, and evaluation of self-assembled nano-bacitracin A as an efficient antibacterial agent in vitro and in vivo.

PubMed

Hong, Wei; Gao, Xiang; Qiu, Peng; Yang, Jie; Qiao, Mingxi; Shi, Hong; Zhang, Dexian; Tian, Chunlian; Niu, Shengli; Liu, Mingchun

2017-01-01

Bacitracin A (BA) is an excellent polypeptide antibiotic that is active against gram-positive bacteria without triggering multidrug resistance. However, BA is inactive against gram-negative bacteria because of its inability to cross the outer membrane of these cells, and it has strong nephrotoxicity, thus limiting its clinical applications. Nanoantibiotics can effectively localize antibiotics to the periplasmic space of bacteria while decreasing the adverse effects of antibiotics. In this study, biodegradable hydrophobic copolymers of poly (d,l-lactide-co-glycolide) (PLGA) were attached to the N-termini of BA to design a novel class of self-assembled nano-bacitracin A (nano-BAs), and their potential as antibacterial agents was evaluated in vitro and in vivo. Nano-BAs had a core-shell structure with a mean diameter <150 nm. Impressively, nano-BAs had strong antibacterial properties against both gram-positive and gram-negative bacteria, and the distribution of antibacterial activity as a function of PLGA block length was skewed toward longer PLGA chains. No cytotoxicity against HK-2 cells or human red blood cells (hRBCs) was observed in vitro, suggesting good biocompatibility. A high local density of BA mass on the surface promoted endocytotic cellular uptake, and hydrophobic interactions between the PLGA block and lipopolysaccharide (LPS) facilitated the uptake of nano-BAs, thereby leading to greater antibacterial activities. In addition, Nano-BA 5K was found to be effective in vivo, and it served as an anti-infective agent for wound healing. Collectively, this study provides a cost-effective means of developing self-assembling nano-polypeptide antibiotic candidates with a broader antibacterial spectrum and a lower toxicity than commercially available peptide antibiotics, owing to their modification with biodegradable copolymers.

Functional selection of a type IV pili-binding peptide that specifically inhibits Salmonella Typhi adhesion to/invasion of human monocytic cells.

PubMed

Wu, Hong-Yan; Zhang, Xiao-Lian; Pan, Qin; Wu, Jianguo

2005-11-01

Salmonella enterica serovar Typhi (S. Typhi) is an important pathogen which infects humans exclusively and causes typhoid or enteric fever. Recently it has been discovered that type IVB pili, encoded by the S. Typhi pil operon located in the major pathogenicity island, may be important in the pathogenesis of epidemic enteric fever. To further investigate the roles of type IVB pili of S. Typhi, a 12-mer peptide (RQERSSLSKPVV), binding to the structural protein PilS of the type IVB pili of S. Typhi, was isolated with a ribosome display system. This peptide was designated as peptide R. We found that peptide R inhibited adhesion to/invasion of human monocytic THP-1 cells by piliated S. Typhi bacteria, but had no effects on nonpiliated S. Typhi bacteria. A random 12-mer peptide, of size and solubility equal to peptide R, served as a control on the specificity of peptide R. The specific interaction and binding equilibrium between the 12-mer peptide R and PilS protein was determined by isothermal titration calorimetry (ITC) and a binding constant Ka determined to be between 0.4 x 10(5) and 2.2 x 10(5)L mol(-1). Our findings suggest that the type IV pili-binding peptide R holds potential as an antibacterial peptide effective against S. Typhi infections, both in terms of prevention and therapeutic treatment. The data further provide insights into the understanding of the pathogenic roles of the type IVB pili of S. Typhi.

Polymeric micellar nanoplatforms for Fenton reaction as a new class of antibacterial agents.

PubMed

Park, Seong-Cheol; Kim, Nam-Hong; Yang, Wonseok; Nah, Jae-Woon; Jang, Mi-Kyeong; Lee, Dongwon

2016-01-10

Reactive oxygen species (ROS) produced by host phagocytes exert antibacterial action against a variety of pathogens and ROS-induced oxidative stress is the governing mechanism for the antibacterial activity of major bactericidal antibiotics. In particular, hydroxyl radical is a strong and nonselective oxidant which can damage biomolecules such as DNA, proteins and lipids. Ferrous ion is known to convert mild oxidant hydrogen peroxide (H2O2) into highly reactive and toxic hydroxyl radicals, referred to as Fenton reaction. Herein, we report a new class of antibacterial agents based on Fenton reaction-performing nanostructures, composed of H2O2-generating polymer (PCAE) and iron-containing ferrocene. Amphiphilic PCAE was designed to incorporate H2O2-generating cinnamaldehyde through acid-cleavable linkages and self-assemble to form thermodynamically stable micelles which could encapsulate ferrocene in their hydrophobic core. All the experiments in vitro display that ferrocene-loaded PCAE micelles produce hydroxyl radicals to kill Escherichia coli and Pseudomonas aeruginosa through membrane damages. Intraperitoneally injected ferrocene-loaded PCAE micelles significantly reduced the lung damages and therefore increased the survival rate of mice infected with drug resistant P. aeruginosa. Given their potent antibacterial activity, ferrocene-loaded PCAE micelles hold great potential as a new class of ROS-manipulating antibacterial agents. Copyright © 2015 Elsevier B.V. All rights reserved.

Virus-cell fusion inhibitory activity of novel analogue peptides based on the HP (2-20) derived from N-terminus of Helicobacter pylori Ribosomal Protein L1.

PubMed

Woo, Eun-Rhan; Lee, Dong Gun; Chang, Young-Su; Park, Yoonkyung; Hahm, Kyung-Soo

2002-12-01

HP (2-20) (AKKVFKRLEKLFSKIQNDK) is the antibacterial sequence derived from N-terminus of Helicobacter pylori Ribosomal Protein L1 (RPL1). It has a broad-spectrum microbicidal activity in vitro that is thought to be related to the membrane-disruptive properties of the peptide. Based on the putative membrane-targeted mode of action, we postulated that HP (2-20) might be possessed virus-cell fusion inhibitory activity. To develop the novel virus-cell fusion inhibitory peptides, several analogues with amino acid substitution were designed to increase or decrease only net hydrophobic region. In particular, substitution of Gln and Asp for hydrophobic amino acid, Trp at position 17 and 19 of HP (2-20) (Anal 3) caused a dramatic increase in virus-cell fusion inhibitory activity without hemolytic effect.

The Development of Antimicrobial α-AApeptides that Suppress Pro-inflammatory Immune Responses

PubMed Central

Padhee, Shruti; Smith, Christina; Wu, Haifan; Li, Yaqiong; Manoj, Namitha; Qiao, Qiao; Khan, Zoya; Cao, Chuanhai

2014-01-01

Herein we describe the development of a new class of antimicrobial and anti-infective peptidomimetics – cyclic lipo-α-AApeptides. They have potent and broad-spectrum antibacterial activity against a range of clinically relevant pathogens, including both multidrug-resistant Gram-positive and Gram-negative bacteria. Fluorescence microscopy suggests that cyclic lipo-α-AApeptides kill bacteria by disrupting bacterial membranes, possibly through a mechanism similar to that of cationic host defense peptides (HDPs). Furthermore, the cyclic lipo-α-AApeptide can mimic cationic host-defense peptides by antagonizing Toll-Like Receptor 4 (TLR4) signaling responses and suppressing pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α). Our results suggest that by mimicking host-defense peptides (HDPs), cyclic lipo-α-AApeptides may emerge to be a new class of antibiotic agents through direct bacteria killing, as well as novel anti-infective agents through immunomodulation. PMID:24677440

Truncated Autoinducing Peptide Conjugates Selectively Recognize and Kill Staphylococcus aureus.

PubMed

Tsuchikama, Kyoji; Shimamoto, Yasuhiro; Anami, Yasuaki

2017-06-09

The accessory gene regulator (agr) of Staphylococcus aureus coordinates various pathogenic events and is recognized as a promising therapeutic target for virulence control. S. aureus utilizes autoinducing peptides (AIPs), cyclic-peptide signaling molecules, to mediate the agr system. Despite the high potency of synthetic AIP analogues in agr inhibition, the potential of AIP molecules as a delivery vehicle for antibacterial agents remains unexplored. Herein, we report that truncated AIP scaffolds can be fused with fluorophore and cytotoxic photosensitizer molecules without compromising their high agr inhibitory activity, binding affinity to the receptor AgrC, or cell specificity. Strikingly, a photosensitizer-AIP conjugate exhibited 16-fold greater efficacy in a S. aureus cell-killing assay than a nontargeting analogue. These findings highlight the potential of truncated AIP conjugates as useful chemical tools for in-depth biological studies and as effective anti-S. aureus agents.

Fragments of the Bacterial Toxin Microcin B17 as Gyrase Poisons

PubMed Central

Collin, Frédéric; Thompson, Robert E.; Jolliffe, Katrina A.; Payne, Richard J.; Maxwell, Anthony

2013-01-01

Fluoroquinolones are very important drugs in the clinical antibacterial arsenal; their success is principally due to their mode of action: the stabilisation of a gyrase-DNA intermediate (the cleavage complex), which triggers a chain of events leading to cell death. Microcin B17 (MccB17) is a modified peptide bacterial toxin that acts by a similar mode of action, but is unfortunately unsuitable as a therapeutic drug. However, its structure and mechanism could inspire the design of new antibacterial compounds that are needed to circumvent the rise in bacterial resistance to current antibiotics. Here we describe the investigation of the structural features responsible for MccB17 activity and the identification of fragments of the toxin that retain the ability to stabilise the cleavage complex. PMID:23593482

Fragments of the bacterial toxin microcin B17 as gyrase poisons.

PubMed

Collin, Frédéric; Thompson, Robert E; Jolliffe, Katrina A; Payne, Richard J; Maxwell, Anthony

2013-01-01

Fluoroquinolones are very important drugs in the clinical antibacterial arsenal; their success is principally due to their mode of action: the stabilisation of a gyrase-DNA intermediate (the cleavage complex), which triggers a chain of events leading to cell death. Microcin B17 (MccB17) is a modified peptide bacterial toxin that acts by a similar mode of action, but is unfortunately unsuitable as a therapeutic drug. However, its structure and mechanism could inspire the design of new antibacterial compounds that are needed to circumvent the rise in bacterial resistance to current antibiotics. Here we describe the investigation of the structural features responsible for MccB17 activity and the identification of fragments of the toxin that retain the ability to stabilise the cleavage complex.

N-Alkyl Urea Hydroxamic Acids as a New Class of Peptide Deformylase Inhibitors with Antibacterial Activity

PubMed Central

Hackbarth, Corinne J.; Chen, Dawn Z.; Lewis, Jason G.; Clark, Kirk; Mangold, James B.; Cramer, Jeffrey A.; Margolis, Peter S.; Wang, Wen; Koehn, Jim; Wu, Charlotte; Lopez, S.; Withers III, George; Gu, Helen; Dunn, Elina; Kulathila, R.; Pan, Shi-Hao; Porter, Wilma L.; Jacobs, Jeff; Trias, Joaquim; Patel, Dinesh V.; Weidmann, Beat; White, Richard J.; Yuan, Zhengyu

2002-01-01

Peptide deformylase (PDF) is a prokaryotic metalloenzyme that is essential for bacterial growth and is a new target for the development of antibacterial agents. All previously reported PDF inhibitors with sufficient antibacterial activity share the structural feature of a 2-substituted alkanoyl at the P1′ site. Using a combination of iterative parallel synthesis and traditional medicinal chemistry, we have identified a new class of PDF inhibitors with N-alkyl urea at the P1′ site. Compounds with MICs of ≤4 μg/ml against gram-positive and gram-negative pathogens, including Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae, have been identified. The concentrations needed to inhibit 50% of enzyme activity (IC50s) for Escherichia coli Ni-PDF were ≤0.1 μM, demonstrating the specificity of the inhibitors. In addition, these compounds were very selective for PDF, with IC50s of consistently >200 μM for matrilysin and other mammalian metalloproteases. Structure-activity relationship analysis identified preferred substitutions resulting in improved potency and decreased cytotoxity. One of the compounds (VRC4307) was cocrystallized with PDF, and the enzyme-inhibitor structure was determined at a resolution of 1.7 Å. This structural information indicated that the urea compounds adopt a binding position similar to that previously determined for succinate hydroxamates. Two compounds, VRC4232 and VRC4307, displayed in vivo efficacy in a mouse protection assay, with 50% protective doses of 30.8 and 17.9 mg/kg of body weight, respectively. These N-alkyl urea hydroxamic acids provide a starting point for identifying new PDF inhibitors that can serve as antimicrobial agents. PMID:12183225

A Peptidomic Analysis of Human Milk Digestion in the Infant Stomach Reveals Protein-Specific Degradation Patterns123

PubMed Central

Dallas, David C.; Guerrero, Andrés; Khaldi, Nora; Borghese, Robyn; Bhandari, Aashish; Underwood, Mark A.; Lebrilla, Carlito B.; German, J. Bruce; Barile, Daniela

2014-01-01

In vitro digestion of isolated milk proteins results in milk peptides with a variety of actions. However, it remains unclear to what degree protein degradation occurs in vivo in the infant stomach and whether peptides previously annotated for bioactivity are released. This study combined nanospray LC separation with time-of-flight mass spectrometry, comprehensive structural libraries, and informatics to analyze milk from 3 human mothers and the gastric aspirates from their 4- to 12-d-old postpartum infants. Milk from the mothers contained almost 200 distinct peptides, demonstrating enzymatic degradation of milk proteins beginning either during lactation or between milk collection and feeding. In the gastric samples, 649 milk peptides were identified, demonstrating that digestion continues in the infant stomach. Most peptides in both the intact milk and gastric samples were derived from β-casein. The numbers of peptides from β-casein, lactoferrin, α-lactalbumin, lactadherin, κ-casein, serum albumin, bile salt–associated lipase, and xanthine dehydrogenase/oxidase were significantly higher in the gastric samples than in the milk samples (P < 0.05). A total of 603 peptides differed significantly in abundance between milk and gastric samples (P < 0.05). Most of the identified peptides have previously identified biologic activity. Gastric proteolysis occurs in the term infant in the first 2 wk of life, releasing biologically active milk peptides with immunomodulatory and antibacterial properties of clinical relevance to the proximal intestinal tract. Data are available via ProteomeXchange (identifier PXD000688). PMID:24699806

A peptidomic analysis of human milk digestion in the infant stomach reveals protein-specific degradation patterns.

PubMed

Dallas, David C; Guerrero, Andrés; Khaldi, Nora; Borghese, Robyn; Bhandari, Aashish; Underwood, Mark A; Lebrilla, Carlito B; German, J Bruce; Barile, Daniela

2014-06-01

In vitro digestion of isolated milk proteins results in milk peptides with a variety of actions. However, it remains unclear to what degree protein degradation occurs in vivo in the infant stomach and whether peptides previously annotated for bioactivity are released. This study combined nanospray LC separation with time-of-flight mass spectrometry, comprehensive structural libraries, and informatics to analyze milk from 3 human mothers and the gastric aspirates from their 4- to 12-d-old postpartum infants. Milk from the mothers contained almost 200 distinct peptides, demonstrating enzymatic degradation of milk proteins beginning either during lactation or between milk collection and feeding. In the gastric samples, 649 milk peptides were identified, demonstrating that digestion continues in the infant stomach. Most peptides in both the intact milk and gastric samples were derived from β-casein. The numbers of peptides from β-casein, lactoferrin, α-lactalbumin, lactadherin, κ-casein, serum albumin, bile salt-associated lipase, and xanthine dehydrogenase/oxidase were significantly higher in the gastric samples than in the milk samples (P < 0.05). A total of 603 peptides differed significantly in abundance between milk and gastric samples (P < 0.05). Most of the identified peptides have previously identified biologic activity. Gastric proteolysis occurs in the term infant in the first 2 wk of life, releasing biologically active milk peptides with immunomodulatory and antibacterial properties of clinical relevance to the proximal intestinal tract. Data are available via ProteomeXchange (identifier PXD000688). © 2014 American Society for Nutrition.

Investigation of the antibiofilm capacity of peptide-modified stainless steel

PubMed Central

Cao, Pan; Li, Wen-Wu; Morris, Andrew R.; Horrocks, Paul D.; Yuan, Cheng-Qing

2018-01-01

Biofilm formation on surfaces is an important research topic in ship tribology and medical implants. In this study, dopamine and two types of synthetic peptides were designed and attached to 304 stainless steel surfaces, aiming to inhibit the formation of biofilms. A combinatory surface modification procedure was applied in which dopamine was used as a coupling agent, allowing a strong binding ability with the two peptides. X-ray photoelectron spectroscopy (XPS), elemental analysis, contact angle measurement and surface roughness test were used to evaluate the efficiency of the peptide modification. An antibiofilm assay against Staphylococcus aureus was conducted to validate the antibiofilm capacity of the peptide-modified stainless steel samples. XPS analysis confirmed that the optimal dopamine concentration was 40 µg ml−1 in the coupling reaction. Element analysis showed that dopamine and the peptides had bound to the steel surfaces. The robustness assay of the modified surface demonstrated that most peptide molecules had bound on the surface of the stainless steel firmly. The contact angle of the modified surfaces was significantly changed. Modified steel samples exhibited improved antibiofilm properties in comparison to untreated and dopamine-only counterpart, with the peptide 1 modification displaying the best antibiofilm effect. The modified surfaces showed antibacterial capacity. The antibiofilm capacity of the modified surfaces was also surface topography sensitive. The steel sample surfaces polished with 600# sandpaper exhibited stronger antibiofilm capacity than those polished with other types of sandpapers after peptide modification. These findings present valuable information for future antifouling material research. PMID:29657809

Investigation of the antibiofilm capacity of peptide-modified stainless steel.

PubMed

Cao, Pan; Li, Wen-Wu; Morris, Andrew R; Horrocks, Paul D; Yuan, Cheng-Qing; Yang, Ying

2018-03-01

Biofilm formation on surfaces is an important research topic in ship tribology and medical implants. In this study, dopamine and two types of synthetic peptides were designed and attached to 304 stainless steel surfaces, aiming to inhibit the formation of biofilms. A combinatory surface modification procedure was applied in which dopamine was used as a coupling agent, allowing a strong binding ability with the two peptides. X-ray photoelectron spectroscopy (XPS), elemental analysis, contact angle measurement and surface roughness test were used to evaluate the efficiency of the peptide modification. An antibiofilm assay against Staphylococcus aureus was conducted to validate the antibiofilm capacity of the peptide-modified stainless steel samples. XPS analysis confirmed that the optimal dopamine concentration was 40 µg ml -1 in the coupling reaction. Element analysis showed that dopamine and the peptides had bound to the steel surfaces. The robustness assay of the modified surface demonstrated that most peptide molecules had bound on the surface of the stainless steel firmly. The contact angle of the modified surfaces was significantly changed. Modified steel samples exhibited improved antibiofilm properties in comparison to untreated and dopamine-only counterpart, with the peptide 1 modification displaying the best antibiofilm effect. The modified surfaces showed antibacterial capacity. The antibiofilm capacity of the modified surfaces was also surface topography sensitive. The steel sample surfaces polished with 600# sandpaper exhibited stronger antibiofilm capacity than those polished with other types of sandpapers after peptide modification. These findings present valuable information for future antifouling material research.

Phytochemistry and Preliminary Assessment of the Antibacterial Activity of Chloroform Extract of Amburana cearensis (Allemão) A.C. Sm. against Klebsiella pneumoniae Carbapenemase-Producing Strains

PubMed Central

Sá, Mirivaldo Barros; Ralph, Maria Taciana; Nascimento, Danielle Cristina Oliveira; Ramos, Clécio Souza; Barbosa, Isvânia Maria Serafin; Sá, Fabrício Bezerra; Lima-Filho, J. V.

2014-01-01

The chloroform extract of the stem bark of Amburana cearensis was chemically characterized and tested for antibacterial activity.The extract was analyzed by gas chromatography and mass spectrometry. The main compounds identified were 4-methoxy-3-methylphenol (76.7%), triciclene (3.9%), α-pinene (1.0%), β-pinene (2.2%), and 4-hydroxybenzoic acid (3.1%). Preliminary antibacterial tests were carried out against species of distinct morphophysiological characteristics: Escherichia coli, Salmonella enterica Serotype Typhimurium, Pseudomonas aeruginosa, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. The minimum inhibitory concentration (MIC) was determinate in 96-well microplates for the chloroform extract and an analogue of themain compound identified, which was purchased commercially.We have shown that plant's extract was only inhibitory (but not bactericidal) at the maximum concentration of 6900 μg/mL against Pseudomonas aeruginosa and Bacillus cereus. Conversely, the analogue 2-methoxy-4-methylphenol produced MICs ranging from215 to 431 μg/mL against all bacterial species.New antibacterial assays conducted with such chemical compound against Klebsiella pneumoniae carbapenemase-producing strains have shown similarMICresults and minimumbactericidal concentration (MBC) of 431 μg/mL.We conclude that A. cearensis is a good source of methoxy-methylphenol compounds,which could be screened for antibacterial activity againstmultiresistant bacteria fromdifferent species PMID:24772183

A review of the biomaterials technologies for infection-resistant surfaces.

PubMed

Campoccia, Davide; Montanaro, Lucio; Arciola, Carla Renata

2013-11-01

Anti-infective biomaterials need to be tailored according to the specific clinical application. All their properties have to be tuned to achieve the best anti-infective performance together with safe biocompatibility and appropriate tissue interactions. Innovative technologies are developing new biomaterials and surfaces endowed with anti-infective properties, relying either on antifouling, or bactericidal, or antibiofilm activities. This review aims at thoroughly surveying the numerous classes of antibacterial biomaterials and the underlying strategies behind them. Bacteria repelling and antiadhesive surfaces, materials with intrinsic antibacterial properties, antibacterial coatings, nanostructured materials, and molecules interfering with bacterial biofilm are considered. Among the new strategies, the use of phages or of antisense peptide nucleic acids are discussed, as well as the possibility to modulate the local immune response by active cytokines. Overall, there is a wealth of technical solutions to contrast the establishment of an implant infection. Many of them exhibit a great potential in preclinical models. The lack of well-structured prospective multicenter clinical trials hinders the achievement of conclusive data on the efficacy and comparative performance of anti-infective biomaterials. © 2013 Elsevier Ltd. All rights reserved.

Goat mammary gland expression of Cecropin B to inhibit bacterial pathogens causing mastitis.

PubMed

Luo, Chao-chao; Yin, De-yun; Gao, Xue-jun; Li, Qing-zhang; Zhang, Li

2013-01-01

The antibacterial peptide Cecropin B (CB), isolated from the giant silk moth, has been shown to effectively eliminate bacteria. In this study, the effects of transgenic CB on dairy goat mammary epithelial cells (DGMECs) and dairy goat mammary gland were investigated. The DNA of CB from silkworm was amplified by reverse transcription PCR (RT-PCR) and then fused to the eukaryotic expression vector pECFP-C1. The recombinant plasmid pECFP-Cecropin B (pECFP-CB) was used for the transfection of DGMECs, and the expression of transgenic CB and the antibacterial activity of it were confirmed by western blot and agar diffusion reaction respectively. The stable DGMEC line transfected by pECFP-CB was obtained by screening with G418. In vivo experiment, pECFP-CB was injected into dairy goat mammary gland, and also the expression and antibacterial activity of transgenic CB were confirmed. Results of this study: transgenic CB can be expressed in DGMECs and dairy goat mammary gland, and inhibit the mastitis caused by Staphylococcus aureus.

Production of novel antibacterial liamocins by strains of Aureobasidium pullulans

USDA-ARS?s Scientific Manuscript database

Certain strains of Aureobasidium pullulans produce liamocins, heavier-than-water “oils” that accumulate in liquid cultures. Liamocins are surface active, and inhibit mammalian cancer cell lines. Recently, we discovered that liamocins have antibacterial activity with specificity against Streptococcus...

Indonesian honey protein isolation Apis dorsata dorsata and Tetragonula sp. as antibacterial and antioxidant agent

NASA Astrophysics Data System (ADS)

Sahlan, Muhamad; Damayanti, Vina; Azizah, Nurul; Hakamada, Kazuaki; Yohda, Masafumi; Hermansyah, Heri; Wijanarko, Anondho; Rohmatin, Etin

2018-02-01

Honey is a natural product that has many properties and been widely used for many theurapeutic purposes. Research on honey has been very rapid but not yet for Indonesia. Like local Indonesian honey Apis dorsata dorsata and Tetragonula sp. which has been widely consumed by the public but not yet known for certain efficacy of each content. The function of honey as antibacterial and antioxidant has not been specifically explained by the components contained in honey. Protein is one of the content of honey that turned out to have activity as an antibacterial and antioxidant in certain types of honey because of it antimicrobial peptide. Testing of honey activity as antibacterial and antioxidant through several stages including isolation, SDS-PAGE analysis, Bradford test, antibacterial activity test with well diffusion method and antioxidant activity test by DPPH method. Bacteria used were gram-positive bacteria Staphylococcus aureus and gram negative Escherichia coli. After some experiment finally got protein isolation method that is in the form of further concentration using Millipore membrane for honey Tetragonula sp. and membrane filtration dot blot for honey Apis dorsata dorsata. The Bradford assay showed that Apis dorsata dorsata honey contains protein <5 µg / ml, while honey Tetragonula sp. has a protein content of 97 µg / ml. The characteristic profile of molecular weight of the protein showed honey Tetragonula sp. has 3 protein bands composed of 52, 96 - 61,9 kDa, 63,35 - 65,92 kDa and 86,16 - 91,4 kDa, whereas Apis dorsata dorsata honey has 5 protein bands consisting of 45,2 - 46,6 kDa, 50,2 - 50,9 kDa, 62,5 - 62,9 kDa, 73,1 - 73,9 kDa, 83,9 - 86,9 kDa. Isolate honey protein Apis dorsata dorsata has no antioxidant and antibacterial activity (Staphylococcus aureus and Escherichia coli), whereas honey protein isolates Tetragonula sp. has antibacterial activity against Escherichia coli.

Current state of purification, isolation and analysis of bacteriocins produced by lactic acid bacteria.

PubMed

Kaškonienė, Vilma; Stankevičius, Mantas; Bimbiraitė-Survilienė, Kristina; Naujokaitytė, Gintarė; Šernienė, Loreta; Mulkytė, Kristina; Malakauskas, Mindaugas; Maruška, Audrius

2017-02-01

The scientific interest for the search of natural means of microbial inhibitors has not faded for several years. A search of natural antibiotics, so-called bacteriocins which are produced by lactic acid bacteria (LAB), gains a huge attention of the scientists in the last century, in order to reduce the usage of synthetic food additives. Pure bacteriocins with wide spectra of antibacterial activity are promising among the natural biopreservatives. The usage of bacteriocin(s) producing LAB as starter culture for the fermentation of some food products, in order to increase their shelf-life, when synthetic preservatives are not allowable, is also possible. There are a lot of studies focusing on the isolation of new bacteriocins from traditional fermented food, dairy products and other foods or sometimes even from unusual non-food matrices. Bacteriocins producing bacteria have been isolated from different sources with the different antibacterial activity against food-borne microorganisms. This review covers the classification of bacteriocins, diversity of sources of bacteriocin(s) producing LAB, antibacterial spectra of isolated bacteriocins and analytical methods for the bacteriocin purification and analysis within the last 15 years.

Rational Design of Cyclic Antimicrobial Peptides Based on BPC194 and BPC198.

PubMed

Cirac, Anna D; Torné, Maria; Badosa, Esther; Montesinos, Emilio; Salvador, Pedro; Feliu, Lidia; Planas, Marta

2017-06-24

A strategy for the design of antimicrobial cyclic peptides derived from the lead compounds c(KKLKKFKKLQ) ( BPC194 ) and c(KLKKKFKKLQ) ( BPC198 ) is reported. First, the secondary β-structure of BPC194 and BPC198 was analyzed by carrying out molecular dynamics (MD) simulations. Then, based on the sequence pattern and the β-structure of BPC194 or BPC198 , fifteen analogues were designed and synthesized on solid-phase. The best peptides ( BPC490 , BPC918, and BPC924 ) showed minimum inhibitory concentration (MIC) values <6.2 μM against Pseudomonas syringae pv. syringae and Xanthomonas axonopodis pv. vesicatoria , and an MIC value of 12.5 to 25 μM against Erwinia amylovora , being as active as BPC194 and BPC198 . Interestingly, these three analogues followed the structural pattern defined from the MD simulations of the parent peptides. Thus, BPC490 maintained the parallel alignment of the hydrophilic pairs K¹-K⁸, K²-K⁷, and K⁴-K⁵, whereas BPC918 and BPC924 included the two hydrophilic interactions K³-Q 10 and K⁵-K⁸. In short, MD simulations have proved to be very useful for ascertaining the structural features of cyclic peptides that are crucial for their biological activity. Such approaches could be further employed for the development of new antibacterial cyclic peptides.

Synthetic Molecular Evolution of Membrane-Active Peptides

NASA Astrophysics Data System (ADS)

Wimley, William

The physical chemistry of membrane partitioning largely determines the function of membrane active peptides. Membrane-active peptides have potential utility in many areas, including in the cellular delivery of polar compounds, cancer therapy, biosensor design, and in antibacterial, antiviral and antifungal therapies. Yet, despite decades of research on thousands of known examples, useful sequence-structure-function relationships are essentially unknown. Because peptide-membrane interactions within the highly fluid bilayer are dynamic and heterogeneous, accounts of mechanism are necessarily vague and descriptive, and have little predictive power. This creates a significant roadblock to advances in the field. We are bypassing that roadblock with synthetic molecular evolution: iterative peptide library design and orthogonal high-throughput screening. We start with template sequences that have at least some useful activity, and create small, focused libraries using structural and biophysical principles to design the sequence space around the template. Orthogonal high-throughput screening is used to identify gain-of-function peptides by simultaneously selecting for several different properties (e.g. solubility, activity and toxicity). Multiple generations of iterative library design and screening have enabled the identification of membrane-active sequences with heretofore unknown properties, including clinically relevant, broad-spectrum activity against drug-resistant bacteria and enveloped viruses as well as pH-triggered macromolecular poration.

Antibacterial resistance: an emerging 'zoonosis'?

PubMed

Labro, Marie-Thérèse; Bryskier, Jean-Marie

2014-12-01

Antibacterial resistance is a worldwide threat, and concerns have arisen about the involvement of animal commensal and pathogenic bacteria in the maintenance and spread of resistance genes. However, beyond the facts related to the occurrence of resistant microorganisms in food, food-producing animals and companion animals and their transmission to humans, it is important to consider the vast environmental 'resistome', the selective pathways underlying the emergence of antibacterial resistance and how we can prepare answers for tomorrow.

Exploring biological effects of MoS2 nanosheets on native structures of α-helical peptides

NASA Astrophysics Data System (ADS)

Gu, Zonglin; Li, Weifeng; Hong, Linbi; Zhou, Ruhong

2016-05-01

Recent reports of mono- and few-layer molybdenum disulfide (MoS2), a representative transition metal dichacogenide (TMD), as antibacterial and anticancer agents have shed light on their potential in biomedical applications. To better facilitate these promising applications, one needs to understand the biological effects of these TMDs as well, such as their potential adverse effects on protein structure and function. Here, we sought to understand the interaction of MoS2 nanosheets with peptides using molecular dynamics simulations and a simple model polyalanine with various lengths (PAn, n = 10, 20, 30, and 40; mainly α - helices). Our results demonstrated that MoS2 monolayer has an exceptional capability to bind all peptides in a fast and strong manner. The strong attraction from the MoS2 nanosheet is more than enough to compensate the energy needed to unfold the peptide, regardless of the length, which induces drastic disruptions to the intra-peptide hydrogen bonds and subsequent secondary structures of α - helices. This universal phenomenon may point to the potential nanotoxicity of MoS2 when used in biological systems. Moreover, these results aligned well with previous findings on the potential cytotoxicity of TMD nanomaterials.

An ancestral host defence peptide within human β-defensin 3 recapitulates the antibacterial and antiviral activity of the full-length molecule

PubMed Central

Nigro, Ersilia; Colavita, Irene; Sarnataro, Daniela; Scudiero, Olga; Zambrano, Gerardo; Granata, Vincenzo; Daniele, Aurora; Carotenuto, Alfonso; Galdiero, Stefania; Folliero, Veronica; Galdiero, Massimiliano; Urbanowicz, Richard A.; Ball, Jonathan K.; Salvatore, Francesco; Pessi, Antonello

2015-01-01

Host defence peptides (HDPs) are critical components of innate immunity. Despite their diversity, they share common features including a structural signature, designated “γ-core motif”. We reasoned that for each HDPs evolved from an ancestral γ-core, the latter should be the evolutionary starting point of the molecule, i.e. it should represent a structural scaffold for the modular construction of the full-length molecule, and possess biological properties. We explored the γ-core of human β-defensin 3 (HBD3) and found that it: (a) is the folding nucleus of HBD3; (b) folds rapidly and is stable in human serum; (c) displays antibacterial activity; (d) binds to CD98, which mediates HBD3 internalization in eukaryotic cells; (e) exerts antiviral activity against human immunodeficiency virus and herpes simplex virus; and (f) is not toxic to human cells. These results demonstrate that the γ-core within HBD3 is the ancestral core of the full-length molecule and is a viable HDP per se, since it is endowed with the most important biological features of HBD3. Notably, the small, stable scaffold of the HBD3 γ-core can be exploited to design disease-specific antimicrobial agents. PMID:26688341

Effects of pig antibacterial peptides on growth performance and intestine mucosal immune of broiler chickens.

PubMed

Bao, H; She, R; Liu, T; Zhang, Y; Peng, K S; Luo, D; Yue, Z; Ding, Y; Hu, Y; Liu, W; Zhai, L

2009-02-01

Currently, substitutions for antibiotic growth promoters in animals are attracting interest. This study investigated the effects of pig antibacterial peptides (PABP) on growth performance and small intestine mucosal immune responses in broilers. Three hundred 1-d-old Arbor Acre male broiler chickens were randomly allocated to 5 groups with 60 birds per group. The groups were control group; PABP administered in drinking water at 20 and 30 mg/L of water; or PABP supplemented in feed at 150 and 200 mg/kg of diet. The birds were fed a corn-soybean based diet for 6 wk. Chickens were weighed weekly and killed after 42 d of feeding, and growth performance was measured. Samples of the duodenum and jejunum were collected. The villus height, mucosa thickness, alkaline phosphatase activity, and numbers of secreting IgA and goblet cells were evaluated. The PABP-treated groups had greater BW and average daily gain, greater height of villus and thickness of gut mucosa, greater activity of alkaline phosphatase, higher ratio of secreting IgA, and a greater number of goblet cells compared with the control group (P<0.05). In conclusion, PABP can improve the growth performance, increase the intestinal ability to absorb nutrients, and improve the mucosal immunity of the intestine.

Effects of Cold Atmospheric Plasma (CAP) on ß-Defensins, Inflammatory Cytokines, and Apoptosis-Related Molecules in Keratinocytes In Vitro and In Vivo

PubMed Central

Arndt, Stephanie; Landthaler, Michael; Zimmermann, Julia L.; Unger, Petra; Wacker, Eva; Shimizu, Tetsuji; Li, Yang-Fang; Morfill, Gregor E.

2015-01-01

Cold atmospheric plasma (CAP) has been gaining increasing interest as a new approach for the treatment of skin diseases or wounds. Although this approach has demonstrated promising antibacterial activity, its exact mechanism of action remains unclear. This study explored in vitro and in vivo whether CAP influences gene expression and molecular mechanisms in keratinocytes. Our results revealed that a 2 min CAP treatment using the MicroPlaSter ß in analogy to the performed clinical studies for wound treatment induces expression of IL-8, TGF-ß1, and TGF-ß2. In vitro and in vivo assays indicated that keratinocyte proliferation, migration, and apoptotic mechanisms were not affected by the CAP treatment under the applied conditions. Further, we observed that antimicrobial peptides of the ß-defensin family are upregulated after CAP treatment. In summary, our results suggest that a 2 min application of CAP induces gene expression of key regulators important for inflammation and wound healing without causing proliferation, migration or cell death in keratinocytes. The induction of ß-defensins in keratinocytes describes an absolutely new plasma strategy. Activation of antimicrobial peptides supports the well-known antibacterial effect of CAP treatment, whereas the mechanism of ß-defensin activation by CAP is not investigated so far. PMID:25768736

Thionin-like peptides from Capsicum annuum fruits with high activity against human pathogenic bacteria and yeasts.

PubMed

Taveira, Gabriel B; Mathias, Luciana S; da Motta, Olney V; Machado, Olga L T; Rodrigues, Rosana; Carvalho, André O; Teixeira-Ferreira, André; Perales, Jonas; Vasconcelos, Ilka M; Gomes, Valdirene M

2014-01-01

Plants defend themselves against pathogens with production of antimicrobial peptides (AMPs). Herein we describe the discovery of a new antifungal and antibacterial peptide from fruits of Capsicum annuum that showed similarity to an already well characterized family of plant AMPs, thionins. Other fraction composed of two peptides, in which the major peptide also showed similarity to thionins. Among the obtained fractions, fraction 1, which is composed of a single peptide of 7 kDa, was sequenced by Edman method and its comparative sequence analysis in database (nr) showed similarity to thionin-like peptides. Tests against microorganisms, fraction 1 presented inhibitory activity to the cells of yeast Saccharomyces cerevisiae, Candida albicans, and Candida tropicalis and caused growth reduction to the bacteria species Escherichia coli and Pseudomonas aeruginosa. Fraction 3 caused inhibitory activity only for C. albicans and C. tropicalis. This fraction was composed of two peptides of ∼7 and 10 kDa, and the main protein band correspondent to the 7 kDa peptide, also showed similarity to thionins. This plasma membrane permeabilization assay demonstrates that the peptides present in the fractions 1 and 3 induced changes in the membranes of all yeast strains, leading to their permeabilization. Fraction 1 was capable of inhibiting acidification of the medium of glucose-induced S. cerevisiae cells 78% after an incubation time of 30 min, and opposite result was obtained for C. albicans. Experiments demonstrate that the fraction 1 and 3 were toxic and induced changes in the membranes of all yeast strains, leading to their permeabilization. Copyright © 2013 Wiley Periodicals, Inc.

Bioaccessible peptides released by in vitro gastrointestinal digestion of fermented goat milks.

PubMed

Moreno-Montoro, Miriam; Jauregi, Paula; Navarro-Alarcón, Miguel; Olalla-Herrera, Manuel; Giménez-Martínez, Rafael; Amigo, Lourdes; Miralles, Beatriz

2018-06-01

In this study, ultrafiltered goat milks fermented with the classical starter bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarus subsp. thermophilus or with the classical starter plus the Lactobacillus plantarum C4 probiotic strain were analyzed using ultra-high performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) and/or high performance liquid chromatography-ion trap (HPLC-IT-MS/MS). Partial overlapping of the identified sequences with regard to fermentation culture was observed. Evaluation of the cleavage specificity suggested a lower proteolytic activity of the probiotic strain. Some of the potentially identified peptides had been previously reported as angiotensin-converting enzyme (ACE) inhibitory, antioxidant, and antibacterial and might account for the in vitro activity previously reported for these fermented milks. Simulated digestion of the products was conducted in the presence of a dialysis membrane to retrieve the bioaccessible peptide fraction. Some sequences with reported physiological activity resisted digestion but were found in the non-dialyzable fraction. However, new forms released by digestion, such as the antioxidant α s1 -casein 144 YFYPQL 149 , the antihypertensive α s2 -casein 90 YQKFPQY 96 , and the antibacterial α s2 -casein 165 LKKISQ 170 , were found in the dialyzable fraction of both fermented milks. Moreover, in the fermented milk including the probiotic strain, the k-casein dipeptidyl peptidase IV inhibitor (DPP-IV) 51 INNQFLPYPY 60 as well as additional ACE inhibitory or antioxidant sequences could be identified. With the aim of anticipating further biological outcomes, quantitative structure activity relationship (QSAR) analysis was applied to the bioaccessible fragments and led to potential ACE inhibitory sequences being proposed. Graphical abstract Ultrafiltered goat milks were fermented with the classical starter bacteria (St) and with St plus the L. plantarum C4 probiotic strain. Samples were analyzed using HPLC-IT-MS/MS and UPLC-Q-TOF-MS/MS. After simulated digestion and dialysis, some of the active sequences remained and new peptides with reported beneficial activities were released.

Preclinical advantages of intramuscularly administered peptide A3-APO over existing therapies in Acinetobacter baumannii wound infections.

PubMed

Ostorhazi, Eszter; Rozgonyi, Ferenc; Sztodola, Andras; Harmos, Ferenc; Kovalszky, Ilona; Szabo, Dora; Knappe, Daniel; Hoffmann, Ralf; Cassone, Marco; Wade, John D; Bonomo, Robert A; Otvos, Laszlo

2010-11-01

The designer antibacterial peptide A3-APO is efficacious in mouse models of Escherichia coli and Acinetobacter baumannii systemic infections. Here we compare the efficacy of the peptide with that of imipenem and colistin in A. baumannii wound infections after burn injury. CD-1 mice were inflicted with burn wounds and different inocula of A. baumannii, isolated from an injured soldier, were placed into the wound sites. The antibiotics were given intramuscularly (im) one to five times. Available free peptide in the blood and the systemic toxicity of colistin and A3-APO were studied in healthy mice. While toxicity of colistin was observed at 25 mg/kg bolus drug administration, the lowest toxic dose of A3-APO was 75 mg/kg. In the A. baumannii blast injury models, 5 mg/kg A3-APO improved survival and reduced bacterial counts in the blood as well as in the wounds and improved wound appearance significantly better than any other antibiotic treatment. The free peptide concentration in the blood did not reach 1 µg/mL. Peptide A3-APO, with an intramuscular therapeutic index of 15, is more efficacious and less toxic than any existing burn injury infection therapy modality against multidrug-resistant Gram-negative pathogens. A3-APO administered by the im route probably binds to a biopolymer that promotes the peptide's biodistribution.

Bacillus spp. produce antibacterial activities against lactic acid bacteria that contaminate fuel ethanol plants

USDA-ARS?s Scientific Manuscript database

Lactic acid bacteria (LAB) frequently contaminate commercial fuel ethanol fermentations, reducing yields and decreasing profitability of biofuel production. Microorganisms from environmental sources in different geographic regions of Thailand were tested for antibacterial activity against LAB. Fou...

Antibacterial effects of the artificial surface of nanoimprinted moth-eye film

PubMed Central

Kaneko, Toshihiro; Nishiyama, Kyoko; Ozminskyj, Mari; Koshizuka, Tetsuo; Wada, Ikuo; Suzutani, Tatsuo

2017-01-01

The antibacterial effect of a nanostructured film, known as “moth-eye film,” was investigated. The moth-eye film has artificially formed nano-pillars, consisting of hydrophilic resin with urethane acrylate and polyethylene glycol (PEG) derivatives, all over its surface that replicates a moth’s eye. Experiments were performed to compare the moth-eye film with a flat-surfaced film produced from the same materials. The JIS Z2801 film-covering method revealed that the two films produced a decrease in Staphylococcus aureus and Esherichia coli titers of over 5 and 3 logs, respectively. There was no marked difference in the antibacterial effects of the two surfaces. However, the antibacterial effects were reduced by immersion of the films in water. These results indicated that a soluble component(s) of the resin possessed the antibacterial activity, and this component was identified as PEG derivatives by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and Fourier transform infrared spectroscopy (FT-IR). When a small volume of bacterial suspension was dropped on the films as an airborne droplet model, both films showed antibacterial effects, but that of the moth-eye film was more potent. It was considered that the moth-eye structure allowed the bacteria-loaded droplet to spread and allow greater contact between the bacteria and the film surface, resulting in strong adherence of the bacteria to the film and synergistically enhanced bactericidal activity with chemical components. The antibacterial effect of the moth-eye film has been thus confirmed under a bacterial droplet model, and it appears attractive due to its antibacterial ability, which is considered to result not only from its chemical make-up but also from physical adherence. PMID:28934372

Antibacterial effects of the artificial surface of nanoimprinted moth-eye film.

PubMed

Minoura, Kiyoshi; Yamada, Miho; Mizoguchi, Takashi; Kaneko, Toshihiro; Nishiyama, Kyoko; Ozminskyj, Mari; Koshizuka, Tetsuo; Wada, Ikuo; Suzutani, Tatsuo

2017-01-01

The antibacterial effect of a nanostructured film, known as "moth-eye film," was investigated. The moth-eye film has artificially formed nano-pillars, consisting of hydrophilic resin with urethane acrylate and polyethylene glycol (PEG) derivatives, all over its surface that replicates a moth's eye. Experiments were performed to compare the moth-eye film with a flat-surfaced film produced from the same materials. The JIS Z2801 film-covering method revealed that the two films produced a decrease in Staphylococcus aureus and Esherichia coli titers of over 5 and 3 logs, respectively. There was no marked difference in the antibacterial effects of the two surfaces. However, the antibacterial effects were reduced by immersion of the films in water. These results indicated that a soluble component(s) of the resin possessed the antibacterial activity, and this component was identified as PEG derivatives by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and Fourier transform infrared spectroscopy (FT-IR). When a small volume of bacterial suspension was dropped on the films as an airborne droplet model, both films showed antibacterial effects, but that of the moth-eye film was more potent. It was considered that the moth-eye structure allowed the bacteria-loaded droplet to spread and allow greater contact between the bacteria and the film surface, resulting in strong adherence of the bacteria to the film and synergistically enhanced bactericidal activity with chemical components. The antibacterial effect of the moth-eye film has been thus confirmed under a bacterial droplet model, and it appears attractive due to its antibacterial ability, which is considered to result not only from its chemical make-up but also from physical adherence.

Halophilic and halotolerant actinomycetes from a marine saltern of Goa, India producing anti-bacterial metabolites.

PubMed

Ballav, Shuvankar; Kerkar, Savita; Thomas, Sabu; Augustine, Nimmy

2015-03-01

Marine salterns are estuarine ecosystems in Goa, receiving inputs from riverine and marine waters. The Salinity fluctuates between 0 and 300 psu which makes it a conducive niche for salt tolerant and salt loving Actinomycetales. Halotolerant and halophilic Actinomycetales producing anti-bacterial metabolites were studied from crystallizer pond sediments of Ribandar saltern, Goa. Three media viz. Starch casein, R2A and Inorganic salt starch agar at four different salinities (35, 50, 75 and 100 psu) were used for isolation. R2A agar at 35 psu was the most preferred by hypersaline actinomycetes. The dominant group was halotolerant Streptomyces spp. others being rare actinomycetes viz. Nocardiopsis, Micromonospora and Kocuria spp. More than 50% of the isolates showed anti-bacterial activity against one or more of the fifteen human pathogens tested. Eight strains from 4 genera showed consistent anti-bacterial activity and studied in detail. Most halotolerant isolates grew from 0 to 75 psu, with optimum antibiotic production at 35 psu whereas halophiles grew at 20 to 100 psu with optimum antibiotic production at 35 psu. Four Streptomyces strains showed multiple inhibition against test organisms while four rare actinomycetes were specific in their inhibitory activity. This is the first report of a halophilic Kocuria sp., Nocardiopsis sp., and halotolerant Micromonospora sp. producing anti-bacterial compound(s) against Staphylococcus aureus, Staphylococcus citreus, and Vibrio cholerae, respectively. Sequential extraction with varying polarity of organic solvents showed that the extracts inhibited different test pathogens. These results suggest that halophilic and halotolerant actinomycetes from marine salterns are a potential source of anti-bacterial compounds. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Characterization of the Biosynthetic Operon for the Antibacterial Peptide Herbicolin in Pantoea vagans Biocontrol Strain C9-1 and Incidence in Pantoea Species

PubMed Central

Kamber, Tim; Lansdell, Theresa A.; Stockwell, Virginia O.; Ishimaru, Carol A.; Smits, Theo H. M.

2012-01-01

Pantoea vagans C9-1 is a biocontrol strain that produces at least two antibiotics inhibiting the growth of Erwinia amylovora, the causal agent of fire blight disease of pear and apple. One antibiotic, herbicolin I, was purified from culture filtrates of P. vagans C9-1 and determined to be 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine, also known as Nß-epoxysuccinamoyl-DAP-valine. A plasposon library was screened for mutants that had lost the ability to produce herbicolin I. It was shown that mutants had reduced biocontrol efficacy in immature pear assays. The biosynthetic gene cluster in P. vagans C9-1 was identified by sequencing the flanking regions of the plasposon insertion sites. The herbicolin I biosynthetic gene cluster consists of 10 coding sequences (CDS) and is located on the 166-kb plasmid pPag2. Sequence comparisons identified orthologous gene clusters in Pantoea agglomerans CU0119 and Serratia proteamaculans 568. A low incidence of detection of the biosynthetic cluster in a collection of 45 Pantoea spp. from biocontrol, environmental, and clinical origins showed that this is a rare trait among the tested strains. PMID:22504810

Comparative study of microbiological, chemical and sensory properties of kefirs produced in Estonia, Latvia and Lithuania.

PubMed

Anton, Dea; Raudsepp, Piret; Roasto, Mati; Meremäe, Kadrin; Kuusik, Sirje; Toomik, Peeter; Elias, Priit; Laikoja, Katrin; Kaart, Tanel; Lepiku, Martin; Püssa, Tõnu

2016-02-01

In the current study the microbiological, sensory and chemical properties of 24 kefirs (12 producers) from Estonian, Latvian and Lithuanian retail market were determined using gas chromatography (GC), high performance liquid chromatography (HPLC-MS/MS-Q-TOF and LC-ion trap MS/MS), spectrophotometry and other methods. Antihypertensive, angiotensin-converting enzyme (ACE) inhibiting, antioxidant and antibacterial peptides were found in the kefir samples. According to the results of principal component analysis of 200 most abundant compounds obtained with HPLC-MS/MS-Q-TOF analysis, Estonian kefirs differed from the rest. Kefirs of Latvian and Lithuanian origin showed similarities in several characteristics, probably related to the starter cultures and technological processes. The fatty acids composition of all Baltic kefirs was uniform. The antioxidant capacity of the kefirs varied slightly, whereas intermediate positive correlation (r = 0.32, P < 0.05) was found between antioxidativity and total bacterial count. The lipid oxidation level, estimated as the content of linoleic and oleic acid primary oxidation products, oxylipins, was very low in all studied kefirs. Only one third of analysed kefirs met the requirements of the minimum sum of viable microorganisms, indicated in the Codex Standard for Fermented Milks.

In situ plasma fabrication of ceramic-like structure on polymeric implant with enhanced surface hardness, cytocompatibility and antibacterial capability.

PubMed

Liu, Jun; Zhang, Wei; Shi, Haigang; Yang, Kun; Wang, Gexia; Wang, Pingli; Ji, Junhui; Chu, Paul K

2016-05-01

Polymeric materials are commonly found in orthopedic implants due to their unique mechanical properties and biocompatibility but the poor surface hardness and bacterial infection hamper many biomedical applications. In this study, a ceramic-like surface structure doped with silver is produced by successive plasma implantation of silicon (Si) and silver (Ag) into the polyamine 66 (PA66) substrate. Not only the surface hardness and elastic modulus are greatly enhanced due to the partial surface carbonization and the ceramic-like structure produced by the reaction between energetic Si and the carbon chain of PA66, but also the antibacterial activity is improved because of the combined effects rendered by Ag and SiC structure. Furthermore, the modified materials which exhibit good cytocompatibility upregulate bone-related genes and proteins expressions of the contacted bone mesenchymal stem cells (BMSCs). For the first time, it explores out that BMSCs osteogenesis on the antibacterial ceramic-like structure is mediated via the iNOS and nNOS signal pathways. The results reveal that in situ plasma fabrication of an antibacterial ceramic-like structure can endow PA66 with excellent surface hardness, cytocompatibility, as well as antibacterial capability. © 2016 Wiley Periodicals, Inc.

Characterization of defensin gene from abalone Haliotis discus hannai and its deduced protein

NASA Astrophysics Data System (ADS)

Hong, Xuguang; Sun, Xiuqin; Zheng, Minggang; Qu, Lingyun; Zan, Jindong; Zhang, Jinxing

2008-11-01

Defensin is one of preserved ancient host defensive materials formed in biological evolution. As a regulator and effector molecule, it is very important in animals’ acquired immune system. This paper reports the defensin gene from the mixed liver and kidney cDNA library of abalone Haliotis discus hannai Ino. Sequence analysis shows that the gene sequence of full-length cDNA encodes 42 mature peptides (including six Cys), molecular weight of 4 323 Da, and pI of 8.02. Amino acid sequence homology analysis shows that the peptides are highly similar (70% in common) to other insects defensin. Because of a typical insect-defensin structural character of mature peptide in the secondary structure, the polypeptide named Haliotis discus defensin (hd-def), a novel of antimicrobial peptides, belongs to insects defensin subfamily. The RT-PCR result of Haliotis discus defensin shows that the gene can be expressed only in the hepatopancreas by Gram-negative and positive bacteria stimulation, which is ascribed to inducible expression. Therefore, it is revealed that the Haliotis discus defensin gene expression was related to the antibacterial infection of Haliotis discus hannai Ino.

Antimicrobial Effects of Helix D-derived Peptides of Human Antithrombin III*

PubMed Central

Papareddy, Praveen; Kalle, Martina; Bhongir, Ravi K. V.; Mörgelin, Matthias; Malmsten, Martin; Schmidtchen, Artur

2014-01-01

Antithrombin III (ATIII) is a key antiproteinase involved in blood coagulation. Previous investigations have shown that ATIII is degraded by Staphylococcus aureus V8 protease, leading to release of heparin binding fragments derived from its D helix. As heparin binding and antimicrobial activity of peptides frequently overlap, we here set out to explore possible antibacterial effects of intact and degraded ATIII. In contrast to intact ATIII, the results showed that extensive degradation of the molecule yielded fragments with antimicrobial activity. Correspondingly, the heparin-binding, helix d-derived, peptide FFFAKLNCRLYRKANKSSKLV (FFF21) of human ATIII, was found to be antimicrobial against particularly the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Fluorescence microscopy and electron microscopy studies demonstrated that FFF21 binds to and permeabilizes bacterial membranes. Analogously, FFF21 was found to induce membrane leakage of model anionic liposomes. In vivo, FFF21 significantly reduced P. aeruginosa infection in mice. Additionally, FFF21 displayed anti-endotoxic effects in vitro. Taken together, our results suggest novel roles for ATIII-derived peptide fragments in host defense. PMID:25202017

Antimicrobial effects of helix D-derived peptides of human antithrombin III.

PubMed

Papareddy, Praveen; Kalle, Martina; Bhongir, Ravi K V; Mörgelin, Matthias; Malmsten, Martin; Schmidtchen, Artur

2014-10-24

Antithrombin III (ATIII) is a key antiproteinase involved in blood coagulation. Previous investigations have shown that ATIII is degraded by Staphylococcus aureus V8 protease, leading to release of heparin binding fragments derived from its D helix. As heparin binding and antimicrobial activity of peptides frequently overlap, we here set out to explore possible antibacterial effects of intact and degraded ATIII. In contrast to intact ATIII, the results showed that extensive degradation of the molecule yielded fragments with antimicrobial activity. Correspondingly, the heparin-binding, helix D-derived, peptide FFFAKLNCRLYRKANKSSKLV (FFF21) of human ATIII, was found to be antimicrobial against particularly the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Fluorescence microscopy and electron microscopy studies demonstrated that FFF21 binds to and permeabilizes bacterial membranes. Analogously, FFF21 was found to induce membrane leakage of model anionic liposomes. In vivo, FFF21 significantly reduced P. aeruginosa infection in mice. Additionally, FFF21 displayed anti-endotoxic effects in vitro. Taken together, our results suggest novel roles for ATIII-derived peptide fragments in host defense. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Development of electrospun nanofibers containing chitosan/PEO blend and phenolic compounds with antibacterial activity.

PubMed

Kuntzler, Suelen Goettems; Costa, Jorge Alberto Vieira; Morais, Michele Greque de

2018-05-31

Electrospun nanofibers can be formed with chitosan as the polymers found in biological sources have antibacterial ability. The objective of this work was to evaluate whether chitosan/polyethylene oxide (PEO) blend nanofibers containing microalgal phenolic compounds exhibit antibacterial activity. Nanofibers produced with a 3% chitosan/2% PEO blend containing 1% phenolic compounds had an average diameter of 214 ± 37 nm, which resulted in a high temperature of maximum degradation, an important parameter for food packaging. The potential antibacterial activity of this nanofibers was confirmed by their inhibition of Staphylococcus aureus ATCC 25923 (6.4 ± 1.1 mm) and Escherichia coli ATCC 25972 (5.5 ± 0.4 mm). The polymeric nanofibers produced from chitosan and containing phenolic compounds have properties that therefore allow their application as active packaging. In addition, chitosan is an excellent polymer for packaging as it presents biodegradability, biocompatibility and, non-toxicity. Copyright © 2018. Published by Elsevier B.V.

LL-37-Derived Peptides Eradicate Multidrug-Resistant Staphylococcus aureus from Thermally Wounded Human Skin Equivalents

PubMed Central

de Breij, Anna; Chan, Heelam; van Dissel, Jaap T.; Drijfhout, Jan W.; Hiemstra, Pieter S.; El Ghalbzouri, Abdoelwaheb; Nibbering, Peter H.

2014-01-01

Burn wound infections are often difficult to treat due to the presence of multidrug-resistant bacterial strains and biofilms. Currently, mupirocin is used to eradicate methicillin-resistant Staphylococcus aureus (MRSA) from colonized persons; however, mupirocin resistance is also emerging. Since we consider antimicrobial peptides to be promising candidates for the development of novel anti-infective agents, we studied the antibacterial activities of a set of synthetic peptides against different strains of S. aureus, including mupirocin-resistant MRSA strains. The peptides were derived from P60.4Ac, a peptide based on the human cathelicidin LL-37. The results showed that peptide 10 (P10) was the only peptide more efficient than P60.4Ac, which is better than LL-37, in killing MRSA strain LUH14616. All three peptides displayed good antibiofilm activities. However, both P10 and P60.4Ac were more efficient than LL-37 in eliminating biofilm-associated bacteria. No toxic effects of these three peptides on human epidermal models were detected, as observed morphologically and by staining for mitochondrial activity. In addition, P60.4Ac and P10, but not LL-37, eradicated MRSA LUH14616 and the mupirocin-resistant MRSA strain LUH15051 from thermally wounded human skin equivalents (HSE). Interestingly, P60.4Ac and P10, but not mupirocin, eradicated LUH15051 from the HSEs. None of the peptides affected the excretion of interleukin 8 (IL-8) by thermally wounded HSEs upon MRSA exposure. In conclusion, the synthetic peptides P60.4Ac and P10 appear to be attractive candidates for the development of novel local therapies to treat patients with burn wounds infected with multidrug-resistant bacteria. PMID:24841266

Database-Guided Discovery of Potent Peptides to Combat HIV-1 or Superbugs

PubMed Central

Wang, Guangshun

2013-01-01

Antimicrobial peptides (AMPs), small host defense proteins, are indispensable for the protection of multicellular organisms such as plants and animals from infection. The number of AMPs discovered per year increased steadily since the 1980s. Over 2,000 natural AMPs from bacteria, protozoa, fungi, plants, and animals have been registered into the antimicrobial peptide database (APD). The majority of these AMPs (>86%) possess 11–50 amino acids with a net charge from 0 to +7 and hydrophobic percentages between 31–70%. This article summarizes peptide discovery on the basis of the APD. The major methods are the linguistic model, database screening, de novo design, and template-based design. Using these methods, we identified various potent peptides against human immunodeficiency virus type 1 (HIV-1) or methicillin-resistant Staphylococcus aureus (MRSA). While the stepwise designed anti-HIV peptide is disulfide-linked and rich in arginines, the ab initio designed anti-MRSA peptide is linear and rich in leucines. Thus, there are different requirements for antiviral and antibacterial peptides, which could kill pathogens via different molecular targets. The biased amino acid composition in the database-designed peptides, or natural peptides such as θ-defensins, requires the use of the improved two-dimensional NMR method for structural determination to avoid the publication of misleading structure and dynamics. In the case of human cathelicidin LL-37, structural determination requires 3D NMR techniques. The high-quality structure of LL-37 provides a solid basis for understanding its interactions with membranes of bacteria and other pathogens. In conclusion, the APD database is a comprehensive platform for storing, classifying, searching, predicting, and designing potent peptides against pathogenic bacteria, viruses, fungi, parasites, and cancer cells. PMID:24276259

Odilorhabdins, Antibacterial Agents that Cause Miscoding by Binding at a New Ribosomal Site.

PubMed

Pantel, Lucile; Florin, Tanja; Dobosz-Bartoszek, Malgorzata; Racine, Emilie; Sarciaux, Matthieu; Serri, Marine; Houard, Jessica; Campagne, Jean-Marc; de Figueiredo, Renata Marcia; Midrier, Camille; Gaudriault, Sophie; Givaudan, Alain; Lanois, Anne; Forst, Steve; Aumelas, André; Cotteaux-Lautard, Christelle; Bolla, Jean-Michel; Vingsbo Lundberg, Carina; Huseby, Douglas L; Hughes, Diarmaid; Villain-Guillot, Philippe; Mankin, Alexander S; Polikanov, Yury S; Gualtieri, Maxime

2018-04-05

Growing resistance of pathogenic bacteria and shortage of antibiotic discovery platforms challenge the use of antibiotics in the clinic. This threat calls for exploration of unconventional sources of antibiotics and identification of inhibitors able to eradicate resistant bacteria. Here we describe a different class of antibiotics, odilorhabdins (ODLs), produced by the enzymes of the non-ribosomal peptide synthetase gene cluster of the nematode-symbiotic bacterium Xenorhabdus nematophila. ODLs show activity against Gram-positive and Gram-negative pathogens, including carbapenem-resistant Enterobacteriaceae, and can eradicate infections in animal models. We demonstrate that the bactericidal ODLs interfere with protein synthesis. Genetic and structural analyses reveal that ODLs bind to the small ribosomal subunit at a site not exploited by current antibiotics. ODLs induce miscoding and promote hungry codon readthrough, amino acid misincorporation, and premature stop codon bypass. We propose that ODLs' miscoding activity reflects their ability to increase the affinity of non-cognate aminoacyl-tRNAs to the ribosome. Copyright © 2018 Elsevier Inc. All rights reserved.

Structural Diversity, Biological Properties and Applications of Natural Products from Cyanobacteria. A Review †

PubMed Central

Shah, Sayed Asmat Ali; Akhter, Najeeb; Auckloo, Bibi Nazia; Khan, Ishrat; Lu, Yanbin; Wang, Kuiwu; Wu, Bin

2017-01-01

Nowadays, various drugs on the market are becoming more and more resistant to numerous diseases, thus declining their efficacy for treatment purposes in human beings. Antibiotic resistance is one among the top listed threat around the world which eventually urged the discovery of new potent drugs followed by an increase in the number of deaths caused by cancer due to chemotherapy resistance as well. Accordingly, marine cyanobacteria, being the oldest prokaryotic microorganisms belonging to a monophyletic group, have proven themselves as being able to generate pharmaceutically important natural products. They have long been known to produce distinct and structurally complex secondary metabolites including peptides, polyketides, alkaloids, lipids, and terpenes with potent biological properties and applications. As such, this review will focus on recently published novel compounds isolated from marine cyanobacteria along with their potential bioactivities such as antibacterial, antifungal, anticancer, anti-tuberculosis, immunosuppressive and anti-inflammatory capacities. Moreover, various structural classes, as well as their technological uses will also be discussed. PMID:29125580

Anti-bacterial Treatments Using Peptide-Based Inhibitors of the STAT3-IL10 Pathway | NCI Technology Transfer Center | TTC

Cancer.gov

Tuberculosis (TB) is an infectious disease that typically affects the lungs. Current therapies include a panel of antibiotics given over a range of 6-9 months. As a result of the expense of treatment, the extended timeframe needed for effective treatment, and the scarcity of medicines in some developing countries, patient compliance with TB treatment is very low and results in multi-drug resistant TB (MDR-TB). There remains a need for a faster, more effective treatment for TB. NCI researchers seek licensing and/or co-development of peptide inhibitors of STAT3 and IL-10 developed to treat bacterial infections such as tuberculosis. See aslo: NIH inventions E-164-2007 and E-167-2010

Hit 'em where it hurts: The growing and structurally diverse family of peptides that target lipid-II.

PubMed

Oppedijk, Sabine F; Martin, Nathaniel I; Breukink, Eefjan

2016-05-01

Understanding the mode of action of antibiotics is becoming more and more important in the time that microorganisms start to develop resistance. One very well validated target of several classes of antibiotics is the peptidoglycan precursor lipid II. In this review different classes of lipid II targeting antibiotics will be discussed in detail, including the lantibiotics, human invertebrate defensins and the recently discovered teixobactin. By hitting bacteria where it hurts, at the level of lipid II, we expect to be able to develop efficient antibacterial agents in the future. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert. Copyright © 2015 Elsevier B.V. All rights reserved.

An immunological method for quantifying antibacterial activity in Salmo salar (Linnaeus, 1758) skin mucus.

PubMed

Narvaez, Edgar; Berendsen, Jorge; Guzmán, Fanny; Gallardo, José A; Mercado, Luis

2010-01-01

Antimicrobial peptides (AMPs) are a pivotal component of innate immunity in lower vertebrates. The aim of this study was to develop an immunological method for quantifying AMPs in Salmo salar skin mucus. A known antimicrobial peptide derived from histone H1 previously purified and described from S. salar skin mucus (SAMP H1) was chemically synthesized and used to obtain antibodies for the quantification of the molecule via ELISA. Using skin mucus samples, a correlation of bacterial growth inhibition versus SAMP H1 concentration (ELISA) was established. The results provide the first evidence for quantifying the presence of active AMPs in the skin mucus of S. salar through the use of an immunological method. Copyright 2009 Elsevier Ltd. All rights reserved.

Consumption of antibacterial molecules in broiler production in Morocco.

PubMed

Rahmatallah, Naoufal; El Rhaffouli, Hicham; Lahlou Amine, Idriss; Sekhsokh, Yassine; Fassi Fihri, Ouafaa; El Houadfi, Mohammed

2018-05-01

Monitoring the use of antibacterial agents in food-producing animals is crucial in order to reduce antimicrobial resistance, selection and dissemination of resistant bacterial strains, and drug residues in the animal food products. The broiler production sector is considered a great consumer of antibacterials and incriminated in the rise of antimicrobial resistance level in zoonotic bacterial pathogens such as Escherichia coli, Salmonella and Campylobacter. Following recommendations from the OIE and WHO, a survey was conducted about the use and consumption of several antibacterial agents in Moroccan broiler flocks. More than 5 million broilers were randomly surveyed at the prescriber level, that is, via the veterinary clinics involved in their health management. The results showed that 93% of the flocks received at least one antibacterial treatment of minimum 3 days duration. Enrofloxacin, colistin and trimethoprim/sulphonamides were the most used antibacterials followed by oxytetracycline, florfenicol and amoxicillin. Oxytetracycline, enrofloxacin and colistin were overdosed in most of the administration, while amoxicillin and the combination of trimethoprim/sulphonamides were under-dosed. The total amount of antibacterial consumed in the survey was 63.48 mg/kg and the Animal Level of Exposure to Antimicrobials (ALEA) was 94.45%. The reasons for this frequent use were related mainly to the poor quality of broiler production management. Chicks and animal feed provided to producers were of variable quality. Management of rearing stock density was often poor and biosecurity inadequate, and broilers were challenged by a high prevalence of infectious diseases. © 2018 The Authors. Veterinary Medicine and Science Published by John Wiley & Sons Ltd.

Vibrio sp. DSM 14379 pigment production--a competitive advantage in the environment?

PubMed

Starič, Nejc; Danevčič, Tjaša; Stopar, David

2010-10-01

The ability to produce several antibacterial agents greatly increases the chance of producer's survival. In this study, red-pigmented Vibrio sp. DSM 14379 and Bacillus sp., both isolated from the same sampling volume from estuarine waters of the Northern Adriatic Sea, were grown in a co-culture. The antibacterial activity of the red pigment extract was tested on Bacillus sp. in microtiter plates. The MIC(50) for Bacillus sp. was estimated to be around 10⁻⁵ mg/L. The extract prepared form the nonpigmented mutant of Vibrio sp. had no antibacterial effect. The pigment production of Vibrio sp. was studied under different physicochemical conditions. There was no pigment production at high or low temperatures, high or low salt concentrations in peptone yeast extract (PYE) medium, low glucose concentration in mineral growth medium or high glucose concentration in PYE medium. This indicates that the red pigment production is a luxurious good that Vibrio sp. makes only under favorable conditions. The Malthusian fitness of Bacillus sp. in a co-culture with Vibrio sp. under optimal environmental conditions dropped from 4.0 to -7.6, which corresponds to three orders of magnitude decrease in the number of CFU relative to the monoculture. The nonpigmented mutant of Vibrio sp. in a co-culture with Bacillus sp. had a significant antibacterial activity. This result shows that studying antibacterial properties in isolation (i.e. pigment extract only) may not reveal full antibacterial potential of the bacterial strain. The red pigment is a redundant antibacterial agent of Vibrio sp.

High-level SUMO-mediated fusion expression of ABP-dHC-cecropin A from multiple joined genes in Escherichia coli.

PubMed

Zhang, Jiaxin; Movahedi, Ali; Wei, Zhiheng; Sang, Ming; Wu, Xiaolong; Wang, Mengyang; Wei, Hui; Pan, Huixin; Yin, Tongming; Zhuge, Qiang

2016-09-15

The antimicrobial peptide ABP-dHC-cecropin A is a small cationic peptide with potent activity against a wide range of bacterial species. Evidence of antifungal activity has also been suggested; however, evaluation of this peptide has been limited due to the low expression of cecropin proteins in Escherichia coli. To improve the expression level of ABP-dHC-cecropin A in E. coli, tandem repeats of the ABP-dHC-cecropin A gene were constructed and expressed as fusion proteins (SUMO-nABP-dHC-cecropin, n = 1, 2, 3, 4) via pSUMO-nABP-dHC-cecropin A vectors (n = 1, 2, 3, 4). Comparison of the expression levels of soluble SUMO-nABP-dHC-cecropin A fusion proteins (n = 1, 2, 3, 4) suggested that BL21 (DE3)/pSUMO-3ABP-dHC-cecropin A is an ideal recombinant strain for ABP-dHC-cecropin A production. Under the selected conditions of cultivation and isopropylthiogalactoside (IPTG) induction, the expression level of ABP-dHC-cecropin A was as high as 65 mg/L, with ∼21.3% of the fusion protein in soluble form. By large-scale fermentation, protein production reached nearly 300 mg/L, which is the highest yield of ABP-dHC-cecropin A reported to date. In antibacterial experiments, the efficacy was approximately the same as that of synthetic ABP-dHC-cecropin A. This method provides a novel and effective means of producing large amounts of ABP-dHC-cecropin A. Copyright © 2016 Elsevier Inc. All rights reserved.

Antimicrobial peptides secreted by equine mesenchymal stromal cells inhibit the growth of bacteria commonly found in skin wounds.

PubMed

Harman, Rebecca M; Yang, Steven; He, Megan K; Van de Walle, Gerlinde R

2017-07-04

The prevalence of chronic skin wounds in humans is high, and treatment is often complicated by the presence of pathogenic bacteria. Therefore, safe and innovative treatments to reduce the bacterial load in cutaneous wounds are needed. Mesenchymal stromal cells (MSC) are known to provide paracrine signals that act on resident skin cells to promote wound healing, but their potential antibacterial activities are not well described. The present study was designed to examine the antibacterial properties of MSC from horses, as this animal model offers a readily translatable model for MSC therapies in humans. Specifically, we aimed to (i) evaluate the in vitro effects of equine MSC on the growth of representative gram-negative and gram-positive bacterial species commonly found in skin wounds and (ii) define the mechanisms by which MSC inhibit bacterial growth. MSC were isolated from the peripheral blood of healthy horses. Gram-negative E. coli and gram-positive S. aureus were cultured in the presence of MSC and MSC conditioned medium (CM), containing all factors secreted by MSC. Bacterial growth was measured by plating bacteria and counting viable colonies or by reading the absorbance of bacterial cultures. Bacterial membrane damage was detected by incorporation of N-phenyl-1-naphthylamine (NPN). Antimicrobial peptide (AMP) gene and protein expression by equine MSC were determined by RT-PCR and Western blot analysis, respectively. Blocking of AMP activity of MSC CM was achieved using AMP-specific antibodies. We found that equine MSC and MSC CM inhibit the growth of E. coli and S. aureus, and that MSC CM depolarizes the cell membranes of these bacteria. In addition, we found that equine MSC CM contains AMPs, and blocking these AMPs with antibodies reduces the effects of MSC CM on bacteria. Our results demonstrate that equine MSC inhibit bacterial growth and secrete factors that compromise the membrane integrity of bacteria commonly found in skin wounds. We also identified four specific AMPs produced by equine MSC. The secretion of AMPs may contribute to the value of MSC as a therapy for cutaneous wounds in both horses and humans.

Antimicrobial Synthetic Polymers: An Update on Structure-Activity Relationships.

PubMed

Ergene, Cansu; Palermo, Edmund F

2018-01-01

The rising incidence of antibiotic-resistant infections, combined with a declining number of new antibiotic drug approvals, has generated an alarming therapeutic gap that critically undermines public health. Host Defense Peptides (HDPs), sometimes referred to as "Nature's Antibiotics", are short chain, amphiphilic and cationic peptide sequences found in all multicellular organisms as part of their innate immunity. While there is a vast diversity in terms of HDP sequence and secondary structure, they all seem to share physiochemical characteristics that can be appropriated for macromolecular design by the synthetic polymer chemist. Over the past decade, remarkable progress has been made in the design and synthesis of polymer-based materials that effectively mimic HDP action - broad-spectrum antibacterial potency, rapid bactericidal kinetics, and minimal toxicity to human cells - while offering the additional benefits of low cost, high scalability, and lower propensity to induce resistance, relative to their peptide-based counterparts. A broad range of different macromolecular structures and architectures have been explored in this design space, including polynorbornenes, poly(meth)acrylates, poly(meth)acrylamides, nylon-2 polymers, and polycarbonates, to name a just few. Across all of these diverse chemical categories, the key determinants of antibacterial and hemolytic activity are the same as in HDPs: net cationic charge at neutral pH, well-balanced facial amphiphilicity, and the molecular weight of the compounds. In this review, we focus in particular on recent progress in the polymethacrylate category first pioneered by Kuroda and DeGrado and later modified, expanded upon and rigorously optimized by Kuroda's and many other groups. Key findings and future challenges will be highlighted. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Antimicrobial lipids: novel innate defense molecules are elevated in sinus secretions of patients with chronic rhinosinusitis.

PubMed

Lee, Jivianne T; Jansen, Mike; Yilma, Abebayehu N; Nguyen, Angels; Desharnais, Robert; Porter, Edith

2010-01-01

Airway secretions possess intrinsic antimicrobial properties that contribute to the innate host defense of the respiratory tract. These microbicidal capabilities have largely been attributed to the presence of antibacterial polypeptides. However, recent investigation has indicated that host-derived lipids including cholesteryl esters also exhibit antimicrobial properties. The purpose of this study was to determine whether sinus secretions contain such antimicrobial lipids and to compare the lipid composition in patients with and without chronic rhinosinusitis (CRS). Maxillary sinus fluid was obtained via antral lavage from subjects with (seven patients) and without (nine patients) a history of CRS. After specimen collection, total lipid was extracted according to Bligh and Dyer (Bligh EG and Dyer WJ, A rapid method of total lipid extraction and purification, Can J Biochem Physiol 37:911-918, 1959) and lipid profiles were obtained by reverse phase high-performance liquid chromatography on an amide-embedded C18 column. In addition, the neutrophil-specific antimicrobial peptides human neutrophil peptides 1-3 (HNP1-3) were quantified by Western immunoblotting. Lipids, including cholesteryl esters, were identified in the maxillary sinus secretions of patients with and without CRS. However, levels of lipid composition differed between the two groups with CRS patients exhibiting greater amounts of all classes of lipids, reaching over 10-fold higher concentration when compared with non-CRS patients. This increase was independent of HNP1-3 content. Sinus secretions of patients with CRS appear to show elevated levels of antimicrobial lipids compared with controls independent from neutrophil influx. This up-regulation suggests that host-derived lipids act as mediators of mucosal immunity in CRS. Further study is necessary to determine if such antimicrobial lipids function alone or synergistically with antibacterial peptides in conferring such inherent microbicidal properties.

A cationic amphiphilic peptide ABP-CM4 exhibits selective cytotoxicity against leukemia cells.

PubMed

Chen, Yu Qing; Min, Cui; Sang, Ming; Han, Yang Yang; Ma, Xiao; Xue, Xiao Qing; Zhang, Shuang Quan

2010-08-01

Some cationic antibacterial peptides exhibit a broad spectrum of cytotoxic activity against cancer cells, which could provide a new class of anticancer drugs. In the present study, the anticancer activity of ABP-CM4, an antibacterial peptide from Bombyx mori, against leukemic cell lines THP-1, K562 and U937 was evaluated, and the cytotoxicity compared with the effects on non-cancerous mammalian cells, including peripheral blood mononuclear cells (PBMCs), HEK-293 and erythrocytes. ABP-CM4 reduced the number of viable cells of the leukemic cell lines after exposure for 24h. The reduction was concentration dependent, and the IC50 values ranged from 14 to 18 microM. Conversely, ABP-CM4, even at 120 microM, exhibited no cytotoxicity toward HEK-293 or PBMCs, indicating that there was no significant effect on these two types of non-cancer cells. ABP-CM4 at a concentration of 200 microM had no hemolytic activity on mammalian erythrocytes. Together, these results suggested a selective cytotoxicity in leukemia cells. Flow cytometry demonstrated that the binding activity of ABP-CM4 to leukemia cells was much higher than that to HEK-293 or PBMCs, and there was almost no binding to erythrocytes. FITC-labeled ABP-CM4 molecules were examined under a confocal microscope and found to be concentrated at the surface of leukemia cells and changes of the cell membrane were determined by a cell permeability assay, which led us to the conclusion that ABP-CM4 could act at the cell membrane for its anticancer activity on leukemia cells. Collectively, our results indicated that ABP-CM4 has the potential for development as a novel antileukemic agent. Copyright 2010 Elsevier Inc. All rights reserved.

Bioautography-guided isolation of antibacterial compounds of essential oils from Thai spices against histamine-producing bacteria.

PubMed

Lomarat, Pattamapan; Phanthong, Phanida; Wongsariya, Karn; Chomnawang, Mullika Traidej; Bunyapraphatsara, Nuntavan

2013-05-01

The outbreak of histamine fish poisoning has been being an issue in food safety and international trade. The growth of contaminated bacterial species including Morganella morganii which produce histidine decarboxylase causes histamine formation in fish during storage. Histamine, the main toxin, causes mild to severe allergic reaction. At present, there is no well-established solution for histamine fish poisoning. This study was performed to determine the antibacterial activity of essential oils from Thai spices against histamine-producing bacteria. Among the essential oils tested, clove, lemongrass and sweet basil oils were found to possess the antibacterial activity. Clove oil showed the strongest inhibitory activity against Morganella morganii, followed by lemongrass and sweet basil oils. The results indicated that clove, lemongrass and sweet basil oils could be useful for the control of histamine-producing bacteria. The attempt to identify the active components using preparative TLC and GC/MS found eugenol, citral and methyl chavicol as the active components of clove, lemongrass and sweet basil oils, respectively. The information from this study would be useful in the research and development for the control of histamine-producing bacteria in fish or seafood products to reduce the incidence of histamine fish poisoning.

Antimicrobial activity of bovine NK-lysin-derived peptides on bovine respiratory pathogen Histophilus somni

PubMed Central

Falkenberg, Shollie M.; Briggs, Robert E.; Tatum, Fred M.; Sacco, Randy E.

2017-01-01

Bovine NK-lysins, which are functionally and structurally similar to human granulysin and porcine NK-lysin, are predominantly found in the granules of cytotoxic T-lymphocytes and NK-cells. Although antimicrobial activity of bovine NK-lysin has been assessed for several bacterial pathogens, not all the important bacterial pathogens that are involved in the bovine respiratory disease complex have been studied. Therefore the objective of the present study was to evaluate the antimicrobial activity of bovine NK-lysin-derived peptides on bovine respiratory pathogen Histophilus somni. Four, 30-mer peptides corresponding to the functional region of NK-lysin helices 2 and 3 were synthesized and assessed for antibacterial activity on four bovine pneumonic H. somni isolates. Although there were some differences in the efficiency of bactericidal activity among the NK-lysin peptides at lower concentrations (2–5 μM), all four peptides effectively killed most H. somni isolates at higher concentrations (10–30 μM) as determined by a bacterial killing assay. Confocal microscopic and flow cytometric analysis of Live/Dead Baclight stained H. somni (which were preincubated with NK-lysin peptides) were consistent with the killing assay findings and suggest NK-lysin peptides are bactericidal for H. somni. Among the four peptides, NK2A-derived peptide consistently showed the highest antimicrobial activity against all four H. somni isolates. Electron microscopic examination of H. somni following incubation with NK-lysin revealed extensive cell membrane damage, protrusions of outer membranes, and cytoplasmic content leakage. Taken together, the findings from this study clearly demonstrate the antimicrobial activity of all four bovine NK-lysin-derived peptides against bovine H. somni isolates. PMID:28827826

Antimicrobial activity of bovine NK-lysin-derived peptides on bovine respiratory pathogen Histophilus somni.

PubMed

Dassanayake, Rohana P; Falkenberg, Shollie M; Briggs, Robert E; Tatum, Fred M; Sacco, Randy E

2017-01-01

Bovine NK-lysins, which are functionally and structurally similar to human granulysin and porcine NK-lysin, are predominantly found in the granules of cytotoxic T-lymphocytes and NK-cells. Although antimicrobial activity of bovine NK-lysin has been assessed for several bacterial pathogens, not all the important bacterial pathogens that are involved in the bovine respiratory disease complex have been studied. Therefore the objective of the present study was to evaluate the antimicrobial activity of bovine NK-lysin-derived peptides on bovine respiratory pathogen Histophilus somni. Four, 30-mer peptides corresponding to the functional region of NK-lysin helices 2 and 3 were synthesized and assessed for antibacterial activity on four bovine pneumonic H. somni isolates. Although there were some differences in the efficiency of bactericidal activity among the NK-lysin peptides at lower concentrations (2-5 μM), all four peptides effectively killed most H. somni isolates at higher concentrations (10-30 μM) as determined by a bacterial killing assay. Confocal microscopic and flow cytometric analysis of Live/Dead Baclight stained H. somni (which were preincubated with NK-lysin peptides) were consistent with the killing assay findings and suggest NK-lysin peptides are bactericidal for H. somni. Among the four peptides, NK2A-derived peptide consistently showed the highest antimicrobial activity against all four H. somni isolates. Electron microscopic examination of H. somni following incubation with NK-lysin revealed extensive cell membrane damage, protrusions of outer membranes, and cytoplasmic content leakage. Taken together, the findings from this study clearly demonstrate the antimicrobial activity of all four bovine NK-lysin-derived peptides against bovine H. somni isolates.

Structural and biophysical characterization of an antimicrobial peptide chimera comprised of lactoferricin and lactoferrampin.

PubMed

Haney, Evan F; Nazmi, Kamran; Bolscher, Jan G M; Vogel, Hans J

2012-03-01

Lactoferricin and lactoferrampin are two antimicrobial peptides found in the N-terminal lobe of bovine lactoferrin with broad spectrum antimicrobial activity against a range of Gram-positive and Gram-negative bacteria as well as Candida albicans. A heterodimer comprised of lactoferrampin joined to a fragment of lactoferricin was recently reported in which these two peptides were joined at their C-termini through the two amino groups of a single Lys residue (Bolscher et al., 2009, Biochimie 91(1):123-132). This hybrid peptide, termed LFchimera, has significantly higher antimicrobial activity compared to the individual peptides or an equimolar mixture of the two. In this work, the underlying mechanism behind the increased antibacterial activity of LFchimera was investigated. Differential scanning calorimetry studies demonstrated that all the peptides influenced the thermotropic phase behaviour of anionic phospholipid suspensions. Calcein leakage and vesicle fusion experiments with anionic liposomes revealed that LFchimera had enhanced membrane perturbing properties compared to the individual peptides. Peptide structures were evaluated using circular dichroism and NMR spectroscopy to gain insight into the structural features of LFchimera that contribute to the increased antimicrobial activity. The NMR solution structure, determined in a miscible co-solvent mixture of chloroform, methanol and water, revealed that the Lys linkage increased the helical content in LFchimera compared to the individual peptides, but it did not fix the relative orientations of lactoferricin and lactoferrampin with respect to each other. The structure of LFchimera provides insight into the conformation of this peptide in a membranous environment and improves our understanding of its antimicrobial mechanism of action. Copyright © 2011 Elsevier B.V. All rights reserved.

In-vitro screening of Malaysian honey from different floral sources for antibacterial activity on human pathogenic bacteria.

PubMed

Ng, Wen-Jie; Ken, Khai-Wei; Kumar, Roshani-Vijaya; Gunasagaran, Hemamalani; Chandramogan, Vanaysha; Lee, Ying-Yee

2014-01-01

Different researches on therapeutic effects of honey have been conducted in different regions; however the study on the potential antibacterial activity of Malaysian honey is still limited. In this study, antibacterial activities of different monofloral honey samples were tested against several common human pathogenic bacteria. The well-diffusion method, minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) techniques were employed to investigate the putative antibacterial activity of Malaysian monofloral honey from Koompassia excelsa (Becc.) Taub (Tualang), Melaleuca cajuputi Powell (Gelam) and Durio zibethinus Murr. (Durian). Honey samples were tested against Staphylococcus aureus ATCC6518 and ATCC25923, Staphylococcus epidermidis ATCC12228, Enterococcus faecium LMG16192, Enterococcus faecalis LMG16216 and ATCC29212, Escherichia coli ATCC25922, Salmonella enterica serovar Typhimurium ATCC14028 and Klebsiella pneumoniae ATCC13883. Marked variations were observed in the antibacterial activity of these honey samples. Durian honey failed to produce substantial antibacterial activity, whereas Tualang and Gelam honey showed a spectrum of antibacterial activity with their growth inhibitory effects against all of the tested bacterial species including vancomycin-resistant enterococci (VRE). Present findings suggested Gelam honey possesses highest antibacterial effect among the tested Malaysian honey samples.

Antibacterial properties and mechanisms of gold-silver nanocages

NASA Astrophysics Data System (ADS)

Wang, Yulan; Wan, Jiangshan; Miron, Richard J.; Zhao, Yanbin; Zhang, Yufeng

2016-05-01

Despite the number of antibiotics used in routine clinical practice, bacterial infections continue to be one of the most important challenges faced in humans. The main concerns arise from the continuing emergence of antibiotic-resistant bacteria and the difficulties faced with the pharmaceutical development of new antibiotics. Thus, advancements in the avenue of novel antibacterial agents are essential. In this study, gold (Au) was combined with silver (Ag), a well-known antibacterial material, to form silver nanoparticles producing a gold-silver alloy structure with hollow interiors and porous walls (gold-silver nanocage). This novel material was promising in antibacterial applications due to its better biocompatibility than Ag nanoparticles, potential in photothermal effects and drug delivery ability. The gold-silver nanocage was then tested for its antibacterial properties and the mechanism involved leading to its antibacterial properties. This study confirms that this novel gold-silver nanocage has broad-spectrum antibacterial properties exerting its effects through the destruction of the cell membrane, production of reactive oxygen species (ROS) and induction of cell apoptosis. Therefore, we introduce a novel gold-silver nanocage that serves as a potential nanocarrier for the future delivery of antibiotics.

Characterization of the unique function of a reduced amide bond in a cytolytic peptide that acts on phospholipid membranes.

PubMed Central

Oh, J E; Lee, K H

2000-01-01

The incorporation of a reduced amide bond, psi(CH(2)NH), into peptide results in an increase in the net positive charge and the perturbation of alpha-helical structure. By using this characteristic of the reduced amide bond, we designed and synthesized novel pseudopeptides containing reduced amide bonds, which had a great selectivity between bacterial and mammalian cells. A structure-activity relationship study on pseudopeptides indicated that the decrease in alpha-helicity and the increase in net positive charge in the backbone, caused by the incorporation of a reduced amide bond into the peptide, both contributed to an improvement in the selectivity between lipid membranes with various surface charges. However, activity results in vitro indicated that a perturbation of alpha-helical structure rather than an increase in net positive charge in the backbone is more important in the selectivity between bacterial and mammalian cells. The present result revealed that the backbone of membrane-active peptides were important not only in maintaining the secondary structure for the interactions with lipid membranes but also in direct interactions with lipid membranes. The present study showed the unique function of a reduced amide bond in cytolytic peptides and a direction for developing novel anti-bacterial agents from cytolytic peptides that act on the lipid membrane of micro-organisms. PMID:11104671

Anti-endotoxic and antibacterial effects of a dermal substitute coated with host defense peptides.

PubMed

Kasetty, Gopinath; Kalle, Martina; Mörgelin, Matthias; Brune, Jan C; Schmidtchen, Artur

2015-01-01

Biomaterials used during surgery and wound treatment are of increasing importance in modern medical care. In the present study we set out to evaluate the addition of thrombin-derived host defense peptides to human acellular dermis (hAD, i.e. epiflex(®)). Antimicrobial activity of the functionalized hAD was demonstrated using radial diffusion and viable count assays against Gram-negative Escherichia coli, Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria. Electron microscopy analyses showed that peptide-mediated bacterial killing led to reduced hAD degradation. Furthermore, peptide-functionalized hAD displayed endotoxin-binding activity in vitro, as evidenced by inhibition of NF-κB activation in human monocytic cells (THP-1 cells) and a reduction of pro-inflammatory cytokine production in whole blood in response to lipopolysaccharide stimulation. The dermal substitute retained its anti-endotoxic activity after washing, compatible with results showing that the hAD bound a significant amount of peptide. Furthermore, bacteria-induced contact activation was inhibited by peptide addition to the hAD. E. coli infected hAD, alone, or after treatment with the antiseptic substance polyhexamethylenebiguanide (PHMB), yielded NF-κB activation in THP-1 cells. The activation was abrogated by peptide addition. Thus, thrombin-derived HDPs should be of interest in the further development of new biomaterials with combined antimicrobial and anti-endotoxic functions for use in surgery and wound treatment. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

In vitro production and antifungal activity of peptide ABP-dHC-cecropin A.

PubMed

Zhang, Jiaxin; Movahedi, Ali; Xu, Junjie; Wang, Mengyang; Wu, Xiaolong; Xu, Chen; Yin, Tongming; Zhuge, Qiang

2015-04-10

The antimicrobial peptide ABP-dHC-cecropin A is a small cationic peptide with potent activity against a wide range of bacterial species. Evidence of antifungal activity has also been suggested; however, testing of this peptide has been limited due to the low expression of cecropin proteins in Escherichia coli. To improve expression of this peptide in E. coli, ABP-dHC-cecropin A was cloned into a pSUMO vector and transformed into E. coli, resulting in the production of a pSUMO-ABP-dHC-cecropin A fusion protein. The soluble form of this protein was then purified by Ni-IDA chromatography, yielding a total of 496-mg protein per liter of fermentation culture. The SUMO-ABP-dHC-cecropin A fusion protein was then cleaved using a SUMO protease and re-purified by Ni-IDA chromatography, yielding a total of 158-mg recombinant ABP-dHC-cecropin A per liter of fermentation culture at a purity of ≥94%, the highest yield reported to date. Antifungal activity assays performed using this purified recombinant peptide revealed strong antifungal activity against both Candida albicans and Neurospora crassa, as well as Rhizopus, Fusarium, Alternaria, and Mucor species. Combined with previous analyses demonstrating strong antibacterial activity against a number of important bacterial pathogens, these results confirm the use of ABP-dHC-cecropin A as a broad-spectrum antimicrobial peptide, with significant therapeutic potential. Copyright © 2015 Elsevier B.V. All rights reserved.

Antibacterial and anticancer PDMS surface for mammalian cell growth using the Chinese herb extract paeonol(4-methoxy-2-hydroxyacetophenone)

NASA Astrophysics Data System (ADS)

Jiao, Jiajia; Sun, Lili; Guo, Zaiyu; Hou, Sen; Holyst, Robert; Lu, Yun; Feng, Xizeng

2016-12-01

Polydimethylsiloxane (PDMS) is widely used as a cell culture platform to produce micro- and nano-technology based microdevices. However, the native PDMS surface is not suitable for cell adhesion and is always subject to bacterial pollution and cancer cell invasion. Coating the PDMS surface with antibacterial or anticancer materials often causes considerable harm to the non-cancer mammalian cells on it. We have developed a method to fabricate a biocompatible PDMS surface which not only promotes non-cancer mammalian cell growth but also has antibacterial and anticancer activities, by coating the PDMS surface with a Chinese herb extract, paeonol. Coating changes the wettability and the elemental composition of the PDMS surface. Molecular dynamic simulation indicates that the absorption of paeonol onto the PDMS surface is an energy favourable process. The paeonol-coated PDMS surface exhibits good antibacterial activity against both Gram-positive and Gram-negative bacteria. Moreover considerable antibacterial activity is maintained after the coated surface is rinsed or incubated in water. The coated PDMS surface inhibits bacterial growth on the contact surface and promotes non-cancer mammalian cell growth with low cell toxicity; meanwhile the growth of cancer cells is significantly inhibited. Our study will potentially guide PDMS surface modification approaches to produce biomedical devices.

Antibacterial and anti-inflammatory drug delivery properties on cotton fabric using betamethasone-loaded mesoporous silica particles stabilized with chitosan and silicone softener.

PubMed

Hashemikia, Samaneh; Hemmatinejad, Nahid; Ahmadi, Ebrahim; Montazer, Majid

2016-10-01

In this study, mesoporous silica particles with a hexagonal structure (SBA-15) were synthesized and modified with (3-aminopropyl) triethoxysilane, and used as a carrier for anti-inflammatory drug, betamethasone sodium phosphate. Drug-loaded silica particles were grafted on the cotton fabric surface using chitosan and polysiloxane reactive softener as a soft and safe fixing agent to develop an antibacterial cotton fabric with drug delivery properties. Cytometry assays revealed that synthesized silica have no cytotoxicity against human peripheral blood mononuclear cells. Accordingly, the produced drug-loaded nanostructures can be applied via different routes, such as wound dressing. Drug delivery profile of the treated fabrics were investigated and compared. The drug release rate followed the conventional Higuchi model. The treated cotton fabrics were tested and evaluated using scanning electron microscope images, bending length, air permeability, washing durability and anti-bacterial properties. It was found that the chitosan-/softener-treated fabrics compounded with drug-loaded silica particles have a good drug delivery performance and exhibited a powerful antibacterial activity against both Escherichia coli and Staphylococcus aureus even after five washing cycles. The produced antibacterial cotton fabric with drug delivery properties could be proposed as a suitable material for many medical and hygienic applications.

The route of infection determines Wolbachia antibacterial protection in Drosophila.

PubMed

Gupta, Vanika; Vasanthakrishnan, Radhakrishnan B; Siva-Jothy, Jonathon; Monteith, Katy M; Brown, Sam P; Vale, Pedro F

2017-06-14

Bacterial symbionts are widespread among metazoans and provide a range of beneficial functions. Wolbachia -mediated protection against viral infection has been extensively demonstrated in Drosophila. In mosquitoes that are artificially transinfected with Drosophila melanogaster Wolbachia (wMel), protection from both viral and bacterial infections has been demonstrated. However, no evidence for Wolbachia -mediated antibacterial protection has been demonstrated in Drosophila to date. Here, we show that the route of infection is key for Wolbachia -mediated antibacterial protection. Drosophila melanogaster carrying Wolbachia showed reduced mortality during enteric-but not systemic-infection with the opportunist pathogen Pseudomonas aeruginosa Wolbachia -mediated protection was more pronounced in male flies and is associated with increased early expression of the antimicrobial peptide Attacin A , and also increased expression of a reactive oxygen species detoxification gene ( Gst D8 ). These results highlight that the route of infection is important for symbiont-mediated protection from infection, that Wolbachia can protect hosts by eliciting a combination of resistance and disease tolerance mechanisms, and that these effects are sexually dimorphic. We discuss the importance of using ecologically relevant routes of infection to gain a better understanding of symbiont-mediated protection. © 2017 The Authors.

Isolation, antimicrobial activities, and primary structures of hamster neutrophil defensins.

PubMed Central

Mak, P; Wójcik, K; Thogersen, I B; Dubin, A

1996-01-01

Hamster (Mesocricetus auratus) neutrophil granules contain at least four microbicidal peptides belonging to the defensin family. These compounds were purified from granule acid extracts by reverse-phase chromatography and termed HaNP-1 to -4 (hamster neutrophil peptide). HaNP-1 and HaNP-3 revealed the most bactericidal activity, with a 50% inhibitory concentration of 0.3 to 0.8 microg/ml for Staphylococcus aureus and Streptococcus pyogenes strains. The HaNP-4 was always isolated in concentrations exceeding about 10 times the concentrations of other hamster peptides, but its antibacterial activity as well as that of HaNP-2 was relatively lower, probably as a result of conserved Arg residue substitutions. Other microorganisms were also tested, and generally, hamster defensins exhibited less potency against gram-negative bacteria. The amino acid sequence of hamster defensins showed a high percentage of identity to the sequence of mouse enteric defensins, reaching about 60% identical residues in the case of HaNP-3 and cryptdin 3. PMID:8890190

Novel short antibacterial and antifungal peptides with low cytotoxicity: Efficacy and action mechanisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Xiaobao; Zhou, Chuncai; Li, Peng

Research highlights: {yields} Short antimicrobial peptides with nine and eleven residues were developed. {yields} These peptides show strong bactericidal activity against clinically important bacterial and fungal pathogens. {yields} These peptides exhibit high stability in the presence of salts, and low cytotoxicity. {yields} These peptides exert their action by disrupting membrane lipids. -- Abstract: Short antimicrobial peptides with nine and eleven residues were developed against several clinically important bacterial and fungal pathogens (specifically Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Fusarium solani). Twelve analogues of previously reported peptides BP76 (KKLFKKILKFL) and Pac-525 (KWRRWVRWI) were designed, synthesized, and tested formore » their antimicrobial activities. Two of our eleven amino acid peptides, P11-5 (GKLFKKILKIL) and P11-6 (KKLIKKILKIL), have very low MICs of 3.1-12.5 {mu}g ml{sup -1} against all five pathogens. The MICs of these two peptides against S. aureus, C. albicans and F. solani are four to ten times lower than the corresponding MICs of the reference peptide BP76. P9-4 (KWRRWIRWL), our newly designed nine-amino acid analogue, also has particularly low MICs of 3.1-6.2 {mu}g ml{sup -1} against four of the tested pathogens; these MICs are two to eight times lower than those reported for Pac-525 (6.2-50 {mu}g ml{sup -1}).These new peptides (P11-5, P11-6 and P9-4) also exhibit improved stability in the presence of salts, and have low cytotoxicity as shown by the hemolysis and MTT assays. From the results of field-emission scanning electron microscopy, membrane depolarization and dye-leakage assays, we propose that these peptides exert their action by disrupting membrane lipids. Molecular dynamics simulation studies confirm that P11-6 peptide maintains relatively stable helical structure and exerts more perturbation action on the order of acyl tail of lipid bilayer.« less

Komodo dragon-inspired synthetic peptide DRGN-1 promotes wound-healing of a mixed-biofilm infected wound.

PubMed

M C Chung, Ezra; Dean, Scott N; Propst, Crystal N; Bishop, Barney M; van Hoek, Monique L

2017-01-01

Cationic antimicrobial peptides are multifunctional molecules that have a high potential as therapeutic agents. We have identified a histone H1-derived peptide from the Komodo dragon ( Varanus komodoensis) , called VK25. Using this peptide as inspiration, we designed a synthetic peptide called DRGN-1. We evaluated the antimicrobial and anti-biofilm activity of both peptides against Pseudomonas aeruginosa and Staphylococcus aureus . DRGN-1, more than VK25, exhibited potent antimicrobial and anti-biofilm activity, and permeabilized bacterial membranes. Wound healing was significantly enhanced by DRGN-1 in both uninfected and mixed biofilm ( Pseudomonas aeruginosa and Staphylococcus aureus )-infected murine wounds. In a scratch wound closure assay used to elucidate the wound healing mechanism, the peptide promoted the migration of HEKa keratinocyte cells, which was inhibited by mitomycin C (proliferation inhibitor) and AG1478 (epidermal growth factor receptor inhibitor). DRGN-1 also activated the EGFR-STAT1/3 pathway. Thus, DRGN-1 is a candidate for use as a topical wound treatment. Wound infections are a major concern; made increasingly complicated by the emerging, rapid spread of bacterial resistance. The novel synthetic peptide DRGN-1 (inspired by a peptide identified from Komodo dragon) exhibits pathogen-directed and host-directed activities in promoting the clearance and healing of polymicrobial ( Pseudomonas aeruginosa & Staphylococcus aureus ) biofilm infected wounds. The effectiveness of this peptide cannot be attributed solely to its ability to act upon the bacteria and disrupt the biofilm, but also reflects the peptide's ability to promsote keratinocyte migration. When applied in a murine model, infected wounds treated with DRGN-1 healed significantly faster than did untreated wounds, or wounds treated with other peptides. The host-directed mechanism of action was determined to be via the EGFR-STAT1/3 pathway. The pathogen-directed mechanism of action was determined to be via anti-biofilm activity and antibacterial activity through membrane permeabilization. This novel peptide may have potential as a future therapeutic for treating infected wounds.

Exploring biological effects of MoS{sub 2} nanosheets on native structures of α-helical peptides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Zonglin; Li, Weifeng, E-mail: wfli@suda.edu.cn, E-mail: ruhong@us.ibm.com; Hong, Linbi

Recent reports of mono- and few-layer molybdenum disulfide (MoS{sub 2}), a representative transition metal dichacogenide (TMD), as antibacterial and anticancer agents have shed light on their potential in biomedical applications. To better facilitate these promising applications, one needs to understand the biological effects of these TMDs as well, such as their potential adverse effects on protein structure and function. Here, we sought to understand the interaction of MoS{sub 2} nanosheets with peptides using molecular dynamics simulations and a simple model polyalanine with various lengths (PA{sub n}, n = 10, 20, 30, and 40; mainly α − helices). Our results demonstratedmore » that MoS{sub 2} monolayer has an exceptional capability to bind all peptides in a fast and strong manner. The strong attraction from the MoS{sub 2} nanosheet is more than enough to compensate the energy needed to unfold the peptide, regardless of the length, which induces drastic disruptions to the intra-peptide hydrogen bonds and subsequent secondary structures of α − helices. This universal phenomenon may point to the potential nanotoxicity of MoS{sub 2} when used in biological systems. Moreover, these results aligned well with previous findings on the potential cytotoxicity of TMD nanomaterials.« less

Antimicrobial Peptides: Insights into Membrane Permeabilization, Lipopolysaccharide Fragmentation and Application in Plant Disease Control.

PubMed

Datta, Aritreyee; Ghosh, Anirban; Airoldi, Cristina; Sperandeo, Paola; Mroue, Kamal H; Jiménez-Barbero, Jesús; Kundu, Pallob; Ramamoorthy, Ayyalusamy; Bhunia, Anirban

2015-07-06

The recent increase in multidrug resistance against bacterial infections has become a major concern to human health and global food security. Synthetic antimicrobial peptides (AMPs) have recently received substantial attention as potential alternatives to conventional antibiotics because of their potent broad-spectrum antimicrobial activity. These peptides have also been implicated in plant disease control for replacing conventional treatment methods that are polluting and hazardous to the environment and to human health. Here, we report de novo design and antimicrobial studies of VG16, a 16-residue active fragment of Dengue virus fusion peptide. Our results reveal that VG16KRKP, a non-toxic and non-hemolytic analogue of VG16, shows significant antimicrobial activity against Gram-negative E. coli and plant pathogens X. oryzae and X. campestris, as well as against human fungal pathogens C. albicans and C. grubii. VG16KRKP is also capable of inhibiting bacterial disease progression in plants. The solution-NMR structure of VG16KRKP in lipopolysaccharide features a folded conformation with a centrally located turn-type structure stabilized by aromatic-aromatic packing interactions with extended N- and C-termini. The de novo design of VG16KRKP provides valuable insights into the development of more potent antibacterial and antiendotoxic peptides for the treatment of human and plant infections.

Cationic host defense peptides; novel antimicrobial therapeutics against Category A pathogens and emerging infections

PubMed Central

Findlay, Fern; Proudfoot, Lorna; Stevens, Craig

2016-01-01

Cationic Host Defense Peptides (HDP, also known as antimicrobial peptides) are crucial components of the innate immune system and possess broad-spectrum antibacterial, antiviral, and immunomodulatory activities. They can contribute to the rapid clearance of biological agents through direct killing of the organisms, inhibition of pro-inflammatory mediators such as lipopolysaccharide, and by modulating the inflammatory response to infection. Category A biological agents and materials, as classified by the United States National Institutes for Health, the US Centers for Disease Control and Prevention, and the US Department of Homeland Security, carry the most severe threat in terms of human health, transmissibility, and preparedness. As such, there is a pressing need for novel frontline approaches for prevention and treatment of diseases caused by these organisms, and exploiting the broad antimicrobial activity exhibited by cationic host defense peptides represents an exciting priority area for clinical research. This review will summarize what is known about the antimicrobial and antiviral effects of the two main families of cationic host defense peptides, cathelicidins, and defensins in the context of Category A biological agents which include, but are not limited to; anthrax (Bacillus anthracis), plague (Yersinia pestis), smallpox (Variola major), tularemia (Francisella tularensis). In addition, we highlight priority areas, particularly emerging viral infections, where more extensive research is urgently required. PMID:27315342

Cationic host defense peptides; novel antimicrobial therapeutics against Category A pathogens and emerging infections.

PubMed

Findlay, Fern; Proudfoot, Lorna; Stevens, Craig; Barlow, Peter G

2016-01-01

Cationic Host Defense Peptides (HDP, also known as antimicrobial peptides) are crucial components of the innate immune system and possess broad-spectrum antibacterial, antiviral, and immunomodulatory activities. They can contribute to the rapid clearance of biological agents through direct killing of the organisms, inhibition of pro-inflammatory mediators such as lipopolysaccharide, and by modulating the inflammatory response to infection. Category A biological agents and materials, as classified by the United States National Institutes for Health, the US Centers for Disease Control and Prevention, and the US Department of Homeland Security, carry the most severe threat in terms of human health, transmissibility, and preparedness. As such, there is a pressing need for novel frontline approaches for prevention and treatment of diseases caused by these organisms, and exploiting the broad antimicrobial activity exhibited by cationic host defense peptides represents an exciting priority area for clinical research. This review will summarize what is known about the antimicrobial and antiviral effects of the two main families of cationic host defense peptides, cathelicidins, and defensins in the context of Category A biological agents which include, but are not limited to; anthrax (Bacillus anthracis), plague (Yersinia pestis), smallpox (Variola major), tularemia (Francisella tularensis). In addition, we highlight priority areas, particularly emerging viral infections, where more extensive research is urgently required.

Identification of a moronecidin-like antimicrobial peptide in the venomous fish Pterois volitans: Functional and structural study of pteroicidin-α.

PubMed

Houyvet, Baptiste; Bouchon-Navaro, Yolande; Bouchon, Claude; Goux, Didier; Bernay, Benoît; Corre, Erwan; Zatylny-Gaudin, Céline

2018-01-01

The present study characterizes for the first time an antimicrobial peptide in lionfish (Pterois volitans), a venomous fish. Using a peptidomic approach, we identified a mature piscidin in lionfish and called it pteroicidin-α. We detected an amidated form (pteroicidin-α- CONH 2 ) and a non-amidated form (pteroicidin-α-COOH), and then performed their functional and structural study. Interestingly, the two peptides displayed different antibacterial and hemolytic activity levels. Pteroicidin-α-CONH 2 was bactericidal on human pathogens like Staphylococcus aureus or Escherichia coli, as well as on the fish pathogen Aeromonas salmonicida, while pteroicidin-α-COOH only inhibited their growth. Furthermore, the two peptides induced hemolysis of red blood cells from different vertebrates, namely humans, sea bass and lesser-spotted dogfish. Hemolysis occurred with low concentrations of pteroicidin-α-CONH 2 , indicating greater toxicity of the amidated form. Circular dichroism analysis showed that both peptides adopted a helical conformation, yet with a greater α-helix content in pteroicidin-α-CONH 2 . Overall, these results suggest that amidation strongly influences pteroicidin-α by modifying its structure and its physico-chemical characteristics and by increasing its hemolytic activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Halloysite Nanotubes Supported Ag and ZnO Nanoparticles with Synergistically Enhanced Antibacterial Activity

NASA Astrophysics Data System (ADS)

Shu, Zhan; Zhang, Yi; Yang, Qian; Yang, Huaming

2017-02-01

Novel antimicrobial nanocomposite incorporating halloysite nanotubes (HNTs) and silver (Ag) into zinc oxide (ZnO) nanoparticles is prepared by integrating HNTs and decorating Ag nanoparticles. ZnO nanoparticles (ZnO NPs) and Ag nanoparticles (Ag NPs) with a size of about 100 and 8 nm, respectively, are dispersively anchored onto HNTs. The synergistic effects of ZnO NPs, Ag NPs, and HNTs led to the superior antibacterial activity of the Ag-ZnO/HNTs antibacterial nanocomposites. HNTs facilitated the dispersion and stability of ZnO NPs and brought them in close contact with bacteria, while Ag NPs could promote the separation of photogenerated electron-hole pairs and enhanced the antibacterial activity of ZnO NPs. The close contact with cell membrane enabled the nanoparticles to produce the increased concentration of reactive oxygen species and the metal ions to permeate into the cytoplasm, thus induced quick death of bacteria, indicating that Ag-ZnO/HNTs antibacterial nanocomposite is a promising candidate in the antibacterial fields.

A simple and low-cost platform technology for producing pexiganan antimicrobial peptide in E. coli.

PubMed

Zhao, Chun-Xia; Dwyer, Mirjana Dimitrijev; Yu, Alice Lei; Wu, Yang; Fang, Sheng; Middelberg, Anton P J

2015-05-01

Antimicrobial peptides, as a new class of antibiotics, have generated tremendous interest as potential alternatives to classical antibiotics. However, the large-scale production of antimicrobial peptides remains a significant challenge. This paper reports a simple and low-cost chromatography-free platform technology for producing antimicrobial peptides in Escherichia coli (E. coli). A fusion protein comprising a variant of the helical biosurfactant protein DAMP4 and the known antimicrobial peptide pexiganan is designed by joining the two polypeptides, at the DNA level, via an acid-sensitive cleavage site. The resulting DAMP4(var)-pexiganan fusion protein expresses at high level and solubility in recombinant E. coli, and a simple heat-purification method was applied to disrupt cells and deliver high-purity DAMP4(var)-pexiganan protein. Simple acid cleavage successfully separated the DAMP4 variant protein and the antimicrobial peptide. Antimicrobial activity tests confirmed that the bio-produced antimicrobial peptide has the same antimicrobial activity as the equivalent product made by conventional chemical peptide synthesis. This simple and low-cost platform technology can be easily adapted to produce other valuable peptide products, and opens a new manufacturing approach for producing antimicrobial peptides at large scale using the tools and approaches of biochemical engineering. © 2014 Wiley Periodicals, Inc.

A miniature mimic of host defense peptides with systemic antibacterial efficacy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarig, Hadar; Livne, Liran; Held-Kuznetsov, Victoria

Oligomers of acylated lysines (OAKs) are synthetic mimics of host defense peptides (HDPs) with promising antimicrobial properties. Here we challenged the OAK concept for its ability to generate both systemically efficient and economically viable lead compounds for fighting multidrug-resistant bacteria. We describe the design and characterization of a miniature OAK composed of only 3 lysyls and 2 acyls (designated C{sub 12({omega}7)}K-{beta}{sub 12}) that preferentially targets gram-positive species by a bacteriostatic mode of action. To gain insight into the mechanism of action, we examined the interaction of OAK with various potential targets, including phospholipid bilayers, using surface plasmon resonance, and Langmuirmore » monolayers, using insertion assays, epifluorescence microscopy, and grazing incidence X-ray diffraction, in a complementary manner. Collectively, the data support the notion that C{sub 12({omega}7)}K-{beta}{sub 12} damages the plasma-membrane architecture similarly to HDPs, that is, following a near-classic 2-step interaction including high-affinity electrostatic adhesion and a subsequent shallow insertion that was limited to the phospholipid head group region. Notably, preliminary acute toxicity and efficacy studies performed with mouse models of infection have consolidated the potential of OAK for treating bacterial infections, including systemic treatments of methicillin-resistant Staphylococcus aureus. Such simple yet robust chemicals might be useful for various antibacterial applications while circumventing potential adverse effects associated with cytolytic compounds.« less

Functional significance of the E loop, a novel motif conserved in the lantibiotic immunity ATP-binding cassette transport systems.

PubMed

Okuda, Ken-ichi; Yanagihara, Sae; Sugayama, Tomomichi; Zendo, Takeshi; Nakayama, Jiro; Sonomoto, Kenji

2010-06-01

Lantibiotics are peptide-derived antibacterial substances produced by some Gram-positive bacteria and characterized by the presence of unusual amino acids, like lanthionines and dehydrated amino acids. Because lantibiotic producers may be attacked by self-produced lantibiotics, they express immunity proteins on the cytoplasmic membrane. An ATP-binding cassette (ABC) transport system mediated by the LanFEG protein complex is a major system in lantibiotic immunity. Multiple-sequence alignment analysis revealed that LanF proteins contain the E loop, a variant of the Q loop, which is a well-conserved motif in the nucleotide-binding domains (NBDs) of general ABC transporters. To elucidate E loop function, we introduced a mutation in the NukF protein, which is involved in the nukacin-ISK-1 immunity system. Amino acid replacement of glutamic acid in the E loop with glutamine (E85Q) resulted in slight decreases in the immunity level and transport activity. Additionally, the E85A mutation severely impaired the immunity level and transport activity. On the other hand, ATPase activities of purified E85Q and E85A mutants were almost similar to that of the wild type. These results suggested that the E loop found in ABC transporters involved in lantibiotic immunity plays a significant role in the function of these transporters, especially in the structural change of transmembrane domains.

Curvulamine, a new antibacterial alkaloid incorporating two undescribed units from a Curvularia species.

PubMed

Han, Wen Bo; Lu, Yan Hua; Zhang, Ai Hua; Zhang, Gao Fei; Mei, Ya Ning; Jiang, Nan; Lei, Xinxiang; Song, Yong Chun; Ng, Seik Weng; Tan, Ren Xiang

2014-10-17

The white croaker (Argyrosomus argentatus) derived Curvularia sp. IFB-Z10 produces curvulamine as a skeletally unprecedented alkaloid incorporating two undescribed extender units. Curvulamine is more selectively antibacterial than tinidazole and biosynthetically unique in the new extenders formed through a decarboxylative condensation between an oligoketide motif and alanine.

Combined antibacterial/tissue regeneration response in thermal burns promoted by functional chitosan/silver nanocomposites.

PubMed

Luna-Hernández, E; Cruz-Soto, M E; Padilla-Vaca, F; Mauricio-Sánchez, R A; Ramirez-Wong, D; Muñoz, R; Granados-López, L; Ovalle-Flores, L R; Menchaca-Arredondo, J L; Hernández-Rangel, A; Prokhorov, E; García-Rivas, J L; España-Sánchez, B L; Luna-Bárcenas, G

2017-12-01

We report the combined antibacterial/tissue regeneration responses to thermal burns promoted by functional chitosan/silver nanocomposites (CS/nAg) with ultralow silver content (0.018wt.%, 7-30nm). Our approach allows one to produce CS/nAg nanocomposites without silver nanoparticles (nAg) agglomeration, with bactericide potency higher than 1wt.% of nAg (ca. 10nm) content and, promoting the healing process in controlled thermal burns. CS/nAg films exhibit high antibacterial activity against S. aureus and P. aeruginosa after 1.5h of incubation, demonstrating the bacterial penetration into hydrated films and their interaction with nAg. Additionally, exceptional healing of induced thermal burns was obtained by increasing myofibroblasts, collagen remodeling, and blood vessel neoformation. These factors are associated with epiderma regeneration after 7days of treatment with no nAg release. Our results corroborate the controlled synthesis of nAg embedded in CS matrix with combined antibacterial/biocompatibility properties aiming to produce functional nanocomposites with potential use in wound dressing and health care applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Rice terpene synthase 24 (OsTPS24) encodes a jasmonate-responsive monoterpene synthase that produces an antibacterial γ-terpinene against rice pathogen.

PubMed

Yoshitomi, Kayo; Taniguchi, Shiduku; Tanaka, Keiichiro; Uji, Yuya; Akimitsu, Kazuya; Gomi, Kenji

2016-02-01

Rice is one of the most important crops worldwide and is widely used as a model plant for molecular studies of monocotyledonous species. The plant hormone jasmonic acid (JA) is involved in rice-pathogen interactions. In addition, volatile compounds, including terpenes, whose production is induced by JA, are known to be involved in the rice defense system. In this study, we analyzed the JA-induced terpene synthase OsTPS24 in rice. We found that OsTPS24 was localized in chloroplasts and produced a monoterpene, γ-terpinene. The amount of γ-terpinene increased after JA treatment. γ-Terpinene had significant antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo); however, it did not show significant antifungal activity against Magnaporthe oryzae. The antibacterial activity of the γ-terpinene against Xoo was caused by damage to bacterial cell membranes. These results suggest that γ-terpinene plays an important role in JA-induced resistance against Xoo, and that it functions as an antibacterial compound in rice. Copyright © 2015 Elsevier GmbH. All rights reserved.

Antimicrobial Properties of Copper Nanoparticles and Amino Acid Chelated Copper Nanoparticles Produced by Using a Soya Extract.

PubMed

DeAlba-Montero, I; Guajardo-Pacheco, Jesús; Morales-Sánchez, Elpidio; Araujo-Martínez, Rene; Loredo-Becerra, G M; Martínez-Castañón, Gabriel-Alejandro; Ruiz, Facundo; Compeán Jasso, M E

2017-01-01

This paper reports a comparison of the antibacterial properties of copper-amino acids chelates and copper nanoparticles against Escherichia coli , Staphylococcus aureus , and Enterococcus faecalis . These copper-amino acids chelates were synthesized by using a soybean aqueous extract and copper nanoparticles were produced using as a starting material the copper-amino acids chelates species. The antibacterial activity of the samples was evaluated by using the standard microdilution method (CLSI M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates over E. faecalis . Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used.

Antimicrobial Properties of Copper Nanoparticles and Amino Acid Chelated Copper Nanoparticles Produced by Using a Soya Extract

PubMed Central

DeAlba-Montero, I.; Morales-Sánchez, Elpidio; Araujo-Martínez, Rene

2017-01-01

This paper reports a comparison of the antibacterial properties of copper-amino acids chelates and copper nanoparticles against Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis. These copper-amino acids chelates were synthesized by using a soybean aqueous extract and copper nanoparticles were produced using as a starting material the copper-amino acids chelates species. The antibacterial activity of the samples was evaluated by using the standard microdilution method (CLSI M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates over E. faecalis. Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used. PMID:28286459

Alternating Current Electrophoretic Deposition of Antibacterial Bioactive Glass-Chitosan Composite Coatings

PubMed Central

Seuss, Sigrid; Lehmann, Maja; Boccaccini, Aldo R.

2014-01-01

Alternating current (AC) electrophoretic deposition (EPD) was used to produce multifunctional composite coatings combining bioactive glass (BG) particles and chitosan. BG particles of two different sizes were used, i.e., 2 μm and 20–80 nm in average diameter. The parameter optimization and characterization of the coatings was conducted by visual inspection and by adhesion strength tests. The optimized coatings were investigated in terms of their hydroxyapatite (HA) forming ability in simulated body fluid (SBF) for up to 21 days. Fourier transform infrared (FTIR) spectroscopy results showed the successful HA formation on the coatings after 21 days. The first investigations were conducted on planar stainless steel sheets. In addition, scaffolds made from a TiAl4V6 alloy were considered to show the feasibility of coating of three dimensional structures by EPD. Because both BG and chitosan are antibacterial materials, the antibacterial properties of the as-produced coatings were investigated using E. coli bacteria cells. It was shown that the BG particle size has a strong influence on the antibacterial properties of the coatings. PMID:25007822

Small RNA-Seq analysis reveals microRNA-regulation of the Imd pathway during Escherichia coli infection in Drosophila.

PubMed

Li, Shengjie; Shen, Li; Sun, Lianjie; Xu, Jiao; Jin, Ping; Chen, Liming; Ma, Fei

2017-05-01

Drosophila have served as a model for research on innate immunity for decades. However, knowledge of the post-transcriptional regulation of immune gene expression by microRNAs (miRNAs) remains rudimentary. In the present study, using small RNA-seq and bioinformatics analysis, we identified 67 differentially expressed miRNAs in Drosophila infected with Escherichia coli compared to injured flies at three time-points. Furthermore, we found that 21 of these miRNAs were potentially involved in the regulation of Imd pathway-related genes. Strikingly, based on UAS-miRNAs line screening and Dual-luciferase assay, we identified that miR-9a and miR-981 could both negatively regulate Drosophila antibacterial defenses and decrease the level of the antibacterial peptide, Diptericin. Taken together, these data support the involvement of miRNAs in the regulation of the Drosophila Imd pathway. Copyright © 2017 Elsevier Ltd. All rights reserved.

Insights into the functionality of the putative residues involved in enterocin AS-48 maturation.

PubMed

Cebrián, Rubén; Maqueda, Mercedes; Neira, José Luis; Valdivia, Eva; Martínez-Bueno, Manuel; Montalbán-López, Manuel

2010-11-01

AS-48 is a 70-residue, α-helical, cationic bacteriocin produced by Enterococcus faecalis and is very singular in its circular structure and its broad antibacterial spectrum. The AS-48 preprotein consists of an N-terminal signal peptide (SP) (35 residues) followed by a proprotein moiety that undergoes posttranslational modifications to yield the mature and active circular protein. For the study of the specificity of the region of AS-48 that is responsible for maturation, three single mutants have been generated by site-directed mutagenesis in the as-48A structural gene. The substitutions were made just in the residues that are thought to constitute a recognition site for the SP cleavage enzyme (His-1, Met1) and in those involved in circularization (Met1, Trp70). Each derivative was expressed in the enterococcal JH2-2 strain containing the necessary native biosynthetic machinery for enterocin production. The importance of these derivatives in AS-48 processing has been evaluated on the basis of the production and structural characterization of the corresponding derivatives. Notably, only two of them (Trp70Ala and Met1Ala derivatives) could be purified in different forms and amounts and are characterized for their bactericidal activity and secondary structure. We could not detect any production of AS-48 in JH2-2(pAM401-81(His-1Ile)) by using the conventional chromatographic techniques, despite the high efficiency of the culture conditions applied to produce this enterocin. Our results underline the different important roles of the mutated residues in (i) the elimination of the SP, (ii) the production levels and antibacterial activity of the mature proteins, and (iii) protein circularization. Moreover, our findings suggest that His-1 is critically involved in cleavage site recognition, its substitution being responsible for the blockage of processing, thereby hampering the production of the specific protein in the cellular culture supernatant.

Anti-inflammatory and anti-endotoxin properties of peptides derived from the carboxy-terminal region of a defensin from the tick Ornithodoros savignyi.

PubMed

Malan, Melissa; Serem, June C; Bester, Megan J; Neitz, Albert W H; Gaspar, Anabella R M

2016-01-01

Antimicrobial peptides are small cationic peptides that possess a large spectrum of bioactivities, including antimicrobial, anti-inflammatory and antioxidant activities. Several antimicrobial peptides are known to inhibit lipopolysaccharide (LPS)-induced inflammation in vitro and to protect animals from sepsis. In this study, the cellular anti-inflammatory and anti-endotoxin activities of Os and Os-C, peptides derived from the carboxy-terminal of a tick defensin, were investigated. Both Os and Os-C were found to bind LPS in vitro, albeit to a lesser extent than polymyxin B and melittin, known endotoxin-binding peptides. Binding to LPS was found to reduce the bactericidal activity of Os and Os-C against Escherichia coli confirming the affinity of both peptides for LPS. At a concentration of 25 µM, the nitric oxide (NO) scavenging activity of Os was higher than glutathione, a known NO scavenger. In contrast, Os-C showed no scavenging activity. Os and Os-C inhibited LPS/IFN-γ induced NO and TNF-α production in RAW 264.7 cells in a concentration-dependent manner, with no cellular toxicity even at a concentration of 100 µM. Although inhibition of NO and TNF-α secretion was more pronounced for melittin and polymyxin B, significant cytotoxicity was observed at concentrations of 1.56 µM and 25 µM for melittin and polymyxin B, respectively. In addition, Os, Os-C and glutathione protected RAW 264.7 cells from oxidative damage at concentrations as low as 25 µM. This study identified that besides previously reported antibacterial activity of Os and Os-C, both peptides have in addition anti-inflammatory and anti-endotoxin properties. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.

New Paradigm Shift for the Green Synthesis of Antibacterial Silver Nanoparticles Utilizing Plant Extracts

PubMed Central

2014-01-01

This review covers general information regarding the green synthesis of antibacterial silver nanoparticles. Owing to their antibacterial properties, silver nanoparticles are widely used in many areas, especially biomedical applications. In green synthesis practices, the chemical reducing agents are eliminated, and biological entities are utilized to convert silver ions to silver nanoparticles. Among the various biological entities, natural plant extracts have emerged as green reducing agents, providing eco-friendly routes for the preparation of silver nanomaterials. The most obvious merits of green synthesis are the increased biocompatibility of the resulting silver nanoparticles and the ease with which the reaction can be carried out. This review summarizes some of the plant extracts that are used to produce antibacterial silver nanoparticles. Additionally, background information regarding the green synthesis and antibacterial activity of silver nanoparticles is provided. Finally, the toxicological aspects of silver nanoparticles are briefly mentioned. PMID:25343010

Antibacterial Constituents of Hainan Morinda citrifolia (Noni) Leaves.

PubMed

Zhang, Wei-Min; Wang, Wei; Zhang, Jing-Jing; Wang, Zhi-Rong; Wang, Yu; Hao, Wang-Jun; Huang, Wu-Yang

2016-05-01

Noni (Morinda citrifolia L.) is an edible and medicinal plant distributed in Hainan, China. The antibacterial activities of the extracts of water (WE), petroleum ether (PEE), ethyl acetate (EAE), chloroform (CE), and n-butanol (BE) were assayed by the disk diffusion method. The results showed that the extracts from Noni leaves possessed antibacterial effects against Bacillus subtilis, Escherichia coli, Proteus vulgaris, and Staphylococcus aureus. Among 5 different extracts, the BE produced the best antibacterial activity. The samples were first extracted by ethanol, and the primary compounds in the BE fraction of ethanol extract was further isolated and identified. Six phenolic compounds, including 5, 15-dimethylmorindol, ferulic acid, p-hydroxycinamic acid, methyl 4-hydroxybenzoate, methyl ferulate, and methyl 4-hydroxycinnamate, were identifiedby NMR. The results indicated that the phenolic compounds might significantly contribute to antibacterial activities of Noni leaves. © 2016 Institute of Food Technologists®

Bactericidal Activity of Ceragenin CSA-13 in Cell Culture and in an Animal Model of Peritoneal Infection.

PubMed

Bucki, Robert; Niemirowicz, Katarzyna; Wnorowska, Urszula; Byfield, Fitzroy J; Piktel, Ewelina; Wątek, Marzena; Janmey, Paul A; Savage, Paul B

2015-10-01

Ceragenins constitute a novel family of cationic antibiotics characterized by a broad spectrum of antimicrobial activities, which have mostly been assessed in vitro. Using a polarized human lung epithelial cell culture system, we evaluated the antibacterial activities of the ceragenin CSA-13 against two strains of Pseudomonas aeruginosa (PAO1 and Xen5). Additionally, the biodistribution and bactericidal activity of a CSA-13-IRDye 800CW derivate were assessed using an animal model of peritoneal infection after PAO1 challenge. In cell culture, CSA-13 bactericidal activities against PAO1 and Xen5 were higher than the activities of the human cathelicidin peptide LL-37. Increased CSA-13 activity was observed in polarized human lung epithelial cell cultures subjected to butyric acid treatment, which is known to increase endogenous LL-37 production. Eight hours after intravenous or intraperitoneal injection, the greatest CSA-13-IRDye 800CW accumulation was observed in mouse liver and kidneys. CSA-13-IRDye 800CW administration resulted in decreased bacterial outgrowth from abdominal fluid collected from animals subjected to intraperitoneal PAO1 infection. These observations indicate that CSA-13 may synergistically interact with antibacterial factors that are naturally present at mucosal surfaces and it maintains its antibacterial activity in the infected abdominal cavity. Cationic lipids such as CSA-13 represent excellent candidates for the development of new antibacterial compounds. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Fmoc-phenylalanine displays antibacterial activity against Gram-positive bacteria in gel and solution phases.

PubMed

Gahane, Avinash Y; Ranjan, Pritish; Singh, Virender; Sharma, Raj K; Sinha, Neeraj; Sharma, Mandeep; Chaudhry, Rama; Thakur, Ashwani K

2018-03-28

In the quest for new antimicrobial materials, hydrogels of Fmoc-protected peptides and amino acids have gained momentum due to their ease of synthesis and cost effectiveness; however, their repertoire is currently limited, and the mechanistic details of their function are not well understood. Herein, we report the antibacterial activity of the hydrogel and solution phases of Fmoc-phenylalanine (Fmoc-F) against a variety of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Fmoc-F, a small molecule hydrogelator, reduces the bacterial load both in vitro and in the skin wound infections of mice. The antibacterial activity of Fmoc-F is predominantly due to its release from the hydrogel. Fmoc-F shows surfactant-like properties with critical micelle concentration nearly equivalent to its minimum bactericidal concentration. Similar to Fmoc-F, some Fmoc-conjugated amino acids (Fmoc-AA) have also shown antibacterial effects that are linearly correlated with their surfactant properties. At low concentrations, where Fmoc-F does not form micelles, it inhibits bacterial growth by entering the cell and reducing the glutathione levels. However, at higher concentrations, Fmoc-F triggers oxidative and osmotic stress and, alters the membrane permeabilization and integrity, which kills Gram-positive bacteria. Herein, we proposed the use of the Fmoc-F hydrogel and its solution for several biomedical applications. This study will open up new avenues to enhance the repertoire of Fmoc-AA to act as antimicrobial agents and improve their structure-activity relationship.

Ribonuclease 7, an antimicrobial peptide upregulated during infection, contributes to microbial defense of the human urinary tract.

PubMed

Spencer, John David; Schwaderer, Andrew L; Wang, Huanyu; Bartz, Julianne; Kline, Jennifer; Eichler, Tad; DeSouza, Kristin R; Sims-Lucas, Sunder; Baker, Peter; Hains, David S

2013-04-01

The mechanisms that maintain sterility in the urinary tract are incompletely understood; however, recent studies stress the importance of antimicrobial peptides in protecting the urinary tract from infection. Ribonuclease 7 (RNase 7), a potent antimicrobial peptide contributing to urinary tract sterility, is expressed by intercalated cells in the renal collecting tubules and is present in the urine at levels sufficient to kill bacteria at baseline. Here, we characterize the expression and function of RNase 7 in the human urinary tract during infection. Both quantitative real-time PCR and enzyme-linked immunosorbant assays demonstrated increases in RNASE7 expression in the kidney along with kidney and urinary RNase 7 peptide concentrations with infection. While immunostaining localized RNase 7 production to the intercalated cells of the collecting tubule during sterility, its expression during pyelonephritis was found to increase throughout the nephron but not in glomeruli or the interstitium. Recombinant RNase 7 exhibited antimicrobial activity against uropathogens at low micromolar concentrations by disrupting the microbial membrane as determined by atomic force microscopy. Thus, RNase 7 expression is increased in the urinary tract with infection and has antibacterial activity against uropathogens at micromolar concentrations.

Ribonuclease 7, an antimicrobial peptide up-regulated during infection, contributes to microbial defense of the human urinary tract

PubMed Central

Spencer, John David; Schwaderer, Andrew L.; Wang, Huanyu; Bartz, Julianne; Kline, Jennifer; Eichler, Tad; DeSouza, Kristin R.; Sims-Lucas, Sunder; Baker, Peter; Hains, David S.

2012-01-01

The mechanisms that maintain sterility in the urinary tract are incompletely understood; however, recent studies stress the importance of antimicrobial peptides in protecting the urinary tract from infection. Ribonuclease 7 (RNase 7), a potent antimicrobial peptide contributing to urinary tract sterility, is expressed by intercalated cells in the renal collecting tubules and is present in the urine at levels sufficient to kill bacteria at baseline. Here, we characterize the expression and function of RNase 7 in the human urinary tract during infection. Both quantitative real-time PCR and ELISA assays demonstrated increases in RNASE7 expression in the kidney along with kidney and urinary RNase 7 peptide concentrations with infection. While immunostaining localized RNase 7 production to the intercalated cells of the collecting tubule during sterility, its expression during pyelonephritis was found to increase throughout the nephron but not in glomeruli or the interstitium. Recombinant RNase 7 exhibited antimicrobial activity against uropathogens at low micromolar concentrations by disrupting the microbial membrane as determined by atomic force microscopy. Thus, RNase 7 expression is increased in the urinary tract with infection, and has antibacterial activity against uropathogens at micromolar concentrations. PMID:23302724

Antimicrobial peptide from mucus of Andrias davidianus: screening and purification by magnetic cell membrane separation technique.

PubMed

Pei, Jinjin; Jiang, Lei

2017-07-01

Andrias davidianus, the Chinese giant salamander, has been used in traditional Chinese medicine for many decades. However, no antimicrobial peptides (AMPs) have been described from A. davidianus until now. Here we describe a novel AMP (andricin 01) isolated from the mucus of A. davidianus. The peptide was recovered using an innovative magnetic cell membrane separation technique and was characterised using mass spectrometry and circular dichroism (CD) spectroscopy. Andricin 01 is comprised of ten amino acid residues with a total molecular mass of 955.1 Da. CD spectrum analysis gave results similar to the archetypal random coil spectrum, consistent with the three-dimensional rendering calculated by current bioinformatics tools. Andricin 01 was found to be inhibitory both to Gram-negative and Gram-positive bacteria. Furthermore, the peptide at the minimal bacterial concentration did not show cell cytotoxicity against human hepatocytes or renal cells and did not show haemolytic activity against red blood cells, indicating that is potentially safe and effective for human use. Andricin 01 shows promise as a novel antibacterial that may provide an insight into the development of new drugs. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Structural and Antimicrobial Features of Peptides Related to Myticin C, a Special Defense Molecule from the Mediterranean Mussel Mytilus galloprovincialis.

PubMed

Domeneghetti, Stefania; Franzoi, Marco; Damiano, Nunzio; Norante, Rosa; El Halfawy, Nancy M; Mammi, Stefano; Marin, Oriano; Bellanda, Massimo; Venier, Paola

2015-10-28

Mussels (Mytilus spp.) have a large repertoire of cysteine-stabilized α,β peptides, and myticin C (MytC) was identified in some hundreds of transcript variants after in vivo immunostimulation. Using a sequence expressed in Italian mussels, we computed the MytC structure and synthesized the mature MytC and related peptide fragments (some of them also prepared in oxidized form) to accurately assess their antibacterial and antifungal activity. Only when tested at pH 5 was the reduced MytC as well as reduced and oxidized fragments including structural β-elements able to inhibit Gram-positive and -negative bacteria (MIC ranges of 4-32 and 8-32 μM, respectively). Such fragments caused selective Escherichia coli killing (MBC of 8-32 μM) but scarcely inhibited two fungal strains. In detail, the antimicrobial β-hairpin MytC[19-40]SOX caused membrane-disrupting effects in E. coli despite its partially ordered conformation in membrane-mimetic environments. In perspective, MytC-derived peptides could be employed to protect acidic mucosal tissues, in cosmetic and food products, and, possibly, as adjuvants in aquaculture.

Marine Antimicrobial Peptides: Nature Provides Templates for the Design of Novel Compounds against Pathogenic Bacteria.

PubMed

Falanga, Annarita; Lombardi, Lucia; Franci, Gianluigi; Vitiello, Mariateresa; Iovene, Maria Rosaria; Morelli, Giancarlo; Galdiero, Massimiliano; Galdiero, Stefania

2016-05-21

The discovery of antibiotics for the treatment of bacterial infections brought the idea that bacteria would no longer endanger human health. However, bacterial diseases still represent a worldwide treat. The ability of microorganisms to develop resistance, together with the indiscriminate use of antibiotics, is mainly responsible for this situation; thus, resistance has compelled the scientific community to search for novel therapeutics. In this scenario, antimicrobial peptides (AMPs) provide a promising strategy against a wide array of pathogenic microorganisms, being able to act directly as antimicrobial agents but also being important regulators of the innate immune system. This review is an attempt to explore marine AMPs as a rich source of molecules with antimicrobial activity. In fact, the sea is poorly explored in terms of AMPs, but it represents a resource with plentiful antibacterial agents performing their role in a harsh environment. For the application of AMPs in the medical field limitations correlated to their peptide nature, their inactivation by environmental pH, presence of salts, proteases, or other components have to be solved. Thus, these peptides may act as templates for the design of more potent and less toxic compounds.

Marine Antimicrobial Peptides: Nature Provides Templates for the Design of Novel Compounds against Pathogenic Bacteria

PubMed Central

Falanga, Annarita; Lombardi, Lucia; Franci, Gianluigi; Vitiello, Mariateresa; Iovene, Maria Rosaria; Morelli, Giancarlo; Galdiero, Massimiliano; Galdiero, Stefania

2016-01-01

The discovery of antibiotics for the treatment of bacterial infections brought the idea that bacteria would no longer endanger human health. However, bacterial diseases still represent a worldwide treat. The ability of microorganisms to develop resistance, together with the indiscriminate use of antibiotics, is mainly responsible for this situation; thus, resistance has compelled the scientific community to search for novel therapeutics. In this scenario, antimicrobial peptides (AMPs) provide a promising strategy against a wide array of pathogenic microorganisms, being able to act directly as antimicrobial agents but also being important regulators of the innate immune system. This review is an attempt to explore marine AMPs as a rich source of molecules with antimicrobial activity. In fact, the sea is poorly explored in terms of AMPs, but it represents a resource with plentiful antibacterial agents performing their role in a harsh environment. For the application of AMPs in the medical field limitations correlated to their peptide nature, their inactivation by environmental pH, presence of salts, proteases, or other components have to be solved. Thus, these peptides may act as templates for the design of more potent and less toxic compounds. PMID:27213366

Mutagenesis of NosM Leader Peptide Reveals Important Elements in Nosiheptide Biosynthesis

PubMed Central

Jin, Liang; Wu, Xuri; Xue, Yanjiu; Jin, Yue; Wang, Shuzhen

2016-01-01

ABSTRACT Nosiheptide, a typical member of the ribosomally synthesized and posttranslationally modified peptides (RiPPs), exhibits potent activity against multidrug-resistant Gram-positive bacterial pathogens. The precursor peptide of nosiheptide (NosM) is comprised of a leader peptide with 37 amino acids and a core peptide containing 13 amino acids. To pinpoint elements in the leader peptide that are essential for nosiheptide biosynthesis, a collection of mutants with unique sequence features, including N- and C-terminal motifs, peptide length, and specific sites in the leader peptide, was generated by mutagenesis in vivo. The effects of various mutants on nosiheptide biosynthesis were evaluated. In addition to the necessity of a conserved motif LEIS box, native length and the N-terminal 12 amino acid residues were indispensable, and single-site substitutions of these 12 amino acid residues resulted in changes ranging from a greater-than-5-fold decrease to a 2-fold increase of nosiheptide production, depending on the sites and substituted residues. Moreover, although the C-terminal motif is not conservative, significant effects of this portion on nosiheptide production were also evident. Taken together, the present results further highlight the importance of the leader peptide in nosiheptide biosynthesis, and provide new insights into the diversity and specificity of leader peptides in the biosynthesis of various RiPPs. IMPORTANCE As a representative thiopeptide, nosiheptide exhibits excellent antibacterial activity. Although the biosynthetic gene cluster and several modification steps have been revealed, the presence and roles of the leader peptide within the precursor peptide of the nosiheptide gene cluster remain elusive. Thus, identification of specific elements in the leader peptide can significantly facilitate the genetic manipulation of the gene cluster for increasing nosiheptide production or generating diverse analogues. Given the complexity of the biosynthetic process, the instability of the leader peptide, and the unavailability of intermediates, cocrystallization of intermediates, leader peptide, and modification enzymes is currently not feasible. Therefore, a mutagenesis approach was used to construct a series of leader peptide mutants to uncover a number of crucial and characteristic elements affecting nosiheptide biosynthesis, which moves a considerable distance toward a thorough understanding of the biosynthetic machinery for thiopeptides. PMID:27913416

Evaluation of the antibacterial activity of a conventional orthodontic composite containing silver/hydroxyapatite nanoparticles.

PubMed

Sodagar, Ahmad; Akhavan, Azam; Hashemi, Ehsan; Arab, Sepideh; Pourhajibagher, Maryam; Sodagar, Kosar; Kharrazifard, Mohammad Javad; Bahador, Abbas

2016-12-01

One of the most important complications of fixed orthodontic treatment is the formation of white spots which are initial carious lesions. Addition of antimicrobial agents into orthodontic adhesives might be a wise solution for prevention of white spot formation. The aim of this study was to evaluate the antibacterial properties of a conventional orthodontic adhesive containing three different concentrations of silver/hydroxyapatite nanoparticles. One hundred and sixty-two Transbond XT composite discs containing 0, 1, 5, and 10 % silver/hydroxyapatite nanoparticles were prepared and sterilized. Antibacterial properties of these composite groups against Streptococcus mutans, Lactobacillus acidophilus, and Streptococcus sanguinis were investigated using three different antimicrobial tests. Disk agar diffusion test was performed to assess the diffusion of antibacterial agent on brain heart infusion agar plate by measuring bacterial growth inhibition zones. Biofilm inhibition test showed the antibacterial capacity of composite discs against resistant bacterial biofilms. Antimicrobial activity of eluted components from composite discs was investigated by comparing the viable counts of bacteria after 3, 15, and 30 days. Composite discs containing 5 and 10 % silver/hydroxyapatite nanoparticles were capable of producing growth inhibition zones for all bacterial types. Results of biofilm inhibition test showed that all of the study groups reduced viable bacterial count in comparison to the control group. Antimicrobial activity of eluted components from composite discs was immensely diverse based on the bacterial type and the concentration of nanoparticles. Transbond XT composite discs containing 5 and 10 % silver/hydroxyapatite nanoparticles produce bacterial growth inhibition zones and show antibacterial properties against biofilms.

Influence of Niche-Specific Nutrients on Secondary Metabolism in Vibrionaceae.

PubMed

Giubergia, Sonia; Phippen, Christopher; Gotfredsen, Charlotte H; Nielsen, Kristian Fog; Gram, Lone

2016-07-01

Many factors, such as the substrate and the growth phase, influence biosynthesis of secondary metabolites in microorganisms. Therefore, it is crucial to consider these factors when establishing a bioprospecting strategy. Mimicking the conditions of the natural environment has been suggested as a means of inducing or influencing microbial secondary metabolite production. The purpose of the present study was to determine how the bioactivity of Vibrionaceae was influenced by carbon sources typical of their natural environment. We determined how mannose and chitin, compared to glucose, influenced the antibacterial activity of a collection of Vibrionaceae strains isolated because of their ability to produce antibacterial compounds but that in subsequent screenings seemed to have lost this ability. The numbers of bioactive isolates were 2- and 3.5-fold higher when strains were grown on mannose and chitin, respectively, than on glucose. As secondary metabolites are typically produced during late growth, potential producers were also allowed 1 to 2 days of growth before exposure to the pathogen. This strategy led to a 3-fold increase in the number of bioactive strains on glucose and an 8-fold increase on both chitin and mannose. We selected two bioactive strains belonging to species for which antibacterial activity had not previously been identified. Using ultrahigh-performance liquid chromatography-high-resolution mass spectrometry and bioassay-guided fractionation, we found that the siderophore fluvibactin was responsible for the antibacterial activity of Vibrio furnissii and Vibrio fluvialis These results suggest a role of chitin in the regulation of secondary metabolism in vibrios and demonstrate that considering bacterial ecophysiology during development of screening strategies will facilitate bioprospecting. A challenge in microbial natural product discovery is the elicitation of the biosynthetic gene clusters that are silent when microorganisms are grown under standard laboratory conditions. We hypothesized that, since the clusters are not lost during proliferation in the natural niche of the microorganisms, they must, under such conditions, be functional. Here, we demonstrate that an ecology-based approach in which the producer organism is allowed a temporal advantage and where growth conditions are mimicking the natural niche remarkably increases the number of Vibrionaceae strains producing antibacterial compounds. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Asia Pacific Military Medicine Conference (APMMC) Simulation Symposium (16th) Held in New Delhi, India on March 26-31, 2006. Abstracts

DTIC Science & Technology

2006-04-01

Results: H1- 171 2 adopted an alpha-helical structure in membrane environments. This antimicrobial peptide exhibited potent antibacterial activity against a...PLASMODIUM VIVAX MALARIA IN VIETNAM 2 Mody,2 Marc 206 ColonelAlberto Gabriel, Philippines THE TREND OF MALARIA INFECTION IN THE ARMED FORCES OF THE PHILIPPINES ...United States - Thailand CHARACTERIZATION OF DENGUE CASES PRESENTING TO A TERTIARY MEDICAL CENTER IN METRO MANILA, PHILIPPINES Sen ior Colonel Nguyen

Retraction: Two novel duck antibacterial peptides, avian β-defensins 9 and 10, with antimicrobial activity.

PubMed

2013-01-01

The article by Ma et al. that published in the Journal of Microbiology and Biotechnology (2009, 19: 1447-1455) was used the same data in two journal articles (Acta Veterinaria et Zootechnica Sinica, 2009, 40(9): 1320-1326, Scientia Agricultura Sinica, 2009, 42(4): 1406-1412). Therefore, the article is retracted from JMB as a misconduct of the authors. JMB as the publisher regrets for any inconvenience may have caused by the retraction to readers.

Potential Pharmacological Resources: Natural Bioactive Compounds from Marine-Derived Fungi

PubMed Central

Jin, Liming; Quan, Chunshan; Hou, Xiyan; Fan, Shengdi

2016-01-01

In recent years, a considerable number of structurally unique metabolites with biological and pharmacological activities have been isolated from the marine-derived fungi, such as polyketides, alkaloids, peptides, lactones, terpenoids and steroids. Some of these compounds have anticancer, antibacterial, antifungal, antiviral, anti-inflammatory, antioxidant, antibiotic and cytotoxic properties. This review partially summarizes the new bioactive compounds from marine-derived fungi with classification according to the sources of fungi and their biological activities. Those fungi found from 2014 to the present are discussed. PMID:27110799

Expression of a Recombinant Anti-HIV and Anti-Tumor Protein, MAP30, in Nicotiana tobacum Hairy Roots: A pH-Stable and Thermophilic Antimicrobial Protein.

PubMed

Moghadam, Ali; Niazi, Ali; Afsharifar, Alireza; Taghavi, Seyed Mohsen

2016-01-01

In contrast to conventional antibiotics, which microorganisms can readily evade, it is nearly impossible for a microbial strain that is sensitive to antimicrobial proteins to convert to a resistant strain. Therefore, antimicrobial proteins and peptides that are promising alternative candidates for the control of bacterial infections are under investigation. The MAP30 protein of Momordica charantia is a valuable type I ribosome-inactivating protein (RIP) with anti-HIV and anti-tumor activities. Whereas the antimicrobial activity of some type I RIPs has been confirmed, less attention has been paid to the antimicrobial activity of MAP30 produced in a stable, easily handled, and extremely cost-effective protein-expression system. rMAP30-KDEL was expressed in Nicotiana tobacum hairy roots, and its effect on different microorganisms was investigated. Analysis of the extracted total proteins of transgenic hairy roots showed that rMAP30-KDEL was expressed effectively and that this protein exhibited significant antibacterial activity in a dose-dependent manner. rMAP30-KDEL also possessed thermal and pH stability. Bioinformatic analysis of MAP30 and other RIPs regarding their conserved motifs, amino-acid contents, charge, aliphatic index, GRAVY value, and secondary structures demonstrated that these factors accounted for their thermophilicity. Therefore, RIPs such as MAP30 and its derived peptides might have promising applications as food preservatives, and their analysis might provide useful insights into designing clinically applicable antibiotic agents.

Expression of a Recombinant Anti-HIV and Anti-Tumor Protein, MAP30, in Nicotiana tobacum Hairy Roots: A pH-Stable and Thermophilic Antimicrobial Protein

PubMed Central

Moghadam, Ali; Niazi, Ali; Afsharifar, Alireza; Taghavi, Seyed Mohsen

2016-01-01

In contrast to conventional antibiotics, which microorganisms can readily evade, it is nearly impossible for a microbial strain that is sensitive to antimicrobial proteins to convert to a resistant strain. Therefore, antimicrobial proteins and peptides that are promising alternative candidates for the control of bacterial infections are under investigation. The MAP30 protein of Momordica charantia is a valuable type I ribosome-inactivating protein (RIP) with anti-HIV and anti-tumor activities. Whereas the antimicrobial activity of some type I RIPs has been confirmed, less attention has been paid to the antimicrobial activity of MAP30 produced in a stable, easily handled, and extremely cost-effective protein-expression system. rMAP30-KDEL was expressed in Nicotiana tobacum hairy roots, and its effect on different microorganisms was investigated. Analysis of the extracted total proteins of transgenic hairy roots showed that rMAP30-KDEL was expressed effectively and that this protein exhibited significant antibacterial activity in a dose-dependent manner. rMAP30-KDEL also possessed thermal and pH stability. Bioinformatic analysis of MAP30 and other RIPs regarding their conserved motifs, amino-acid contents, charge, aliphatic index, GRAVY value, and secondary structures demonstrated that these factors accounted for their thermophilicity. Therefore, RIPs such as MAP30 and its derived peptides might have promising applications as food preservatives, and their analysis might provide useful insights into designing clinically applicable antibiotic agents. PMID:27459300

Identification and partial characterization of a bacteriocin-like inhibitory substance (BLIS) from Lb. Bulgaricus K41 isolated from indigenous yogurts.

PubMed

Zaeim, Davood; Soleimanian-Zad, Sabihe; Sheikh-Zeinoddin, Mahmoud

2014-01-01

Forty-two strains of Lactobacillus bulgaricus isolated from locally made yogurts were examined and compared for bacteriocin producing ability using spot on lawn assay which improved by taking photo and image processing. Lb. bulgaricus K41 exhibited the highest inhibition level against indicators. K41 Bacteriocin-like inhibitory substance is sensitive to proteolytic enzymes (proteinase K, pepsin, and trypsin) but α-amylase makes slight reduction in its activity and it is resistant to lipase. This antibacterial peptide is extremely heat-stable (121 °C for 15 min) and remains active over a wide pH range (pH = 2 to 10); also nonionic detergents (Tween-20, Tween-80, and Triton X100) showed no effect on its activity. The inhibitory spectrum is against Gram-positive bacteria (except Staphylococcus aureus) with extremely antilisterial activity and it is almost ineffective against Gram-negative bacteria. The mode of its action was identified as bactericidal against Listeria monocytogenes. The properties of K41 bacteriocin-like inhibitory substance add to its safety as a biopreservative produced by a generally recognized as safe (GRAS) bacterium suggesting it can be used in hurdle technology for ready-to-eat foods as one of the main sources of Listeria contaminations. © 2013 Institute of Food Technologists®

Comparative mode of action of novel hybrid peptide CS-1a and its rearranged amphipathic analogue CS-2a.

PubMed

Joshi, Seema; Bisht, Gopal S; Rawat, Diwan S; Maiti, Souvik; Pasha, Santosh

2012-10-01

Cell selective, naturally occurring, host defence cationic peptides present a good template for the design of novel peptides with the aim of achieving a short length with improved antimicrobial potency and selectivity. A novel, short peptide CS-1a (14 residues) was derived using a sequence hybridization approach on sarcotoxin I (39 residues) and cecropin B (35 residues). The sequence of CS-1a was rearranged to enhance amphipathicity with the help of a Schiffer-Edmundson diagram to obtain CS-2a. Both peptides showed good antibacterial activity in the concentration range 4-16 μg·mL(-1) against susceptible as well as drug-resistant bacterial strains, including the clinically relevant pathogens Acenatobacter sp. and methicillin-resistant Staphylococcus aureus. The major thrust of these peptides is their nonhaemolytic activity against human red blood cells up to a high concentration of 512 μg·mL(-1). Compared to CS-1a, amphipathic peptide CS-2a showed a more pronounced α-helical conformation, along with a better membrane insertion depth in bacterial mimic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) small unilamellar vesicles. With equivalent lipid-binding affinity, the two peptides assumed different pathways of membrane disruption, as demonstrated by calcein leakage and the results of transmission electron microscopy on model bacterial mimic large unilamellar vesicles. Extending the work from model membranes to intact Escherichia coli cells, differences in membrane perturbation were visible in microscopic images of peptide-treated E. coli. The present study describes two novel short peptides with potent activity, cell selectivity and divergent modes of action that will aid in the future design of peptides with better therapeutic potential. © 2012 The Authors Journal compilation © 2012 FEBS.

Structure-activity relationship of HP (2-20) analog peptide: enhanced antimicrobial activity by N-terminal random coil region deletion.

PubMed

Park, Yoonkyung; Park, Seong-Cheol; Park, Hae-Kyun; Shin, Song Yub; Kim, Yangmee; Hahm, Kyung-Soo

2007-01-01

HP (2-20) (AKKVFKRLEKLFSKIQNDK) is a 19-aa antimicrobial peptide derived from N-terminus of Helicobacter pylori Ribosomal protein L1 (RpL1). In the previous study, several analogs with amino acid substitutions were designed to increase or decrease only the net hydrophobicity. In particular, substitutions of Gln(16) and Asp(18) with Trp (Anal 3) for hydrophobic amino acid caused a dramatic increase in antibiotic activity without a hemolytic effect. HP-A3 is a potent antimicrobial peptide that forms, in a hydrophobic medium, an amphipathic structure consisting of an N-terminal random coil region (residues 2-5) and extended C-terminal regular alpha-helical region (residues 6-20). To obtain the short and potent alpha-helical antimicrobial peptide, we synthesized a N-terminal random coil deleted HP-A3 (A3-NT) and examined their antimicrobial activity and mechanism of action. The resulting 15mer peptide showed increased antibacterial and antifungal activity to 2- and 4-fold, respectively, without hemolysis. Confocal fluorescence microscopy studies showed that A3-NT was accumulated in the plasma membrane. Flow cytometric analysis revealed that A3-NT acted in salt- and energy-independent manner. Furthermore, A3-NT causes significant morphological alterations of the bacterial surfaces as shown by scanning electron microscopy. Circular dichroism (CD) analysis revealed that A3-NT showed higher alpha-helical contents than the HP-A3 peptide in 50% TFE solution. Therefore, the cell-lytic efficiency of HP-A3, which depended on the alpha-helical content of peptide, correlated linearly with their antimicrobial potency.

β-Boomerang Antimicrobial and Antiendotoxic Peptides: Lipidation and Disulfide Bond Effects on Activity and Structure.

PubMed

Mohanram, Harini; Bhattacharjya, Surajit

2014-04-21

Drug-resistant Gram-negative bacterial pathogens and endotoxin- or lipopolysaccharide (LPS)-mediated inflammations are among some of the most  prominent health issues globally. Antimicrobial peptides (AMPs) are eminent molecules that can kill drug-resistant strains and neutralize LPS toxicity. LPS, the outer layer of the outer membrane of Gram-negative bacteria safeguards cell integrity against hydrophobic compounds, including antibiotics and AMPs. Apart from maintaining structural integrity, LPS, when released into the blood stream, also induces inflammatory pathways leading to septic shock. In previous works, we have reported the de novo design of a set of 12-amino acid long cationic/hydrophobic peptides for LPS binding and activity. These peptides adopt β-boomerang like conformations in complex with LPS. Structure-activity studies demonstrated some critical features of the β-boomerang scaffold that may be utilized for the further development of potent analogs. In this work, β-boomerang lipopeptides were designed and structure-activity correlation studies were carried out. These lipopeptides were homo-dimerized through a disulfide bridge to stabilize conformations and for improved activity. The designed peptides exhibited potent antibacterial activity and efficiently neutralized LPS toxicity under in vitro assays. NMR structure of C4YI13C in aqueous solution demonstrated the conserved folding of the lipopeptide with a boomerang aromatic lock stabilized with disulfide bond at the C-terminus and acylation at the N-terminus. These lipo-peptides displaying bacterial sterilization and low hemolytic activity may be useful for future applications as antimicrobial and antiendotoxin molecules.

Hydrolytic breakdown of lactoferricin by lactic acid bacteria.

PubMed

Paul, Moushumi; Somkuti, George A

2010-02-01

Lactoferricin is a 25-amino acid antimicrobial peptide fragment that is liberated by pepsin digestion of lactoferrin present in bovine milk. Along with its antibacterial properties, lactoferricin has also been reported to have immunostimulatory, antiviral, and anticarcinogenic effects. These attributes provide lactoferricin and other natural bioactive peptides with the potential to be functional food ingredients that can be used by the food industry in a variety of applications. At present, commercial uses of these types of compounds are limited by the scarcity of information on their ability to survive food processing environments. We have monitored the degradation of lactoferricin during its incubation with two types of lactic acid bacteria used in the yogurt-making industry, Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus, with the aim of assessing the stability of this milk protein-derived peptide under simulated yogurt-making conditions. Analysis of the hydrolysis products isolated from these experiments indicates degradation of this peptide near neutral pH by lactic acid bacteria-associated peptidases, the extent of which was influenced by the bacterial strain used. However, the data also showed that compared to other milk-derived bioactive peptides that undergo complete degradation under these conditions, the 25-amino acid lactoferricin is apparently more resistant, with approximately 50% of the starting material remaining after 4 h of incubation. These findings imply that lactoferricin, as a natural milk protein-derived peptide, has potential applications in the commercial production of yogurt-like fermented dairy products as a multi-functional food ingredient.

Some probiotic and antibacterial properties of Lactobacillus acidophilus cultured from dahi a native milk product.

PubMed

Mahmood, Talat; Masud, Tariq; Sohail, Asma

2014-08-01

In this study, different strains of Lactobacillus acidophilus from dahi were analyzed for certain probiotic and antibacterial properties. Initially, these strains were confirmed by the amplification of 16S rRNA regions and then screened for antibacterial activities against food borne pathogens. The phenotypic relationship between apparent antibacterial activity and cell wall proteins were established by cluster analysis. It was observed that those strains, which have prominent bands having size 22-25 kDa possess antibacterial activity. On the basis of wide spectrum of killing pattern, a strain LA06FT was further characterized that showed no change in its behavior when subjected to the antibiotic protected environment and grow well in acid-bile conditions. The bacteriocin produced by this strain has specific antibacterial activity of 5369.13 AU mg(-1). It remained stable at 60-90 °C and pH range of 4.5-6.5 while proteolytic enzymes inactivate the bacteriocin that confirm its proteinic nature having molecular weight of ≤8.5 kDa.

[Screening and antibacterial function of Bacillus amyloliquefaciens X030].

PubMed

He, Hao; Zhu, Yingling; Chi, Liqing; Zhao, Zizhao; Wang, Ting; Zuo, Mingxing; Zhang, Tong; Zhou, Fengjuan; Xia, Liqiu; Ding, Xuezhi

2015-09-04

We isolated 339 bacillus strains from 72 soil samples all over the country, then purified their antimicrobial compounds and studied the antibacterial activity, to enrich bacillus resources and explore their second metabolites. A bacillus strain with strong antibacterial activity was selected by dilution plate and water bath heating from a soil sample from a peanut plantation in Henan Province; this strain was identified according to morphological observation, physiological and biochemical characteristics, and consequences of 16S rRNA homologous analysis. Antibacterial compound from the identified strain, Bacillus amyloliquefaciens X030, was separated and purified by acetone precipitation, Sephadex chromatography, C18 reverse phase column chromatography. Its molecular weight was analyzed by LC-MS/MS. The antibacterial activity was characterized by disc diffusion and plate two-way cultivation. Bacillus amyloliquefaciens was isolated that not only has antibacterial activity against Staphylococcus aureus, Candida albican and Saccharomycetes; but also against Pyriculariaoryzae, Chili pointed cell anthrax, Gloeosporium eriobotryae speg and Phytophthora parasitica. The compound was confirmed as polypeptide. Bacillus amyloliquefaciens X030 can produce a polypeptide that inhibits pathogenic bacteria and plant pathogenic fungi.

Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banu, Afreen; Rathod, Vandana, E-mail: drvandanarathod@rediffmail.com; Ranganath, E.

Highlights: {yields} Silver nanoparticle production by using Rhizopus stolonifer. {yields} Antibacterial activity of silver nanoparticles against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae. {yields} Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. {yields} Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silvermore » nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.« less

Antibiotic and synergistic effect of Leu-Lys rich peptide against antibiotic resistant microorganisms isolated from patients with cholelithiasis.

PubMed

Jeong, Nari; Kim, Jin-Young; Park, Seong-Cheol; Lee, Jong-Kook; Gopal, Ramamourthy; Yoo, Suyeon; Son, Byoung Kwan; Hahm, Joon Soo; Park, Yoonkyung; Hahm, Kyung-Soo

2010-09-03

Pseudomonas aeruginosa has eventually developed resistance against flomoxef sodium, isepamicin and cefpiramide. Therefore, in this study, the antibacterial activity and synergistic effects of the amphipathic-derived P5-18mer antimicrobial peptide were tested against pathogens associated with cholelithiasis that have developed resistance against commonly used antibiotics. The results were then compared with the activities of the amphipathic-derived peptide, P5-18mer, melittin and common antibiotics. Growth inhibition of planktonic bacteria was tested using the National Committee for Clinical Laboratory Standards (NCCLS). The bactericidal activity of the antimicrobial peptides was measured using time-kill curves. Synergistic effects were evaluated by testing the effects of P5-18mer alone and in combination with flomoxef sodium, isepamicin or cefpiramide at 0.5xMIC. P5-18mer peptide displayed strong activity against pathogens and flomoxef sodium, isepamicin and cefpiramide-resistant bacteria cell lines obtained from a patient with gallstones; however, it did not exert cytotoxicity against the human keratinocyte HaCat cell line. In addition, the results of time-kill curves indicated that P5-18mer peptide exerted bactericidal activity against four strains of P. aeruginosa. Finally, the use of P5-18mer and antibiotics exerted synergistic effects against cell lines that were resistant to commonly used antibiotics. These results indicate that this class of peptides has a rapid microbicidal effect on flomoxef sodium, isepamicin and cefpiramide-resistant strains of P. aeruginosa. Therefore, these peptides may be used as a lead drug for the treatment of acquired pathogens from patients with cholelithiasis who are affected with antibiotic-resistant bacteria. Copyright 2010 Elsevier Inc. All rights reserved.

Optimization of mechanical properties, biocorrosion properties and antibacterial properties of as-cast Ti-Cu alloys.

PubMed

Zhang, Erlin; Ren, Jing; Li, Shengyi; Yang, Lei; Qin, Gaowu

2016-10-21

Ti-Cu sintered alloys have shown good antibacterial abilities. However, the sintered method (powder metallurgy) is not convenient to produce devices with a complex structure. In this paper, Ti-Cu alloys with 2.0, 3.0 and 4.0 wt.% Cu were prepared in an arc melting furnace and subjected to different heat treatments: solid solution and ageing, to explore the possibility of preparing an antibacterial Ti-Cu alloy by a casting method and to examine the effect of Cu content. Phase identification was conducted on an XRD diffraction meter, and the microstructure was observed by a metallographic microscope, a scanning electron microscope (SEM) with energy disperse spectroscopy (EDS) and transmission electron microscopy (TEM). Microhardness and the compressive property of Ti-Cu alloys were tested, and the corrosion resistance and antibacterial activity were assessed in order to investigate the effect of the Cu content. Results showed that the as-cast Ti-Cu alloys exhibited a very low antibacterial rate against Staphylococcus aureus (S. aureus). Heat treatment improved the antibacterial rate significantly, especially after a solid and ageing treatment (T6). Antibacterial rates as high as 90.33% and 92.57% were observed on Ti-3Cu alloy and Ti-4Cu alloy, respectively. The hardness, the compressive yield strength, the anticorrosion resistance and the antibacterial rate of Ti-Cu alloys increased with an increase of Cu content in all conditions. It was demonstrated that homogeneous distribution and a fine Ti 2 Cu phase played a very important role in the mechanical property, anticorrosion and antibacterial properties. Furthermore, it should be pointed out that the Cu content should be at least 3 wt.% to obtain good antibacterial properties (>90% antibacterial rate) as well as satisfactory mechanical properties.

NLF20: an antimicrobial peptide with therapeutic potential against invasive Pseudomonas aeruginosa infection.

PubMed

Papareddy, Praveen; Kasetty, Gopinath; Kalle, Martina; Bhongir, Ravi K V; Mörgelin, Matthias; Schmidtchen, Artur; Malmsten, Martin

2016-01-01

Increasing resistance to antibiotics makes antimicrobial peptides interesting as novel therapeutics. Here, we report on studies of the peptide NLF20 (NLFRKLTHRLFRRNFGYTLR), corresponding to an epitope of the D helix of heparin cofactor II (HCII), a plasma protein mediating bacterial clearance. Peptide effects were evaluated by a combination of in vitro and in vivo methods, including antibacterial, anti-inflammatory and cytotoxicity assays, fluorescence and electron microscopy, and experimental models of endotoxin shock and Pseudomonas aeruginosa sepsis. The results showed that NLF20 displayed potent antimicrobial effects against the Gram-negative bacteria Escherichia coli and P. aeruginosa, the Gram-positive Bacillus subtilis and Staphylococcus aureus and the fungi Candida albicans and Candida parapsilosis. Importantly, this antimicrobial effect was retained in human blood, particularly for P. aeruginosa. Fluorescence and electron microscopy studies showed that the peptide exerted membrane-breaking effects. In an animal model of P. aeruginosa sepsis, NLF20 reduced bacterial levels, resulting in improved survival. Reduced mortality was also observed in experimental animal models of endotoxin shock, which was paralleled with modulated IFN-γ, IL-10 and coagulation responses. Together, these results indicate that functional epitopes of HCII may have therapeutic potential against bacterial infection. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Structure of the complex between teicoplanin and a bacterial cell-wall peptide: use of a carrier-protein approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Economou, Nicoleta J.; Zentner, Isaac J.; Lazo, Edwin

2013-04-01

Using a carrier-protein strategy, the structure of teicoplanin bound to its bacterial cell-wall target has been determined. The structure reveals the molecular determinants of target recognition, flexibility in the antibiotic backbone and intrinsic radiation sensitivity of teicoplanin. Multidrug-resistant bacterial infections are commonly treated with glycopeptide antibiotics such as teicoplanin. This drug inhibits bacterial cell-wall biosynthesis by binding and sequestering a cell-wall precursor: a d-alanine-containing peptide. A carrier-protein strategy was used to crystallize the complex of teicoplanin and its target peptide by fusing the cell-wall peptide to either MBP or ubiquitin via native chemical ligation and subsequently crystallizing the protein–peptide–antibiotic complex.more » The 2.05 Å resolution MBP–peptide–teicoplanin structure shows that teicoplanin recognizes its ligand through a combination of five hydrogen bonds and multiple van der Waals interactions. Comparison of this teicoplanin structure with that of unliganded teicoplanin reveals a flexibility in the antibiotic peptide backbone that has significant implications for ligand recognition. Diffraction experiments revealed an X-ray-induced dechlorination of the sixth amino acid of the antibiotic; it is shown that teicoplanin is significantly more radiation-sensitive than other similar antibiotics and that ligand binding increases radiosensitivity. Insights derived from this new teicoplanin structure may contribute to the development of next-generation antibacterials designed to overcome bacterial resistance.« less

A New Synthetic Peptide with In vitro Antibacterial Potential Against Escherichia coli O157:H7 and Methicillin-Resistant Staphylococcus aureus (MRSA).

PubMed

Prada, Y A; Guzmán, F; Rondón, P; Escobar, P; Ortíz, C; Sierra, D A; Torres, R; Mejía-Ospino, E

2016-09-01

In this work, we performed the rational design of a cationic antimicrobial peptide, GIBIMPY4, using the software DEPRAMPs developed at the GIBIM research group. GIBIMPY4 has a length of 17 amino acids, it is amphipathic, its structure is α-helix and it has a net charge of (+5). Solid-phase peptide synthesis was performed using the Fmoc strategy in acid medium. The primary structure was confirmed by MALDI-TOF mass spectrometry. The antimicrobial activity of the peptide was evaluated by broth microdilution method by measuring optical density in 96-well microplates. The minimal inhibitory concentration of GIBIMPY4 to kill 50 % of the bacterial cells (MIC50) was 6.20 ± 0.02 µM for MRSA and 4.55 ± 0.02 µM for E. coli O157:H7, while also reporting a bacteriostatic effect for the later. GIBIMPY4 activity was sensitive to salt concentration in E. coli but insignificant effect in its activity against MRSA. The peptide seems to be a broad-spectrum antimicrobial agent based on the results against Gram-positive and Gram-negative bacteria and was specific for bacterial cells E. coli O157:H7 with index of specificity equal to 9.01 in vitro assays.

Identification of a new peptide deformylase gene from enterococcus faecium and establishment of a new screening model targeted on PDF for novel antibiotics.

PubMed

Tang, Xian-Bing; Si, Shu-Yi; Zhang, Yue-Qin

2004-09-01

To identify a new peptide deformylase (PDF) gene (Genebank Accession AY238515) from Enterococcus faecium and to establish a new screening model targeted on PDF. A new PDF gene was identified by BLAST analysis and PCR and was subsequently over-expressed in the prokaryotic expression host E. coli B121(DE3). Over-expressed protein was purified for enzymatic assay by metal affinity chromatography and a new screening model was established for novel antibiotics. A new PDF gene of Enterococcus faecium was identified successfully. Ten positive samples were picked up from 8000 compound library and the microbial fermentation broth samples. A new PDF of gene Enterococcus faecium was first identified and the model had a high efficacy. Positive samples screened may be antibacterial agents of broad spectrum.

Antibacterial property of Ag nanoparticle-impregnated N-doped titania films under visible light

PubMed Central

Wong, Ming-Show; Chen, Chun-Wei; Hsieh, Chia-Chun; Hung, Shih-Che; Sun, Der-Shan; Chang, Hsin-Hou

2015-01-01

Photocatalysts produce free radicals upon receiving light energy; thus, they possess antibacterial properties. Silver (Ag) is an antibacterial material that disrupts bacterial physiology. Our previous study reported that the high antibacterial property of silver nanoparticles on the surfaces of visible light-responsive nitrogen-doped TiO2 photocatalysts [TiO2(N)] could be further enhanced by visible light illumination. However, the major limitation of this Ag-TiO2 composite material is its durability; the antibacterial property decreased markedly after repeated use. To overcome this limitation, we developed TiO2(N)/Ag/TiO2(N) sandwich films in which the silver is embedded between two TiO2(N) layers. Various characteristics, including silver and nitrogen amounts, were examined in the composite materials. Various analyses, including electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and ultraviolet–visible absorption spectrum and methylene blue degradation rate analyses, were performed. The antibacterial properties of the composite materials were investigated. Here we revealed that the antibacterial durability of these thin films is substantially improved in both the dark and visible light, by which bacteria, such as Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, and Acinetobacter baumannii, could be efficiently eliminated. This study demonstrated a feasible approach to improve the visible-light responsiveness and durability of antibacterial materials that contain silver nanoparticles impregnated in TiO2(N) films. PMID:26156001

Antibacterial property of Ag nanoparticle-impregnated N-doped titania films under visible light

NASA Astrophysics Data System (ADS)

Wong, Ming-Show; Chen, Chun-Wei; Hsieh, Chia-Chun; Hung, Shih-Che; Sun, Der-Shan; Chang, Hsin-Hou

2015-07-01

Photocatalysts produce free radicals upon receiving light energy; thus, they possess antibacterial properties. Silver (Ag) is an antibacterial material that disrupts bacterial physiology. Our previous study reported that the high antibacterial property of silver nanoparticles on the surfaces of visible light-responsive nitrogen-doped TiO2 photocatalysts [TiO2(N)] could be further enhanced by visible light illumination. However, the major limitation of this Ag-TiO2 composite material is its durability; the antibacterial property decreased markedly after repeated use. To overcome this limitation, we developed TiO2(N)/Ag/TiO2(N) sandwich films in which the silver is embedded between two TiO2(N) layers. Various characteristics, including silver and nitrogen amounts, were examined in the composite materials. Various analyses, including electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and ultraviolet-visible absorption spectrum and methylene blue degradation rate analyses, were performed. The antibacterial properties of the composite materials were investigated. Here we revealed that the antibacterial durability of these thin films is substantially improved in both the dark and visible light, by which bacteria, such as Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, and Acinetobacter baumannii, could be efficiently eliminated. This study demonstrated a feasible approach to improve the visible-light responsiveness and durability of antibacterial materials that contain silver nanoparticles impregnated in TiO2(N) films.

A pharmaco-epidemiological study of antibacterial treatments and bacterial diseases in Norwegian aquaculture from 2011 to 2016.

PubMed

Lillehaug, Atle; Børnes, Christine; Grave, Kari

2018-05-07

The sales and prescription of antibacterials for use in Norwegian fish-farming according to diagnosis, fish species and production stage from 2011 to 2016 are analysed. The study is based on antibacterial sales data from wholesalers, pharmacies and feed mills and on prescription data obtained from a register of all prescriptions of antibacterials used in farmed fish. The results show that the fish-farming industry uses very small volumes of antibacterials. In 2016, a total of 212 kg were sold; the only antibacterial substances sold were florfenicol and oxolinic acid. The total amount corresponded to 0.16 mg kg-1 fish slaughtered, or to approximately 0.14% of the fish produced that year. The majority of prescriptions were for non-specific bacterial infections; as most common diseases are under control by vaccination. Most prescriptions for salmonid fish were during early production stages. However, due to higher biomasses of fish, the highest quantities of antibacterials were prescribed during the seawater production phase of Atlantic salmon Salmo salar. An increasing proportion of the prescriptions was for other species, including cleaner fish used for salmon lice control; in 2016 most prescriptions were for this fish category. Due to the negligible use of antibacterials in Norwegian aquaculture, in particular for on-growers, the risk of development of antimicrobial resistance and its transmission to humans through consumption of fish is considered negligible.

Metabolic Versatility and Antibacterial Metabolite Biosynthesis Are Distinguishing Genomic Features of the Fire Blight Antagonist Pantoea vagans C9-1

PubMed Central

Smits, Theo H. M.; Rezzonico, Fabio; Kamber, Tim; Blom, Jochen; Goesmann, Alexander; Ishimaru, Carol A.; Frey, Jürg E.; Stockwell, Virginia O.; Duffy, Brion

2011-01-01

Background Pantoea vagans is a commercialized biological control agent used against the pome fruit bacterial disease fire blight, caused by Erwinia amylovora. Compared to other biocontrol agents, relatively little is currently known regarding Pantoea genetics. Better understanding of antagonist mechanisms of action and ecological fitness is critical to improving efficacy. Principal Findings Genome analysis indicated two major factors contribute to biocontrol activity: competition for limiting substrates and antibacterial metabolite production. Pathways for utilization of a broad diversity of sugars and acquisition of iron were identified. Metabolism of sorbitol by P. vagans C9-1 may be a major metabolic feature in biocontrol of fire blight. Biosynthetic genes for the antibacterial peptide pantocin A were found on a chromosomal 28-kb genomic island, and for dapdiamide E on the plasmid pPag2. There was no evidence of potential virulence factors that could enable an animal or phytopathogenic lifestyle and no indication of any genetic-based biosafety risk in the antagonist. Conclusions Identifying key determinants contributing to disease suppression allows the development of procedures to follow their expression in planta and the genome sequence contributes to rationale risk assessment regarding the use of the biocontrol strain in agricultural systems. PMID:21789243

More than anticipated - production of antibiotics and other secondary metabolites by Bacillus amyloliquefaciens FZB42.

PubMed

Chen, Xiao-Hua; Koumoutsi, Alexandra; Scholz, Romy; Borriss, Rainer

2009-01-01

The genome of environmental Bacillus amyloliquefaciens FZB42 harbors numerous gene clusters involved in synthesis of antifungal and antibacterial acting secondary metabolites. Five gene clusters, srf, bmy, fen, nrs, dhb, covering altogether 137 kb, direct non-ribosomal synthesis of the cyclic lipopeptides surfactin, bacillomycin, fengycin, an unknown peptide, and the iron siderophore bacillibactin. Bacillomycin and fengycin were shown to act against phytopathogenic fungi in a synergistic manner. Three gene clusters, mln, bae, and dif, with a total length of 199 kb were shown to direct synthesis of the antibacterial acting polyketides macrolactin, bacillaene, and difficidin. Both, non-ribosomal synthesis of cyclic lipopeptides and synthesis of polyketides are dependent on the presence of a functional sfp gene product, 4'-phosphopantetheinyl transferase, as evidenced by knockout mutation of the sfp gene resulting in complete absence of all those eight compounds. In addition, here we present evidence that a gene cluster encoding enzymes involved in synthesis and export of the antibacterial acting dipeptide bacilysin is also functional in FZB42. In summary, environmental FZB42 devoted about 340 kb, corresponding to 8.5% of its total genetic capacity, to synthesis of secondary metabolites useful to cope with other competing microorganisms present in the plant rhizosphere. Copyright (c) 2008 S. Karger AG, Basel.

A PiggyBac mediated approach for lactoferricin gene transfer in bovine mammary epithelial stem cells for management of bovine mastitis.

PubMed

Sharma, Neelesh; Huynh, Do Luong; Kim, Sung Woo; Ghosh, Mrinmoy; Sodhi, Simrinder Singh; Singh, Amit Kumar; Kim, Nam Eun; Lee, Sung Jin; Hussain, Kafil; Oh, Sung Jong; Jeong, Dong Kee

2017-11-28

The antibacterial and anti-inflammatory properties of lactoferricin have been ascribed to its ability to sequester essential iron. The objective of the study was to clone bovine lactoferricin ( LFcinB ) gene into PiggyBac Transposon vector, expression study in the bovine mammary epithelial stem cells (bMESCs) and also to determine the antimicrobial property of recombinant LFcinB against bovine mastitis-causing organisms. The PiggyBac-LFcinB was transfected into bMESCs by electroporation and a three fold of LFcinB secretion was observed in the transfected bMESCs medium by ELISA assay. Furthermore, the assessment of antimicrobial activity against mastitis causing pathogens Staphylococcus aureus and Escherichia coli demonstrated convincing evidence to prove strong antibacterial activity of LFcinB with 14.0±1.0 mm and 18.0±1.5 mm zone of inhibition against both organisms, respectively. The present study provides the convincing evidence to suggest the potential of PiggyBac transposon system to transfer antibacterial peptide into bMESCs or cow mammary gland and also pave the way to use bovine mammary gland as the bioreactors. Simultaneously, it also suggest toward commercial utilization of LFcinB bioreactor system in pharmaceutical industry.

A PiggyBac mediated approach for lactoferricin gene transfer in bovine mammary epithelial stem cells for management of bovine mastitis

PubMed Central

Sharma, Neelesh; Huynh, Do Luong; Kim, Sung Woo; Ghosh, Mrinmoy; Sodhi, Simrinder Singh; Singh, Amit Kumar; Kim, Nam Eun; Lee, Sung Jin; Hussain, Kafil; Oh, Sung Jong; Jeong, Dong Kee

2017-01-01

The antibacterial and anti-inflammatory properties of lactoferricin have been ascribed to its ability to sequester essential iron. The objective of the study was to clone bovine lactoferricin (LFcinB) gene into PiggyBac Transposon vector, expression study in the bovine mammary epithelial stem cells (bMESCs) and also to determine the antimicrobial property of recombinant LFcinB against bovine mastitis-causing organisms. The PiggyBac-LFcinB was transfected into bMESCs by electroporation and a three fold of LFcinB secretion was observed in the transfected bMESCs medium by ELISA assay. Furthermore, the assessment of antimicrobial activity against mastitis causing pathogens Staphylococcus aureus and Escherichia coli demonstrated convincing evidence to prove strong antibacterial activity of LFcinB with 14.0±1.0 mm and 18.0±1.5 mm zone of inhibition against both organisms, respectively. The present study provides the convincing evidence to suggest the potential of PiggyBac transposon system to transfer antibacterial peptide into bMESCs or cow mammary gland and also pave the way to use bovine mammary gland as the bioreactors. Simultaneously, it also suggest toward commercial utilization of LFcinB bioreactor system in pharmaceutical industry. PMID:29262639

Purification and characterisation of a novel antistaphylococcal peptide (ASP-1) from Bacillus sp. URID 12.1.

PubMed

Chalasani, Ajay Ghosh; Roy, Utpal; Nema, Sushma

2018-01-01

A strong antistaphylococcal peptide (ASP-1) from Bacillus subtilis URID 12.1 strain that is active against cefoxitin- and methicillin-resistant Staphylococcus aureus clinical isolates was purified to homogeneity by solvent extraction, silica gel-based adsorption chromatography and reversed-phase high-performance liquid chromatography. The peptide sequence of ASP-1 as determined by MALDI-TOF/MS and ESI-FTICR-MS was acetylated Phe-Thr-Ala-Val-Dhb-Phe-Ile/Leu. The peptide was further analysed by alkaline hydrolysis, ESI-Q-TOF-MS and an ion mobility assay, which detected the presence of a lactone ring in the intact peptide and a cyclic nature, subsequently revealing the linearised peptide sequence as acPhe-Leu-Phe-Thr-Val-Ala-Dhb. Based on the molecular mass (804.5 Da), peptide sequence and amino acid composition, ASP-1 was identified as a lactone ring-containing peptide similar to TL-119, a poorly studied cyclic depsipeptide. Circular dichroism spectroscopy revealed its predominantly random structure in aqueous solution and its β-sheet conformation in methanol. Minimum inhibitory concentrations (MICs) of the purified peptide against S. aureus and methicillin-resistant S. aureus (MRSA) ranged from 2 µg/mL to 64 µg/mL. At sub-MICs and 1× MIC, ASP-1 showed a strong antibiofilm characteristic. ASP-1 at a concentration of 128 µg/mL did not show haemolytic activity, and no cytotoxicity was observed against hepatic carcinoma and breast carcinoma cell lines at the same concentration. Peptide ASP-1 with anti-MRSA and antibiofilm abilities and non-haemolytic and non-cytotoxic properties has not been reported previously. These findings suggest that it may serve as a lead molecule for developing alternative topical antibacterial agents. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Functional Analysis of the Gene Cluster Involved in Production of the Bacteriocin Circularin A by Clostridium beijerinckii ATCC 25752

PubMed Central

Kemperman, Robèr; Jonker, Marnix; Nauta, Arjen; Kuipers, Oscar P.; Kok, Jan

2003-01-01

A region of 12 kb flanking the structural gene of the cyclic antibacterial peptide circularin A of Clostridium beijerinckii ATCC 25752 was sequenced, and the putative proteins involved in the production and secretion of circularin A were identified. The genes are tightly organized in overlapping open reading frames. Heterologous expression of circularin A in Enterococcus faecalis was achieved, and five genes were identified as minimally required for bacteriocin production and secretion. Two of the putative proteins, CirB and CirC, are predicted to contain membrane-spanning domains, while CirD contains a highly conserved ATP-binding domain. Together with CirB and CirC, this ATP-binding protein is involved in the production of circularin A. The fifth gene, cirE, confers immunity towards circularin A when expressed in either Lactococcus lactis or E. faecalis and is needed in order to allow the bacteria to produce bacteriocin. Additional resistance against circularin A is conferred by the activity of the putative transporter consisting of CirB and CirD. PMID:14532033

Identification of Inhibitors of PvdQ, an Enzyme Involved in the Synthesis of the Siderophore Pyoverdine

PubMed Central

2015-01-01

Pseudomonas aeruginosa produces the peptide siderophore pyoverdine, which is used to acquire essential Fe3+ ions from the environment. PvdQ, an Ntn hydrolase, is required for the biosynthesis of pyoverdine. PvdQ knockout strains are not infectious in model systems, suggesting that disruption of siderophore production via PvdQ inhibition could be exploited as a target for novel antibacterial agents, by preventing cells from acquiring iron in the low iron environments of most biological settings. We have previously described a high-throughput screen to identify inhibitors of PvdQ that identified inhibitors with IC50 values of ∼100 μM. Here, we describe the discovery of ML318, a biaryl nitrile inhibitor of PvdQ acylase. ML318 inhibits PvdQ in vitro (IC50 = 20 nM) by binding in the acyl-binding site, as confirmed by the X-ray crystal structure of PvdQ bound to ML318. Additionally, the PvdQ inhibitor is active in a whole cell assay, preventing pyoverdine production and limiting the growth of P. aeruginosa under iron-limiting conditions. PMID:24824984

Purification and partial characterization of a novel antibacterial agent (Bac1829) Produced by Staphylococcus aureus KSI1829.

PubMed Central

Crupper, S S; Iandolo, J J

1996-01-01

A novel antimicrobial agent from Staphylococcus aureus KSI1829, designated Bac1829, was purified by sequential steps of ammonium sulfate precipitation, Sephadex G-50 gel filtration chromatography, and hydrophobic interaction chromatography. Purified Bac1829 has a molecular mass of 6,418 +/- 2 Da. The peptide in heat stable, since full biological activity is retained after heating at 95 degrees C for 15 min, and it is destroyed by digestion with proteases. Amino acid sequence analysis revealed a high concentration of Ala and Gly residues, which respectively comprised 24 and 19% of the total amino acid content. Additionally, high levels of hydrophobic amino acids were present, accounting for the hydrophobic nature of Bac1829. Purified Bac1829 killed exponentially growing Corynebacterium renale in a dose-dependent manner by a bactericidal mode of action. A partial inhibitory spectrum analysis revealed that the following organisms were sensitive to the inhibitory activity of Bac1829: S. aureus RN4220, Streptococcus suis, Corynebacterium pseudotuberculosis, C. renale, Corynebacterium diptheriae, Haemophilus parasuis, Bordetella pertussis, Bordetella bronchoseptica, Moraxella bovis, and Pasteurella multocida. PMID:8795206

Immunomodulatory Yersinia outer proteins (Yops)–useful tools for bacteria and humans alike

PubMed Central

Grabowski, Benjamin; Schmidt, M. Alexander; Rüter, Christian

2017-01-01

ABSTRACT Human-pathogenic Yersinia produce plasmid-encoded Yersinia outer proteins (Yops), which are necessary to down-regulate anti-bacterial responses that constrict bacterial survival in the host. These Yops are effectively translocated directly from the bacterial into the target cell cytosol by the type III secretion system (T3SS). Cell-penetrating peptides (CPPs) in contrast are characterized by their ability to autonomously cross cell membranes and to transport cargo – independent of additional translocation systems. The recent discovery of bacterial cell-penetrating effector proteins (CPEs) – with the prototype being the T3SS effector protein YopM – established a new class of autonomously translocating immunomodulatory proteins. CPEs represent a vast source of potential self-delivering, anti-inflammatory therapeutics. In this review, we give an update on the characteristic features of the plasmid-encoded Yops and, based on recent findings, propose the further development of these proteins for potential therapeutic applications as natural or artificial cell-penetrating forms of Yops might be of value as bacteria-derived biologics. PMID:28296562

Antibacterial application of engineered bacteriophage nanomedicines: antibody-targeted, chloramphenicol prodrug loaded bacteriophages for inhibiting the growth of Staphylococcus aureus bacteria.

PubMed

Vaks, Lilach; Benhar, Itai

2011-01-01

The increasing development of bacterial resistance to traditional antibiotics has reached alarming levels, thus there is an urgent need to develop new antimicrobial agents. To be effective, these new antimicrobials should possess novel modes of action and/or different cellular targets compared with existing antibiotics. Bacteriophages (phages) have been used for over a century as tools for the treatment of bacterial infections, for nearly half a century as tools in genetic research, for about two decades as tools for the discovery of specific target-binding proteins and peptides, and for almost a decade as tools for vaccine development. We describe a new application in the area of antibacterial nanomedicines where filamentous phages can be formulated as targeted drug-delivery vehicles of nanometric dimensions (phage nanomedicines) and used for therapeutic purposes. This protocol involves both genetic and chemical engineering of these phages. The genetic engineering of the phage coat, which results in the display of a target-specificity-conferring peptide or protein on the phage coat, can be used to design the drug-release mechanism and is not described herein. However, the methods used to chemically conjugate cytotoxic drugs at high density on the phage coat are described. Further, assays to measure the drug load on the surface of the phage and the potency of the system in the inhibition of growth of target cells as well as assessment of the therapeutic potential of the phages in a mouse disease model are discussed.

Peptide Deformylase Inhibitors as Potent Antimycobacterial Agents▿ †

PubMed Central

Teo, Jeanette W. P.; Thayalan, Pamela; Beer, David; Yap, Amelia S. L.; Nanjundappa, Mahesh; Ngew, Xinyi; Duraiswamy, Jeyaraj; Liung, Sarah; Dartois, Veronique; Schreiber, Mark; Hasan, Samiul ; Cynamon, Michael; Ryder, Neil S.; Yang, Xia; Weidmann, Beat; Bracken, Kathryn ; Dick, Thomas; Mukherjee, Kakoli

2006-01-01

Peptide deformylase (PDF) catalyzes the hydrolytic removal of the N-terminal formyl group from nascent proteins. This is an essential step in bacterial protein synthesis, making PDF an attractive target for antibacterial drug development. Essentiality of the def gene, encoding PDF from Mycobacterium tuberculosis, was demonstrated through genetic knockout experiments with Mycobacterium bovis BCG. PDF from M. tuberculosis strain H37Rv was cloned, expressed, and purified as an N-terminal histidine-tagged recombinant protein in Escherichia coli. A novel class of PDF inhibitors (PDF-I), the N-alkyl urea hydroxamic acids, were synthesized and evaluated for their activities against the M. tuberculosis PDF enzyme as well as their antimycobacterial effects. Several compounds from the new class had 50% inhibitory concentration (IC50) values of <100 nM. Some of the PDF-I displayed antibacterial activity against M. tuberculosis, including MDR strains with MIC90 values of <1 μM. Pharmacokinetic studies of potential leads showed that the compounds were orally bioavailable. Spontaneous resistance towards these inhibitors arose at a frequency of ≤5 × 10−7 in M. bovis BCG. DNA sequence analysis of several spontaneous PDF-I-resistant mutants revealed that half of the mutants had acquired point mutations in their formyl methyltransferase gene (fmt), which formylated Met-tRNA. The results from this study validate M. tuberculosis PDF as a drug target and suggest that this class of compounds have the potential to be developed as novel antimycobacterial agents. PMID:16966397

A single WAP domain (SWD)-containing protein with antiviral activity from Pacific white shrimp Litopenaeus vannamei.

PubMed

Yang, Linwei; Niu, Shengwen; Gao, Jiefeng; Zuo, Hongliang; Yuan, Jia; Weng, Shaoping; He, Jianguo; Xu, Xiaopeng

2018-02-01

The single whey acidic protein (WAP) domain (SWD)-containing proteins, also called type III crustins, are a group of antimicrobial peptides (AMPs) in crustaceans. At present, a number of SWDs have been identified in shrimp, which showed essential antibacterial activities. However, the roles of SWDs in antiviral immune responses have not been reported up to now. In this study, a novel SWD (LvSWD3) was identified from Pacific white shrimp, Litopenaeus vannamei, which contained a typical single WAP domain homologous to those of other crustacean SWDs. Although lacking the pro and arg-rich region between the signal peptide and the WAP domain, LvSWD3 was closely clustered with other shrimp SWDs in the phylogenetic tree. Similar to many shrimp SWDs, the highest expression of LvSWD3 was detected in hemocytes. The LvSWD3 expression exhibited only limited changes after challenges with Vibrio parahaemolyticus, Poly (I:C) and lipopolysaccharide, but was significantly up-regulated after white spot syndrome virus (WSSV) infection. Silencing of LvSWDs significantly accelerated the death of the WSSV-infected but not the V. parahaemolyticus-infected shrimp. The recombinant LvSWD3 protein did not show proteinase inhibitory and antibacterial activities but could significantly postpone the death of WSSV-infected shrimp and reduce the viral load in tissues. These suggested that LvSWD3 was a novel SWD with antiviral activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Expression and characterization of the antimicrobial peptide ABP-dHC-cecropin A in the methylotrophic yeast Pichia pastoris.

PubMed

Sang, Ming; Wei, Hui; Zhang, Jiaxin; Wei, Zhiheng; Wu, Xiaolong; Chen, Yan; Zhuge, Qiang

2017-12-01

ABP-dHC-cecropin A is a linear cationic peptide that exhibits antimicrobial properties. To explore a new approach for expression of ABP-dHC-cecropin A using the methylotrophic yeast Pichia pastoris, we cloned the ABP-dHC-cecropin A gene into the vector pPICZαA. The SacI-linearized plasmid pPICZαA-ABP-dHC-cecropin A was then transformed into P. pastoris GS115 by electroporation. Expression was induced after a 96-h incubation with 0.5% methanol at 20 °C in a culture supplied with 2% casamino acids to avoid proteolysis. Under these conditions, approximately 48 mg of ABP-dHC-cecropin A was secreted into 1L (4 × 250-mL)of medium. Recombinant ABP-dHC-cecropin A was purified using size-exclusion chromatography, and 21 mg of pure active ABP-dHC-cecropin A was obtained from 1L (4 × 250-mL)of culture. Electrophoresis on 4-20% gradient gels indicated that recombinant ABP-dHC-cecropin A was secreted as a protein approximately 4 kDa in size. Recombinant ABP-dHC-cecropin A was successfully expressed, as the product displayed antibacterial and antifungal activities (based on an antibacterial assay, scanning electron microscopy, and antifungal assay) indistinguishable from those of the synthesized protein. Copyright © 2017 Elsevier Inc. All rights reserved.

Trypsin-dependent production of an antibacterial substance by a human Peptostreptococcus strain in gnotobiotic rats and in vitro.

PubMed

Ramare, F; Nicoli, J; Dabard, J; Corring, T; Ladire, M; Gueugneau, A M; Raibaud, P

1993-09-01

An antibacterial substance appeared within 1 day in feces of gnotobiotic rats harboring a human intestinal Peptostreptococcus strain. It disappeared when the rat bile-pancreatic duct was ligatured or when the rats ingested a trypsin inhibitor. Anaerobic cultures of the Peptostreptococcus strain in a medium supplemented with trypsin also exhibited an antibacterial activity, which was also inhibited by the trypsin inhibitor. In vitro the antibacterial substance from both feces and culture medium was active against several gram-positive bacteria, including other Peptostreptococcus spp., potentially pathogenic Clostridium spp. such as C. perfringens, C. difficile, C. butyricum, C. septicum, and C. sordellii, Eubacterium spp., Bifidobacterium spp., and Bacillus spp. Whatever the order of inoculation of the strains, a sensitive strain of C. perfringens was eliminated within 1 day from the intestine of rats monoassociated with the Peptostreptococcus strain. These findings demonstrate for the first time that very potent antibacterial substances can be produced through a mechanism involving intestinal bacteria and exocrine pancreatic secretions.

Non-Equilibrium Plasma Processing for the Preparation of Antibacterial Surfaces

PubMed Central

Sardella, Eloisa; Palumbo, Fabio; Camporeale, Giuseppe; Favia, Pietro

2016-01-01

Non-equilibrium plasmas offer several strategies for developing antibacterial surfaces that are able to repel and/or to kill bacteria. Due to the variety of devices, implants, and materials in general, as well as of bacteria and applications, plasma assisted antibacterial strategies need to be tailored to each specific surface. Nano-composite coatings containing inorganic (metals and metal oxides) or organic (drugs and biomolecules) compounds can be deposited in one step, and used as drug delivery systems. On the other hand, functional coatings can be plasma-deposited and used to bind antibacterial molecules, for synthesizing surfaces with long lasting antibacterial activity. In addition, non-fouling coatings can be produced to inhibit the adhesion of bacteria and reduce the formation of biofilm. This paper reviews plasma-based strategies aimed to reduce bacterial attachment and proliferation on biomedical materials and devices, but also onto materials used in other fields. Most of the activities described have been developed in the lab of the authors. PMID:28773637

Soya bean tempe extracts show antibacterial activity against Bacillus cereus cells and spores.

PubMed

Roubos-van den Hil, P J; Dalmas, E; Nout, M J R; Abee, T

2010-07-01

Tempe, a Rhizopus ssp.-fermented soya bean food product, was investigated for bacteriostatic and/or bactericidal effects against cells and spores of the food-borne pathogen Bacillus cereus. Tempe extract showed a high antibacterial activity against B. cereus ATCC 14579 based on optical density and viable count measurements. This growth inhibition was manifested by a 4 log CFU ml(-1) reduction, within the first 15 min of exposure. Tempe extracts also rapidly inactivated B. cereus spores upon germination. Viability and membrane permeability assessments using fluorescence probes showed rapid inactivation and permeabilization of the cytoplasmic membrane confirming the bactericidal mode of action. Cooked beans and Rhizopus grown on different media did not show antibacterial activity, indicating the unique association of the antibacterial activity with tempe. Subsequent characterization of the antibacterial activity revealed that heat treatment and protease addition nullified the bactericidal effect, indicating the proteinaceous nature of the bioactive compound. During fermentation of soya beans with Rhizopus, compounds are released with extensive antibacterial activity against B. cereus cells and spores. The results show the potential of producing natural antibacterial compounds that could be used as ingredients in food preservation and pathogen control. © 2009 The Authors. Journal compilation © 2009 The Society for Applied Microbiology.

Identification and characterization of antimicrobial peptide, defensin, in the taiga tick, Ixodes persulcatus.

PubMed

Saito, Y; Konnai, S; Yamada, S; Imamura, S; Nishikado, H; Ito, T; Onuma, M; Ohashi, K

2009-08-01

Ixodes persulcatus is the primary vector for human tick-borne diseases in Japan. A cDNA library was constructed from whole body homogenates of fed nymphs of I. persulcatus. From this library, one cDNA encoding defensin-like antimicrobial peptide was identified. The amino-acid sequence showed high similarity to those of the defensins of other ticks and arthropods. I. persulcatus defensin mRNA transcripts were detected at all life cycle stages of fed ticks and found to be predominantly expressed in the midguts of adult female ticks, but not in the salivary glands, a finding corroborated by Western blotting analysis. To investigate the function of I. persulcatus defensin, we examined its antibacterial activity by evaluation of growth of several bacterial strains in the presence of the synthetic peptide. The defensin from I. persulcatus markedly inhibited the growth of Gram-positive bacteria including Staphylococcus aureus, Bacillus subtilis and Corynebacterium renale, but not Gram-negative bacteria except Escherichia coli O157. In conclusion, these results suggest that I. persulcatus defensin may be playing a significant role in the defence against microbes from bloodmeals.

Peptide Conjugated Phosphorodiamidate Morpholino Oligomers Increase Survival of Mice Challenged with Ames Bacillus anthracis

PubMed Central

Geller, Bruce L.; Mellbye, Brett; Lane, Douglas; Iversen, Patrick L.; Bavari, Sina

2012-01-01

Targeting bacterial essential genes using antisense phosphorodiamidate morpholino oligomers (PMOs) represents an important strategy in the development of novel antibacterial therapeutics. PMOs are neutral DNA analogues that inhibit gene expression in a sequence-specific manner. In this study, several cationic, membrane-penetrating peptides were conjugated to PMOs (PPMOs) that target 2 bacterial essential genes: acyl carrier protein (acpP) and gyrase A (gyrA). These were tested for their ability to inhibit growth of Bacillus anthracis, a gram-positive spore-forming bacterium and causative agent of anthrax. PPMOs targeted upstream of both target gene start codons and conjugated with the bacterium-permeating peptide (RFF)3R were found to be most effective in inhibiting bacterial growth in vitro. Both of the gene-targeted PPMOs protected macrophages from B. anthracis induced cell death. Subsequent, in vivo testing of the PPMOs resulted in increased survival of mice challenged with the virulent Ames strain of B. anthracis. Together, these studies suggest that PPMOs targeting essential genes have the potential of being used as antisense antibiotics to treat B. anthracis infections. PMID:22978365

An In Vitro Study on the Effects of Nisin on the Antibacterial Activities of 18 Antibiotics against Enterococcus faecalis

PubMed Central

Ling, Junqi; Ma, Jinglei; Huang, Lijia; Zhang, Luodan

2014-01-01

Enterococcus faecalis rank among the leading causes of nosocomial infections worldwide and possesses both intrinsic and acquired resistance to a variety of antibiotics. Development of new antibiotics is limited, and pathogens continually generate new antibiotic resistance. Many researchers aim to identify strategies to effectively kill this drug-resistant pathogen. Here, we evaluated the effect of the antimicrobial peptide nisin on the antibacterial activities of 18 antibiotics against E. faecalis. The MIC and MBC results showed that the antibacterial activities of 18 antibiotics against E. faecalis OG1RF, ATCC 29212, and strain E were significantly improved in the presence of 200 U/ml nisin. Statistically significant differences were observed between the results with and without 200 U/ml nisin at the same concentrations of penicillin or chloramphenicol (p<0.05). The checkerboard assay showed that the combination of nisin and penicillin or chloramphenicol had a synergetic effect against the three tested E. faecalis strains. The transmission electron microscope images showed that E. faecalis was not obviously destroyed by penicillin or chloramphenicol alone but was severely disrupted by either antibiotic in combination with nisin. Furthermore, assessing biofilms by a confocal laser scanning microscope showed that penicillin, ciprofloxacin, and chloramphenicol all showed stronger antibiofilm actions in combination with nisin than when these antibiotics were administered alone. Therefore, nisin can significantly improve the antibacterial and antibiofilm activities of many antibiotics, and certain antibiotics in combination with nisin have considerable potential for use as inhibitors of this drug-resistant pathogen. PMID:24586598

Violacein-producing Collimonas sp. from the sea surface microlayer of costal waters in Trøndelag, Norway.

PubMed

Hakvåg, Sigrid; Fjaervik, Espen; Klinkenberg, Geir; Borgos, Sven Even F; Josefsen, Kjell D; Ellingsen, Trond E; Zotchev, Sergey B

2009-11-12

A new strain belonging to the genus Collimonas was isolated from the sea surface microlayer off the coast of Trøndelag, Norway. The bacterium, designated Collimonas CT, produced an antibacterial compound active against Micrococcus luteus. Subsequent studies using LC-MS identified this antibacterial compound as violacein, known to be produced by several marine-derived bacteria. Fragments of the violacein biosynthesis genes vioA and vioB were amplified by PCR from the Collimonas CT genome and sequenced. Phylogenetic analysis of these sequences demonstrated close relatedness of the Collimonas CT violacein biosynthetic gene cluster to those in Janthinobacterium lividum and Duganella sp., suggesting relatively recent horizontal gene transfer. Considering diverse biological activities of violacein, Collimonas CT shall be further studied as a potential producer of this compound.

Violacein-Producing Collimonas sp. from the Sea Surface Microlayer of Costal Waters in Trøndelag, Norway

PubMed Central

Hakvåg, Sigrid; Fjærvik, Espen; Klinkenberg, Geir; Borgos, Sven Even F.; Josefsen, Kjell D.; Ellingsen, Trond E.; Zotchev, Sergey B.

2009-01-01

A new strain belonging to the genus Collimonas was isolated from the sea surface microlayer off the coast of Trøndelag, Norway. The bacterium, designated Collimonas CT, produced an antibacterial compound active against Micrococcus luteus. Subsequent studies using LC-MS identified this antibacterial compound as violacein, known to be produced by several marine-derived bacteria. Fragments of the violacein biosynthesis genes vioA and vioB were amplified by PCR from the Collimonas CT genome and sequenced. Phylogenetic analysis of these sequences demonstrated close relatedness of the Collimonas CT violacein biosynthetic gene cluster to those in Janthinobacterium lividum and Duganella sp., suggesting relatively recent horizontal gene transfer. Considering diverse biological activities of violacein, Collimonas CT shall be further studied as a potential producer of this compound. PMID:20098599

Peptide hormones and lipopeptides: from self‐assembly to therapeutic applications

PubMed Central

Hutchinson, J. A.; Burholt, S.

2017-01-01

This review describes the properties and activities of lipopeptides and peptide hormones and how the lipidation of peptide hormones could potentially produce therapeutic agents combating some of the most prevalent diseases and conditions. The self‐assembly of these types of molecules is outlined, and how this can impact on bioactivity. Peptide hormones specific to the uptake of food and produced in the gastrointestinal tract are discussed in detail. The advantages of lipidated peptide hormones over natural peptide hormones are summarised, in terms of stability and renal clearance, with potential application as therapeutic agents. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd. PMID:28127868

Combined Systems Approaches Reveal a Multistage Mode of Action of a Marine Antimicrobial Peptide against Pathogenic Escherichia coli and Its Protective Effect against Bacterial Peritonitis and Endotoxemia

PubMed Central

Wang, Xiumin; Teng, Da; Mao, Ruoyu; Yang, Na; Hao, Ya

2016-01-01

ABSTRACT A marine arenicin-3 derivative, N4, displayed potent antibacterial activity against Gram-negative bacteria, but its antibacterial mode of action remains elusive. The mechanism of action of N4 against pathogenic Escherichia coli was first researched by combined cytological and transcriptomic techniques in this study. The N4 peptide permeabilized the outer membrane within 1 min, disrupted the plasma membrane after 0.5 h, and localized in the cytoplasm within 5 min. Gel retardation and circular dichroism (CD) spectrum analyses demonstrated that N4 bound specifically to DNA and disrupted the DNA conformation from the B type to the C type. N4 inhibited 21.1% of the DNA and 20.6% of the RNA synthesis within 15 min. Several hallmarks of apoptosis-like cell death were exhibited by N4-induced E. coli, such as cell cycle arrest in the replication (R) and division(D) phases, reactive oxygen species production, depolarization of the plasma membrane potential, and chromatin condensation within 0.5 h. Deformed cell morphology, disappearance of the plasma membrane, leakage of the contents, and ghost cell formation were demonstrated by transmission electron microscopy, and nearly 100% of the bacteria were killed by N4. A total of 428 to 663 differentially expressed genes are involved in the response to N4, which are associated mainly with membrane biogenesis (53.9% to 56.7%) and DNA binding (13.3% to 14.9%). N4-protected mice that were lethally challenged with lipopolysaccharide (LPS) exhibited reduced levels of interleukin-6 (IL-6), IL-1β, and tumor necrosis factor alpha (TNF-α) in serum and protected the lungs from LPS-induced injury. These data facilitate an enhanced understanding of the mechanisms of marine antimicrobial peptides (AMPs) against Gram-negative bacteria and provide guidelines in developing and applying novel multitarget AMPs in the field of unlimited marine resources as therapeutics. PMID:27795369

Characterization of a Multipeptide Lantibiotic Locus in Streptococcus pneumoniae.

PubMed

Maricic, Natalie; Anderson, Erica S; Opipari, AnneMarie E; Yu, Emily A; Dawid, Suzanne

2016-01-26

Bacterial communities are established through a combination of cooperative and antagonistic interactions between the inhabitants. Competitive interactions often involve the production of antimicrobial substances, including bacteriocins, which are small antimicrobial peptides that target other community members. Despite the nearly ubiquitous presence of bacteriocin-encoding loci, inhibitory activity has been attributed to only a small fraction of gene clusters. In this study, we characterized a novel locus (the pld locus) in the pathogen Streptococcus pneumoniae that drives the production of a bacteriocin called pneumolancidin, which has broad antimicrobial activity. The locus encodes an unusual tandem array of four inhibitory peptides, three of which are absolutely required for antibacterial activity. The three peptide sequences are similar but appear to play distinct roles in regulation and inhibition. A modification enzyme typically found in loci encoding a class of highly modified bacteriocins called lantibiotics was required for inhibitory activity. The production of pneumolancidin is controlled by a two-component regulatory system that is activated by the accumulation of modified peptides. The locus is located on a mobile element that has been found in many pneumococcal lineages, although not all elements carry the pld genes. Intriguingly, a minimal region containing only the genes required for pneumolancidin immunity was found in several Streptococcus mitis strains. The pneumolancidin-producing strain can inhibit nearly all pneumococci tested to date and provided a competitive advantage in vivo. These peptides not only represent a unique strategy for bacterial competition but also are an important resource to guide the development of new antimicrobials. Successful colonization of a polymicrobial host surface is a prerequisite for the subsequent development of disease for many bacterial pathogens. Bacterial factors that directly inhibit the growth of neighbors may provide an advantage during colonization if the inhibition of competitors outweighs the energy for production. In this work, we found that production of a potent antimicrobial called pneumolancidin conferred a competitive advantage to the pathogen Streptococcus pneumoniae. S. pneumoniae secreting pneumolancidin inhibits a wide array of Gram-positive organisms, including all but one tested pneumococcal strain. The pneumolancidin genetic locus is of particular interest because it encodes three similar modified peptides (lantibiotics), each of which has a distinct role in the function of the locus. Lantibiotics represent a relatively untapped resource for the development of clinically useful antibiotics which are desperately needed. The broad inhibitory activity of pneumolancidin makes it an ideal candidate for further characterization and development. Copyright © 2016 Maricic et al.

Biosynthetic Tailoring of Microcin E492m: Post-Translational Modification Affords an Antibacterial Siderophore-Peptide Conjugate

PubMed Central

Nolan, Elizabeth M.; Fischbach, Michael A.; Koglin, Alexander; Walsh, Christopher T.

2008-01-01

The present work reveals that four proteins, MceCDIJ, encoded by the MccE492 gene cluster are responsible for the remarkable post-translational tailoring of Microcin E492 (MccE492), an 84-residue protein toxin secreted by Klebsiella pneumonaie RYC492 that targets neighboring gram-negative species. This modification results in attachment of a linearized and monoglycosylated derivative of enterobactin, a nonribosomal peptide and iron scavenger (siderophore), to the MccE492m C-terminus. MceC and MceD derivatize enterobactin by C-glycosylation at the C5 position of a N-(2,3-dihydroxybenzoyl) serine (DHB-Ser) moiety and regiospecific hydrolysis of an ester linkage in the trilactone scaffold, respectively. MceI and MceJ form a protein complex that attaches C-glycosylated enterobactins to the C-terminal serine residue of both aC10 model peptide and full-length MccE492. In the enzymatic product, the terminal serine residue is covalently attached to the C4′ oxygen of the glucose moiety. Non-enzymatic and base-catalyzed migration of the peptide to the C6′ position affords the C6′ glycosyl ester linkage observed in the mature toxin, MccE492m, isolated from bacterial cultures. PMID:17973380

Insights into the anticancer properties of the first antimicrobial peptide from Archaea.

PubMed

Gaglione, Rosa; Pirone, Luciano; Farina, Biancamaria; Fusco, Salvatore; Smaldone, Giovanni; Aulitto, Martina; Dell'Olmo, Eliana; Roscetto, Emanuela; Del Gatto, Annarita; Fattorusso, Roberto; Notomista, Eugenio; Zaccaro, Laura; Arciello, Angela; Pedone, Emilia; Contursi, Patrizia

2017-09-01

The peptide VLL-28, identified in the sequence of an archaeal protein, the transcription factor Stf76 from Sulfolobus islandicus, was previously identified and characterized as an antimicrobial peptide, possessing a broad-spectrum antibacterial activity. Through a combined approach of NMR and Circular Dichroism spectroscopy, Dynamic Light Scattering, confocal microscopy and cell viability assays, the interaction of VLL-28 with the membranes of both parental and malignant cell lines has been characterized and peptide mechanism of action has been studied. It is here demonstrated that VLL-28 selectively exerts cytotoxic activity against murine and human tumor cells. By means of structural methodologies, VLL-28 interaction with the membranes has been proven and the binding residues have been identified. Confocal microscopy data show that VLL-28 is internalized only into tumor cells. Finally, it is shown that cell death is mainly caused by a time-dependent activation of apoptotic pathways. VLL-28, deriving from the archaeal kingdom, is here found to be endowed with selective cytotoxic activity towards both murine and human cancer cells and consequently can be classified as an ACP. VLL-28 represents the first ACP identified in an archaeal microorganism, exerting a trans-kingdom activity. Copyright © 2017 Elsevier B.V. All rights reserved.

Biosynthetic tailoring of microcin E492m: post-translational modification affords an antibacterial siderophore-peptide conjugate.

PubMed

Nolan, Elizabeth M; Fischbach, Michael A; Koglin, Alexander; Walsh, Christopher T

2007-11-21

The present work reveals that four proteins, MceCDIJ, encoded by the MccE492 gene cluster are responsible for the remarkable post-translational tailoring of microcin E492 (MccE492), an 84-residue protein toxin secreted by Klebsiella pneumonaie RYC492 that targets neighboring Gram-negative species. This modification results in attachment of a linearized and monoglycosylated derivative of enterobactin, a nonribosomal peptide and iron scavenger (siderophore), to the MccE492m C-terminus. MceC and MceD derivatize enterobactin by C-glycosylation at the C5 position of a N-(2,3-dihydroxybenzoyl)serine (DHB-Ser) moiety and regiospecific hydrolysis of an ester linkage in the trilactone scaffold, respectively. MceI and MceJ form a protein complex that attaches C-glycosylated enterobactins to the C-terminal serine residue of both a C10 model peptide and full-length MccE492. In the enzymatic product, the C-terminal serine residue is covalently attached to the C4' oxygen of the glucose moiety. Nonenzymatic and base-catalyzed migration of the peptide to the C6' position affords the C6' glycosyl ester linkage observed in the mature toxin, MccE492m, isolated from bacterial cultures.

Antibacterial activity of glass-ionomer restorative cements exposed to cavity-producing microorganisms.

PubMed

Herrera, M; Castillo, A; Baca, P; Carrión, P

1999-01-01

The antibacterial activity of the glass-ionomer restorative cements Ketac-Fil, Ketac-Silver, Fuji II LC, and Vitremer was studied in vitro, in conjunction with a total of 32 strains of five bacterial genera that may be associated with dental caries: Streptococcus spp, Lactobacillus spp, Actinomyces spp, Porphyromonas spp, and Clostridium spp. Agar plate diffusion was the method used for the bacterial cultures, which included a chlorhexidine control. All four glass-ionomer cements were found to inhibit bacterial growth, though with noteworthy differences in their spheres of action. Vitremer was the cement determined to have the greatest antibacterial effects, whereas Ketac-Silver presented the least inhibitory action.

Antibacterial activity of alimentary plants against Staphylococcus aureus growth.

PubMed

Pérez, C; Anesini, C

1994-01-01

Alimentary plants were screened for antibacterial activity against a penicillin G resistant strain of Staphylococcus aureus. Twenty-five samples of plant material corresponding to 21 species from 13 families were used. Both aqueous and ethanol extracts were obtained from them. Antibacterial activity was determined by the agar-well diffusion method, using cephazolin as a standard antibiotic. Seventeen ethanol extracts were found active. Eugenia caryophyllata (clavo de olor*) flowers, Myristica fragans (nuez moscada*) seeds, Theobroma cacao (cacao*) seed bark, Triticum sp (trigo*) fruit, Zea mays (maíz*) fruit and Piper nigrum (pimienta*) ripe fruit produced some of the more active extracts (* = Argentine vulgar names).

In vitro anti-biofilm and anti-bacterial activity of Junceella juncea for its biomedical application

PubMed Central

Kumar, P; Selvi, S Senthamil; Govindaraju, M

2012-01-01

Objective To investigate the anti-biofilm and anti-bacterial activity of Junceella juncea (J. juncea) against biofilm forming pathogenic strains. Methods Gorgonians were extracted with methanol and analysed with fourier transform infrared spectroscopy. Biofilm forming pathogens were identified by Congo red agar supplemented with sucrose. A quantitative spectrophotometric method was used to monitor in vitro biofilm reduction by microtitre plate assay. Anti-bacterial activity of methanolic gorgonian extract (MGE) was carried out by disc diffusion method followed by calculating the percentage of increase with crude methanol (CM). Results The presence of active functional group was exemplified by FT-IR spectroscopy. Dry, black, crystalline colonies confirm the production of extracellular polymeric substances responsible for biofilm formation in Congo red agar. MGE exhibited potential anti-biofilm activity against all tested bacterial strains. The anti-bacterial activity of methanolic extract was comparably higher in Salmonella typhii followed by Escherichia coli, Vibrio cholerae and Shigella flexneri. The overall percentage of increase was higher by 50.2% to CM. Conclusions To conclude, anti-biofilm and anti-bacterial efficacy of J. juncea is impressive over biofilm producing pathogens and are good source for novel anti-bacterial compounds. PMID:23593571

In vitro study of antibacterial activity of the alga Sargassum oligocystum from the Persian Gulf.

PubMed

Tajbakhsh, S; Pouyan, M; Zandi, K; Bahramian, P; Sartavi, K; Fouladvand, M; Asayesh, G; Barazesh, A

2011-03-01

With due attention to the development of drug-resistant bacteria, discovering of new antibacterial compounds is needed. Algae produce numerous bioactive substances which may have pharmacological properties such as antibacterial activity. The objective of this investigation was to in vitro study of antibacterial activity of brown alga Sargassum oligocystum collected along the Bushehr coast of Persian Gulf (south west of Iran). Hot water extract, cold water extract, and hot glycerin extract were prepared. The effect of the extracts were investigated on Staphylococcus aureus (ATCC 25923), Staphylococcus epidermidis (ATCC 14990), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (ATCC 25922). Hot water extract exhibited antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Cold water extract and hot glycerin extract did not show antibacterial activity on any of the four test bacteria. The minimum inhibitory concentration (MIC) of hot water extract for both Staphylococcus aureus and Staphylococcus epidermidis was 3.175 mg/ml. However, the MIC of this extract for Pseudomonas aeruginosa was 9.556 mg/ml. In this study gram-positive bacteria were more susceptible to hot water extract than gram-negative bacteria. Extract of Sargassum oligocystum could be a candidate for purification and further in vivo studies.

Development and validation of a whole-cell inhibition assay for bacterial methionine aminopeptidase by surface-enhanced laser desorption ionization-time of flight mass spectrometry.

PubMed

Greis, Kenneth D; Zhou, Songtao; Siehnel, Richard; Klanke, Chuck; Curnow, Alan; Howard, Jeremy; Layh-Schmitt, Gerlinde

2005-08-01

Bacterial methionine aminopeptidase (MAP) is a protease that removes methionine from the N termini of newly synthesized bacterial proteins after the peptide deformylase enzyme cleaves the formyl group from the initiator formylmethionine. MAP is an essential bacterial gene product and thus represents a potential target for therapeutic intervention. A fundamental challenge in the antibacterial drug discovery field is demonstrating conclusively that compounds with in vitro enzyme inhibition activity produce the desired antibacterial effect by interfering with the same target in whole bacterial cells. One way to address the activity of inhibitor compounds is by profiling cellular biomarkers in whole bacterial cells using compounds that are known inhibitors of a particular target. However, in the case of MAP, no specific inhibitors were available for such studies. Instead, a genetically attenuated MAP strain was generated in which MAP expression was placed under the control of an inducible arabinose promoter. Thus, MAP inhibition in whole cells could be mimicked by growth in the absence of arabinose. This genetically attenuated strain was used as a benchmark for MAP inhibition by profiling whole-cell lysates for unprocessed proteins using surface-enhanced laser desorption ionization-time of flight mass spectrometry (MS). Eight proteins between 4 and 14 kDa were confirmed as being unprocessed and containing the initiator methionine by adding back purified MAP to the preparations prior to MS analysis. Upon establishing these unprocessed proteins as biomarkers for MAP inhibition, the assay was used to screen small-molecule chemical inhibitors of purified MAP for whole-cell activity. Fifteen compound classes yielded three classes of compound with whole-cell activity for further optimization by chemical expansion. This report presents the development, validation, and implementation of a whole-cell inhibition assay for MAP.

Chimeric Peptides as Implant Functionalization Agents for Titanium Alloy Implants with Antimicrobial Properties

NASA Astrophysics Data System (ADS)

Yucesoy, Deniz T.; Hnilova, Marketa; Boone, Kyle; Arnold, Paul M.; Snead, Malcolm L.; Tamerler, Candan

2015-04-01

Implant-associated infections can have severe effects on the longevity of implant devices and they also represent a major cause of implant failures. Treating these infections associated with implants by antibiotics is not always an effective strategy due to poor penetration rates of antibiotics into biofilms. Additionally, emerging antibiotic resistance poses serious concerns. There is an urge to develop effective antibacterial surfaces that prevent bacterial adhesion and proliferation. A novel class of bacterial therapeutic agents, known as antimicrobial peptides (AMPs), are receiving increasing attention as an unconventional option to treat septic infection, partly due to their capacity to stimulate innate immune responses and for the difficulty of microorganisms to develop resistance towards them. While host and bacterial cells compete in determining the ultimate fate of the implant, functionalization of implant surfaces with AMPs can shift the balance and prevent implant infections. In the present study, we developed a novel chimeric peptide to functionalize the implant material surface. The chimeric peptide simultaneously presents two functionalities, with one domain binding to a titanium alloy implant surface through a titanium-binding domain while the other domain displays an antimicrobial property. This approach gains strength through control over the bio-material interfaces, a property built upon molecular recognition and self-assembly through a titanium alloy binding domain in the chimeric peptide. The efficiency of chimeric peptide both in-solution and absorbed onto titanium alloy surface was evaluated in vitro against three common human host infectious bacteria, Streptococcus mutans, Staphylococcus epidermidis, and Escherichia coli. In biological interactions such as occur on implants, it is the surface and the interface that dictate the ultimate outcome. Controlling the implant surface by creating an interface composed chimeric peptides may therefore open up new possibilities to modify the implant site and tailor it to a desirable bioactivity.

Structural Features Governing the Activity of Lactoferricin-Derived Peptides That Act in Synergy with Antibiotics against Pseudomonas aeruginosa In Vitro and In Vivo▿ †

PubMed Central

Sánchez-Gómez, Susana; Japelj, Bostjan; Jerala, Roman; Moriyón, Ignacio; Fernández Alonso, Mirian; Leiva, José; Blondelle, Sylvie E.; Andrä, Jörg; Brandenburg, Klaus; Lohner, Karl; Martínez de Tejada, Guillermo

2011-01-01

Pseudomonas aeruginosa is naturally resistant to many antibiotics, and infections caused by this organism are a serious threat, especially to hospitalized patients. The intrinsic low permeability of P. aeruginosa to antibiotics results from the coordinated action of several mechanisms, such as the presence of restrictive porins and the expression of multidrug efflux pump systems. Our goal was to develop antimicrobial peptides with an improved bacterial membrane-permeabilizing ability, so that they enhance the antibacterial activity of antibiotics. We carried out a structure activity relationship analysis to investigate the parameters that govern the permeabilizing activity of short (8- to 12-amino-acid) lactoferricin-derived peptides. We used a new class of constitutional and sequence-dependent descriptors called PEDES (peptide descriptors from sequence) that allowed us to predict (Spearman's ρ = 0.74; P < 0.001) the permeabilizing activity of a new peptide generation. To study if peptide-mediated permeabilization could neutralize antibiotic resistance mechanisms, the most potent peptides were combined with antibiotics, and the antimicrobial activities of the combinations were determined on P. aeruginosa strains whose mechanisms of resistance to those antibiotics had been previously characterized. A subinhibitory concentration of compound P2-15 or P2-27 sensitized P. aeruginosa to most classes of antibiotics tested and counteracted several mechanisms of antibiotic resistance, including loss of the OprD porin and overexpression of several multidrug efflux pump systems. Using a mouse model of lethal infection, we demonstrated that whereas P2-15 and erythromycin were unable to protect mice when administered separately, concomitant administration of the compounds afforded long-lasting protection to one-third of the animals. PMID:20956602

Structural features governing the activity of lactoferricin-derived peptides that act in synergy with antibiotics against Pseudomonas aeruginosa in vitro and in vivo.

PubMed

Sánchez-Gómez, Susana; Japelj, Bostjan; Jerala, Roman; Moriyón, Ignacio; Fernández Alonso, Mirian; Leiva, José; Blondelle, Sylvie E; Andrä, Jörg; Brandenburg, Klaus; Lohner, Karl; Martínez de Tejada, Guillermo

2011-01-01

Pseudomonas aeruginosa is naturally resistant to many antibiotics, and infections caused by this organism are a serious threat, especially to hospitalized patients. The intrinsic low permeability of P. aeruginosa to antibiotics results from the coordinated action of several mechanisms, such as the presence of restrictive porins and the expression of multidrug efflux pump systems. Our goal was to develop antimicrobial peptides with an improved bacterial membrane-permeabilizing ability, so that they enhance the antibacterial activity of antibiotics. We carried out a structure activity relationship analysis to investigate the parameters that govern the permeabilizing activity of short (8- to 12-amino-acid) lactoferricin-derived peptides. We used a new class of constitutional and sequence-dependent descriptors called PEDES (peptide descriptors from sequence) that allowed us to predict (Spearman's ρ = 0.74; P < 0.001) the permeabilizing activity of a new peptide generation. To study if peptide-mediated permeabilization could neutralize antibiotic resistance mechanisms, the most potent peptides were combined with antibiotics, and the antimicrobial activities of the combinations were determined on P. aeruginosa strains whose mechanisms of resistance to those antibiotics had been previously characterized. A subinhibitory concentration of compound P2-15 or P2-27 sensitized P. aeruginosa to most classes of antibiotics tested and counteracted several mechanisms of antibiotic resistance, including loss of the OprD porin and overexpression of several multidrug efflux pump systems. Using a mouse model of lethal infection, we demonstrated that whereas P2-15 and erythromycin were unable to protect mice when administered separately, concomitant administration of the compounds afforded long-lasting protection to one-third of the animals.

Purification and MIC analysis of antimicrobial proteins from Cucumis sativus L. seeds.

PubMed

Al Akeel, Raid; Mateen, Ayesha; Alharbi, Khalid K; Alyousef, Abdullah A; Al-Mandeel, Hazem M; Syed, Rabbani

2018-04-03

Cucumis sativus L. (cucumber), from the family Cucurbitaceae, is a therapeutic plant with various pharmacological benefits, broadly utilized as a part of complementary medicine (e.g., Unani, Ayurveda, Siddha, and Traditional Chinese). In light of past research discoveries, this plant had been chosen to consider its potential antibacterial action. Extracts were purified by dialysis and ion exchange chromatography strategy and then assayed for antibacterial activity against four standard pathogenic bacterial strains known to cause foodborne infections and spoilage of food and herbal drugs. Antimicrobial peptides were extracted from seeds using a sodium phosphate citrate (pH 7.2) - CTAB cradle (pH 6.0). The highest protein concentration was seen with elute fractions 1 and 3 (370 mg/mL) compared with elute fractions 2 and 4 (340 mg/mL). Among the bacteria utilized, E. coli was clearly the most sensitive out of selected four strains. Our results suggest that Cucumis sativus L seeds extracts have significant potentials as new antimicrobial agents.

Development of a standardized and safe airborne antibacterial assay, and its evaluation on antibacterial biomimetic model surfaces.

PubMed

Al-Ahmad, Ali; Zou, Peng; Solarte, Diana Lorena Guevara; Hellwig, Elmar; Steinberg, Thorsten; Lienkamp, Karen

2014-01-01

Bacterial infection of biomaterials is a major concern in medicine, and different kinds of antimicrobial biomaterial have been developed to deal with this problem. To test the antimicrobial performance of these biomaterials, the airborne bacterial assay is used, which involves the formation of biohazardous bacterial aerosols. We here describe a new experimental set-up which allows safe handling of such pathogenic aerosols, and standardizes critical parameters of this otherwise intractable and strongly user-dependent assay. With this new method, reproducible, thorough antimicrobial data (number of colony forming units and live-dead-stain) was obtained. Poly(oxonorbornene)-based Synthetic Mimics of Antimicrobial Peptides (SMAMPs) were used as antimicrobial test samples. The assay was able to differentiate even between subtle sample differences, such as different sample thicknesses. With this new set-up, the airborne bacterial assay was thus established as a useful, reliable, and realistic experimental method to simulate the contamination of biomaterials with bacteria, for example in an intraoperative setting.

Anaerobic bacteria growth in the presence of cathelicidin LL-37 and selected ceragenins delivered as magnetic nanoparticles cargo.

PubMed

Durnaś, Bonita; Piktel, Ewelina; Wątek, Marzena; Wollny, Tomasz; Góźdź, Stanisław; Smok-Kalwat, Jolanta; Niemirowicz, Katarzyna; Savage, Paul B; Bucki, Robert

2017-07-26

Cationic antibacterial peptides (CAPs) and synthetic molecules mimicking the amphiphilic structure of CAPs, such as ceragenins, are promising compounds for the development of new antimicrobials. We tested the in vitro activity of ceragenins CSA-13 and CSA-131 against several anaerobic bacteria including Bacteroides spp. and Clostridium difficile. We compared results to the activity of cathelicidin LL-37, metronidazole and nanosystems developed by attachment of CSA-13 and CSA-131 to magnetic nanoparticles (MNPs). The antibacterial effect was tested using killing assay and modified CLSI broth microdilution assay. Ceragenins CSA-13 and CSA-131 displayed stronger bactericidal activity than LL-37 or metronidazole against all of the tested bacterial strains. Additionally CSA-131 revealed an enhanced ability to prevent the formation of Bacteroides fragilis and Propionibacterium acnes biofilms. These data confirmed that ceragenins display antimicrobial activity against a broad range of microorganisms including anaerobic bacteria and deserve further investigations as compounds serving to develop new treatment against anaerobic and mixed infections.

Antibacterial Activity of Ethyl Acetate the Extract of Noni Fruit (Morinda citrifolia L.) Against Bacterial Spoilage in Fish

NASA Astrophysics Data System (ADS)

Nugraheni, E. R.; Adriani, G. R.; Munawaroh, H.

2017-04-01

Noni fruit (Morinda citrifolia L.) contains compounds that have potential as antibacterial agent. Antibacterial compounds produced noni fruit (M. citrifolia L.) can inhibit bacterial growth. This study was conducted to test the antibacterial activity of ethyl acetate extract of noni fruit (M. citrifolia L.) against spoilage bacterial in fish. Pseudomonas aeruginosa, Bacillus cereus, Escherichia coli, Klebsiella oxytoca, and Enterobacter aerogenes isolates and examine antibacterial phytochemical profile. Extraction of noni compounds was done by maceration, followed by partition with ethyl acetate to obtain the soluble and insoluble ethyl acetate fraction. Previews result show that the ethyl acetate extract had very strong activity. Extraction process continued by separation and isolation used preparative thin layer chromatography method, so that obtained five isolates and mark them as A, B, C, D and E. Antibacterial activity assay performed on isolates A, B, C, D, and E with 20 and 30% concentration. The test results showed that isolates A could not be inhibit the growth of bacteria, isolates B, C, D, and E has antibacterial activity with weak to strong inhibition. Isolate B had the greatest inhibition activity against the B. cereus, whereas isolates E had the greatest inhibition activity against P. aeroginosa. MIC (Minimum Inhibitor Concentration) and MBC (Minimum Bactericidal Concentration) test result showed that MIC and MBC values could not be determined. Analysis of compounds by TLC showed that isolate B suspected contains coumarin or flavonoids compounds that have antibacterial activity.

Fractionation and identification of novel antioxidant peptides from buffalo and bovine casein hydrolysates.

PubMed

Shazly, Ahmed Behdal; He, Zhiyong; El-Aziz, Mahmoud Abd; Zeng, Maomao; Zhang, Shuang; Qin, Fang; Chen, Jie

2017-10-01

Buffalo and bovine caseins were hydrolysed by alcalase and trypsin to produce novel antioxidant peptides. The casein hydrolysates were purified using ultrafiltration (UF) and further characterized by RP-HPLC. The fractions produced higher antioxidant activities were identified for their peptides using LC MS/MS. All UF-VI (MW<1kDa) fractions showed higher antioxidant activity. Hydrolysate produced by alcalase for buffalo casein (UF-VI with 54.84-fold purification) showed higher antioxidant activity than that obtained by trypsin. Trypsin hydrolysate contained high amount of hydrophobic amino acids while alcalase hydrolysate consisted mainly of Ser, Arg, Ala and Leu. The antioxidant peptides identified by LC MS/MS were RELEE, MEDNKQ and TVA, EQL in buffalo casein hydrolysates produced by trypsin and alcalase, respectively. Mechanism and reaction pathways of selected antioxidant peptides with ABTS were proposed. Conclusively, buffalo casein provided antioxidant peptides similar to bovine, suggesting that buffalo casein is a novel source of antioxidant. Copyright © 2017 Elsevier Ltd. All rights reserved.

An Extensive Description of the Peptidomic Repertoire of the Hen Egg Yolk Plasma.

PubMed

Arena, Simona; Scaloni, Andrea

2018-03-28

Hen egg is a raw material widely used for the preparation of food,  pharmaceutical and cosmetoceutical products. Dedicated proteomic studies were accomplished on eggshell membrane, egg white, and yolk, identifying the most abundant proteins. No similar peptidomic studies have been performed so far. Only preliminary investigations on bioactive peptides in egg fractions and digestates were accomplished through functional screening assays, characterizing antioxidant, antibacterial, antiviral, immunomodulatory, and antihypertensive preparations and isolated components. This study fills this gap and provides a comprehensive picture of the peptides present in the yolk plasma of different hen egg types after 24 and 264 h of laying, taking advantage of a procedure based on a two-step fractionation followed by combined MALDI-TOF-TOF-MS- and nanoLC-ESI-Q-Orbitrap-MS/MS-based analysis. Six hundred and twenty-eight peptides were characterized as deriving from the proteolytic processing of larger protein components after the physiological action of chicken chymotrypsin-like and pepsin-like enzymes. Structural details on their post-translational modifications were also provided. Identified peptides were subjected to bioinformatic analysis and further compared with available data from the literature, ascertaining 198 peptides associable with putative antihypertensive, antimicrobial, anticancer, antiviral, antibiofilm, anorectic, calcium-binding, and anti-inflammatory activities. This analysis was often confirmative of previous experimental evidence on functional properties of unfractionated preparations or isolated molecules. These results further emphasize the bioactive action of yolk-derived peptides as related to egg consumption, and the potential use of these molecules as additive ingredients in the preparation of functional foods and cosmetics.