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Sample records for antimicrobial peptide cm15

  1. Osmoprotection of bacterial cells from toxicity caused by antimicrobial hybrid peptide CM15.

    PubMed

    Sato, Hiromi; Feix, Jimmy B

    2006-08-22

    Antimicrobial peptides exist ubiquitously as a host defense system in a broad range of species, including insects, amphibians, and mammals. The binding of these peptides is followed by the disruption of cytoplasmic membranes, leading to bacterial cell death; however, the precise mechanism of membrane destruction has remained controversial. In this study, we have examined the mechanism of action for the antimicrobial peptide, CM15 (KWKLFKKIGAVLKVL), a chimeric peptide of cecropin and mellitin. We find that the cytotoxicity of CM15 against either E. coli or Pseudomonas aeruginosa can be mitigated by the addition of sugar or poly(ethylene glycol) osmolytes to the extracellular media. The dependence of osmoprotection on solute size suggests the formation of pores with an effective diameter of 2.2-3.8 nm. In contrast, no osmoprotection was observed for cell killing by the cationic detergent dodecyltrimethylammonium bromide. Osmolytes also protected cells against the cytotoxicity of CM15 expressed intracellularly as a C-terminal extension of the carrier protein ketosteroid isomerase (KSI). Osmoprotection against the intracellularly produced peptide was also dependent on osmolyte size, in a manner that was in agreement with that observed for extracellularly added synthetic CM15. These data indicate that the formation of discrete pores in the cytoplasmic membrane is a key factor in the mechanism of bacterial killing by CM15. PMID:16906758

  2. Using Infrared Spectroscopy of Cyanylated Cysteine to Map Membrane Binding Structure and Orientation of the Hybrid Antimicrobial Peptide CM15

    PubMed Central

    Alfieri, Katherine N.; Vienneau, Alice R.; Londergan, Casey H.

    2011-01-01

    The synthetic antimicrobial peptide CM15, a hybrid of N-terminal sequences from cecropin and melittin peptides, has been shown to be extremely potent. Its mechanism of action has been speculated to involve pore formation based on prior site-directed spin labeling studies. This study examines four single-site β-thiocyanatoalanine variants of CM15 in which the artificial amino acid side chain acts as a vibrational reporter of its local environment through the frequency and lineshape of the unique CN stretching band in the infrared spectrum. Circular dichroism experiments indicate that the placements of the artificial side chain have only small perturbative effects on the membrane-bound secondary structure of the CM15 peptide. All variant peptides were placed in buffer solution, in contact with dodecylphosphatidylcholine micelles, and in contact with vesicles formed from E. coli polar lipid extract. At each site, the CN stretching band reports a different behavior. Time-dependent attenuated total reflectance infrared spectra were also collected for each variant as it was allowed to remodel the E. coli lipid vesicles. These experiments agree with the previously proposed formation of toroidal pores, in which each peptide finds itself in an increasingly homogeneous and curved local environment without apparent peptide-peptide interactions. This work also demonstrates the excellent sensitivity of the SCN stretching vibration to small changes in peptide-lipid interfacial structure. PMID:22103476

  3. Antimicrobial peptides

    PubMed Central

    2014-01-01

    With increasing antibiotics resistance, there is an urgent need for novel infection therapeutics. Since antimicrobial peptides provide opportunities for this, identification and optimization of such peptides have attracted much interest during recent years. Here, a brief overview of antimicrobial peptides is provided, with focus placed on how selected hydrophobic modifications of antimicrobial peptides can be employed to combat also more demanding pathogens, including multi-resistant strains, without conferring unacceptable toxicity. PMID:24758244

  4. Antimicrobial peptides.

    PubMed

    Zhang, Ling-Juan; Gallo, Richard L

    2016-01-11

    Antimicrobial peptides and proteins (AMPs) are a diverse class of naturally occurring molecules that are produced as a first line of defense by all multicellular organisms. These proteins can have broad activity to directly kill bacteria, yeasts, fungi, viruses and even cancer cells. Insects and plants primarily deploy AMPs as an antibiotic to protect against potential pathogenic microbes, but microbes also produce AMPs to defend their environmental niche. In higher eukaryotic organisms, AMPs can also be referred to as 'host defense peptides', emphasizing their additional immunomodulatory activities. These activities are diverse, specific to the type of AMP, and include a variety of cytokine and growth factor-like effects that are relevant to normal immune homeostasis. In some instances, the inappropriate expression of AMPs can also induce autoimmune diseases, thus further highlighting the importance of understanding these molecules and their complex activities. This Primer will provide an update of our current understanding of AMPs. PMID:26766224

  5. Antimicrobial Peptides in 2014

    PubMed Central

    Wang, Guangshun; Mishra, Biswajit; Lau, Kyle; Lushnikova, Tamara; Golla, Radha; Wang, Xiuqing

    2015-01-01

    This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms. PMID:25806720

  6. Antimicrobial peptides in 2014.

    PubMed

    Wang, Guangshun; Mishra, Biswajit; Lau, Kyle; Lushnikova, Tamara; Golla, Radha; Wang, Xiuqing

    2015-01-01

    This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms. PMID:25806720

  7. 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

  8. Antimicrobial Peptides from Fish

    PubMed Central

    Masso-Silva, Jorge A.; Diamond, Gill

    2014-01-01

    Antimicrobial peptides (AMPs) are found widely distributed through Nature, and participate in the innate host defense of each species. Fish are a great source of these peptides, as they express all of the major classes of AMPs, including defensins, cathelicidins, hepcidins, histone-derived peptides, and a fish-specific class of the cecropin family, called piscidins. As with other species, the fish peptides exhibit broad-spectrum antimicrobial activity, killing both fish and human pathogens. They are also immunomodulatory, and their genes are highly responsive to microbes and innate immuno-stimulatory molecules. Recent research has demonstrated that some of the unique properties of fish peptides, including their ability to act even in very high salt concentrations, make them good potential targets for development as therapeutic antimicrobials. Further, the stimulation of their gene expression by exogenous factors could be useful in preventing pathogenic microbes in aquaculture. PMID:24594555

  9. Multidimensional signatures in antimicrobial peptides

    PubMed Central

    Yount, Nannette Y.; Yeaman, Michael R.

    2004-01-01

    Conventional analyses distinguish between antimicrobial peptides by differences in amino acid sequence. Yet structural paradigms common to broader classes of these molecules have not been established. The current analyses examined the potential conservation of structural themes in antimicrobial peptides from evolutionarily diverse organisms. Using proteomics, an antimicrobial peptide signature was discovered to integrate stereospecific sequence patterns and a hallmark three-dimensional motif. This striking multidimensional signature is conserved among disulfide-containing antimicrobial peptides spanning biological kingdoms, and it transcends motifs previously limited to defined peptide subclasses. Experimental data validating this model enabled the identification of previously unrecognized antimicrobial activity in peptides of known identity. The multidimensional signature model provides a unifying structural theme in broad classes of antimicrobial peptides, will facilitate discovery of antimicrobial peptides as yet unknown, and offers insights into the evolution of molecular determinants in these and related host defense effector molecules. PMID:15118082

  10. Synthetic antimicrobial peptide design.

    PubMed

    Powell, W A; Catranis, C M; Maynard, C A

    1995-01-01

    To guide the design of potential plant pathogen-resistance genes, synthetic variants of naturally occurring antimicrobial gene products were evaluated. Five 20-amino acid (ESF1, ESF4, ESF5, ESF6, ESF13), one 18-amino acid (ESF12), and one 17-amino acid (ESF17) amphipathic peptide sequences were designed, synthesized, and tested with in vitro bioassays. Positive charges on the hydrophilic side of the peptide were shown to be essential for antifungal activity, yet the number of positive charges could be varied with little or no change in activity. The size could be reduced to 18 amino acids, but at 17 amino acids a significant reduction in activity was observed. ESF1, 5, 6, and 12 peptides were inhibitory to the germination of conidia from Cryphonectria parasitica, Fusarium oxysporum f. sp. lycopersici, and Septoria musiva but did not inhibit the germination of pollen from Castanea mollissima and Salix lucida. ESF12 also had no effect on the germination of Malus sylvestris and Lycopersicon esculentum pollen, but inhibited the growth of the bacteria Agrobacterium tumefaciens, Erwinia amylovora, and Pseudomonas syringae. The minimal inhibitory concentrations of the active ESF peptides were similar to those of the naturally occurring control peptides, magainin II and cecropin B. The significant differential in sensitivity between the microbes and plant cells indicated that the active ESF peptides are potentially useful models for designing plant pathogen-resistance genes. PMID:7579625

  11. Antimicrobial Peptides from Plants.

    PubMed

    Tam, James P; Wang, Shujing; Wong, Ka H; Tan, Wei Liang

    2015-01-01

    Plant antimicrobial peptides (AMPs) have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs) of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic), lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms. PMID:26580629

  12. Antimicrobial Peptides from Plants

    PubMed Central

    Tam, James P.; Wang, Shujing; Wong, Ka H.; Tan, Wei Liang

    2015-01-01

    Plant antimicrobial peptides (AMPs) have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs) of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic), lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms. PMID:26580629

  13. Novel Formulations for Antimicrobial Peptides

    PubMed Central

    Carmona-Ribeiro, Ana Maria; Carrasco, Letícia Dias de Melo

    2014-01-01

    Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy. PMID:25302615

  14. Antimicrobial peptides: premises and promises.

    PubMed

    Reddy, K V R; Yedery, R D; Aranha, C

    2004-12-01

    Antimicrobial peptides (AMPs) are an important component of the natural defences of most living organisms against invading pathogens. These are relatively small (< 10kDa), cationic and amphipathic peptides of variable length, sequence and structure. During the past two decades several AMPs have been isolated from a wide variety of animals, both vertebrates and invertebrates, and plants as well as from bacteria and fungi. Most of these peptides are obtained from different sources like macrophages, neutrophils, epithelial cells, haemocytes, fat body, reproductive tract, etc. These peptides exhibit broad-spectrum activity against a wide range of microorganisms including Gram-positive and Gram-negative bacteria, protozoa, yeast, fungi and viruses. A few peptides have also been found to be cytotoxic to sperm and tumour cells. AMPs are classified based on the three dimensional structural studies carried out with the help of NMR. The peptides are broadly classified into five major groups namely (a) peptides that form alpha-helical structures, (b) peptides rich in cysteine residues, (c) peptides that form beta-sheet, (d) peptides rich in regular amino acids namely histatin, arginine and proline and (e) peptides composed of rare and modified amino acids. Most of these peptides are believed to act by disrupting the plasma membrane leading to the lysis of the cell. AMPs have been found to be excellent candidates for developing novel antimicrobial agents and a few of these peptides show antimicrobial activity against pathogens causing sexually transmitted infection (STI), including HIV/HSV. Peptides, namely magainin and nisin have been shown to demonstrate contraceptive properties in vitro and in vivo. A few peptides have already entered clinical trials for the treatment of impetigo, diabetic foot ulcers and gastric helicobacter infections. In this review, we discuss the source, structures and mode of action with special reference to therapeutic considerations of various AMPs

  15. Peptides and Peptidomimetics for Antimicrobial Drug Design

    PubMed Central

    Mojsoska, Biljana; Jenssen, Håvard

    2015-01-01

    The purpose of this paper is to introduce and highlight a few classes of traditional antimicrobial peptides with a focus on structure-activity relationship studies. After first dissecting the important physiochemical properties that influence the antimicrobial and toxic properties of antimicrobial peptides, the contributions of individual amino acids with respect to the peptides antibacterial properties are presented. A brief discussion of the mechanisms of action of different antimicrobials as well as the development of bacterial resistance towards antimicrobial peptides follows. Finally, current efforts on novel design strategies and peptidomimetics are introduced to illustrate the importance of antimicrobial peptide research in the development of future antibiotics. PMID:26184232

  16. Collagen-like antimicrobial peptides.

    PubMed

    Masuda, Ryo; Kudo, Masakazu; Dazai, Yui; Mima, Takehiko; Koide, Takaki

    2016-11-01

    Combinatorial library composed of rigid rod-like peptides with a triple-helical scaffold was constructed. The component peptides were designed to have various combinations of basic and neutral (or hydrophobic) amino acid residues based on collagen-like (Gly-Pro-Yaa)-repeating sequences, inspired from the basic and amphiphilic nature of naturally occurring antimicrobial peptides. Screening of the peptide pools resulted in identification of antimicrobial peptides. A structure-activity relationship study revealed that the position of Arg-cluster at N-terminus and cystine knots at C-terminus in the triple helix significantly contributed to the antimicrobial activity. The most potent peptide RO-A showed activity against Gram-negative Escherichia coli and Gram-positive Bacillus subtilis. In addition, Escherichia coli exposed to RO-A resulted in abnormal elongation of the cells. RO-A was also shown to have remarkable stability in human serum and low cytotoxicity to mammalian cells. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 453-459, 2016. PMID:27271210

  17. How antimicrobial peptides disrupt lipid bilayers?

    NASA Astrophysics Data System (ADS)

    Sengupta, Durba

    2011-03-01

    The molecular basis for the activity of cyclic and linear antimicrobial peptides is analysed. We performed multi-scale molecular dynamics simulations and biophysical measurements to probe the interaction of antimicrobial peptides with model membranes. Two linear antimicrobial peptides, magainin and melittin and a cyclic one, BPC194 have been studied. We test different models to determine the generic and specific forces that lead to bilayer disruption. We probe whether interfacial stress or local membrane perturbation is more likely to lead to the porated state. We further analyse the reasons that determine specificity and increase of activity in antimicrobial peptides. The results provide detailed insight in the mode of action of antimicrobial peptides.

  18. Antimicrobial Peptides from Marine Proteobacteria

    PubMed Central

    Desriac, Florie; Jégou, Camille; Balnois, Eric; Brillet, Benjamin; Le Chevalier, Patrick; Fleury, Yannick

    2013-01-01

    After years of inadequate use and the emergence of multidrug resistant (MDR) strains, the efficiency of “classical” antibiotics has decreased significantly. New drugs to fight MDR strains are urgently needed. Bacteria hold much promise as a source of unusual bioactive metabolites. However, the potential of marine bacteria, except for Actinomycetes and Cyanobacteria, has been largely underexplored. In the past two decades, the structures of several antimicrobial compounds have been elucidated in marine Proteobacteria. Of these compounds, polyketides (PKs), synthesised by condensation of malonyl-coenzyme A and/or acetyl-coenzyme A, and non-ribosomal peptides (NRPs), obtained through the linkage of (unusual) amino acids, have recently generated particular interest. NRPs are good examples of naturally modified peptides. Here, we review and compile the data on the antimicrobial peptides isolated from marine Proteobacteria, especially NRPs. PMID:24084784

  19. Antimicrobial Properties of Amyloid Peptides

    PubMed Central

    Kagan, Bruce L.; Jang, Hyunbum; Capone, Ricardo; Arce, Fernando Teran; Ramachandran, Srinivasan; Lal, Ratnesh; Nussinov, Ruth

    2011-01-01

    More than two dozen clinical syndromes known as amyloid diseases are characterized by the buildup of extended insoluble fibrillar deposits in tissues. These amorphous Congo red staining deposits known as amyloids exhibit a characteristic green birefringence and cross-β structure. Substantial evidence implicates oligomeric intermediates of amyloids as toxic species in the pathogenesis of these chronic disease states. A growing body of data has suggested that these toxic species form ion channels in cellular membranes causing disruption of calcium homeostasis, membrane depolarization, energy drainage, and in some cases apoptosis. Amyloid peptide channels exhibit a number of common biological properties including the universal U-shape β-strand-turn-β-strand structure, irreversible and spontaneous insertion into membranes, production of large heterogeneous single-channel conductances, relatively poor ion selectivity, inhibition by Congo red, and channel blockade by zinc. Recent evidence has suggested that increased amounts of amyloids are not only toxic to its host target cells but also possess antimicrobial activity. Furthermore, at least one human antimicrobial peptide, protegrin-1, which kills microbes by a channel-forming mechanism, has been shown to possess the ability to form extended amyloid fibrils very similar to those of classic disease-forming amyloids. In this paper, we will review the reported antimicrobial properties of amyloids and the implications of these discoveries for our understanding of amyloid structure and function. PMID:22081976

  20. Membrane disruption mechanism of antimicrobial peptides

    NASA Astrophysics Data System (ADS)

    Lee, Ka Yee

    2012-04-01

    Largely distributed among living organisms, antimicrobial peptides are a class of small (<100 residues) host defense peptides that induce selective membrane lytic activity against microbial pathogens. The permeabilizing behavior of these diverse peptides has been commonly attributed to the formation of pores, and such pore formation has been categorized as barrel-stave, toroidal, or carpet-like. With the continuing discovery of new peptide species, many are uncharacterized and the exact mechanism is unknown. Through the use of atomic force microscopy, the disruption of supported lipid bilayer patches by protegrin-1 is concentration-dependent. The intercalation of antimicrobial peptide into the bilayer results in structures beyond that of pore formation, but with the formation of worm-like micelles at high peptide concentration. Our results suggest that antimicrobial peptide acts to lower the interfacial energy of the bilayer in a way similar to detergents. Antimicrobial peptides with structural differences, magainin-1 and aurein 1.1, exhibit a mechanistic commonality.

  1. Antimicrobial Peptides: Versatile Biological Properties

    PubMed Central

    Pushpanathan, Muthuirulan; Rajendhran, Jeyaprakash

    2013-01-01

    Antimicrobial peptides are diverse group of biologically active molecules with multidimensional properties. In recent past, a wide variety of AMPs with diverse structures have been reported from different sources such as plants, animals, mammals, and microorganisms. The presence of unusual amino acids and structural motifs in AMPs confers unique structural properties to the peptide that attribute for their specific mode of action. The ability of these active AMPs to act as multifunctional effector molecules such as signalling molecule, immune modulators, mitogen, antitumor, and contraceptive agent makes it an interesting candidate to study every aspect of their structural and biological properties for prophylactic and therapeutic applications. In addition, easy cloning and recombinant expression of AMPs in heterologous plant host systems provided a pipeline for production of disease resistant transgenic plants. Besides these properties, AMPs were also used as drug delivery vectors to deliver cell impermeable drugs to cell interior. The present review focuses on the diversity and broad spectrum antimicrobial activity of AMPs along with its multidimensional properties that could be exploited for the application of these bioactive peptides as a potential and promising drug candidate in pharmaceutical industries. PMID:23935642

  2. The First Salamander Defensin Antimicrobial Peptide

    PubMed Central

    Jiang, Ke; Rong, Mingqiang; Lai, Ren

    2013-01-01

    Antimicrobial peptides have been widely identified from amphibian skins except salamanders. A novel antimicrobial peptide (CFBD) was isolated and characterized from skin secretions of the salamander, Cynops fudingensis. The cDNA encoding CFBD precursor was cloned from the skin cDNA library of C. fudingensis. The precursor was composed of three domains: signal peptide of 17 residues, mature peptide of 41 residues and intervening propeptide of 3 residues. There are six cysteines in the sequence of mature CFBD peptide, which possibly form three disulfide-bridges. CFBD showed antimicrobial activities against Staphylococcus aureus, Bacillus subtilis, Candida albicans and Escherichia coli. This peptide could be classified into family of β-defensin based on its seqeuence similarity with β-defensins from other vertebrates. Evolution analysis indicated that CFBD was close to fish β-defensin. As far as we know, CFBD is the first β-defensin antimicrobial peptide from salamanders. PMID:24386139

  3. Human Antimicrobial Peptides and Proteins

    PubMed Central

    Wang, Guangshun

    2014-01-01

    As the key components of innate immunity, human host defense antimicrobial peptides and proteins (AMPs) play a critical role in warding off invading microbial pathogens. In addition, AMPs can possess other biological functions such as apoptosis, wound healing, and immune modulation. This article provides an overview on the identification, activity, 3D structure, and mechanism of action of human AMPs selected from the antimicrobial peptide database. Over 100 such peptides have been identified from a variety of tissues and epithelial surfaces, including skin, eyes, ears, mouths, gut, immune, nervous and urinary systems. These peptides vary from 10 to 150 amino acids with a net charge between −3 and +20 and a hydrophobic content below 60%. The sequence diversity enables human AMPs to adopt various 3D structures and to attack pathogens by different mechanisms. While α-defensin HD-6 can self-assemble on the bacterial surface into nanonets to entangle bacteria, both HNP-1 and β-defensin hBD-3 are able to block cell wall biosynthesis by binding to lipid II. Lysozyme is well-characterized to cleave bacterial cell wall polysaccharides but can also kill bacteria by a non-catalytic mechanism. The two hydrophobic domains in the long amphipathic α-helix of human cathelicidin LL-37 lays the basis for binding and disrupting the curved anionic bacterial membrane surfaces by forming pores or via the carpet model. Furthermore, dermcidin may serve as ion channel by forming a long helix-bundle structure. In addition, the C-type lectin RegIIIα can initially recognize bacterial peptidoglycans followed by pore formation in the membrane. Finally, histatin 5 and GAPDH(2-32) can enter microbial cells to exert their effects. It appears that granulysin enters cells and kills intracellular pathogens with the aid of pore-forming perforin. This arsenal of human defense proteins not only keeps us healthy but also inspires the development of a new generation of personalized medicine to

  4. Antimicrobial Peptides in Human Sepsis

    PubMed Central

    Martin, Lukas; van Meegern, Anne; Doemming, Sabine; Schuerholz, Tobias

    2015-01-01

    Nearly 100 years ago, antimicrobial peptides (AMPs) were identified as an important part of innate immunity. They exist in species from bacteria to mammals and can be isolated in body fluids and on surfaces constitutively or induced by inflammation. Defensins have anti-bacterial effects against Gram-positive and Gram-negative bacteria as well as anti-viral and anti-yeast effects. Human neutrophil peptides (HNP) 1–3 and human beta-defensins (HBDs) 1–3 are some of the most important defensins in humans. Recent studies have demonstrated higher levels of HNP 1–3 and HBD-2 in sepsis. The bactericidal/permeability-increasing protein (BPI) attenuates local inflammatory response and decreases systemic toxicity of endotoxins. Moreover, BPI might reflect the severity of organ dysfunction in sepsis. Elevated plasma lactoferrin is detected in patients with organ failure. HNP 1–3, lactoferrin, BPI, and heparin-binding protein are increased in sepsis. Human lactoferrin peptide 1–11 (hLF 1–11) possesses antimicrobial activity and modulates inflammation. The recombinant form of lactoferrin [talactoferrin alpha (TLF)] has been shown to decrease mortality in critically ill patients. A phase II/III study with TLF in sepsis did not confirm this result. The growing number of multiresistant bacteria is an ongoing problem in sepsis therapy. Furthermore, antibiotics are known to promote the liberation of pro-inflammatory cell components and thus augment the severity of sepsis. Compared to antibiotics, AMPs kill bacteria but also neutralize pathogenic factors such as lipopolysaccharide. The obstacle to applying naturally occurring AMPs is their high nephro- and neurotoxicity. Therefore, the challenge is to develop peptides to treat septic patients effectively without causing harm. This overview focuses on natural and synthetic AMPs in human and experimental sepsis and their potential to provide significant improvements in the treatment of critically ill with severe infections

  5. Antimicrobial Peptides in Human Sepsis.

    PubMed

    Martin, Lukas; van Meegern, Anne; Doemming, Sabine; Schuerholz, Tobias

    2015-01-01

    Nearly 100 years ago, antimicrobial peptides (AMPs) were identified as an important part of innate immunity. They exist in species from bacteria to mammals and can be isolated in body fluids and on surfaces constitutively or induced by inflammation. Defensins have anti-bacterial effects against Gram-positive and Gram-negative bacteria as well as anti-viral and anti-yeast effects. Human neutrophil peptides (HNP) 1-3 and human beta-defensins (HBDs) 1-3 are some of the most important defensins in humans. Recent studies have demonstrated higher levels of HNP 1-3 and HBD-2 in sepsis. The bactericidal/permeability-increasing protein (BPI) attenuates local inflammatory response and decreases systemic toxicity of endotoxins. Moreover, BPI might reflect the severity of organ dysfunction in sepsis. Elevated plasma lactoferrin is detected in patients with organ failure. HNP 1-3, lactoferrin, BPI, and heparin-binding protein are increased in sepsis. Human lactoferrin peptide 1-11 (hLF 1-11) possesses antimicrobial activity and modulates inflammation. The recombinant form of lactoferrin [talactoferrin alpha (TLF)] has been shown to decrease mortality in critically ill patients. A phase II/III study with TLF in sepsis did not confirm this result. The growing number of multiresistant bacteria is an ongoing problem in sepsis therapy. Furthermore, antibiotics are known to promote the liberation of pro-inflammatory cell components and thus augment the severity of sepsis. Compared to antibiotics, AMPs kill bacteria but also neutralize pathogenic factors such as lipopolysaccharide. The obstacle to applying naturally occurring AMPs is their high nephro- and neurotoxicity. Therefore, the challenge is to develop peptides to treat septic patients effectively without causing harm. This overview focuses on natural and synthetic AMPs in human and experimental sepsis and their potential to provide significant improvements in the treatment of critically ill with severe infections. PMID

  6. The Potential of Antimicrobial Peptides as Biocides

    PubMed Central

    Laverty, Garry; Gorman, Sean P.; Gilmore, Brendan F.

    2011-01-01

    Antimicrobial peptides constitute a diverse class of naturally occurring antimicrobial molecules which have activity against a wide range of pathogenic microorganisms. Antimicrobial peptides are exciting leads in the development of novel biocidal agents at a time when classical antibiotics are under intense pressure from emerging resistance, and the global industry in antibiotic research and development stagnates. This review will examine the potential of antimicrobial peptides, both natural and synthetic, as novel biocidal agents in the battle against multi-drug resistant pathogen infections. PMID:22072905

  7. Combination Effects of Antimicrobial Peptides

    PubMed Central

    Yu, Guozhi; Baeder, Desiree Y.; Regoes, Roland R.

    2016-01-01

    Antimicrobial peptides (AMPs) are ancient and conserved across the tree of life. Their efficacy over evolutionary time has been largely attributed to their mechanisms of killing. Yet, the understanding of their pharmacodynamics both in vivo and in vitro is very limited. This is, however, crucial for applications of AMPs as drugs and also informs the understanding of the action of AMPs in natural immune systems. Here, we selected six different AMPs from different organisms to test their individual and combined effects in vitro. We analyzed their pharmacodynamics based on the Hill function and evaluated the interaction of combinations of two and three AMPs. Interactions of AMPs in our study were mostly synergistic, and three-AMP combinations displayed stronger synergism than two-AMP combinations. This suggests synergism to be a common phenomenon in AMP interaction. Additionally, AMPs displayed a sharp increase in killing within a narrow dose range, contrasting with those of antibiotics. We suggest that our results could lead a way toward better evaluation of AMP application in practice and shed some light on the evolutionary consequences of antimicrobial peptide interactions within the immune system of organisms. PMID:26729502

  8. Antimicrobial peptides in human skin disease

    PubMed Central

    Kenshi, Yamasaki; Richard, L. Gallo

    2009-01-01

    The skin continuously encounters microbial pathogens. To defend against this, cells of the epidermis and dermis have evolved several innate strategies to prevent infection. Antimicrobial peptides are one of the primary mechanisms used by the skin in the early stages of immune defense. In general, antimicrobial peptides have broad antibacterial activity against gram-positive and negative bacteria and also show antifungal and antiviral activity. The antimicrobial activity of most peptides occurs as a result of unique structural characteristics that enable them to disrupt the microbial membrane while leaving human cell membranes intact. However, antimicrobial peptides also act on host cells to stimulate cytokine production, cell migration, proliferation, maturation, and extracellular matrix synthesis. The production by human skin of antimicrobial peptides such as defensins and cathelicidins occurs constitutively but also greatly increases after infection, inflammation or injury. Some skin diseases show altered expression of antimicrobial peptides, partially explaining the pathophysiology of these diseases. Thus, current research suggests that understanding how antimicrobial peptides modify susceptibility to microbes, influence skin inflammation, and modify wound healing, provides greater insight into the pathophysiology of skin disorders and offers new therapeutic opportunities. PMID:18086583

  9. Antimicrobial peptides of multicellular organisms

    NASA Astrophysics Data System (ADS)

    Zasloff, Michael

    2002-01-01

    Multicellular organisms live, by and large, harmoniously with microbes. The cornea of the eye of an animal is almost always free of signs of infection. The insect flourishes without lymphocytes or antibodies. A plant seed germinates successfully in the midst of soil microbes. How is this accomplished? Both animals and plants possess potent, broad-spectrum antimicrobial peptides, which they use to fend off a wide range of microbes, including bacteria, fungi, viruses and protozoa. What sorts of molecules are they? How are they employed by animals in their defence? As our need for new antibiotics becomes more pressing, could we design anti-infective drugs based on the design principles these molecules teach us?

  10. Ultrashort Antimicrobial Peptides with Antiendotoxin Properties

    PubMed Central

    Chih, Ya-Han; Lin, Yen-Shan; Yip, Bak-Sau; Wei, Hsiu-Ju; Chu, Hung-Lun; Yu, Hui-Yuan; Cheng, Hsi-Tsung

    2015-01-01

    Release of lipopolysaccharide (LPS) (endotoxin) from bacteria into the bloodstream may cause serious unwanted stimulation of the host immune system. Some but not all antimicrobial peptides can neutralize LPS-stimulated proinflammatory responses. Salt resistance and serum stability of short antimicrobial peptides can be boosted by adding β-naphthylalanine to their termini. Herein, significant antiendotoxin effects were observed in vitro and in vivo with the β-naphthylalanine end-tagged variants of the short antimicrobial peptides S1 and KWWK. PMID:26033727

  11. Diversity of wheat anti-microbial peptides.

    PubMed

    Egorov, Tsezi A; Odintsova, Tatyana I; Pukhalsky, Vitaliy A; Grishin, Eugene V

    2005-11-01

    From seeds of Triticum kiharae Dorof. et Migusch., 24 novel anti-microbial peptides were isolated and characterized by a combination of three-step HPLC (affinity, size-exclusion and reversed-phase) with matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and Edman degradation. Based on sequence similarity and cysteine motifs, partially sequenced peptides were assigned to 7 families: defensins, thionins, lipid-transfer proteins, hevein-like peptides, knottin-like peptides, glycine-rich peptides, and MBP-1 homologs. A novel subfamily of defensins consisting of 6 peptides and a new family of glycine-rich (8 peptides with different repeat motifs) were identified. Three 6-cysteine knottin-like peptides represented by N- and C-terminally truncated variants revealed no sequence homology to any known plant anti-microbial peptides. A new 8-cysteine hevein-like peptide and three 4-cysteine peptides homologous to MBP-1 from maize were isolated. This is the first communication on the occurrence of nearly all families of plant anti-microbial peptides in a single species. PMID:16269343

  12. [Antimicrobial peptide in dentisty. Literature review].

    PubMed

    Sato, F Simain; Rompen, E; Heinen, E

    2009-12-01

    The use of antimicrobial substances has contributed to the development of multiple antimicrobial resistances (1), challenging the pharmaceutical industry to develop with new, innovative, and effective molecules. Discovered around 1980, molecules called natural antimicrobial peptides (AMPs) appear to hold great potential for the treatment of infections. These cationic peptides are able to stop the bacterial development and to control infections. The purpose of this review is to help improve the understanding of the way AMPs operate in the context of the development of new cures against viruses, bacteria, and mushrooms found in the human body in general and in the oral cavity in particular. PMID:20143750

  13. Antimicrobial Cyclic Peptides for Plant Disease Control

    PubMed Central

    Lee, Dong Wan; Kim, Beom Seok

    2015-01-01

    Antimicrobial cyclic peptides derived from microbes bind stably with target sites, have a tolerance to hydrolysis by proteases, and a favorable degradability under field conditions, which make them an attractive proposition for use as agricultural fungicides. Antimicrobial cyclic peptides are classified according to the types of bonds within the ring structure; homodetic, heterodetic, and complex cyclic peptides, which in turn reflect diverse physicochemical features. Most antimicrobial cyclic peptides affect the integrity of the cell envelope. This is achieved through direct interaction with the cell membrane or disturbance of the cell wall and membrane component biosynthesis such as chitin, glucan, and sphingolipid. These are specific and selective targets providing reliable activity and safety for non-target organisms. Synthetic cyclic peptides produced through combinatorial chemistry offer an alternative approach to develop antimicrobials for agricultural uses. Those synthesized so far have been studied for antibacterial activity, however, the recent advancements in powerful technologies now promise to provide novel antimicrobial cyclic peptides that are yet to be discovered from natural resources. PMID:25774105

  14. Salt-resistant short antimicrobial peptides.

    PubMed

    Mohanram, Harini; Bhattacharjya, Surajit

    2016-05-01

    Antimicrobial peptides (AMPs) are promising leads for the development of antibiotics against drug resistant bacterial pathogens. However, in vivo applications of AMPs remain obscure due to salt and serum mediated inactivation. The high cost of chemical synthesis of AMPs also impedes potential clinical application. Consequently, short AMPs resistant toward salt and serum inactivation are desirable for the development of peptide antibiotics. In this work, we designed a 12-residue amphipathic helical peptide RR12 (R-R-L-I-R-L-I-L-R-L-L-R-amide) and two Trp containing analogs of RR12 namely RR12Wpolar (R-R-L-I-W-L-I-L-R-L-L-R-amide), and RR12Whydro (R-R-L-I-R-L-W-L-R-L-L-R-amide). Designed peptides demonstrated potent antibacterial activity; MIC ranging from 2 to 8 μM, in the presence of sodium chloride (150 mM and 300 mM). Antibacterial activity of these peptides was also detected in the presence of human serum. Designed peptides, in particular RR12 and RR12Whydro, were only poorly hemolytic. As a mode of action; these peptides demonstrated efficient permeabilization of bacterial cell membrane and lysis of cell structure. We further investigated interactions of the designed peptides with lipopolysaccharide (LPS), the major component of the outer membrane permeability barrier of Gram-negative bacteria. Designed peptides adopted helical conformations in complex with LPS. Binding of peptides with LPS has yielded dissociation the aggregated structures of LPS. Collectively, these designed peptides hold ability to be developed for salt-resistant antimicrobial compounds. Most importantly, current work provides insights for designing salt-resistant antimicrobial peptides. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 345-356, 2016. PMID:26849911

  15. Toxins and antimicrobial peptides: interactions with membranes

    NASA Astrophysics Data System (ADS)

    Schlamadinger, Diana E.; Gable, Jonathan E.; Kim, Judy E.

    2009-08-01

    The innate immunity to pathogenic invasion of organisms in the plant and animal kingdoms relies upon cationic antimicrobial peptides (AMPs) as the first line of defense. In addition to these natural peptide antibiotics, similar cationic peptides, such as the bee venom toxin melittin, act as nonspecific toxins. Molecular details of AMP and peptide toxin action are not known, but the universal function of these peptides to disrupt cell membranes of pathogenic bacteria (AMPs) or a diverse set of eukaryotes and prokaryotes (melittin) is widely accepted. Here, we have utilized spectroscopic techniques to elucidate peptide-membrane interactions of alpha-helical human and mouse AMPs of the cathelicidin family as well as the peptide toxin melittin. The activity of these natural peptides and their engineered analogs was studied on eukaryotic and prokaryotic membrane mimics consisting of <200-nm bilayer vesicles composed of anionic and neutral lipids as well as cholesterol. Vesicle disruption, or peptide potency, was monitored with a sensitive fluorescence leakage assay. Detailed molecular information on peptidemembrane interactions and peptide structure was further gained through vibrational spectroscopy combined with circular dichroism. Finally, steady-state fluorescence experiments yielded insight into the local environment of native or engineered tryptophan residues in melittin and human cathelicidin embedded in bilayer vesicles. Collectively, our results provide clues to the functional structures of the engineered and toxic peptides and may impact the design of synthetic antibiotic peptides that can be used against the growing number of antibiotic-resistant pathogens.

  16. Antimicrobial Peptides Design by Evolutionary Multiobjective Optimization

    PubMed Central

    Maccari, Giuseppe; Di Luca, Mariagrazia; Nifosí, Riccardo; Cardarelli, Francesco; Signore, Giovanni; Boccardi, Claudia; Bifone, Angelo

    2013-01-01

    Antimicrobial peptides (AMPs) are an abundant and wide class of molecules produced by many tissues and cell types in a variety of mammals, plant and animal species. Linear alpha-helical antimicrobial peptides are among the most widespread membrane-disruptive AMPs in nature, representing a particularly successful structural arrangement in innate defense. Recently, AMPs have received increasing attention as potential therapeutic agents, owing to their broad activity spectrum and their reduced tendency to induce resistance. The introduction of non-natural amino acids will be a key requisite in order to contrast host resistance and increase compound's life. In this work, the possibility to design novel AMP sequences with non-natural amino acids was achieved through a flexible computational approach, based on chemophysical profiles of peptide sequences. Quantitative structure-activity relationship (QSAR) descriptors were employed to code each peptide and train two statistical models in order to account for structural and functional properties of alpha-helical amphipathic AMPs. These models were then used as fitness functions for a multi-objective evolutional algorithm, together with a set of constraints for the design of a series of candidate AMPs. Two ab-initio natural peptides were synthesized and experimentally validated for antimicrobial activity, together with a series of control peptides. Furthermore, a well-known Cecropin-Mellitin alpha helical antimicrobial hybrid (CM18) was optimized by shortening its amino acid sequence while maintaining its activity and a peptide with non-natural amino acids was designed and tested, demonstrating the higher activity achievable with artificial residues. PMID:24039565

  17. Bacterial strategies of resistance to antimicrobial peptides.

    PubMed

    Joo, Hwang-Soo; Fu, Chih-Iung; Otto, Michael

    2016-05-26

    Antimicrobial peptides (AMPs) are a key component of the host's innate immune system, targeting invasive and colonizing bacteria. For successful survival and colonization of the host, bacteria have a series of mechanisms to interfere with AMP activity, and AMP resistance is intimately connected with the virulence potential of bacterial pathogens. In particular, because AMPs are considered as potential novel antimicrobial drugs, it is vital to understand bacterial AMP resistance mechanisms. This review gives a comparative overview of Gram-positive and Gram-negative bacterial strategies of resistance to various AMPs, such as repulsion or sequestration by bacterial surface structures, alteration of membrane charge or fluidity, degradation and removal by efflux pumps.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. PMID:27160595

  18. Design and Application of Antimicrobial Peptide Conjugates.

    PubMed

    Reinhardt, Andre; Neundorf, Ines

    2016-01-01

    Antimicrobial peptides (AMPs) are an interesting class of antibiotics characterized by their unique antibiotic activity and lower propensity for developing resistance compared to common antibiotics. They belong to the class of membrane-active peptides and usually act selectively against bacteria, fungi and protozoans. AMPs, but also peptide conjugates containing AMPs, have come more and more into the focus of research during the last few years. Within this article, recent work on AMP conjugates is reviewed. Different aspects will be highlighted as a combination of AMPs with antibiotics or organometallic compounds aiming to increase antibacterial activity or target selectivity, conjugation with photosensitizers for improving photodynamic therapy (PDT) or the attachment to particles, to name only a few. Owing to the enormous resonance of antimicrobial conjugates in the literature so far, this research topic seems to be very attractive to different scientific fields, like medicine, biology, biochemistry or chemistry. PMID:27187357

  19. Design and Application of Antimicrobial Peptide Conjugates

    PubMed Central

    Reinhardt, Andre; Neundorf, Ines

    2016-01-01

    Antimicrobial peptides (AMPs) are an interesting class of antibiotics characterized by their unique antibiotic activity and lower propensity for developing resistance compared to common antibiotics. They belong to the class of membrane-active peptides and usually act selectively against bacteria, fungi and protozoans. AMPs, but also peptide conjugates containing AMPs, have come more and more into the focus of research during the last few years. Within this article, recent work on AMP conjugates is reviewed. Different aspects will be highlighted as a combination of AMPs with antibiotics or organometallic compounds aiming to increase antibacterial activity or target selectivity, conjugation with photosensitizers for improving photodynamic therapy (PDT) or the attachment to particles, to name only a few. Owing to the enormous resonance of antimicrobial conjugates in the literature so far, this research topic seems to be very attractive to different scientific fields, like medicine, biology, biochemistry or chemistry. PMID:27187357

  20. Antimicrobial peptides in echinoderm host defense.

    PubMed

    Li, Chun; Blencke, Hans-Matti; Haug, Tor; Stensvåg, Klara

    2015-03-01

    Antimicrobial peptides (AMPs) are important effector molecules in innate immunity. Here we briefly summarize characteristic traits of AMPs and their mechanisms of antimicrobial activity. Echinoderms live in a microbe-rich marine environment and are known to express a wide range of AMPs. We address two novel AMP families from coelomocytes of sea urchins: cysteine-rich AMPs (strongylocins) and heterodimeric AMPs (centrocins). These peptide families have conserved preprosequences, are present in both adults and pluteus stage larvae, have potent antimicrobial properties, and therefore appear to be important innate immune effectors. Strongylocins have a unique cysteine pattern compared to other cysteine-rich peptides, which suggests a novel AMP folding pattern. Centrocins and SdStrongylocin 2 contain brominated tryptophan residues in their native form. This review also includes AMPs isolated from other echinoderms, such as holothuroidins, fragments of beta-thymosin, and fragments of lectin (CEL-III). Echinoderm AMPs are crucial molecules for the understanding of echinoderm immunity, and their potent antimicrobial activity makes them potential precursors of novel drug leads. PMID:25445901

  1. Antimicrobial activity of polycationic peptides.

    PubMed

    Giacometti, A; Cirioni, O; Barchiesi, F; Del Prete, M S; Scalise, G

    1999-11-01

    The in vitro activity of six polycationic peptides, buforin II, cecropin P1, indolicidin, magainin II, nisin, and ranalexin, were evaluated against several clinical isolates of gram-positive and gram-negative aerobic bacteria, yeasts, Pneumocystis carinii and Cryptosporidium parvum, by using microbroth dilution methods. The peptides exhibited different antibacterial activities and rapid time-dependent killing. The gram-negative organisms were more susceptible to buforin II and cecropin P1, whereas buforin II and ranalexin were the most active compounds against the gram-positive strains. Similarly, ranalexin showed the highest activity against Candida spp., whereas magainin II exerted the highest anticryptococcal activity. Finally, the peptides showed high anti-Pneumocystis activity, whereas no compound had strong inhibitory effect on C. parvum. PMID:10612440

  2. Classification of antimicrobial peptides with imbalanced datasets

    NASA Astrophysics Data System (ADS)

    Camacho, Francy L.; Torres, Rodrigo; Ramos Pollán, Raúl

    2015-12-01

    In the last years, pattern recognition has been applied to several fields for solving multiple problems in science and technology as for example in protein prediction. This methodology can be useful for prediction of activity of biological molecules, e.g. for determination of antimicrobial activity of synthetic and natural peptides. In this work, we evaluate the performance of different physico-chemical properties of peptides (descriptors groups) in the presence of imbalanced data sets, when facing the task of detecting whether a peptide has antimicrobial activity. We evaluate undersampling and class weighting techniques to deal with the class imbalance with different classification methods and descriptor groups. Our classification model showed an estimated precision of 96% showing that descriptors used to codify the amino acid sequences contain enough information to correlate the peptides sequences with their antimicrobial activity by means of learning machines. Moreover, we show how certain descriptor groups (pseudoaminoacid composition type I) work better with imbalanced datasets while others (dipeptide composition) work better with balanced ones.

  3. Biologically Active and Antimicrobial Peptides from Plants

    PubMed Central

    Salas, Carlos E.; Badillo-Corona, Jesus A.; Ramírez-Sotelo, Guadalupe; Oliver-Salvador, Carmen

    2015-01-01

    Bioactive peptides are part of an innate response elicited by most living forms. In plants, they are produced ubiquitously in roots, seeds, flowers, stems, and leaves, highlighting their physiological importance. While most of the bioactive peptides produced in plants possess microbicide properties, there is evidence that they are also involved in cellular signaling. Structurally, there is an overall similarity when comparing them with those derived from animal or insect sources. The biological action of bioactive peptides initiates with the binding to the target membrane followed in most cases by membrane permeabilization and rupture. Here we present an overview of what is currently known about bioactive peptides from plants, focusing on their antimicrobial activity and their role in the plant signaling network and offering perspectives on their potential application. PMID:25815307

  4. Membrane Thickening by the Antimicrobial Peptide PGLa

    PubMed Central

    Pabst, Georg; Grage, Stephan L.; Danner-Pongratz, Sabine; Jing, Weiguo; Ulrich, Anne S.; Watts, Anthony; Lohner, Karl; Hickel, Andrea

    2008-01-01

    Using x-ray diffraction, solid-state 2H-NMR, differential scanning calorimetry, and dilatometry, we have observed a perturbation of saturated acyl chain phosphatidylglycerol bilayers by the antimicrobial peptide peptidyl-glycylleucine-carboxyamide (PGLa) that is dependent on the length of the hydrocarbon chain. In the gel phase, PGLa induces a quasi-interdigitated phase, previously reported also for other peptides, which is most pronounced for C18 phosphatidylglycerol. In the fluid phase, we found an increase of the membrane thickness and NMR order parameter for C14 and C16 phosphatidylglycerol bilayers, though not for C18. The data is best understood in terms of a close hydrophobic match between the C18 bilayer core and the peptide length when PGLa is inserted with its helical axis normal to the bilayer surface. The C16 acyl chains appear to stretch to accommodate PGLa, whereas tilting within the bilayer seems to be energetically favorable for the peptide when inserted into bilayers of C14 phosphatidylglycerol. In contrast to the commonly accepted membrane thinning effect of antimicrobial peptides, the data demonstrate that pore formation does not necessarily relate to changes in the overall bilayer structure. PMID:18835902

  5. 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.

  6. Peptides and proteins with antimicrobial activity

    PubMed Central

    Coutinho, Henrique Douglas Melo; Lôbo, Katiuscia Menezes; Bezerra, Denise Aline Casimiro; Lôbo, Inalzuir

    2008-01-01

    The increase of microbial resistance to antibiotics has led to a continuing search for newer and more effective drugs. Antimicrobial peptides are generally found in animals, plants, and microorganisms and are of great interest to medicine, pharmacology, and the food industry. These peptides are capable of inhibiting pathogenic microorganisms. They can attack parasites, while causing little or no harm to the host cells. The defensins are peptides found in granules in the polymorphonuclear neutrophils (PMNs) and are responsible for the defense of the organism. Several animal defensins, like dermaseptin, antileukoprotease, protegrin, and others, have had their activities and efficacy tested and been shown to be effective against bacteria, fungi, and protists; there are also specific defensins from invertebrates, e.g., drosomycin and heliomicin; from plants, e.g., the types A and B; and the bacteriocins, e.g., acrocin, marcescin, etc. The aim of the present work was to compile a comprehensive bibliographic review of the diverse potentially antimicrobial peptides in an effort to systematize the current knowledge on these substances as a contribution for further researches. The currently available bibliography does not give a holistic approach on this subject. The present work intends to show that the mechanism of defense represented by defensins is promising from the perspective of its application in the treatment of infectious diseases in human, animals and plants. PMID:21264153

  7. Antimicrobial peptides: Old Molecules with New Ideas

    PubMed Central

    Nakatsuji, Teruaki; Gallo, Richard L.

    2011-01-01

    Almost 90 years have passed since Alexander Fleming discovered the antimicrobial activity of lysozyme, the first natural antibiotic isolated from our body. Since then, various types of molecules with antibiotic activity have been isolated from animals, insects, plants and bacteria, and their use has revolutionised clinical medicine. So far, more than 1200 types of peptides with antimicrobial activity have been isolated from various cells and tissues, and it appears all living organisms employ these antimicrobial peptides (AMPs) in their host defense. In the last decade, innate AMPs produced by mammals have been shown to be essential for the protection of skin and other organs. Their importance is due to their pleiotrophic functions to not only kill microbes but also control host physiological functions such as inflammation, angiogenesis and wound healing. Recent advances in our understanding of the function of AMPs have associated their altered production with various human diseases such as psoriasis, atopic dermatitis and rosacea. In this review, we summarize the history of AMP biology and provide an overview of recent research progress in this field. PMID:22158560

  8. Resistance to Antimicrobial Peptides in Vibrios

    PubMed Central

    Destoumieux-Garzón, Delphine; Duperthuy, Marylise; Vanhove, Audrey Sophie; Schmitt, Paulina; Wai, Sun Nyunt

    2014-01-01

    Vibrios are associated with a broad diversity of hosts that produce antimicrobial peptides (AMPs) as part of their defense against microbial infections. In particular, vibrios colonize epithelia, which function as protective barriers and express AMPs as a first line of chemical defense against pathogens. Recent studies have shown they can also colonize phagocytes, key components of the animal immune system. Phagocytes infiltrate infected tissues and use AMPs to kill the phagocytosed microorganisms intracellularly, or deliver their antimicrobial content extracellularly to circumvent tissue infection. We review here the mechanisms by which vibrios have evolved the capacity to evade or resist the potent antimicrobial defenses of the immune cells or tissues they colonize. Among their strategies to resist killing by AMPs, primarily vibrios use membrane remodeling mechanisms. In particular, some highly resistant strains substitute hexaacylated Lipid A with a diglycine residue to reduce their negative surface charge, thereby lowering their electrostatic interactions with cationic AMPs. As a response to envelope stress, which can be induced by membrane-active agents including AMPs, vibrios also release outer membrane vesicles to create a protective membranous shield that traps extracellular AMPs and prevents interaction of the peptides with their own membranes. Finally, once AMPs have breached the bacterial membrane barriers, vibrios use RND efflux pumps, similar to those of other species, to transport AMPs out of their cytoplasmic space. PMID:27025756

  9. Antiendotoxin activity of cationic peptide antimicrobial agents.

    PubMed Central

    Gough, M; Hancock, R E; Kelly, N M

    1996-01-01

    The endotoxin from gram-negative bacteria consists of a molecule lipopolysaccharide (LPS) which can be shed by bacteria during antimicrobial therapy. A resulting syndrome, endotoxic shock, is a leading cause of death in the developed world. Thus, there is great interest in the development of antimicrobial agents which can reverse rather than promote sepsis, especially given the recent disappointing clinical performance of antiendotoxin therapies. We describe here two small cationic peptides, MBI-27 and MBI-28, which have both antiendotoxic and antibacterial activities in vitro and in vivo in animal models. We had previously demonstrated that these peptides bind to LPS with an affinity equivalent to that of polymyxin B. Consistent with this, the peptides blocked the ability of LPS and intact cells to induce the endotoxic shock mediator, tumor necrosis factor (TNF), upon incubation with the RAW 264.7 murine macrophage cell line. MBI-28 was equivalent to polymyxin B in its ability to block LPS induction of TNF by this cell line, even when added 60 min after the TNF stimulus. Furthermore, MBI-28 offered significant protection in a galactosamine-sensitized mouse model of lethal endotoxic shock. This protection correlated with the ability of MBI-28 to reduce LPS-induced circulating TNF by nearly 90% in this mouse model. Both MBI-27 and MBI-28 demonstrated antibacterial activity against gram-negative bacteria in vitro and in vivo against Pseudomonas aeruginosa infections in neutropenic mice. PMID:8945527

  10. Antimicrobial peptides in the centipede Scolopendra subspinipes mutilans.

    PubMed

    Yoo, Won Gi; Lee, Joon Ha; Shin, Younhee; Shim, Jae-Young; Jung, Myunghee; Kang, Byeong-Chul; Oh, Jaedon; Seong, Jiyeon; Lee, Hak Kyo; Kong, Hong Sik; Song, Ki-Duk; Yun, Eun-Young; Kim, In-Woo; Kwon, Young-Nam; Lee, Dong Gun; Hwang, Ui-Wook; Park, Junhyung; Hwang, Jae Sam

    2014-06-01

    The centipede Scolopendra subspinipes mutilans is an environmentally beneficial and medically important arthropod species. Although this species is increasingly applied as a reliable source of new antimicrobial peptides, the transcriptome of this species is a prerequisite for more rational selection of antimicrobial peptides. In this report, we isolated total RNA from the whole body of adult centipedes, S. subspinipes mutilans, that were nonimmunized and immunized against Escherichia coli, and we generated a total of 77,063 pooled contigs and singletons using high-throughput sequencing. To screen putative antimicrobial peptides, in silico analyses of the S. subspinipes mutilans transcriptome were performed based on the physicochemical evidence of length, charge, isoelectric point, and in vitro and in vivo aggregation scores together with the existence of continuous antimicrobial peptide stretches. Moreover, we excluded some transcripts that showed similarity with both previously known antimicrobial peptides and the human proteome, had a proteolytic cleavage site, and had downregulated expression compared with the nonimmunized sample. As a result, we selected 17 transcripts and tested their antimicrobial activity with a radial diffusion assay. Among them, ten synthetic peptides experimentally showed antimicrobial activity against microbes and no toxicity to mouse erythrocytes. Our results provide not only a useful set of antimicrobial peptide candidates and an efficient strategy for novel antimicrobial peptide development but also the transcriptome data of a big centipede as a valuable resource. PMID:24652097

  11. Plant Antimicrobial Peptides as Potential Anticancer Agents

    PubMed Central

    Guzmán-Rodríguez, Jaquelina Julia; López-Gómez, Rodolfo

    2015-01-01

    Antimicrobial peptides (AMPs) are part of the innate immune defense mechanism of many organisms and are promising candidates to treat infections caused by pathogenic bacteria to animals and humans. AMPs also display anticancer activities because of their ability to inactivate a wide range of cancer cells. Cancer remains a cause of high morbidity and mortality worldwide. Therefore, the development of methods for its control is desirable. Attractive alternatives include plant AMP thionins, defensins, and cyclotides, which have anticancer activities. Here, we provide an overview of plant AMPs anticancer activities, with an emphasis on their mode of action, their selectivity, and their efficacy. PMID:25815333

  12. Membrane Disruption Mechanism by Antimicrobial Peptides

    NASA Astrophysics Data System (ADS)

    Lee, Ka Yee C.

    2011-03-01

    Antimicrobial peptides (AMPs) are a class of small (less than100 residues) host defense peptides that induce selective membrane lytic activity against microbes. To understand the mechanism of membrane disruption by AMPs, we investigated, via atomic force microscopy, topological changes in supported phospholipid bilayers induced by protegrin-1 (PG-1). We have observed that PG-1 induces structural transformations, progressing from fingerlike instabilities at bilayer edges, to the formation of sievelike nanoporous structures and finally to a network of stripelike structures in a zwitterionic dimyristoylphosphatidylcholine (DMPC) model membrane in buffer, with increasing PG-1 concentration. Our results suggest that AMPs act to lower the interfacial energy of the bilayer in a way similar to detergents. By varying the lipid composition, temperature and using AMPs with different secondary structures, we are able to identify factors other than electrostatics that are important for the efficacy of AMPs.

  13. Antimicrobial Peptides, Infections and the Skin Barrier.

    PubMed

    Clausen, Maja-Lisa; Agner, Tove

    2016-01-01

    The skin serves as a strong barrier protecting us from invading pathogens and harmful organisms. An important part of this barrier comes from antimicrobial peptides (AMPs), which are small peptides expressed abundantly in the skin. AMPs are produced in the deeper layers of the epidermis and transported to the stratum corneum, where they play a vital role in the first line of defense against potential pathogens. Numerous AMPs exist, and they have a broad antibiotic-like activity against bacteria, fungi and viruses. They also act as multifunctional effector molecules, linking innate and adaptive immune responses. AMPs play an essential part in maintaining an optimal and functional skin barrier - not only by direct killing of pathogens, but also by balancing immune responses and interfering in wound healing, cell differentiation, reepithelialization and their synergistic interplay with the skin microflora. PMID:26844896

  14. Epithelial antimicrobial peptides in host defense against infection

    PubMed Central

    Bals, Robert

    2000-01-01

    One component of host defense at mucosal surfaces seems to be epithelium-derived antimicrobial peptides. Antimicrobial peptides are classified on the basis of their structure and amino acid motifs. Peptides of the defensin, cathelicidin, and histatin classes are found in humans. In the airways, α-defensins and the cathelicidin LL-37/hCAP-18 originate from neutrophils. β-Defensins and LL-37/hCAP-18 are produced by the respiratory epithelium and the alveolar macrophage and secreted into the airway surface fluid. Beside their direct antimicrobial function, antimicrobial peptides have multiple roles as mediators of inflammation with effects on epithelial and inflammatory cells, influencing such diverse processes as proliferation, immune induction, wound healing, cytokine release, chemotaxis, protease-antiprotease balance, and redox homeostasis. Further, antimicrobial peptides qualify as prototypes of innovative drugs that might be used as antibiotics, anti-lipopolysaccharide drugs, or modifiers of inflammation. PMID:11667978

  15. Antimicrobial activity of mosquito cecropin peptides against Francisella.

    PubMed

    Kaushal, Akanksha; Gupta, Kajal; Shah, Ruhee; van Hoek, Monique L

    2016-10-01

    Francisella tularensis is the cause of the zoonotic disease tularemia. In Sweden and Scandinavia, epidemiological studies have implicated mosquitoes as a vector. Prior research has demonstrated the presence of Francisella DNA in infected mosquitoes but has not shown definitive transmission of tularemia from a mosquito to a mammalian host. We hypothesized that antimicrobial peptides, an important component of the innate immune system of higher organisms, may play a role in mosquito host-defense to Francisella. We established that Francisella sp. are susceptible to two cecropin antimicrobial peptides derived from the mosquito Aedes albopictus as well as Culex pipiens. We also demonstrated induced expression of Aedes albopictus antimicrobial peptide genes by Francisella infection C6/36 mosquito cell line. We demonstrate that mosquito antimicrobial peptides act against Francisella by disrupting the cellular membrane of the bacteria. Thus, it is possible that antimicrobial peptides may play a role in the inability of mosquitoes to establish an effective natural transmission of tularemia. PMID:27235883

  16. Interaction between antimicrobial peptides and mycobacteria.

    PubMed

    Gutsmann, Thomas

    2016-05-01

    Mycobacteria can cause different severe health problems, including tuberculosis (TB). The treatment of TB with conventional antibiotics is successful, however, the number of multi-drug and extensively-drug resistant Mycobacterium tuberculosis strains increases. Moreover, many classical antimycobacterial antibiotics have severe side effects. Therefore, antimicrobial peptides (AMPs) seem to be good candidates for new therapeutic strategies. On the one hand AMPs can be used as a single drug or in combination with conventional antibiotics to directly kill mycobacteria, or on the other hand to act as immunstimulatory agents. This review summarizes the findings on the role of endogenous human AMPs being involved in TB, the antimycobacterial activity of various AMPs, and the molecular modes of action. Most active AMPs interact with the mycobacterial cell envelope and in particular with the mycomembrane and the plasma membrane. The mycomembrane is a very rigid membrane probably leading to a lower activity of the AMPs against mycobacteria as compared to other Gram-negative or Gram-positive bacteria. For some AMPs also other targets have been identified. Because of the complex environment of intracellular mycobacteria being trapped in the phagosome, within the macrophage, within the granuloma, within the lung, the external administration of AMPs in the latent phase of TB is a challenge. However, in the acute phase the AMPs can attack mycobacteria in a direct way. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert. PMID:26851776

  17. From antimicrobial to anticancer peptides. A review.

    PubMed

    Gaspar, Diana; Veiga, A Salomé; Castanho, Miguel A R B

    2013-01-01

    Antimicrobial peptides (AMPs) are part of the innate immune defense mechanism of many organisms. Although AMPs have been essentially studied and developed as potential alternatives for fighting infectious diseases, their use as anticancer peptides (ACPs) in cancer therapy either alone or in combination with other conventional drugs has been regarded as a therapeutic strategy to explore. As human cancer remains a cause of high morbidity and mortality worldwide, an urgent need of new, selective, and more efficient drugs is evident. Even though ACPs are expected to be selective toward tumor cells without impairing the normal body physiological functions, the development of a selective ACP has been a challenge. It is not yet possible to predict antitumor activity based on ACPs structures. ACPs are unique molecules when compared to the actual chemotherapeutic arsenal available for cancer treatment and display a variety of modes of action which in some types of cancer seem to co-exist. Regardless the debate surrounding the definition of structure-activity relationships for ACPs, great effort has been invested in ACP design and the challenge of improving effective killing of tumor cells remains. As detailed studies on ACPs mechanisms of action are crucial for optimizing drug development, in this review we provide an overview of the literature concerning peptides' structure, modes of action, selectivity, and efficacy and also summarize some of the many ACPs studied and/or developed for targeting different solid and hematologic malignancies with special emphasis on the first group. Strategies described for drug development and for increasing peptide selectivity toward specific cells while reducing toxicity are also discussed. PMID:24101917

  18. From antimicrobial to anticancer peptides. A review

    PubMed Central

    Gaspar, Diana; Veiga, A. Salomé; Castanho, Miguel A. R. B.

    2013-01-01

    Antimicrobial peptides (AMPs) are part of the innate immune defense mechanism of many organisms. Although AMPs have been essentially studied and developed as potential alternatives for fighting infectious diseases, their use as anticancer peptides (ACPs) in cancer therapy either alone or in combination with other conventional drugs has been regarded as a therapeutic strategy to explore. As human cancer remains a cause of high morbidity and mortality worldwide, an urgent need of new, selective, and more efficient drugs is evident. Even though ACPs are expected to be selective toward tumor cells without impairing the normal body physiological functions, the development of a selective ACP has been a challenge. It is not yet possible to predict antitumor activity based on ACPs structures. ACPs are unique molecules when compared to the actual chemotherapeutic arsenal available for cancer treatment and display a variety of modes of action which in some types of cancer seem to co-exist. Regardless the debate surrounding the definition of structure-activity relationships for ACPs, great effort has been invested in ACP design and the challenge of improving effective killing of tumor cells remains. As detailed studies on ACPs mechanisms of action are crucial for optimizing drug development, in this review we provide an overview of the literature concerning peptides' structure, modes of action, selectivity, and efficacy and also summarize some of the many ACPs studied and/or developed for targeting different solid and hematologic malignancies with special emphasis on the first group. Strategies described for drug development and for increasing peptide selectivity toward specific cells while reducing toxicity are also discussed. PMID:24101917

  19. Coleopteran Antimicrobial Peptides: Prospects for Clinical Applications

    PubMed Central

    Ntwasa, Monde; Goto, Akira; Kurata, Shoichiro

    2012-01-01

    Antimicrobial peptides (AMPs) are activated in response to septic injury and have important roles in vertebrate and invertebrate immune systems. AMPs act directly against pathogens and have both wound healing and antitumor activities. Although coleopterans comprise the largest and most diverse order of eukaryotes and occupy an earlier branch than Drosophila in the holometabolous lineage of insects, their immune system has not been studied extensively. Initial research reports, however, indicate that coleopterans possess unique immune response mechanisms, and studies of these novel mechanisms may help to further elucidate innate immunity. Recently, the complete genome sequence of Tribolium was published, boosting research on coleopteran immunity and leading to the identification of Tribolium AMPs that are shared by Drosophila and mammals, as well as other AMPs that are unique. AMPs have potential applicability in the development of vaccines. Here, we review coleopteran AMPs, their potential impact on clinical medicine, and the molecular basis of immune defense. PMID:22500175

  20. Probing protein sequences as sources for encrypted antimicrobial peptides.

    PubMed

    Brand, Guilherme D; Magalhães, Mariana T Q; Tinoco, Maria L P; Aragão, Francisco J L; Nicoli, Jacques; Kelly, Sharon M; Cooper, Alan; Bloch, Carlos

    2012-01-01

    Starting from the premise that a wealth of potentially biologically active peptides may lurk within proteins, we describe here a methodology to identify putative antimicrobial peptides encrypted in protein sequences. Candidate peptides were identified using a new screening procedure based on physicochemical criteria to reveal matching peptides within protein databases. Fifteen such peptides, along with a range of natural antimicrobial peptides, were examined using DSC and CD to characterize their interaction with phospholipid membranes. Principal component analysis of DSC data shows that the investigated peptides group according to their effects on the main phase transition of phospholipid vesicles, and that these effects correlate both to antimicrobial activity and to the changes in peptide secondary structure. Consequently, we have been able to identify novel antimicrobial peptides from larger proteins not hitherto associated with such activity, mimicking endogenous and/or exogenous microorganism enzymatic processing of parent proteins to smaller bioactive molecules. A biotechnological application for this methodology is explored. Soybean (Glycine max) plants, transformed to include a putative antimicrobial protein fragment encoded in its own genome were tested for tolerance against Phakopsora pachyrhizi, the causative agent of the Asian soybean rust. This procedure may represent an inventive alternative to the transgenic technology, since the genetic material to be used belongs to the host organism and not to exogenous sources. PMID:23029273

  1. Studies on Anticancer Activities of Antimicrobial Peptides

    PubMed Central

    Hoskin, David W.; Ramamoorthy, Ayyalusamy

    2008-01-01

    In spite of great advances in cancer therapy, there is considerable current interest in developing anticancer agents with a new mode of action because of the development of resistance by cancer cells towards current anticancer drugs. A growing number of studies have shown that some of the cationic antimicrobial peptides (AMPs), which are toxic to bacteria but not to normal mammalian cells, exhibit a broad spectrum of cytotoxic activity against cancer cells. Such studies have considerably enhanced the significance of AMPs, both synthetic and from natural sources, which have been of importance both for an increased understanding of the immune system and for their potential as clinical antibiotics. The electrostatic attraction between the negatively charged components of bacterial and cancer cells and the positively charged AMPs is believed to play a major role in the strong binding and selective disruption of bacterial and cancer cell membranes, respectively. However, it is unclear why some host defense peptides are able to kill cancer cells when others do not. In addition, it is not clear whether the molecular mechanism(s) underlying the antibacterial and anticancer activities of AMPs are the same or different. In this article, we review various studies on different AMPs that exhibit cytotoxic activity against cancer cells. The suitability of cancer cell-targeting AMPs as cancer therapeutics is also discussed. PMID:18078805

  2. Binding studies of antimicrobial peptides to Escherichia coli cells.

    PubMed

    Avitabile, Concetta; D'Andrea, Luca D; Saviano, Michele; Olivieri, Michele; Cimmino, Amelia; Romanelli, Alessandra

    2016-09-01

    Understanding the mechanism of action of antimicrobial peptides is pivotal to the design of new and more active peptides. In the last few years it has become clear that the behavior of antimicrobial peptides on membrane model systems does not always translate to cells; therefore the need to develop methods aimed at capturing details of the interactions of peptides with bacterial cells is compelling. In this work we analyzed binding of two peptides, namely temporin B and TB_KKG6A, to Escherichia coli cells and to Escherichia coli LPS. Temporin B is a natural peptide active against Gram positive bacteria but inactive against Gram negative bacteria, TB_KKG6A is an analogue of temporin B showing activity against both Gram positive and Gram negative bacteria. We found that binding to cells occurs only for the active peptide TB_KKG6A; stoichiometry and affinity constant of this peptide toward Escherichia coli cells were determined. PMID:27450805

  3. 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. PMID:26687790

  4. Antimicrobial and Immunomodulatory Activities of PR-39 Derived Peptides

    PubMed Central

    Veldhuizen, Edwin J. A.; Schneider, Viktoria A. F.; Agustiandari, Herfita; van Dijk, Albert; Tjeerdsma-van Bokhoven, Johanna L. M.; Bikker, Floris J.; Haagsman, Henk P.

    2014-01-01

    The porcine cathelicidin PR-39 is a host defence peptide that plays a pivotal role in the innate immune defence of the pig against infections. Besides direct antimicrobial activity, it is involved in immunomodulation, wound healing and several other biological processes. In this study, the antimicrobial- and immunomodulatory activity of PR-39, and N- and C-terminal derivatives of PR-39 were tested. PR-39 exhibited an unexpected broad antimicrobial spectrum including several Gram positive strains such as Bacillus globigii and Enterococcus faecalis. Of organisms tested, only Staphylococcus aureus was insensitive to PR-39. Truncation of PR-39 down to 15 (N-terminal) amino acids did not lead to major loss of activity, while peptides corresponding to the C-terminal part of PR-39 were hampered in their antimicrobial activity. However, shorter peptides were all much more sensitive to inhibition by salt. Active peptides induced ATP leakage and loss of membrane potential in Bacillus globigii and Escherichia coli, indicating a lytic mechanism of action for these peptides. Finally, only the mature peptide was able to induce IL-8 production in porcine macrophages, but some shorter peptides also had an effect on TNF-α production showing differential regulation of cytokine induction by PR-39 derived peptides. None of the active peptides showed high cytotoxicity highlighting the potential of these peptides for use as an alternative to antibiotics. PMID:24755622

  5. The role of antimicrobial peptides in chronic inflammatory skin diseases

    PubMed Central

    Majewski, Sławomir

    2016-01-01

    Antimicrobial peptides (AMPs) are effector molecules of the innate immune system of the skin. They present an activity against a broad spectrum of Gram-positive and Gram-negative bacteria as well as some fungi, parasites and enveloped viruses. Several inflammatory skin diseases including psoriasis, atopic dermatitis, acne vulgaris and rosacea are characterized by a dysregulated expression of AMPs. Antimicrobial peptides are excessively produced in lesional psoriatic scales or rosacea in contrast to the atopic skin that shows lower AMP levels when compared with psoriasis. The importance of the AMPs contribution to host immunity is indisputable as alterations in the antimicrobial peptide expression have been associated with various pathologic processes. This review discusses the biology and clinical relevance of antimicrobial peptides expressed in the skin and their role in the pathogenesis of inflammatory skin diseases. PMID:26985172

  6. The role of antimicrobial peptides in chronic inflammatory skin diseases.

    PubMed

    Marcinkiewicz, Małgorzata; Majewski, Sławomir

    2016-02-01

    Antimicrobial peptides (AMPs) are effector molecules of the innate immune system of the skin. They present an activity against a broad spectrum of Gram-positive and Gram-negative bacteria as well as some fungi, parasites and enveloped viruses. Several inflammatory skin diseases including psoriasis, atopic dermatitis, acne vulgaris and rosacea are characterized by a dysregulated expression of AMPs. Antimicrobial peptides are excessively produced in lesional psoriatic scales or rosacea in contrast to the atopic skin that shows lower AMP levels when compared with psoriasis. The importance of the AMPs contribution to host immunity is indisputable as alterations in the antimicrobial peptide expression have been associated with various pathologic processes. This review discusses the biology and clinical relevance of antimicrobial peptides expressed in the skin and their role in the pathogenesis of inflammatory skin diseases. PMID:26985172

  7. 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

  8. Distinct profiling of antimicrobial peptide families

    PubMed Central

    Khamis, Abdullah M.; Essack, Magbubah; Gao, Xin; Bajic, Vladimir B.

    2015-01-01

    Motivation: The increased prevalence of multi-drug resistant (MDR) pathogens heightens the need to design new antimicrobial agents. Antimicrobial peptides (AMPs) exhibit broad-spectrum potent activity against MDR pathogens and kills rapidly, thus giving rise to AMPs being recognized as a potential substitute for conventional antibiotics. Designing new AMPs using current in-silico approaches is, however, challenging due to the absence of suitable models, large number of design parameters, testing cycles, production time and cost. To date, AMPs have merely been categorized into families according to their primary sequences, structures and functions. The ability to computationally determine the properties that discriminate AMP families from each other could help in exploring the key characteristics of these families and facilitate the in-silico design of synthetic AMPs. Results: Here we studied 14 AMP families and sub-families. We selected a specific description of AMP amino acid sequence and identified compositional and physicochemical properties of amino acids that accurately distinguish each AMP family from all other AMPs with an average sensitivity, specificity and precision of 92.88%, 99.86% and 95.96%, respectively. Many of our identified discriminative properties have been shown to be compositional or functional characteristics of the corresponding AMP family in literature. We suggest that these properties could serve as guides for in-silico methods in design of novel synthetic AMPs. The methodology we developed is generic and has a potential to be applied for characterization of any protein family. Contact: vladimir.bajic@kaust.edu.sa Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25388148

  9. DRAMP: a comprehensive data repository of antimicrobial peptides

    PubMed Central

    Fan, Linlin; Sun, Jian; Zhou, Meifeng; Zhou, Jie; Lao, Xingzhen; Zheng, Heng; Xu, Hanmei

    2016-01-01

    The growing problem of antibiotic-resistant microorganisms results in an urgent need for substitutes to conventional antibiotics with novel modes of action and effective activities. Antimicrobial peptides (AMPs), produced by a wide variety of living organisms acting as a defense mechanism against invading pathogenic microbes, are considered to be such promising alternatives. AMPs display a broad spectrum of antimicrobial activity and a low propensity for developing resistance. Therefore, a thorough understanding of AMPs is essential to exploit them as antimicrobial drugs. Considering this, we developed a comprehensive user-friendly data repository of antimicrobial peptides (DRAMP), which holds 17349 antimicrobial sequences, including 4571 general AMPs, 12704 patented sequences and 74 peptides in drug development. Entries in the database have detailed annotations, especially detailed antimicrobial activity data (shown as target organism with MIC value) and structure information. Annotations also include accession numbers crosslinking to Pubmed, Swiss-prot and Protein Data Bank (PDB). The website of the database comes with easy-to-operate browsing as well as searching with sorting and filtering functionalities. Several useful sequence analysis tools are provided, including similarity search, sequence alignment and conserved domain search (CD-Search). DRAMP should be a useful resource for the development of novel antimicrobial peptide drugs. PMID:27075512

  10. DRAMP: a comprehensive data repository of antimicrobial peptides.

    PubMed

    Fan, Linlin; Sun, Jian; Zhou, Meifeng; Zhou, Jie; Lao, Xingzhen; Zheng, Heng; Xu, Hanmei

    2016-01-01

    The growing problem of antibiotic-resistant microorganisms results in an urgent need for substitutes to conventional antibiotics with novel modes of action and effective activities. Antimicrobial peptides (AMPs), produced by a wide variety of living organisms acting as a defense mechanism against invading pathogenic microbes, are considered to be such promising alternatives. AMPs display a broad spectrum of antimicrobial activity and a low propensity for developing resistance. Therefore, a thorough understanding of AMPs is essential to exploit them as antimicrobial drugs. Considering this, we developed a comprehensive user-friendly data repository of antimicrobial peptides (DRAMP), which holds 17349 antimicrobial sequences, including 4571 general AMPs, 12704 patented sequences and 74 peptides in drug development. Entries in the database have detailed annotations, especially detailed antimicrobial activity data (shown as target organism with MIC value) and structure information. Annotations also include accession numbers crosslinking to Pubmed, Swiss-prot and Protein Data Bank (PDB). The website of the database comes with easy-to-operate browsing as well as searching with sorting and filtering functionalities. Several useful sequence analysis tools are provided, including similarity search, sequence alignment and conserved domain search (CD-Search). DRAMP should be a useful resource for the development of novel antimicrobial peptide drugs. PMID:27075512

  11. Archetypal tryptophan-rich antimicrobial peptides: properties and applications.

    PubMed

    Shagaghi, Nadin; Palombo, Enzo A; Clayton, Andrew H A; Bhave, Mrinal

    2016-02-01

    Drug-resistant microorganisms ('superbugs') present a serious challenge to the success of antimicrobial treatments. Subsequently, there is a crucial need for novel bio-control agents. Many antimicrobial peptides (AMPs) show a broad-spectrum activity against bacteria, fungi or viruses and are strong candidates to complement or substitute current antimicrobial agents. Some AMPs are also effective against protozoa or cancer cells. The tryptophan (Trp)-rich peptides (TRPs) are a subset of AMPs that display potent antimicrobial activity, credited to the unique biochemical properties of tryptophan that allow it to insert into biological membranes. Further, many Trp-rich AMPs cross bacterial membranes without compromising their integrity and act intracellularly, suggesting interactions with nucleic acids and enzymes. In this work, we overview some archetypal TRPs derived from natural sources, i.e., indolicidin, tritrpticin and lactoferricin, summarising their biochemical properties, structures, antimicrobial activities, mechanistic studies and potential applications. PMID:26748808

  12. Immune modulation by multifaceted cationic host defense (antimicrobial) peptides.

    PubMed

    Hilchie, Ashley L; Wuerth, Kelli; Hancock, Robert E W

    2013-12-01

    Cationic host defense (antimicrobial) peptides were originally studied for their direct antimicrobial activities. They have since been found to exhibit multifaceted immunomodulatory activities, including profound anti-infective and selective anti-inflammatory properties, as well as adjuvant and wound-healing activities in animal models. These biological properties suggest that host defense peptides, and synthetic derivatives thereof, possess clinical potential beyond the treatment of antibiotic-resistant infections. In this Review, we provide an overview of the biological activities of host defense and synthetic peptides, their mechanism(s) of action and new therapeutic applications and challenges that are associated with their clinical use. PMID:24231617

  13. Antimicrobial Peptides and Their Analogs: Searching for New Potential Therapeutics

    PubMed Central

    Midura-Nowaczek, Krystyna; Markowska, Agnieszka

    2014-01-01

    Antimicrobial peptides (AMPs) are an essential part of innate immunity. These compounds have been considered as potential therapeutics because of their broad-spectrum activities and proven ability to avoid antimicrobial resistance, but their clinical and commercial developments have some limitations, such as susceptibility to proteases and a high cost of peptide production. To overcome these problems, many researchers have tried to develop short active peptides, their modifications and mimics with better properties while retaining their basic features of natural AMPs such as cationic charge and the amphipathic structure. PMID:25374459

  14. Nanomechanical Response of Bacterial Cells to Cationic Antimicrobial Peptides

    NASA Astrophysics Data System (ADS)

    Lu, Shun; Walters, Grant; Parg, Richard; Dutcher, John

    2014-03-01

    The effectiveness of antimicrobial compounds can be easily screened, however their mechanism of action is much more difficult to determine. Many compounds act by compromising the mechanical integrity of the bacterial cell envelope, and our study introduces an atomic force microscopy (AFM)-based creep deformation technique to evaluate changes in the time-dependent mechanical properties of Pseudomonas aeruginosa PAO1 bacterial cells upon exposure to two different but structurally related antimicrobial peptides: polymyxin B and polymyxin B nonapeptide. We observed a distinctive signature for the loss of integrity of the bacterial cell envelope following exposure to the peptides. Measurements performed before and after exposure, as well as time-resolved measurements and those performed at different concentrations, revealed large changes to the viscoelastic parameters that are consistent with differences in the membrane permeabilizing effects of the peptides. The AFM creep deformation measurement provides new, unique insight into the kinetics and mechanism of action of antimicrobial peptides on bacteria.

  15. Evolution of Antimicrobial Peptides to Self-Assembled Peptides for Biomaterial Applications

    PubMed Central

    McCloskey, Alice P.; Gilmore, Brendan F.; Laverty, Garry

    2014-01-01

    Biomaterial-related infections are a persistent burden on patient health, recovery, mortality and healthcare budgets. Self-assembled antimicrobial peptides have evolved from the area of antimicrobial peptides. Peptides serve as important weapons in nature, and increasingly medicine, for combating microbial infection and biofilms. Self-assembled peptides harness a “bottom-up” approach, whereby the primary peptide sequence may be modified with natural and unnatural amino acids to produce an inherently antimicrobial hydrogel. Gelation may be tailored to occur in the presence of physiological and infective indicators (e.g. pH, enzymes) and therefore allow local, targeted antimicrobial therapy at the site of infection. Peptides demonstrate inherent biocompatibility, antimicrobial activity, biodegradability and numerous functional groups. They are therefore prime candidates for the production of polymeric molecules that have the potential to be conjugated to biomaterials with precision. Non-native chemistries and functional groups are easily incorporated into the peptide backbone allowing peptide hydrogels to be tailored to specific functional requirements. This article reviews an area of increasing interest, namely self-assembled peptides and their potential therapeutic applications as innovative hydrogels and biomaterials in the prevention of biofilm-related infection. PMID:25436505

  16. Cathelicidin peptides as candidates for a novel class of antimicrobials.

    PubMed

    Zanetti, Margherita; Gennaro, Renato; Skerlavaj, Barbara; Tomasinsig, Linda; Circo, Raffaella

    2002-01-01

    Cathelicidin peptides are a numerous group of mammalian cationic antimicrobial peptides. Despite a common evolutionary origin of their genes, peptides display a remarkable variety of sizes, sequences and structures. Their spectra of antimicrobial activity are varied and cover a range of organisms that includes bacteria, fungi and enveloped viruses. In addition, they bind to and neutralize the effects of endotoxin. These features make this family of peptides good candidates in view of a therapeutic use. The most promising ones are currently under evaluation as leads for the development of novel anti-infectives, and synthetic variants are in an advanced stage of development for specific clinical applications. This review focuses on recent studies on the structure and in vitro and in vivo biological activities of these peptides. PMID:11945171

  17. Improved methods for classification, prediction, and design of antimicrobial peptides.

    PubMed

    Wang, Guangshun

    2015-01-01

    Peptides with diverse amino acid sequences, structures, and functions are essential players in biological systems. The construction of well-annotated databases not only facilitates effective information management, search, and mining but also lays the foundation for developing and testing new peptide algorithms and machines. The antimicrobial peptide database (APD) is an original construction in terms of both database design and peptide entries. The host defense antimicrobial peptides (AMPs) registered in the APD cover the five kingdoms (bacteria, protists, fungi, plants, and animals) or three domains of life (bacteria, archaea, and eukaryota). This comprehensive database ( http://aps.unmc.edu/AP ) provides useful information on peptide discovery timeline, nomenclature, classification, glossary, calculation tools, and statistics. The APD enables effective search, prediction, and design of peptides with antibacterial, antiviral, antifungal, antiparasitic, insecticidal, spermicidal, anticancer activities, chemotactic, immune modulation, or antioxidative properties. A universal classification scheme is proposed herein to unify innate immunity peptides from a variety of biological sources. As an improvement, the upgraded APD makes predictions based on the database-defined parameter space and provides a list of the sequences most similar to natural AMPs. In addition, the powerful pipeline design of the database search engine laid a solid basis for designing novel antimicrobials to combat resistant superbugs, viruses, fungi, or parasites. This comprehensive AMP database is a useful tool for both research and education. PMID:25555720

  18. Improved Methods for Classification, Prediction and Design of Antimicrobial Peptides

    PubMed Central

    Wang, Guangshun

    2015-01-01

    Peptides with diverse amino acid sequences, structures and functions are essential players in biological systems. The construction of well-annotated databases not only facilitates effective information management, search and mining, but also lays the foundation for developing and testing new peptide algorithms and machines. The antimicrobial peptide database (APD) is an original construction in terms of both database design and peptide entries. The host defense antimicrobial peptides (AMPs) registered in the APD cover the five kingdoms (bacteria, protists, fungi, plants, and animals) or three domains of life (bacteria, archaea, and eukaryota). This comprehensive database (http://aps.unmc.edu/AP) provides useful information on peptide discovery timeline, nomenclature, classification, glossary, calculation tools, and statistics. The APD enables effective search, prediction, and design of peptides with antibacterial, antiviral, antifungal, antiparasitic, insecticidal, spermicidal, anticancer activities, chemotactic, immune modulation, or anti-oxidative properties. A universal classification scheme is proposed herein to unify innate immunity peptides from a variety of biological sources. As an improvement, the upgraded APD makes predictions based on the database-defined parameter space and provides a list of the sequences most similar to natural AMPs. In addition, the powerful pipeline design of the database search engine laid a solid basis for designing novel antimicrobials to combat resistant superbugs, viruses, fungi or parasites. This comprehensive AMP database is a useful tool for both research and education. PMID:25555720

  19. De Novo Designed Synthetic Mimics of Antimicrobial Peptides

    PubMed Central

    Scott, Richard W.; DeGrado, William F.; Tew, Gregory N.

    2008-01-01

    Summary Antimicrobial peptides are small cationic amphiphiles that play an important role in the innate immune system. Given their broad specificity, they appear to be ideal therapeutic agents. As a result, over the last decade, there has been considerable interest in developing them as intravenously administered antibiotics. However, it has proven difficult to accomplish this goal with peptide-based structures. While it has been possible to solve some relatively simple problems such as susceptibility to proteolysis, more severe problems have included the expense of the materials, toxicity, limited efficacy, and limited tissue distribution. As a result, we developed small synthetic oligomers designed to adopt amphiphilic conformations and exhibit potent antimicrobial activity while being non-toxic to host cells. One class of these synthetic mimics of antimicrobial peptides (SMAMPs) is being developed as intravenous antibiotics PMID:18996193

  20. A Novel Peptide Hydrogel for an Antimicrobial Bandage Contact Lens.

    PubMed

    Gallagher, Andrew G; Alorabi, Jamal A; Wellings, Donald A; Lace, Rebecca; Horsburgh, Mal J; Williams, Rachel L

    2016-08-01

    A peptide hydrogel with an antimicrobial activity is developed as a bandage contact lens. The antimicrobial activity is enhanced with the addition of the biomolecules penicillin G or poly-ε-lysine and is positive against Staphylococcus aureus and Escherichia coli. The lens is also noncytotoxic toward a human corneal epithelial cell line and as a consequence is of great potential as a drug-eluting bandage lens replacing conventional corneal ulcer treatment. PMID:27276231

  1. Insights into Antimicrobial Peptides from Spiders and Scorpions.

    PubMed

    Wang, Xiuqing; Wang, Guangshun

    2016-01-01

    The venoms of spiders and scorpions contain a variety of chemical compounds. Antimicrobial peptides (AMPs) from these organisms were first discovered in the 1990s. As of May 2015, there were 42 spider's and 63 scorpion's AMPs in the Antimicrobial Peptide Database (http://aps.unmc.edu/AP). These peptides have demonstrated broad or narrow-spectrum activities against bacteria, fungi, viruses, and parasites. In addition, they can be toxic to cancer cells, insects and erythrocytes. To provide insight into such an activity spectrum, this article discusses the discovery, classification, structure and activity relationships, bioinformatics analysis, and potential applications of spider and scorpion AMPs. Our analysis reveals that, in the case of linear peptides, spiders use both glycine-rich and helical peptide models for defense, whereas scorpions use two distinct helical peptide models with different amino acid compositions to exert the observed antimicrobial activities and hemolytic toxicity. Our structural bioinformatics study improves the knowledge in the field and can be used to design more selective peptides to combat tumors, parasites, and viruses. PMID:27165405

  2. Acne Inversa: Evaluating Antimicrobial Peptides and Proteins

    PubMed Central

    Sand, Michael; Skrygan, Marina; Kreuter, Alexander; Altmeyer, Peter; Gambichler, Thilo

    2012-01-01

    Background Acne inversa is a chronic, suppurative relapsing inflammatory skin disease that primarily affects the axillae, perineum and inframammary regions. Evidence suggests that the innate immune system is involved in the pathogenesis of acne inversa. Objective To investigate the role of the innate immune system in acne inversa. Methods Skin biopsies were obtained from inflammatory skin lesions (n=17) and from non-lesional skin (intraindividual control, n=17) of patients with acne inversa. Additional skin lesions were taken from patients with chronic venous leg ulcers (interindividual control, n=5). Quantitative real-time reverse transcription-polymerase chain reaction was used to determine the mRNA levels of antimicrobial peptides and proteins (AMPs), including human β-defensin (hBD)-1, hBD-2 and hBD-3, LL-37 (cathelicidin) and Ribonuclease 7 (RNase 7). mRNA levels were also determined for inflammatory and anti-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase-1 (MMP1), interleukin (IL)-1β, IL-6, IL-8 and IL-10. Results The mRNA levels of hBD-2, LL-37, IL-1β, IL-6, IL-8, IL-10 and MMP1 were significantly higher in acne inversa lesions compared to non-lesional skin (p<0.05). A significant positive correlation expression was observed between hBD-2 mRNA expression and LL-37 (ρ=0.53, p=0.03), and between hBD-2 and RNAse 7 (ρ=0.68, p=0.006). When compared to the chronic venous leg ulcer lesions, acne inversa lesions showed a significantly higher expression of RNase 7 mRNA, while IL-1 β, IL-6, IL-8, TNF-α and MMP1 mRNA expression was significantly higher in the chronic venous leg ulcer lesions (p<0.05). Conclusion The AMP, cytokine milieu and tissue proteases in acne inversa lesions differ significantly from non-lesional skin and chronic venous leg ulcers. The positively correlating up-regulation of AMPs in acne inversa indicates an important role of the innate immune system in the pathogenesis of this disorder

  3. LPS interactions with immobilized and soluble antimicrobial peptides.

    PubMed

    Gustafsson, Anna; Olin, Anders I; Ljunggren, Lennart

    2010-04-19

    A promising approach in sepsis therapy is the use of peptides truncated from serum- and membrane-proteins with binding domains for LPS: antimicrobial peptides (AMPs). AMPs can be useful in combination with conventional antibiotics to increase killing and neutralize LPS. Although many AMPs show a high specificity towards bacterial membranes, they can also exhibit toxicity, i.e. non-specific membrane lysis, of mammalian cells such as erythrocytes and therefore, unsuitable as systemic drugs. A way to overcome this problem may be an extracorporeal therapy with immobilized peptides. This study will compare neutralization of LPS using different AMPs in solution and when immobilized on to solid phases. The peptides ability to neutralize LPS-induced cytokine release in whole blood will also be tested. The peptides are truncated derivates from the known AMPs LL-37, SC4, BPI, S3 Delta and CEME. Two different methods were used to immobilize peptides, biomolecular interaction analysis, and Pierce SulfoLink Coupling Gel. To investigate LPS binding in solution the LAL test was used. After whole blood incubation with LPS and AMPs ELISA was used to measure TNFalpha, IL-1 beta and IL-6 production. The results suggest that immobilization of antimicrobial peptides does not inhibit their capacity to neutralize LPS, although there are differences between the peptides tested. Thus, peptides derived from LL-37 and CEME were more efficient both in LPS binding and neutralizing LPS-induced cytokine production. PMID:20233038

  4. NMR and computational data of two novel antimicrobial peptides.

    PubMed

    Falcigno, Lucia; Palmieri, Gianna; Balestrieri, Marco; Proroga, Yolande T R; Facchiano, Angelo; Riccio, Alessia; Capuano, Federico; Marrone, Raffaele; Campanile, Giuseppe; Anastasio, Aniello

    2016-09-01

    Here we report details on the design and conformational analysis of two novel peptides showing antimicrobial properties, as reported in the research article, "New antimicrobial peptides against foodborne pathogens: from in silico design to experimental evidence" G. Palmieri, M. Balestrieri, Y.T.R. Proroga, L. Falcigno, A. Facchiano, A. Riccio, F. Capuano, R. Marrone, G. Campanile, A. Anastasio (2016) [1]. NMR data, such as chemical shifts in two different solvents as well as aCH protons deviations from random coil values and NOE patterns, are shown together with the statistics of structural calculations. Strategy and particulars of molecular design are presented. PMID:27508217

  5. Resistance to Antimicrobial Peptides and Stress Response in Mycoplasma pulmonis

    PubMed Central

    Fehri, Lina Fassi; Sirand-Pugnet, Pascal; Gourgues, Géraldine; Jan, Gwenaël; Wróblewski, Henri; Blanchard, Alain

    2005-01-01

    Antimicrobial peptides are widely distributed in nature, and in vertebrates, they play a key function in the innate immune defense system. It is generally agreed that these molecules may provide new antibiotics with therapeutic value. However, there are still many unsolved questions regarding the mechanisms underlying their antimicrobial activity as well as the mechanisms of resistance evolved by microorganisms against these molecules. The second point was addressed in this study. After determining the activity of 10 antimicrobial peptides against Mycoplasma pulmonis, a murine respiratory pathogen, the development of resistance was investigated. Following in vitro selection using subinhibitory concentrations of peptides, clones of this bacterium showing increased resistance to melittin or gramicidin D were obtained. For some of the clones, a cross-resistance was observed between these two peptides, in spite of their deep structural differences, and also with tetracycline. A proteomic analysis suggested that the stress response in these clones was constitutively activated, and this was confirmed by finding mutations in the hrcA gene; in mycoplasmas, bacteria which lack alternative sigma factors, the HrcA protein is supposed to play a key role as a negative regulator of heat shock proteins. By complementation of the hrcA mutants with the wild-type gene, the initial MICs of melittin and gramicidin D decreased to values close to the initial ones. This indicates that the resistance of M. pulmonis to these two antimicrobial peptides could result from a stress response involving HrcA-regulated genes. PMID:16189093

  6. Imaging the action of antimicrobial peptides on living bacterial cells

    PubMed Central

    Gee, Michelle L.; Burton, Matthew; Grevis-James, Alistair; Hossain, Mohammed Akhter; McArthur, Sally; Palombo, Enzo A.; Wade, John D.; Clayton, Andrew H. A.

    2013-01-01

    Antimicrobial peptides hold promise as broad-spectrum alternatives to conventional antibiotics. The mechanism of action of this class of peptide is a topical area of research focused predominantly on their interaction with artificial membranes. Here we compare the interaction mechanism of a model antimicrobial peptide with single artificial membranes and live bacterial cells. The interaction kinetics was imaged using time-lapse fluorescence lifetime imaging of a fluorescently-tagged melittin derivative. Interaction with the synthetic membranes resulted in membrane pore formation. In contrast, the interaction with bacteria led to transient membrane disruption and corresponding leakage of the cytoplasm, but surprisingly with a much reduced level of pore formation. The discovery that pore formation is a less significant part of lipid-peptide interaction in live bacteria highlights the mechanistic complexity of these interactions in living cells compared to simple artificial systems. PMID:23532056

  7. Antimicrobial peptides: a new class of antimalarial drugs?

    PubMed Central

    Vale, Nuno; Aguiar, Luísa; Gomes, Paula

    2014-01-01

    A range of antimicrobial peptides (AMP) exhibit activity on malaria parasites, Plasmodium spp., in their blood or mosquito stages, or both. These peptides include a diverse array of both natural and synthetic molecules varying greatly in size, charge, hydrophobicity, and secondary structure features. Along with an overview of relevant literature reports regarding AMP that display antiplasmodial activity, this review makes a few considerations about those molecules as a potential new class of antimalarial drugs. PMID:25566072

  8. SMALL CYSTEINE-RICH PEPTIDES RESEMBLING ANTIMICROBIAL PEPTIDES HAVE BEEN UNDER-PREDICTED IN PLANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multicellular organisms produce small cysteine-rich anti-microbial peptides as an innate defense against pathogens. While defensins, a well-known class of such peptides, are common among eukaryotes, there are classes restricted to the plant kingdom. These include thionins, lipid transfer proteins,...

  9. Linear antimicrobial peptides from Ectatomma quadridens ant venom.

    PubMed

    Pluzhnikov, Kirill A; Kozlov, Sergey A; Vassilevski, Alexander A; Vorontsova, Olga V; Feofanov, Alexei V; Grishin, Eugene V

    2014-12-01

    Venoms from three poneromorph ant species (Paraponera clavata, Ectatomma quadridens and Ectatomma tuberculatum) were investigated for the growth inhibition of Gram-positive and Gram-negative bacteria. It was shown that the venom of E. quadridens and its peptide fraction in particular possess marked antibacterial action. Three linear antimicrobial peptides sharing low similarity to the well-known ponericin peptides were isolated from this ant venom by means of size-exclusion and reversed-phase chromatography. The peptides showed antimicrobial activity at low micromolar concentrations. Their primary structure was established by direct Edman sequencing in combination with mass spectrometry. The most active peptide designated ponericin-Q42 was chemically synthesized. Its secondary structure was investigated in aqueous and membrane-mimicking environment, and the peptide was shown to be partially helical already in water, which is unusual for short linear peptides. Analysis of its activity on different bacterial strains, human erythrocytes and chronic myelogenous leukemia K562 cells revealed that the peptide shows broad spectrum cytolytic activity at micromolar and submicromolar concentrations. Ponericin-Q42 also possesses weak toxic activity on flesh fly larvae with LD50 of ∼105 μg/g. PMID:25220871

  10. 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

  11. Selected antimicrobial peptides inhibit in vitro growth of Campylobacter spp.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Novel alternatives to traditional antibiotics are urgently needed for food-animal production. A goal of our laboratory is to develop and evaluate antimicrobial peptides (AMP) to control and reduce foodborne pathogens in poultry. AMP have been found in most every class of living organism where they h...

  12. Synergistic Effects of Antimicrobial Peptides and Antibiotics against Clostridium difficile

    PubMed Central

    Nuding, Sabine; Frasch, Tina; Schaller, Martin; Stange, Eduard F.

    2014-01-01

    Accelerating rates of health care-associated infections caused by Clostridium difficile, with increasing recurrence and rising antibiotic resistance rates, have become a serious problem in recent years. This study was conducted to explore whether a combination of antibiotics with human antimicrobial peptides may lead to an increase in antibacterial activity. The in vitro activities of the antimicrobial peptides HBD1 to HBD3, HNP1, HD5, and LL-37 and the antibiotics tigecycline, moxifloxacin, piperacillin-tazobactam, and meropenem alone or in combination against 10 toxinogenic and 10 nontoxinogenic C. difficile strains were investigated. Bacterial viability was determined by flow cytometry and toxin production by enzyme-linked immunosorbent assay (ELISA). When combined at subinhibitory concentrations, antimicrobial peptides and antibiotics generally led to an additive killing effect against toxinogenic and nontoxinogenic C. difficile strains. However, LL-37 and HBD3 acted in synergism with all the antibiotics that were tested. Electron microscopy revealed membrane perturbation in bacterial cell walls by HBD3. In 3 out of 10 toxinogenic strains, HBD3, LL-37, piperacillin-tazobactam, and meropenem administration led to an increased toxin release which was not neutralized by the addition of HNP1. Antimicrobial peptides increase the bacterial killing of antibiotics against C. difficile regardless of the antibiotics' mode of action. Membrane perturbation in or pore formation on the bacterial cell wall may enhance the uptake of antibiotics and increase their antibacterial effect. Therefore, a combination of antibiotics with antimicrobial peptides may represent a promising novel approach to the treatment of C. difficile infections. PMID:25022581

  13. Rational design of tryptophan-rich antimicrobial peptides with enhanced antimicrobial activities and specificities.

    PubMed

    Yu, Hui-Yuan; Huang, Kuo-Chun; Yip, Bak-Sau; Tu, Chih-Hsiang; Chen, Heng-Li; Cheng, Hsi-Tsung; Cheng, Jya-Wei

    2010-11-01

    Trp-rich antimicrobial peptides play important roles in the host innate defense mechanism of many plants and animals. A series of short Trp-rich peptides derived from the C-terminal region of Bothrops asper myothoxin II, a Lys49 phospholipase A(2) (PLA(2)), were found to reproduce the antimicrobial activities of their parent molecule. Of these peptides, KKWRWWLKALAKK-designated PEM-2-was found to display improved activity against both Gram-positive and Gram-negative bacteria. To improve the antimicrobial activity of PEM-2 for potential clinical applications further, we determined the solution structure of PEM-2 bound to membrane-mimetic dodecylphosphocholine (DPC) micelles by two-dimensional NMR methods. The DPC micelle-bound structure of PEM-2 adopts an α-helical conformation and the positively charged residues are clustered together to form a hydrophilic patch. The surface electrostatic potential map indicates that two of the three tryptophan residues are packed against the peptide backbone and form a hydrophobic face with Leu7, Ala9, and Leu10. A variety of biophysical and biochemical experiments, including circular dichroism, fluorescence spectroscopy, and microcalorimetry, were used to show that PEM-2 interacted with negatively charged phospholipid vesicles and efficiently induced dye release from these vesicles, suggesting that the antimicrobial activity of PEM-2 could be due to interactions with bacterial membranes. Potent analogues of PEM-2 with enhanced antimicrobial and less pronounced hemolytic activities were designed with the aid of these structural studies. PMID:20865718

  14. Novel Antimicrobial Peptides with High Anticancer Activity and Selectivity

    PubMed Central

    Chen, Kuan-Hao; Yu, Hui-Yuan; Chih, Ya-Han; Cheng, Hsi-Tsung; Chou, Yu-Ting; Cheng, Jya-Wei

    2015-01-01

    We describe a strategy to boost anticancer activity and reduce normal cell toxicity of short antimicrobial peptides by adding positive charge amino acids and non-nature bulky amino acid β-naphthylalanine residues to their termini. Among the designed peptides, K4R2-Nal2-S1 displayed better salt resistance and less toxicity to hRBCs and human fibroblast than Nal2-S1 and K6-Nal2-S1. Fluorescence microscopic studies indicated that the FITC-labeled K4R2-Nal2-S1 preferentially binds cancer cells and causes apoptotic cell death. Moreover, a significant inhibition in human lung tumor growth was observed in the xenograft mice treated with K4R2-Nal2-S1. Our strategy provides new opportunities in the development of highly effective and selective antimicrobial and anticancer peptide-based therapeutics. PMID:25970292

  15. Epithelial Antimicrobial Peptides: Guardian of the Oral Cavity

    PubMed Central

    Hans, Mayank; Madaan Hans, Veenu

    2014-01-01

    Gingival epithelium provides first line of defence from the microorganisms present in dental plaque. It not only provides a mechanical barrier but also has an active immune function too. Gingival epithelial cells participate in innate immunity by producing a range of antimicrobial peptides to protect the host against oral pathogens. These epithelial antimicrobial peptides (EAPs) include the β-defensin family, cathelicidin (LL-37), calprotectin, and adrenomedullin. While some are constitutively expressed in gingival epithelial cells, others are induced upon exposure to microbial insults. It is likely that these EAPs have a role in determining the initiation and progression of oral diseases. EAPs are broad spectrum antimicrobials with a different but overlapping range of activity. Apart from antimicrobial activity, they participate in several other crucial roles in host tissues. Some of these, for instance, β-defensins, are chemotactic to immune cells. Others, such as calprotectin are important for wound healing and cell proliferation. Adrenomedullin, a multifunctional peptide, has its biological action in a wide range of tissues. Not only is it a potent vasodilator but also it has several endocrine effects. Knowing in detail the various bioactions of these EAPs may provide us with useful information regarding their utility as therapeutic agents. PMID:25435884

  16. Design and Engineering Strategies for Synthetic Antimicrobial Peptides

    NASA Astrophysics Data System (ADS)

    Tossi, Alessandro

    Thousands of antimicrobial peptides (AMPs) of prokaryotic, fungal, plant, or animal origin have been identified, and their potential as lead compounds for the design of novel therapeutic agents in the treatment of infection, for stimulating the immune system, or in countering septic shock has been widely recognized. Added to this is their possible use in prophylaxis of infectious diseases for animal or plant protection, for disinfection of surgical instruments or industrial surfaces, and for food preservation among other commercially important applications. Since the early eighties, AMPs have been subject to a vast number of studies aimed at understanding what determines their potency and spectrum of activities against bacterial or fungal pathogens, and at maximizing these while limiting cytotoxic activities toward host cells. Much research has also been directed toward understanding specific mechanisms of action underlying the antimicrobial activity and selectivity, to be able to redesign the peptides for optimal performance. A central theme in the mode of action of many AMPs is their dynamic interaction with biological membranes, which involves various properties of these peptides such as, among others, surface hydrophobicity and polarity, charge, structure, and induced conformational variations. These features are often intimately interconnected so that engineering peptides to independently adjust any one property in particular is not an easy task. However, solid-phase peptide synthesis allows the use of a large repertoire of nonproteinogenic amino acids that can be used in the rational design of peptides to finely tune structural and physicochemical properties and precisely probe structure-function relationships.

  17. The role of antimicrobial peptides in animal defenses

    NASA Astrophysics Data System (ADS)

    Hancock, Robert E. W.; Scott, Monisha G.

    2000-08-01

    It is becoming clear that the cationic antimicrobial peptides are an important component of the innate defenses of all species of life. Such peptides can be constitutively expressed or induced by bacteria or their products. The best peptides have good activities vs. a broad range of bacterial strains, including antibiotic-resistant isolates. They kill very rapidly, do not easily select resistant mutants, are synergistic with conventional antibiotics, other peptides, and lysozyme, and are able to kill bacteria in animal models. It is known that bacterial infections, especially when treated with antibiotics, can lead to the release of bacterial products such as lipopolysaccharide (LPS) and lipoteichoic acid, resulting in potentially lethal sepsis. In contrast to antibiotics, the peptides actually prevent cytokine induction by bacterial products in tissue culture and human blood, and they block the onset of sepsis in mouse models of endotoxemia. Consistent with this, transcriptional gene array experiments using a macrophage cell line demonstrated that a model peptide, CEMA, blocks the expression of many genes whose transcription was induced by LPS. The peptides do this in part by blocking LPS interaction with the serum protein LBP. In addition, CEMA itself has a direct effect on macrophage gene expression. Because cationic antimicrobial peptides are induced by LPS and are able to dampen the septic response of animal cells to LPS, we propose that, in addition to their role in direct and lysozyme-assisted killing of microbes, they have a role in feedback regulation of cytokine responses. We are currently developing variant peptides as therapeutics against antibiotic-resistant infections.

  18. Design and characterization of an acid-activated antimicrobial peptide.

    PubMed

    Li, Lina; He, Jian; Eckert, Randal; Yarbrough, Daniel; Lux, Renate; Anderson, Maxwell; Shi, Wenyuan

    2010-01-01

    Dental caries is a microbial biofilm infection in which the metabolic activities of plaque bacteria result in a dramatic pH decrease and shift the demineralization/remineralization equilibrium on the tooth surface towards demineralization. In addition to causing a net loss in tooth minerals, creation of an acidic environment favors growth of acid-enduring and acid-generating species, which causes further reduction in the plaque pH. In this study, we developed a prototype antimicrobial peptide capable of achieving high activity exclusively at low environmental pH to target bacterial species like Streptococcus mutans that produce acid and thrive under the low pH conditions detrimental for tooth integrity. The features of clavanin A, a naturally occurring peptide rich in histidine and phenylalanine residues with pH-dependent antimicrobial activity, served as a design basis for these prototype 'acid-activated peptides' (AAPs). Employing the major cariogenic species S. mutans as a model system, the two AAPs characterized in this study exhibited a striking pH-dependent antimicrobial activity, which correlated well with the calculated charge distribution. This type of peptide represents a potential new way to combat dental caries. PMID:19878192

  19. Defensins and Other Antimicrobial Peptides at the Ocular Surface

    PubMed Central

    McDermott, Alison M.

    2006-01-01

    Although constantly exposed to the environment and “foreign bodies” such as contact lenses and unwashed fingertips, the ocular surface succumbs to infection relatively infrequently. This is, in large part, due to a very active and robust innate immune response mounted at the ocular surface. Studies over the past 20 years have revealed that small peptides with antimicrobial activity are a major component of the human innate immune response system. The ocular surface is no exception, with peptides of the defensin and cathelicidin families being detected in the tear film and secreted by corneal and conjunctival epithelial cells. There is also much evidence to suggest that the role of some antimicrobial peptides is not restricted to direct killing of pathogens, but, rather, that they function in various aspects of the immune response, including recruitment of immune cells, and through actions on dendritic cells provide a link to adaptive immunity. A role in wound healing is also supported. In this article, the properties, mechanisms of actions and functional roles of antimicrobial peptides are reviewed, with particular emphasis on the potential multifunctional roles of defensins and LL-37 (the only known human cathelicidin) at the ocular surface. PMID:17216098

  20. Bacterial resistance to antimicrobial peptides: an evolving phenomenon.

    PubMed

    Fleitas, Osmel; Agbale, Caleb M; Franco, Octavio L

    2016-01-01

    Bacterial resistance to conventional antibiotics is currently a real problem all over the world, making novel antimicrobial compounds a real research priority. Some of the most promising compounds found to date are antimicrobial peptides (AMPs). The benefits of these drugs include their broad spectrum of activity that affects several microbial processes, making the emergence of resistance less likely. However, bacterial resistance to AMPs is an evolving phenomenon that compromises the therapeutic potential of these compounds. Therefore, it is mandatory to understand bacterial mechanisms of resistance to AMPs in depth, in order to develop more powerful AMPs that overcome the bacterial resistance response. PMID:27100488

  1. 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

  2. APD2: the updated antimicrobial peptide database and its application in peptide design

    PubMed Central

    Wang, Guangshun; Li, Xia; Wang, Zhe

    2009-01-01

    The antimicrobial peptide database (APD, http://aps.unmc.edu/AP/main.php) has been updated and expanded. It now hosts 1228 entries with 65 anticancer, 76 antiviral (53 anti-HIV), 327 antifungal and 944 antibacterial peptides. The second version of our database (APD2) allows users to search peptide families (e.g. bacteriocins, cyclotides, or defensins), peptide sources (e.g. fish, frogs or chicken), post-translationally modified peptides (e.g. amidation, oxidation, lipidation, glycosylation or d-amino acids), and peptide binding targets (e.g. membranes, proteins, DNA/RNA, LPS or sugars). Statistical analyses reveal that the frequently used amino acid residues (>10%) are Ala and Gly in bacterial peptides, Cys and Gly in plant peptides, Ala, Gly and Lys in insect peptides, and Leu, Ala, Gly and Lys in amphibian peptides. Using frequently occurring residues, we demonstrate database-aided peptide design in different ways. Among the three peptides designed, GLK-19 showed a higher activity against Escherichia coli than human LL-37. PMID:18957441

  3. Occurrence and function of D-amino acid-containing peptides and proteins: antimicrobial peptides.

    PubMed

    Mignogna, G; Simmaco, M; Barra, D

    1998-01-01

    Antimicrobial peptides are widely distributed in living organisms, where they represent a constitutive defence system acting as a first line of response against infections. The number of such peptides discovered has increased rapidly in the last few years, and more than 100 have been described from different sources. So far, antimicrobial peptides containing a D-amino acid have only been found in the skin secretions of frogs belonging to the genus Bombina. In the second position of the sequence of the mature peptides either D-alloisoleucine or D-leucine were detected. The D-amino acids are derived from the corresponding L forms by an as yet unknown posttranslational reaction. PMID:9949866

  4. Antimicrobial Lactoferrin Peptides: The Hidden Players in the Protective Function of a Multifunctional Protein

    PubMed Central

    Sinha, Mau; Kaushik, Sanket; Kaur, Punit; Singh, Tej P.

    2013-01-01

    Lactoferrin is a multifunctional, iron-binding glycoprotein which displays a wide array of modes of action to execute its primary antimicrobial function. It contains various antimicrobial peptides which are released upon its hydrolysis by proteases. These peptides display a similarity with the antimicrobial cationic peptides found in nature. In the current scenario of increasing resistance to antibiotics, there is a need for the discovery of novel antimicrobial drugs. In this context, the structural and functional perspectives on some of the antimicrobial peptides found in N-lobe of lactoferrin have been reviewed. This paper provides the comparison of lactoferrin peptides with other antimicrobial peptides found in nature as well as interspecies comparison of the structural properties of these peptides within the native lactoferrin. PMID:23554820

  5. Antimicrobial peptides and proteins of the horse - insights into a well-armed organism

    PubMed Central

    2011-01-01

    Antimicrobial peptides play a pivotal role as key effectors of the innate immune system in plants and animals and act as endogenous antibiotics. The molecules exhibit an antimicrobial activity against bacteria, viruses, and eukaryotic pathogens with different specificities and potencies depending on the structure and amino-acid composition of the peptides. Several antimicrobial peptides were comprehensively investigated in the last three decades and some molecules with remarkable antimicrobial properties have reached the third phase of clinical studies. Next to the peptides themselves, numerous organisms were examined and analyzed regarding their repertoire of antimicrobial peptides revealing a huge number of candidates with potencies and properties for future medical applications. One of these organisms is the horse, which possesses numerous peptides that are interesting candidates for therapeutical applications in veterinary medicine. Here we summarize investigations and knowledge on equine antimicrobial peptides, point to interesting candidates, and discuss prospects for therapeutical applications. PMID:21888650

  6. Inhibition of Escherichia coli ATP synthase by amphibian antimicrobial peptides

    PubMed Central

    Laughlin, Thomas F.; Ahmad, Zulfiqar

    2010-01-01

    Previously melittin, the α-helical basic honey bee venom peptide, was shown to inhibit F1-ATPase by binding at the β-subunit DELSEED motif of F1Fo ATP synthase. Herein, we present the inhibitory effects of the basic α-helical amphibian antimicrobial peptides, ascaphin-8, aurein 2.2, aurein 2.3, carein 1.8, carein 1.9, citropin 1.1, dermaseptin, maculatin 1.1, maganin II, MRP, or XT-7, on purified F1 and membrane bound F1Fo E. coli ATP synthase. We found that the extent of inhibition by amphibian peptides is variable. Whereas MRP-amide inhibited ATPase essentially completely (~96% inhibition), carein 1.8 did not inhibit at all (0% inhibition). Inhibition by other peptides was partial with a range of ~13% to 70%. MRP-amide was also the most potent inhibitor on molar scale (IC50 ~3.25 µM). Presence of an amide group at the c-terminal of peptides was found to be critical in exerting potent inhibition of ATP synthase (~20–40% additional inhibition). Inhibition was fully reversible and found to be identical in both F1Fo membrane preparations as well as in isolated purified F1. Interestingly, growth of Escherichia coli was abrogated in the presence of ascaphin-8, aurein 2.2, aurein 2.3, citropin 1.1, dermaseptin, magainin II-amide, MRP, MRP-amide, melittin, or melittin-amide but was unaffected in the presence of carein 1.8, carein 1.9, maculatin 1.1, magainin II, or XT-7. Hence inhibition of F1-ATPase and E. coli cell growth by amphibian antimicrobial peptides suggests that their antimicrobial/anticancer properties are in part linked to their actions on ATP synthase. PMID:20100509

  7. Inhibition of Escherichia coli ATP synthase by amphibian antimicrobial peptides.

    PubMed

    Laughlin, Thomas F; Ahmad, Zulfiqar

    2010-04-01

    Previously melittin, the alpha-helical basic honey bee venom peptide, was shown to inhibit F(1)-ATPase by binding at the beta-subunit DELSEED motif of F(1)F(o)-ATP synthase. Herein, we present the inhibitory effects of the basic alpha-helical amphibian antimicrobial peptides, ascaphin-8, aurein 2.2, aurein 2.3, carein 1.8, carein 1.9, citropin 1.1, dermaseptin, maculatin 1.1, maganin II, MRP, or XT-7, on purified F(1) and membrane bound F(1)F(0)Escherichia coli ATP synthase. We found that the extent of inhibition by amphibian peptides is variable. Whereas MRP-amide inhibited ATPase essentially completely (approximately 96% inhibition), carein 1.8 did not inhibit at all (0% inhibition). Inhibition by other peptides was partial with a range of approximately 13-70%. MRP-amide was also the most potent inhibitor on molar scale (IC(50) approximately 3.25 microM). Presence of an amide group at the c-terminal of peptides was found to be critical in exerting potent inhibition of ATP synthase ( approximately 20-40% additional inhibition). Inhibition was fully reversible and found to be identical in both F(1)F(0) membrane preparations as well as in isolated purified F(1). Interestingly, growth of E. coli was abrogated in the presence of ascaphin-8, aurein 2.2, aurein 2.3, citropin 1.1, dermaseptin, magainin II-amide, MRP, MRP-amide, melittin, or melittin-amide but was unaffected in the presence of carein 1.8, carein 1.9, maculatin 1.1, magainin II, or XT-7. Hence inhibition of F(1)-ATPase and E. coli cell growth by amphibian antimicrobial peptides suggests that their antimicrobial/anticancer properties are in part linked to their actions on ATP synthase. PMID:20100509

  8. Peptides from the scorpion Vaejovis punctatus with broad antimicrobial activity.

    PubMed

    Ramírez-Carreto, Santos; Jiménez-Vargas, Juana María; Rivas-Santiago, Bruno; Corzo, Gerardo; Possani, Lourival D; Becerril, Baltazar; Ortiz, Ernesto

    2015-11-01

    The antimicrobial potential of two new non-disulfide bound peptides, named VpAmp1.0 (LPFFLLSLIPSAISAIKKI, amidated) and VpAmp2.0 (FWGFLGKLAMKAVPSLIGGNKSSSK) is here reported. These are 19- and 25-aminoacid-long peptides with +2 and +4 net charges, respectively. Their sequences correspond to the predicted mature regions from longer precursors, putatively encoded by cDNAs derived from the venom glands of the Mexican scorpion Vaejovis punctatus. Both peptides were chemically synthesized and assayed against a variety of microorganisms, including pathogenic strains from clinical isolates and strains resistant to conventional antibiotics. Two shorter variants, named VpAmp1.1 (FFLLSLIPSAISAIKKI, amidated) and VpAmp2.1 (FWGFLGKLAMKAVPSLIGGNKK), were also synthesized and tested. The antimicrobial assays revealed that the four synthetic peptides effectively inhibit the growth of both Gram-positive (Staphylococcus aureus and Streptococcus agalactiaea) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria, with MICs in the range of 2.5-24.0 μM; yeasts (Candida albicans and Candida glabrata) with MICs of 3.1-50.0 μM; and two clinically isolated strains of Mycobacterium tuberculosis-including a multi-drug resistant one- with MICs in the range of 4.8-30.5 μM. A comparison between the activities of the original peptides and their derivatives gives insight into the structural/functional role of their distinctive residues. PMID:26352292

  9. Salivary Antimicrobial Peptides in Early Detection of Periodontitis

    PubMed Central

    Güncü, Güliz N.; Yilmaz, Dogukan; Könönen, Eija; Gürsoy, Ulvi K.

    2015-01-01

    In the pathogenesis of periodontitis, an infection-induced inflammatory disease of the tooth-supporting tissues, there is a complex interaction between the subgingival microbiota and host tissues. A periodontal diagnostic tool for detecting the initiation and progression of the disease, monitoring the response to therapy, or measuring the degree of susceptibility to future disease progression has been of interest for a long time. The value of various enzymes, proteins, and immunoglobulins, which are abundant constituents of saliva, as potential biomarkers has been recognized and extensively investigated for periodontal diseases. Gingival defensins and cathelicidins are small cationic antimicrobial peptides that play an important role in innate immune response. However, their applicability as salivary biomarkers is still under debate. The present review focuses on proteomic biomarkers and antimicrobial peptides, in particular, to be used at early phases of periodontitis. PMID:26734583

  10. A Large-Scale Structural Classification of Antimicrobial Peptides

    PubMed Central

    Lee, Chen-Che; Yang, Je-Ruei; Lai, Jim Z. C.

    2015-01-01

    Antimicrobial peptides (AMPs) are potent drug candidates against microbial organisms such as bacteria, fungi, parasites, and viruses. AMPs have abundant sequences and structures, two fundamental resources for bioinformatics researches, but analyses on how they associate with each other are either nonexistent or limited to partial classification and data. We thus present A Database of Anti-Microbial peptides (ADAM), which contains 7,007 unique sequences and 759 structures, to systematically establish comprehensive associations between AMP sequences and structures through structural folds and to provide an easy access to view their relationships. 30 distinct AMP structural fold clusters with more than one structure are detected and about a thousand AMPs are associated with at least one structural fold cluster. According to ADAM, AMP structural folds are limited—AMPs only cover about 3% of the overall protein fold space. PMID:26000295

  11. Bactericidal synergy of lysostaphin in combination with antimicrobial peptides.

    PubMed

    Desbois, A P; Coote, P J

    2011-08-01

    Drug-resistant staphylococci constitute a serious problem that urgently requires the discovery of new therapeutic agents. There has been a resurgence in interest in using lysostaphin (a specific anti-staphylococcal enzyme) as a treatment for infections caused by these important pathogens. However, bacterial resistance to lysostaphin is a problem, but the use of a combination treatment may surmount this issue. In this present study, using viable counts from suspension incubations, lysostaphin is shown to be synergistically bactericidal in combination with various conventional antimicrobial peptides, the antimicrobial protein bovine lactoferrin, a lantibiotic (nisin), and certain lipopeptides used clinically (colistin, daptomycin and polymyxin B). Combinations that act in synergy are of clinical importance as these reduce the doses of the compounds needed for effective treatments and decrease the chances of resistance being selected. The use of lysostaphin in combination with a peptide may represent a new avenue in tackling drug-resistant staphylococci. PMID:21311938

  12. Collectins and Cationic Antimicrobial Peptides of the Respiratory Epithelia

    PubMed Central

    Grubor, B.; Meyerholz, D. K.; Ackermann, M. R.

    2009-01-01

    The respiratory epithelium is a primary site for the deposition of microorganisms that are acquired during inspiration. The innate immune system of the respiratory tract eliminates many of these potentially harmful agents preventing their colonization. Collectins and cationic antimicrobial peptides are antimicrobial components of the pulmonary innate immune system produced by respiratory epithelia, which have integral roles in host defense and inflammation in the lung. Synthesis and secretion of these molecules are regulated by the developmental stage, hormones, as well as many growth and immunoregulatory factors. The purpose of this review is to discuss antimicrobial innate immune elements within the respiratory tract of healthy and pneumonic lung with emphasis on hydrophilic surfactant proteins and β-defensins. PMID:16966437

  13. Context Mediates Antimicrobial Efficacy of Kinocidin Congener Peptide RP-1

    PubMed Central

    Yount, Nannette Y.; Cohen, Samuel E.; Kupferwasser, Deborah; Waring, Alan J.; Ruchala, Piotr; Sharma, Shantanu; Wasserman, Karlman; Jung, Chun-Ling; Yeaman, Michael R.

    2011-01-01

    Structure-mechanism relationships are key determinants of host defense peptide efficacy. These relationships are influenced by anatomic, physiologic and microbiologic contexts. Structure-mechanism correlates were assessed for the synthetic peptide RP-1, modeled on microbicidal domains of platelet kinocidins. Antimicrobial efficacies and mechanisms of action against susceptible (S) or resistant (R) Salmonella typhimurium (ST), Staphylococcus aureus (SA), and Candida albicans (CA) strain pairs were studied at pH 7.5 and 5.5. Although RP-1 was active against all study organisms, it exhibited greater efficacy against bacteria at pH 7.5, but greater efficacy against CA at pH 5.5. RP-1 de-energized SA and CA, but caused hyperpolarization of ST in both pH conditions. However, RP-1 permeabilized STS and CA strains at both pH, whereas permeabilization was modest for STR or SA strain at either pH. Biochemical analysis, molecular modeling, and FTIR spectroscopy data revealed that RP-1 has indistinguishable net charge and backbone trajectories at pH 5.5 and 7.5. Yet, concordant with organism-specific efficacy, surface plasmon resonance, and FTIR, molecular dynamics revealed modest helical order increases but greater RP-1 avidity and penetration of bacterial than eukaryotic lipid systems, particularly at pH 7.5. The present findings suggest that pH– and target–cell lipid contexts influence selective antimicrobial efficacy and mechanisms of RP-1 action. These findings offer new insights into selective antimicrobial efficacy and context–specificity of antimicrobial peptides in host defense, and support design strategies for potent anti-infective peptides with minimal concomitant cytotoxicity. PMID:22073187

  14. Nanomechanical Response of Bacterial Cells to Antimicrobial Peptides

    NASA Astrophysics Data System (ADS)

    Parg, Richard; Dutcher, John

    2015-03-01

    The effectiveness of antimicrobial compounds can be easily screened, however their mechanism of action is much more difficult to determine. Many compounds act by compromising the mechanical integrity of the bacterial cell envelope, and we have developed an atomic force microscopy (AFM)-based creep deformation technique to evaluate changes in the time-dependent mechanical properties of bacterial cells upon exposure to antimicrobial peptides. Measurements performed before and after exposure, as well as time-resolved measurements and those performed at different antimicrobial concentrations, revealed large changes to the viscoelastic parameters including a distinctive signature for the loss of integrity of the bacterial cell envelope. Our previous experiments have focused on Pseudomonas aeruginosaPAO1 bacterial cells in Milli-Q water, for which the cells can withstand the large osmotic pressure. In the present study we have focused on performing the measurements in buffer to obtain more biologically relevant results. The AFM creep deformation measurement provides new, unique insight into the kinetics and mechanism of action of antimicrobial peptides on bacteria.

  15. Inhibitory Effects of Antimicrobial Peptides on Lipopolysaccharide-Induced Inflammation

    PubMed Central

    Sun, Yue; Shang, Dejing

    2015-01-01

    Antimicrobial peptides (AMPs) are usually small molecule peptides, which display broad-spectrum antimicrobial activity, high efficiency, and stability. For the multiple-antibiotic-resistant strains, AMPs play a significant role in the development of novel antibiotics because of their broad-spectrum antimicrobial activities and specific antimicrobial mechanism. Besides broad-spectrum antibacterial activity, AMPs also have anti-inflammatory activity. The neutralization of lipopolysaccharides (LPS) plays a key role in anti-inflammatory action of AMPs. On the one hand, AMPs can readily penetrate the cell wall barrier by neutralizing LPS to remove Gram-negative bacteria that can lead to infection. On the contrary, AMPs can also inhibit the production of biological inflammatory cytokines to reduce the inflammatory response through neutralizing circulating LPS. In addition, AMPs also modulate the host immune system by chemotaxis of leukocytes, to promote immune cell proliferation, epithelialization, and angiogenesis and thus play a protective role. This review summarizes some recent researches about anti-inflammatory AMPs, with a focus on the interaction of AMPs and LPS on the past decade. PMID:26612970

  16. Sphingolipids and Antimicrobial Peptides: Function and Roles in Atopic Dermatitis

    PubMed Central

    Park, Kyungho; Lee, Sinhee; Lee, Yong-Moon

    2013-01-01

    Inflammatory skin diseases such as atopic dermatitis (AD) and rosacea were complicated by barrier abrogation and deficiency in innate immunity. The first defender of epidermal innate immune response is the antimicrobial peptides (AMPs) that exhibit a broad-spectrum antimicrobial activity against multiple pathogens, including Gram-positive and Gram-negative bacteria, viruses, and fungi. The deficiency of these AMPs in the skin of AD fails to protect our body against virulent pathogen infections. In contrast to AD where there is a suppression of AMPs, rosacea is characterized by overexpression of cathelicidin antimicrobial peptide (CAMP), the products of which result in chronic epidermal inflammation. In this regard, AMP generation that is controlled by a key ceramide metabolite S1P-dependent mechanism could be considered as alternate therapeutic approaches to treat these skin disorders, i.e., Increased S1P levels strongly stimulated the CAMP expression which elevated the antimicrobial activity against multiple pathogens resulting the improved AD patient skin. PMID:24244808

  17. Diversity, evolution and medical applications of insect antimicrobial peptides.

    PubMed

    Mylonakis, Eleftherios; Podsiadlowski, Lars; Muhammed, Maged; Vilcinskas, Andreas

    2016-05-26

    Antimicrobial peptides (AMPs) are short proteins with antimicrobial activity. A large portion of known AMPs originate from insects, and the number and diversity of these molecules in different species varies considerably. Insect AMPs represent a potential source of alternative antibiotics to address the limitation of current antibiotics, which has been caused by the emergence and spread of multidrug-resistant pathogens. To get more insight into AMPs, we investigated the diversity and evolution of insect AMPs by mapping their phylogenetic distribution, allowing us to predict the evolutionary origins of selected AMP families and to identify evolutionarily conserved and taxon-specific families. Furthermore, we highlight the use of the nematode Caenorhabditis elegans as a whole-animal model in high-throughput screening methods to identify AMPs with efficacy against human pathogens, including Acinetobacter baumanii and methicillin-resistant Staphylococcus aureus We also discuss the potential medical applications of AMPs, including their use as alternatives for conventional antibiotics in ectopic therapies, their combined use with antibiotics to restore the susceptibility of multidrug-resistant pathogens, and their use as templates for the rational design of peptidomimetic drugs that overcome the disadvantages of therapeutic peptides.The article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. PMID:27160593

  18. Avian Antimicrobial Host Defense Peptides: From Biology to Therapeutic Applications

    PubMed Central

    Zhang, Guolong; Sunkara, Lakshmi T.

    2014-01-01

    Host defense peptides (HDPs) are an important first line of defense with antimicrobial and immunomoduatory properties. Because they act on the microbial membranes or host immune cells, HDPs pose a low risk of triggering microbial resistance and therefore, are being actively investigated as a novel class of antimicrobials and vaccine adjuvants. Cathelicidins and β-defensins are two major families of HDPs in avian species. More than a dozen HDPs exist in birds, with the genes in each HDP family clustered in a single chromosomal segment, apparently as a result of gene duplication and diversification. In contrast to their mammalian counterparts that adopt various spatial conformations, mature avian cathelicidins are mostly α-helical. Avian β-defensins, on the other hand, adopt triple-stranded β-sheet structures similar to their mammalian relatives. Besides classical β-defensins, a group of avian-specific β-defensin-related peptides, namely ovodefensins, exist with a different six-cysteine motif. Like their mammalian counterparts, avian cathelicidins and defensins are derived from either myeloid or epithelial origin expressed in a majority of tissues with broad-spectrum antibacterial and immune regulatory activities. Structure-function relationship studies with several avian HDPs have led to identification of the peptide analogs with potential for use as antimicrobials and vaccine adjuvants. Dietary modulation of endogenous HDP synthesis has also emerged as a promising alternative approach to disease control and prevention in chickens. PMID:24583933

  19. Insect Antimicrobial Peptide Complexes Prevent Resistance Development in Bacteria

    PubMed Central

    Chernysh, Sergey; Gordya, Natalia; Suborova, Tatyana

    2015-01-01

    In recent decades much attention has been paid to antimicrobial peptides (AMPs) as natural antibiotics, which are presumably protected from resistance development in bacteria. However, experimental evolution studies have revealed prompt resistance increase in bacteria to any individual AMP tested. Here we demonstrate that naturally occurring compounds containing insect AMP complexes have clear advantage over individual peptide and small molecule antibiotics in respect of drug resistance development. As a model we have used the compounds isolated from bacteria challenged maggots of Calliphoridae flies. The compound isolated from blow fly Calliphora vicina was found to contain three distinct families of cell membrane disrupting/permeabilizing peptides (defensins, cecropins and diptericins), one family of proline rich peptides and several unknown antimicrobial substances. Resistance changes under long term selective pressure of the compound and reference antibiotics cefotaxime, meropenem and polymyxin B were tested using Escherichia coli, Klebsiella pneumonia and Acinetobacter baumannii clinical strains. All the strains readily developed resistance to the reference antibiotics, while no signs of resistance growth to the compound were registered. Similar results were obtained with the compounds isolated from 3 other fly species. The experiments revealed that natural compounds containing insect AMP complexes, in contrast to individual AMP and small molecule antibiotics, are well protected from resistance development in bacteria. Further progress in the research of natural AMP complexes may provide novel solutions to the drug resistance problem. PMID:26177023

  20. A synthetic peptide adhesion epitope as a novel antimicrobial agent.

    PubMed

    Kelly, C G; Younson, J S; Hikmat, B Y; Todryk, S M; Czisch, M; Haris, P I; Flindall, I R; Newby, C; Mallet, A I; Ma, J K; Lehner, T

    1999-01-01

    The earliest step in microbial infection is adherence by specific microbial adhesins to the mucosa of the oro-intestinal, nasorespiratory, or genitourinary tract. We inhibited binding of a cell surface adhesin of Streptococcus mutans to salivary receptors in vitro, as measured by surface plasmon resonance, using a synthetic peptide (p1025) corresponding to residues 1025-1044 of the adhesin. Two residues within p1025 that contribute to binding (Q1025, E1037) were identified by site-directed mutagenesis. In an in vivo human streptococcal adhesion model, direct application of p1025 to the teeth prevented recolonization of S. mutans but not Actinomyces, as compared with a control peptide or saline. This novel antimicrobial strategy, applying competitive peptide inhibitors of adhesion, may be used against other microorganisms in which adhesins mediate colonization of mucosal surfaces. PMID:9920267

  1. Transmembrane Pores Formed by Human Antimicrobial Peptide LL-37

    SciTech Connect

    Qian, Shuo

    2011-01-01

    Human LL-37 is a multifunctional cathelicidin peptide that has shown a wide spectrum of antimicrobial activity by permeabilizing microbial membranes similar to other antimicrobial peptides; however, its molecular mechanism has not been clarified. Two independent experiments revealed LL-37 bound to membranes in the {alpha}-helical form with the axis lying in the plane of membrane. This led to the conclusion that membrane permeabilization by LL-37 is a nonpore carpet-like mechanism of action. Here we report the detection of transmembrane pores induced by LL-37. The pore formation coincided with LL-37 helices aligning approximately normal to the plane of the membrane. We observed an unusual phenomenon of LL-37 embedded in stacked membranes, which are commonly used in peptide orientation studies. The membrane-bound LL-37 was found in the normal orientation only when the membrane spacing in the multilayers exceeded its fully hydrated value. This was achieved by swelling the stacked membranes with excessive water to a swollen state. The transmembrane pores were detected and investigated in swollen states by means of oriented circular dichroism, neutron in-plane scattering, and x-ray lamellar diffraction. The results are consistent with the effect of LL-37 on giant unilamellar vesicles. The detected pores had a water channel of radius 2333 {angstrom}. The molecular mechanism of pore formation by LL-37 is consistent with the two-state model exhibited by magainin and other small pore-forming peptides. The discovery that peptide-membrane interactions in swollen states are different from those in less hydrated states may have implications for other large membrane-active peptides and proteins studied in stacked membranes.

  2. Prediction of Antimicrobial Activity of Synthetic Peptides by a Decision Tree Model

    PubMed Central

    Lira, Felipe; Perez, Pedro S.; Baranauskas, José A.

    2013-01-01

    Antimicrobial resistance is a persistent problem in the public health sphere. However, recent attempts to find effective substitutes to combat infections have been directed at identifying natural antimicrobial peptides in order to circumvent resistance to commercial antibiotics. This study describes the development of synthetic peptides with antimicrobial activity, created in silico by site-directed mutation modeling using wild-type peptides as scaffolds for these mutations. Fragments of antimicrobial peptides were used for modeling with molecular modeling computational tools. To analyze these peptides, a decision tree model, which indicated the action range of peptides on the types of microorganisms on which they can exercise biological activity, was created. The decision tree model was processed using physicochemistry properties from known antimicrobial peptides available at the Antimicrobial Peptide Database (APD). The two most promising peptides were synthesized, and antimicrobial assays showed inhibitory activity against Gram-positive and Gram-negative bacteria. Colossomin C and colossomin D were the most inhibitory peptides at 5 μg/ml against Staphylococcus aureus and Escherichia coli. The methods described in this work and the results obtained are useful for the identification and development of new compounds with antimicrobial activity through the use of computational tools. PMID:23455341

  3. Diversity in penaeidin antimicrobial peptide form and function

    PubMed Central

    Cuthbertson, Brandon J.; Deterding, Leesa J.; Williams, Jason G.; Tomer, Kenneth B.; Etienne, Kizee; Blackshear, Perry J.; Büllesbach, Erika E.; Gross, Paul S.

    2008-01-01

    Penaeidins are a diverse family of two-domain antimicrobial peptides expressed in shrimp. Variation in penaeidin sequence results in functional diversity, which was discovered using synthetic reproductions of native penaeidins. An isoform of penaeidin class 3 from L. setiferus (Litset Pen3−4) was synthesized using native ligation and compared directly with the synthetic penaeidin class 4 known to be expressed in the same organism. New antimicrobial activity data is included in this review that emphasizes differences in effectiveness that are apparent from a direct comparison of two classes. A novel approach to intact penaeidin analysis is presented in the form of Fourier Transform Ion-Cyclotron Resonance Mass Spectrometry, which has implications for the identification of individual penaeidin isoforms without chemical modification or enzymatic cleavage. The new information included in this review helps gather the perspective on relevance of penaeidin diversity to antimicrobial function, the use of synthetic peptides as tools to evaluate specific immune functions and the application of high mass resolution, top-down sequencing methods to the intact analysis of individual penaeidin isoforms. PMID:17716729

  4. Diversity, evolution and medical applications of insect antimicrobial peptides

    PubMed Central

    Mylonakis, Eleftherios; Podsiadlowski, Lars; Muhammed, Maged

    2016-01-01

    Antimicrobial peptides (AMPs) are short proteins with antimicrobial activity. A large portion of known AMPs originate from insects, and the number and diversity of these molecules in different species varies considerably. Insect AMPs represent a potential source of alternative antibiotics to address the limitation of current antibiotics, which has been caused by the emergence and spread of multidrug-resistant pathogens. To get more insight into AMPs, we investigated the diversity and evolution of insect AMPs by mapping their phylogenetic distribution, allowing us to predict the evolutionary origins of selected AMP families and to identify evolutionarily conserved and taxon-specific families. Furthermore, we highlight the use of the nematode Caenorhabditis elegans as a whole-animal model in high-throughput screening methods to identify AMPs with efficacy against human pathogens, including Acinetobacter baumanii and methicillin-resistant Staphylococcus aureus. We also discuss the potential medical applications of AMPs, including their use as alternatives for conventional antibiotics in ectopic therapies, their combined use with antibiotics to restore the susceptibility of multidrug-resistant pathogens, and their use as templates for the rational design of peptidomimetic drugs that overcome the disadvantages of therapeutic peptides. The article is part of the themed issue ‘Evolutionary ecology of arthropod antimicrobial peptides’. PMID:27160593

  5. Comparative Evaluation of the Antimicrobial Activity of Different Antimicrobial Peptides against a Range of Pathogenic Bacteria

    PubMed Central

    Ebbensgaard, Anna; Mordhorst, Hanne; Overgaard, Michael Toft; Nielsen, Claus Gyrup; Aarestrup, Frank Møller; Hansen, Egon Bech

    2015-01-01

    Analysis of a Selected Set of Antimicrobial Peptides The rapid emergence of resistance to classical antibiotics has increased the interest in novel antimicrobial compounds. Antimicrobial peptides (AMPs) represent an attractive alternative to classical antibiotics and a number of different studies have reported antimicrobial activity data of various AMPs, but there is only limited comparative data available. The mode of action for many AMPs is largely unknown even though several models have suggested that the lipopolysaccharides (LPS) play a crucial role in the attraction and attachment of the AMP to the bacterial membrane in Gram-negative bacteria. We compared the potency of Cap18, Cap11, Cap11-1-18m2, Cecropin P1, Cecropin B, Bac2A, Bac2A-NH2, Sub5-NH2, Indolicidin, Melittin, Myxinidin, Myxinidin-NH2, Pyrrhocoricin, Apidaecin and Metalnikowin I towards Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, Aeromonas salmonicida, Listeria monocytogenes, Campylobacter jejuni, Flavobacterium psychrophilum, Salmonella typhimurium and Yersinia ruckeri by minimal inhibitory concentration (MIC) determinations. Additional characteristics such as cytotoxicity, thermo and protease stability were measured and compared among the different peptides. Further, the antimicrobial activity of a selection of cationic AMPs was investigated in various E. coli LPS mutants. Cap18 Shows a High Broad Spectrum Antimicrobial Activity Of all the tested AMPs, Cap18 showed the most efficient antimicrobial activity, in particular against Gram-negative bacteria. In addition, Cap18 is highly thermostable and showed no cytotoxic effect in a hemolytic assay, measured at the concentration used. However, Cap18 is, as most of the tested AMPs, sensitive to proteolytic digestion in vitro. Thus, Cap18 is an excellent candidate for further development into practical use; however, modifications that should reduce the protease sensitivity would be needed. In addition, our

  6. Circular Dichroism studies on the interactions of antimicrobial peptides with bacterial cells

    NASA Astrophysics Data System (ADS)

    Avitabile, Concetta; D'Andrea, Luca Domenico; Romanelli, Alessandra

    2014-03-01

    Studying how antimicrobial peptides interact with bacterial cells is pivotal to understand their mechanism of action. In this paper we explored the use of Circular Dichroism to detect the secondary structure of two antimicrobial peptides, magainin 2 and cecropin A, with E. coli bacterial cells. The results of our studies allow us to gain two important information in the context of antimicrobial peptides- bacterial cells interactions: peptides fold mainly due to interaction with LPS, which is the main component of the Gram negative bacteria outer membrane and the time required for the folding on the bacterial cells depends on the peptide analyzed.

  7. Mammalian antimicrobial peptide influences control of cutaneous Leishmania infection

    PubMed Central

    Kulkarni, Manjusha M.; Barbi, Joseph; McMaster, W. Robert; Gallo, Richard L.; Satoskar, Abhay R.; McGwire, Bradford S.

    2011-01-01

    Summary Cathelicidin-type antimicrobial peptides (CAMP) are important mediators of innate immunity against microbial pathogens acting through direct interaction with and disruption of microbial membranes and indirectly through modulation of host cell migration and activation. Using a mouse knock-out model in CAMP we studied the role of this host peptide in control of dissemination of cutaneous infection by the parasitic protozoan Leishmania. The presence of pronounced host inflammatory infiltration in lesions and lymph nodes of infected animals was CAMP-dependent. Lack of CAMP expression was associated with higher levels of IL-10 receptor expression in bone marrow, splenic and lymph node macrophages as well as higher anti-inflammatory IL-10 production by bone marrow macrophages and spleen cells but reduced production of the pro-inflammatory cytokines IL-12 and IFN-γ by lymph nodes. Unlike wild-type mice, local lesions were exacerbated and parasites were found largely disseminated in CAMP knockouts. Infection of CAMP knockouts with parasite mutants lacking the surface metalloprotease virulence determinant resulted in more robust disseminated infection than in control animals suggesting that CAMP activity is negatively regulated by parasite surface proteolytic activity. This correlated with the ability of the pro-tease to degrade CAMP in vitro and co-localization of CAMP with parasites within macrophages. Our results highlight the interplay of antimicrobial peptides and Leishmania that influence the host immune response and the outcome of infection. PMID:21501359

  8. Antimicrobial Peptides as Mediators of Innate Immunity in Teleosts

    PubMed Central

    Katzenback, Barbara A.

    2015-01-01

    Antimicrobial peptides (AMPs) have been identified throughout the metazoa suggesting their evolutionarily conserved nature and their presence in teleosts is no exception. AMPs are short (18–46 amino acids), usually cationic, amphipathic peptides. While AMPs are diverse in amino acid sequence, with no two AMPs being identical, they collectively appear to have conserved functions in the innate immunity of animals towards the pathogens they encounter in their environment. Fish AMPs are upregulated in response to pathogens and appear to have direct broad-spectrum antimicrobial activity towards both human and fish pathogens. However, an emerging role for AMPs as immunomodulatory molecules has become apparent—the ability of AMPs to activate the innate immune system sheds light onto the multifaceted capacity of these small peptides to combat pathogens through direct and indirect means. Herein, this review focuses on the role of teleost AMPs as modulators of the innate immune system and their regulation in response to pathogens or other exogenous molecules. The capacity to regulate AMP expression by exogenous factors may prove useful in modulating AMP expression in fish to prevent disease, particularly in aquaculture settings where crowded conditions and environmental stress pre-dispose these fish to infection. PMID:26426065

  9. Antimicrobial Peptides as Mediators of Innate Immunity in Teleosts.

    PubMed

    Katzenback, Barbara A

    2015-01-01

    Antimicrobial peptides (AMPs) have been identified throughout the metazoa suggesting their evolutionarily conserved nature and their presence in teleosts is no exception. AMPs are short (18-46 amino acids), usually cationic, amphipathic peptides. While AMPs are diverse in amino acid sequence, with no two AMPs being identical, they collectively appear to have conserved functions in the innate immunity of animals towards the pathogens they encounter in their environment. Fish AMPs are upregulated in response to pathogens and appear to have direct broad-spectrum antimicrobial activity towards both human and fish pathogens. However, an emerging role for AMPs as immunomodulatory molecules has become apparent-the ability of AMPs to activate the innate immune system sheds light onto the multifaceted capacity of these small peptides to combat pathogens through direct and indirect means. Herein, this review focuses on the role of teleost AMPs as modulators of the innate immune system and their regulation in response to pathogens or other exogenous molecules. The capacity to regulate AMP expression by exogenous factors may prove useful in modulating AMP expression in fish to prevent disease, particularly in aquaculture settings where crowded conditions and environmental stress pre-dispose these fish to infection. PMID:26426065

  10. Importance of Tryptophan in Transforming an Amphipathic Peptide into a Pseudomonas aeruginosa-Targeted Antimicrobial Peptide

    PubMed Central

    Zhu, Xin; Ma, Zhi; Wang, Jiajun; Chou, Shuli; Shan, Anshan

    2014-01-01

    Here, we found that simple substitution of amino acids in the middle position of the hydrophobic face of an amphipathic peptide RI16 with tryptophan (T9W) considerably transformed into an antimicrobial peptide specifically targeting Pseudomonas aeruginosa. Minimal inhibitory concentration (MIC) results demonstrated that T9W had a strong and specifically antimicrobial activity against P. aeruginosa, including antibiotic-resistant strains, but was not active against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Staphyfococcus epidermidis. Fluorescent spectroscopic assays indicated that T9W interacted with the membrane of P. aeruginosa, depolarizing the outer and the inner membrane of bacterial cells. Salt susceptibility assay showed that T9W still maintained its strong anti-pseudomonas activity in the presence of salts at physiological concentrations, and in hemolytic and MTT assays T9W also showed no toxicity against human blood cells and macrophages. In vivo assay demonstrated that T9W also displayed no toxicity to Chinese Kun Ming (KM) mice. Furthermore, the strong antibiofilm activity was also observed with the peptide T9W, which decreased the percentage of biomass formation in a dose-dependent manner. Overall, these findings indicated that design of single-pathogen antimicrobial agents can be achieved by simple amino acid mutation in naturally occurring peptide sequences and this study suggested a model of optimization/design of anti-pseudomonas drugs in which the tryptophan residue was a conserved element. PMID:25494332

  11. Characterization of Antimicrobial Peptides toward the Development of Novel Antibiotics

    PubMed Central

    Aoki, Wataru; Ueda, Mitsuyoshi

    2013-01-01

    Antimicrobial agents have eradicated many infectious diseases and significantly improved our living environment. However, abuse of antimicrobial agents has accelerated the emergence of multidrug-resistant microorganisms, and there is an urgent need for novel antibiotics. Antimicrobial peptides (AMPs) have attracted attention as a novel class of antimicrobial agents because AMPs efficiently kill a wide range of species, including bacteria, fungi, and viruses, via a novel mechanism of action. In addition, they are effective against pathogens that are resistant to almost all conventional antibiotics. AMPs have promising properties; they directly disrupt the functions of cellular membranes and nucleic acids, and the rate of appearance of AMP-resistant strains is very low. However, as pharmaceuticals, AMPs exhibit unfavorable properties, such as instability, hemolytic activity, high cost of production, salt sensitivity, and a broad spectrum of activity. Therefore, it is vital to improve these properties to develop novel AMP treatments. Here, we have reviewed the basic biochemical properties of AMPs and the recent strategies used to modulate these properties of AMPs to enhance their safety. PMID:24276381

  12. Dynamical and Phase Behavior of a Phospholipid Membrane Altered by an Antimicrobial Peptide at Low Concentration.

    PubMed

    Sharma, V K; Mamontov, E; Tyagi, M; Qian, S; Rai, D K; Urban, V S

    2016-07-01

    The mechanism of action of antimicrobial peptides is traditionally attributed to the formation of pores in the lipid cell membranes of pathogens, which requires a substantial peptide to lipid ratio. However, using incoherent neutron scattering, we show that even at a concentration too low for pore formation, an archetypal antimicrobial peptide, melittin, disrupts the regular phase behavior of the microscopic dynamics in a phospholipid membrane, dimyristoylphosphatidylcholine (DMPC). At the same time, another antimicrobial peptide, alamethicin, does not exert a similar effect on the DMPC microscopic dynamics. The melittin-altered lateral motion of DMPC at physiological temperature no longer resembles the fluid-phase behavior characteristic of functional membranes of the living cells. The disruptive effect demonstrated by melittin even at low concentrations reveals a new mechanism of antimicrobial action relevant in more realistic scenarios, when peptide concentration is not as high as would be required for pore formation, which may facilitate treatment with antimicrobial peptides. PMID:27232190

  13. Antimicrobial peptides as an opportunity against bacterial diseases.

    PubMed

    Galdiero, Stefania; Falanga, Annarita; Berisio, Rita; Grieco, Paolo; Morelli, Giancarlo; Galdiero, Massimiliano

    2015-01-01

    Antimicrobial peptides (AMPs) are an heterogeneous group of small amino acidic molecules produced by the innate immune system of a variety of organisms encompassing all orders of life from eukaryotes to amphibians, insects and plants. Numerous AMPs have been isolated from natural sources and many others have been de novo designed and synthetically produced. AMPs have antimicrobial activity in the micromolar range and compared with traditional antibiotics, they kill bacteria very rapidly. They act, principally, by the electrostatic attraction to negatively charged bacterial cells and consequently membrane disruption, but their antibacterial activity may also involve interference with metabolic processes or different cytoplasmic targets. AMPs are a group of unique and incredible compounds that may be directed to a therapeutic use either alone or in combination with existing antibiotics. PMID:25760092

  14. On the Physiology and Pathophysiology of Antimicrobial Peptides

    PubMed Central

    Pálffy, Roland; Gardlík, Roman; Behuliak, Michal; Kadasi, Ludevit; Turna, Jan; Celec, Peter

    2009-01-01

    Antimicrobial peptides (AMP) are a heterogeneous group of molecules involved in the nonspecific immune responses of a variety of organisms ranging from prokaryotes to mammals, including humans. AMP have various physical and biological properties, yet the most common feature is their antimicrobial effect. The majority of AMP disrupt the integrity of microbial cells by 1 of 3 known mechanisms—the barrel-stave pore model, the thoroidal pore model, or the carpet model. Results of growing numbers of descriptive and experimental studies show that altered expression of AMP in various tissues is important in the pathogenesis of several gastrointestinal, respiratory, and other diseases. We discuss novel approaches and strategies to further improve the promising future of therapeutic applications of AMP. The spread of antibiotic resistance increases the importance of developing a clinical role for AMP. PMID:19015736

  15. Supramolecular amphipathicity for probing antimicrobial propensity of host defence peptides.

    PubMed

    Ravi, Jascindra; Bella, Angelo; Correia, Ana J V; Lamarre, Baptiste; Ryadnov, Maxim G

    2015-06-28

    Host defence peptides (HDPs) are effector components of innate immunity that provide defence against pathogens. These are small-to-medium sized proteins which fold into amphipathic conformations toxic to microbial membranes. Here we explore the concept of supramolecular amphipathicity for probing antimicrobial propensity of HDPs using elementary HDP-like amphiphiles. Such amphiphiles are individually inactive, but when ordered into microscopic micellar assemblies, respond to membrane binding according to the orthogonal type of their primary structure. The study demonstrates that inducible supramolecular amphipathicity can discriminate against bacterial growth and colonisation thereby offering a physico-chemical rationale for tuneable targeting of biological membranes. PMID:25966444

  16. Antimicrobial peptides and wound healing: biological and therapeutic considerations.

    PubMed

    Mangoni, Maria Luisa; McDermott, Alison M; Zasloff, Michael

    2016-03-01

    Repair of tissue wounds is a fundamental process to re-establish tissue integrity and regular function. Importantly, infection is a major factor that hinders wound healing. Multicellular organisms have evolved an arsenal of host-defense molecules, including antimicrobial peptides (AMPs), aimed at controlling microbial proliferation and at modulating the host's immune response to a variety of biological or physical insults. In this brief review, we provide the evidence for a role of AMPs as endogenous mediators of wound healing and their promising therapeutic potential for the treatment of non-life-threatening skin and other epithelial injuries. PMID:26738772

  17. Structure and Biological Functions of β-Hairpin Antimicrobial Peptides

    PubMed Central

    Panteleev, P. V.; Bolosov, I. A.; Balandin, S. V.; Ovchinnikova, T. V.

    2015-01-01

    Antimicrobial peptides (AMPs) are evolutionarily ancient factors of the innate immune system that serve as a crucial first line of defense for humans, animals, and plants against infection. This review focuses on the structural organization, biosynthesis, and biological functions of AMPs that possess a β-hairpin spatial structure. Representatives of this class of AMPs are among the most active antibiotic molecules of animal origin. Due to their wide spectrum of activity and resistance to internal environmental factors, natural β-hairpin AMPbased compounds might become the most promising drug candidates. PMID:25927000

  18. Challenges and Limits Using Antimicrobial Peptides in Boar Semen Preservation.

    PubMed

    Schulze, M; Grobbel, M; Müller, K; Junkes, C; Dathe, M; Rüdiger, K; Jung, M

    2015-07-01

    Antibiotics are of great importance for the preservation of ejaculates for livestock breading. The use of antibiotics, however, is not an appropriate compensation for a lack of hygiene standards in artificial insemination (AI) centres. Sophisticated hygiene management and the proper identification of hygienic critical control points (HCCPs) at AI centres provide the basis for counteracting the development of antibiotic resistance in contaminant bacteria and their settlement in AI centres. In recent years, efforts have been made to use antimicrobial peptides (AMPs) in the preservation of boar semen. Investigations have included the testing of synthetic magainin derivatives and cyclic hexapeptides. One prerequisite for the application of AMPs is that they have a minor impact on eukaryotic cells. Bacterial selectivity, proteolytic stability, thermodynamic resistance, and mechanisms including synergistic interaction with conventional antibiotics have made cyclic hexapeptides highly promising candidates for potential application as peptide antibiotics for semen preservation. PMID:26174913

  19. Expression profiles of seven channel catfish antimicrobial peptides in response to Edwardsiella ictaluri infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using quantitative PCR technique, the relative transcriptional levels of seven channel catfish antimicrobial peptide (AMP) genes [NK-lysin type 1, NK-lysin type 2, NK-lysin type 3, bactericidal permeability-increasing protein (BPI), cathepsin D, hepcidin, and liver-expressed antimicrobial peptide 2 ...

  20. Protocols to test the activity of antimicrobial peptides against the honey bee pathogen Paenibacillus larvae.

    PubMed

    Khilnani, Jasmin C; Wing, Helen J

    2015-10-01

    Paenibacillus larvae is the causal agent of the honey bee disease American Foulbrood. Two enhanced protocols that allow the activity of antimicrobial peptides to be tested against P. larvae are presented. Proof of principle experiments demonstrate that the honey bee antimicrobial peptide defensin 1 is active in both assays. PMID:26210039

  1. The Amazing World of Peptide Engineering: the Example of Antimicrobial Peptides from Frogs and Their Analogues.

    PubMed

    Guimarães, Aline B; Costa, Fabiano J Q; Pires, Osmindo R; Fontes, Wagner; Castro, Mariana S

    2016-01-01

    This review discusses the importance and properties of antimicrobial peptides from frogs and their synthetic analogues as potential therapeutic alternatives in fighting not only bacterial infections, but also protozoans involved with the major neglected diseases, which afflict human populations (e.g., Chagas disease, African sleeping sickness, Leishmaniasis and malaria). Here, we emphasize their multifunctional properties such as promising broad-spectrum drugs that target protozoan parasites too. PMID:27262306

  2. The Roles of Antimicrobial Peptides in Innate Host Defense

    PubMed Central

    Diamond, Gill; Beckloff, Nicholas; Weinberg, Aaron; Kisich, Kevin O.

    2009-01-01

    Antimicrobial peptides (AMPs) are multi-functional peptides whose fundamental biological role in vivo has been proposed to be the elimination of pathogenic microorganisms, including Gram-positive and -negative bacteria, fungi, and viruses. Genes encoding these peptides are expressed in a variety of cells in the host, including circulating phagocytic cells and mucosal epithelial cells, demonstrating a wide range of utility in the innate immune system. Expression of these genes is tightly regulated; they are induced by pathogens and cytokines as part of the host defense response, and they can be suppressed by bacterial virulence factors and environmental factors which can lead to increased susceptibility to infection. New research has also cast light on alternative functionalities, including immunomodulatory activities, which are related to their unique structural characteristics. These peptides represent not only an important component of innate host defense against microbial colonization and a link between innate and adaptive immunity, but also form a foundation for the development of new therapeutic agents. PMID:19601838

  3. Antimicrobial peptides from frog skin: biodiversity and therapeutic promises.

    PubMed

    Ladram, Ali; Nicolas, Pierre

    2016-01-01

    More than a thousand antimicrobial peptides (AMPs) have been reported in the last decades arising from the skin secretion of amphibian species. Generally, each frog species can express its own repertoire of AMPs (typically, 10-20 peptides) with differing sequences, sizes, and spectrum of action, which implies very rapid divergence, even between closely related species. Frog skin AMPs are highly potent against antibiotic-resistant bacteria, protozoa, yeasts, and fungi by permeating and destroying their plasma membrane and/or inactivating intracellular targets. These peptides have attracted considerable interest as a therapeutic alternative to conventional anti-infective agents. However, efforts to obtain a new generation of drugs using these peptides are still challenging because of high associated R&D costs due to their large size (up to 46 residues) and cytotoxicity. This review deals with the biodiversity of frog skin AMPs and assesses the therapeutic possibilities of temporins, the shortest AMPs found in the frog skin, with 8-17 residues. Such short sequences are easily amenable to optimization of the structure and to solution-phase synthesis that offer reduced costs over solid-phase chemistry. PMID:27100511

  4. Analysis of the antimicrobial activities of a chemokine-derived peptide (CDAP-4) on Pseudomonas aeruginosa

    SciTech Connect

    Martinez-Becerra, Francisco; Dominguez-Ramirez, Lenin; Mendoza-Hernandez, Guillermo; Lopez-Vidal, Yolanda; Soldevila, Gloria . E-mail: garciaze@servidor.unam.mx

    2007-04-06

    Chemokines are key molecules involved in the control of leukocyte trafficking. Recently, a novel function as antimicrobial proteins has been described. CCL13 is the only member of the MCP chemokine subfamily displaying antimicrobial activity. To determine Key residues involved in its antimicrobial activity, CCL13 derived peptides were synthesized and tested against several bacterial strains, including Pseudomonas aeruginosa. One of these peptides, corresponding to the C-terminal region of CCL13 (CDAP-4) displayed good antimicrobial activity. Electron microscopy studies revealed remarkable morphological changes after CDAP-4 treatment. By computer modeling, CDAP-4 in {alpha} helical configuration generated a positive electrostatic potential that extended beyond the surface of the molecule. This feature is similar to other antimicrobial peptides. Altogether, these findings indicate that the antimicrobial activity was displayed by CCL13 resides to some extent at the C-terminal region. Furthermore, CDAP-4 could be considered a good antimicrobial candidate with a potential use against pathogens including P. aeruginosa.

  5. Insect antimicrobial peptides act synergistically to inhibit a trypanosome parasite.

    PubMed

    Marxer, Monika; Vollenweider, Vera; Schmid-Hempel, Paul

    2016-05-26

    The innate immune system provides protection from infection by producing essential effector molecules, such as antimicrobial peptides (AMPs) that possess broad-spectrum activity. This is also the case for bumblebees, Bombus terrestris, when infected by the trypanosome, Crithidia bombi Furthermore, the expressed mixture of AMPs varies with host genetic background and infecting parasite strain (genotype). Here, we used the fact that clones of C. bombi can be cultivated and kept as strains in medium to test the effect of various combinations of AMPs on the growth rate of the parasite. In particular, we used pairwise combinations and a range of physiological concentrations of three AMPs, namely Abaecin, Defensin and Hymenoptaecin, synthetized from the respective genomic sequences. We found that these AMPs indeed suppress the growth of eight different strains of C. bombi, and that combinations of AMPs were typically more effective than the use of a single AMP alone. Furthermore, the most effective combinations were rarely those consisting of maximum concentrations. In addition, the AMP combination treatments revealed parasite strain specificity, such that strains varied in their sensitivity towards the same mixtures. Hence, variable expression of AMPs could be an alternative strategy to combat highly variable infections.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. PMID:27160603

  6. Antimicrobial peptides and cell processes tracking endosymbiont dynamics.

    PubMed

    Masson, Florent; Zaidman-Rémy, Anna; Heddi, Abdelaziz

    2016-05-26

    Many insects sustain long-term relationships with intracellular symbiotic bacteria that provide them with essential nutrients. Such endosymbiotic relationships likely emerged from ancestral infections of the host by free-living bacteria, the genomes of which experience drastic gene losses and rearrangements during the host-symbiont coevolution. While it is well documented that endosymbiont genome shrinkage results in the loss of bacterial virulence genes, whether and how the host immune system evolves towards the tolerance and control of bacterial partners remains elusive. Remarkably, many insects rely on a 'compartmentalization strategy' that consists in secluding endosymbionts within specialized host cells, the bacteriocytes, thus preventing direct symbiont contact with the host systemic immune system. In this review, we compile recent advances in the understanding of the bacteriocyte immune and cellular regulators involved in endosymbiont maintenance and control. We focus on the cereal weevils Sitophilus spp., in which bacteriocytes form bacteriome organs that strikingly evolve in structure and number according to insect development and physiological needs. We discuss how weevils track endosymbiont dynamics through at least two mechanisms: (i) a bacteriome local antimicrobial peptide synthesis that regulates endosymbiont cell cytokinesis and helps to maintain a homeostatic state within bacteriocytes and (ii) some cellular processes such as apoptosis and autophagy which adjust endosymbiont load to the host developmental requirements, hence ensuring a fine-tuned integration of symbiosis costs and benefits.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. PMID:27160600

  7. Antimicrobial peptides in marine invertebrate health and disease.

    PubMed

    Destoumieux-Garzón, Delphine; Rosa, Rafael Diego; Schmitt, Paulina; Barreto, Cairé; Vidal-Dupiol, Jeremie; Mitta, Guillaume; Gueguen, Yannick; Bachère, Evelyne

    2016-05-26

    Aquaculture contributes more than one-third of the animal protein from marine sources worldwide. A significant proportion of aquaculture products are derived from marine protostomes that are commonly referred to as 'marine invertebrates'. Among them, penaeid shrimp (Ecdysozosoa, Arthropoda) and bivalve molluscs (Lophotrochozoa, Mollusca) are economically important. Mass rearing of arthropods and molluscs causes problems with pathogens in aquatic ecosystems that are exploited by humans. Remarkably, species of corals (Cnidaria) living in non-exploited ecosystems also suffer from devastating infectious diseases that display intriguing similarities with those affecting farmed animals. Infectious diseases affecting wild and farmed animals that are present in marine environments are predicted to increase in the future. This paper summarizes the role of the main pathogens and their interaction with host immunity, with a specific focus on antimicrobial peptides (AMPs) and pathogen resistance against AMPs. We provide a detailed review of penaeid shrimp AMPs and their role at the interface between the host and its resident/pathogenic microbiota. We also briefly describe the relevance of marine invertebrate AMPs in an applied context.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. PMID:27160602

  8. Cationic Antimicrobial Peptides Disrupt the Streptococcus pyogenes ExPortal

    PubMed Central

    Vega, Luis Alberto; Caparon, Michael G.

    2012-01-01

    Summary Although they possess a well-characterized ability to porate the bacterial membrane, emerging research suggests that cationic antimicrobial peptides (CAPs) can influence pathogen behavior at levels that are sub-lethal. In this study, we investigated the interaction of polymyxin B and human neutrophil peptide (HNP-1) with the human pathogen Streptococcus pyogenes. At sub-lethal concentrations, these CAPs preferentially targeted the ExPortal, a unique microdomain of the S. pyogenes membrane, specialized for protein secretion and processing. A consequence of this interaction was the disruption of ExPortal organization and a redistribution of ExPortal components into the peripheral membrane. Redistribution was associated with inhibition of secretion of certain toxins, including the SpeB cysteine protease and the Streptolysin O (SLO) cytolysin, but not SIC, a protein that protects S. pyogenes from CAPs. These data suggest a novel function for CAPs in targeting the ExPortal and interfering with secretion of factors required for infection and survival. This mechanism may prove valuable for the design of new types of antimicrobial agents to combat the emergence of antibiotic-resistant pathogens. PMID:22780862

  9. Antimicrobial activities of amphiphilic peptides covalently bonded to a water-insoluble resin.

    PubMed Central

    Haynie, S L; Crum, G A; Doele, B A

    1995-01-01

    A series of polymer-bound antimicrobial peptides was prepared, and the peptides were tested for their antimicrobial activities. The immobilized peptides were prepared by a strategy that used solid-phase peptide synthesis that linked the carboxy-terminal amino acid with an ethylenediamine-modified polyamide resin (PepsynK). The acid-stable, permanent amide bond between the support and the nascent peptide renders the peptide resistant to cleavage from the support during the final acid-catalyzed deprotection step in the synthesis. Select immobilized peptides containing amino acid sequences that ranged from the naturally occurring magainin to simpler synthetic sequences with idealized secondary structures were excellent antimicrobial agents against several organisms. The immobilized peptides typically reduced the number of viable cells by > or = 5 log units. We show that the reduction in cell numbers cannot be explained by the action of a soluble component. We observed no leached or hydrolyzed peptide from the resin, nor did we observe any antimicrobial activity in soluble extracts from the immobilized peptide. The immobilized peptides were washed and reused for repeated microbial contact and killing. These results suggest that the surface actions by magainins and structurally related antimicrobial peptides are sufficient for their lethal activities. PMID:7726486

  10. A molecular dynamics and circular dichroism study of a novel synthetic antimicrobial peptide

    NASA Astrophysics Data System (ADS)

    Rodina, N. P.; Yudenko, A. N.; Terterov, I. N.; Eliseev, I. E.

    2013-08-01

    Antimicrobial peptides are a class of small, usually positively charged amphiphilic peptides that are used by the innate immune system to combat bacterial infection in multicellular eukaryotes. Antimicrobial peptides are known for their broad-spectrum antimicrobial activity and thus can be used as a basis for a development of new antibiotics against multidrug-resistant bacteria. The most challengeous task on the way to a therapeutic use of antimicrobial peptides is a rational design of new peptides with enhanced activity and reduced toxicity. Here we report a molecular dynamics and circular dichroism study of a novel synthetic antimicrobial peptide D51. This peptide was earlier designed by Loose et al. using a linguistic model of natural antimicrobial peptides. Molecular dynamics simulation of the peptide folding in explicit solvent shows fast formation of two antiparallel beta strands connected by a beta-turn that is confirmed by circular dichroism measurements. Obtained from simulation amphipatic conformation of the peptide is analysed and possible mechanism of it's interaction with bacterial membranes together with ways to enhance it's antibacterial activity are suggested.

  11. Comparative surface antimicrobial properties of synthetic biocides and novel human apolipoprotein E derived antimicrobial peptides.

    PubMed

    Forbes, Sarah; McBain, Andrew J; Felton-Smith, Susan; Jowitt, Thomas A; Birchenough, Holly L; Dobson, Curtis B

    2013-07-01

    Medical device infection remains a major clinical concern. Biocidal compounds have been incorporated into medical device materials ideally to inhibit bacterial colonisation whilst exhibiting relatively low cytotoxicity. We compared the antibacterial activity, anti-biofilm efficacy and cytotoxicity of a novel peptide derivative of human apolipoprotein E (apoEdpL-W) to that of commonly used biocides, before and after coating onto a range of standard polymers. Since the antimicrobial function of most biocides frequently involves associations with cellular membranes, we have also studied the detailed interactions of the test antimicrobials with phospholipid bilayers, using the quartz crystal microbalance device combined with dual-polarisation interferometry. ApoEdpL-W displayed broad-spectrum antibacterial activity and marked efficacy against nascent Staphylococcus aureus biofilms. Compounds showed better antimicrobial activity when combined with hydrogel materials than with non-porous materials. The membrane interactions of apoEdpL-W were most similar to that of PHMB, with both agents appearing to readily bind and insert into lipid bilayers, possibly forming pores. However apoEdpL-W showed lower cytotoxicity than PHMB, its efficacy was less affected by the presence of serum, and it demonstrated the highest level of biocompatibility of all the biocides, as indicated by our measurement of its antimicrobial biocompatibility index. This work shows the potential of apoEdpL-W as an effective antiseptic coating agent. PMID:23623325

  12. Identification and characterization of a novel antimicrobial peptide from the venom of the ant Tetramorium bicarinatum.

    PubMed

    Rifflet, Aline; Gavalda, Sabine; Téné, Nathan; Orivel, Jérôme; Leprince, Jérôme; Guilhaudis, Laure; Génin, Eric; Vétillard, Angélique; Treilhou, Michel

    2012-12-01

    A novel antimicrobial peptide, named Bicarinalin, has been isolated from the venom of the ant Tetramorium bicarinatum. Its amino acid sequence has been determined by de novo sequencing using mass spectrometry and by Edman degradation. Bicarinalin contained 20 amino acid residues and was C-terminally amidated as the majority of antimicrobial peptides isolated to date from insect venoms. Interestingly, this peptide had a linear structure and exhibited no meaningful similarity with any known peptides. Antibacterial activities against Staphylococcus aureus and S. xylosus strains were evaluated using a synthetic replicate. Bicarinalin had a potent and broad antibacterial activity of the same magnitude as Melittin and other hymenopteran antimicrobial peptides such as Pilosulin or Defensin. Moreover, this antimicrobial peptide has a weak hemolytic activity compared to Melittin on erythrocytes, suggesting potential for development into an anti-infective agent for use against emerging antibiotic-resistant pathogens. PMID:22960382

  13. Controlling the release of peptide antimicrobial agents from surfaces.

    PubMed

    Shukla, Anita; Fleming, Kathleen E; Chuang, Helen F; Chau, Tanguy M; Loose, Christopher R; Stephanopoulos, Gregory N; Hammond, Paula T

    2010-03-01

    Medical conditions are often exacerbated by the onset of infection caused by hospital dwelling bacteria such as Staphylococcus aureus. Antibiotics taken orally or intravenously can require large and frequent doses, further contributing to the sharp rise in resistant bacteria observed over the past several decades. These existing antibiotics are also often ineffective in preventing biofilm formation, a common cause of medical device failure. Local delivery of new therapeutic agents that do not allow bacterial resistance to occur, such as antimicrobial peptides, could alleviate many of the problems associated with current antibacterial treatments. By taking advantage of the versatility of layer-by-layer assembly of polymer thin films, ponericin G1, an antimicrobial peptide known to be highly active against S. aureus, was incorporated into a hydrolytically degradable polyelectrolyte multilayer film. Several film architectures were examined to obtain various drug loadings that ranged from 20 to 150 microg/cm2. Release was observed over approximately ten days, with varying release profiles, including burst as well as linear release. Results indicated that film-released peptide did not suffer any loss in activity against S. aureus and was able to inhibit bacteria attachment, a necessary step in preventing biofilm formation. Additionally, all films were found to be biocompatible with the relevant wound healing cells, NIH 3T3 fibroblasts and human umbilical vein endothelial cells. These films provide the level of control over drug loading and release kinetics required in medically relevant applications including coatings for implant materials and bandages, while eliminating susceptibility to bacterial resistance. PMID:20004967

  14. In Vitro Antimicrobial Properties of Recombinant ASABF, an Antimicrobial Peptide Isolated from the Nematode Ascaris suum

    PubMed Central

    Zhang, Hong; Yoshida, Shigenobu; Aizawa, Tomoyasu; Murakami, Ritsuko; Suzuki, Masato; Koganezawa, Nozomu; Matsuura, Atsushi; Miyazawa, Mitsuhiro; Kawano, Keiichi; Nitta, Katsutoshi; Kato, Yusuke

    2000-01-01

    ASABF is a CSαβ-type antimicrobial peptide that contains four intramolecular disulfide bridges (Y. Kato and S. Komatsu, J. Biol. Chem. 271:30493–30498, 1996). In the present study, a recombinant ASABF was produced by using a yeast expression system, and its antimicrobial activity was characterized in detail. The recombinant ASABF was active against all gram-positive bacteria tested (7 of 7; minimum bactericidal concentration [MBC], 0.03 to 1 μg/ml) except Leuconostoc mesenteroides, some gram-negative bacteria (8 of 14; MBC, >0.5 μg/ml), and some yeasts (3 of 9; MBC >3 μg/ml). Slight hemolytic activity (4.2% at 100 μg/ml) against human erythrocytes was observed only under low-ionic-strength conditions. Less than 1 min of contact was enough to kill Staphylococcus aureus ATCC 6538P. The bactericidal activity against S. aureus was inhibited by salts. PMID:10991847

  15. Antimicrobial function of the GAPDH-related antimicrobial peptide in the skin of skipjack tuna, Katsuwonus pelamis.

    PubMed

    Seo, Jung-Kil; Lee, Min Jeong; Go, Hye-Jin; Kim, Yeon Jun; Park, Nam Gyu

    2014-02-01

    A 3.4 kDa of antimicrobial peptide was purified from an acidified skin extract of skipjack tuna, Katsuwonus pelamis, by preparative acid-urea-polyacrylamide gel electrophoresis and C18 reversed-phase HPLC. A comparison of the N-terminal amino acid sequence of the purified peptide with that of other known polypeptides revealed high sequence homology with the YFGAP (Yellowfin tuna Glyceraldehyde-3-phosphate dehydrogenase-related Antimicrobial Peptide); thus, this peptide was identified as the skipjack tuna GAPDH-related antimicrobial peptide (SJGAP). SJGAP showed potent antimicrobial activity against Gram-positive bacteria, such as Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, and Streptococcus iniae (minimal effective concentrations [MECs], 1.2-17.0 μg/mL), Gram-negative bacteria, such as Aeromonas hydrophila, Escherichia coli D31, and Vibrio parahaemolyticus (MECs, 3.1-12.0 μg/mL), and against Candida albicans (MEC, 16.0 μg/mL) without significant hemolytic activity. Antimicrobial activity of this peptide is heat-stable but salt-sensitive. According to the secondary structural prediction and the homology modeling, this peptide consists of three secondary structural motifs, including one α-helix and two parallel β-strands, and forms an amphipathic structure. This peptide showed neither membrane permeabilization ability nor killing ability, but did display a small degree of leakage ability. These results suggest that SJGAP acts through a bacteriostatic process rather than bactericidal one. SJGAP is another GAPDH-related antimicrobial peptide isolated from skipjack tuna and likely plays an important role for GAPDH in the innate immune defense of tuna fish. PMID:24412436

  16. Effects of Antimicrobial Peptide Revealed by Simulations: Translocation, Pore Formation, Membrane Corrugation and Euler Buckling

    PubMed Central

    Chen, Licui; Jia, Nana; Gao, Lianghui; Fang, Weihai; Golubovic, Leonardo

    2013-01-01

    We explore the effects of the peripheral and transmembrane antimicrobial peptides on the lipid bilayer membrane by using the coarse grained Dissipative Particle Dynamics simulations. We study peptide/lipid membrane complexes by considering peptides with various structure, hydrophobicity and peptide/lipid interaction strength. The role of lipid/water interaction is also discussed. We discuss a rich variety of membrane morphological changes induced by peptides, such as pore formation, membrane corrugation and Euler buckling. PMID:23579956

  17. Antimicrobial peptides as novel anti-tuberculosis therapeutics.

    PubMed

    Silva, João P; Appelberg, Rui; Gama, Francisco Miguel

    2016-01-01

    Tuberculosis (TB), a disease caused by the human pathogen Mycobacterium tuberculosis, has recently joined HIV/AIDS as the world's deadliest infectious disease, affecting around 9.6 million people worldwide in 2014. Of those, about 1.2 million died from the disease. Resistance acquisition to existing antibiotics, with the subsequent emergence of Multi-Drug Resistant mycobacteria strains, together with an increasing economic burden, has urged the development of new anti-TB drugs. In this scope, antimicrobial peptides (AMPs), which are small, cationic and amphipathic peptides that make part of the innate immune system, now arise as promising candidates for TB treatment. In this review, we analyze the potential of AMPs for this application. We address the mechanisms of action, advantages and disadvantages over conventional antibiotics and how problems associated with its use may be overcome to boost their therapeutic potential. Additionally, we address the challenges of translational development from benchside to bedside, evaluate the current development pipeline and analyze the expected global impact from a socio-economic standpoint. The quest for more efficient and more compliant anti-TB drugs, associated with the great therapeutic potential of emerging AMPs and the rising peptide market, provide an optimal environment for the emergence of AMPs as promising therapies. Still, their pharmacological properties need to be enhanced and manufacturing-associated issues need to be addressed. PMID:27235189

  18. Perspectives on the evolutionary ecology of arthropod antimicrobial peptides.

    PubMed

    Rolff, Jens; Schmid-Hempel, Paul

    2016-05-26

    Antimicrobial peptides (AMPs) are important elements of the innate immune defence in multicellular organisms that target and kill microbes. Here, we reflect on the various points that are raised by the authors of the 11 contributions to a special issue of Philosophical Transactions on the 'evolutionary ecology of arthropod antimicrobial peptides'. We see five interesting topics emerging. (i) AMP genes in insects, and perhaps in arthropods more generally, evolve much slower than most other immune genes. One explanation refers to the constraints set by AMPs being part of a finely tuned defence system. A new view argues that AMPs are under strong stabilizing selection. Regardless, this striking observation still invites many more questions than have been answered so far. (ii) AMPs almost always are expressed in combinations and sometimes show expression patterns that are dependent on the infectious agent. While it is often assumed that this can be explained by synergistic interactions, such interactions have rarely been demonstrated and need to be studied further. Moreover, how to define synergy in the first place remains difficult and needs to be addressed. (iii) AMPs play a very important role in mediating the interaction between a host and its mutualistic or commensal microbes. This has only been studied in a very small number of (insect) species. It has become clear that the very same AMPs play different roles in different situations and hence are under concurrent selection. (iv) Different environments shape the physiology of organisms; especially the host-associated microbial communities should impact on the evolution host AMPs. Studies in social insects and some organisms from extreme environments seem to support this notion, but, overall, the evidence for adaptation of AMPs to a given environment is scant. (v) AMPs are considered or already developed as new drugs in medicine. However, bacteria can evolve resistance to AMPs. Therefore, in the light of our

  19. Snake Cathelicidin NA-CATH and Smaller Helical Antimicrobial Peptides Are Effective against Burkholderia thailandensis.

    PubMed

    Blower, Ryan J; Barksdale, Stephanie M; van Hoek, Monique L

    2015-01-01

    Burkholderia thailandensis is a Gram-negative soil bacterium used as a model organism for B. pseudomallei, the causative agent of melioidosis and an organism classified category B priority pathogen and a Tier 1 select agent for its potential use as a biological weapon. Burkholderia species are reportedly "highly resistant" to antimicrobial agents, including cyclic peptide antibiotics, due to multiple resistance systems, a hypothesis we decided to test using antimicrobial (host defense) peptides. In this study, a number of cationic antimicrobial peptides (CAMPs) were tested in vitro against B. thailandensis for both antimicrobial activity and inhibition of biofilm formation. Here, we report that the Chinese cobra (Naja atra) cathelicidin NA-CATH was significantly antimicrobial against B. thailandensis. Additional cathelicidins, including the human cathelicidin LL-37, a sheep cathelicidin SMAP-29, and some smaller ATRA peptide derivatives of NA-CATH were also effective. The D-enantiomer of one small peptide (ATRA-1A) was found to be antimicrobial as well, with EC50 in the range of the L-enantiomer. Our results also demonstrate that human alpha-defensins (HNP-1 & -2) and a short beta-defensin-derived peptide (Peptide 4 of hBD-3) were not bactericidal against B. thailandensis. We also found that the cathelicidin peptides, including LL-37, NA-CATH, and SMAP-29, possessed significant ability to prevent biofilm formation of B. thailandensis. Additionally, we show that LL-37 and its D-enantiomer D-LL-37 can disperse pre-formed biofilms. These results demonstrate that although B. thailandensis is highly resistant to many antibiotics, cyclic peptide antibiotics such as polymyxin B, and defensing peptides, some antimicrobial peptides including the elapid snake cathelicidin NA-CATH exert significant antimicrobial and antibiofilm activity towards B. thailandensis. PMID:26196513

  20. Design and characterization of short antimicrobial peptides using leucine zipper templates with selectivity towards microorganisms.

    PubMed

    Ahmad, Aqeel; Azmi, Sarfuddin; Srivastava, Saurabh; Kumar, Amit; Tripathi, Jitendra Kumar; Mishra, Nripendra N; Shukla, Praveen K; Ghosh, Jimut Kanti

    2014-11-01

    Design of antimicrobial peptides with selective activity towards microorganisms is an important step towards the development of new antimicrobial agents. Leucine zipper sequence has been implicated in cytotoxic activity of naturally occurring antimicrobial peptides; moreover, this motif has been utilized for the design of novel antimicrobial peptides with modulated cytotoxicity. To understand further the impact of substitution of amino acids at 'a' and/or 'd' position of a leucine zipper sequence of an antimicrobial peptides on its antimicrobial and cytotoxic properties four short peptides (14-residue) were designed on the basis of a leucine zipper sequence without or with replacement of leucine residues in its 'a' and 'd' positions with D-leucine or alanine or proline residue. The original short leucine zipper peptide (SLZP) and its D-leucine substituted analog, DLSA showed comparable activity against the tested Gram-positive and negative bacteria and the fungal strains. The alanine substituted analog (ASA) though showed appreciable activity against the tested bacteria, it showed to some extent lower activity against the tested fungi. However, the proline substituted analog (PSA) showed lower activity against the tested bacterial or fungal strains. Interestingly, DLSA, ASA and PSA showed significantly lower cytotoxicity than SLZP against both human red blood cells (hRBCs) and murine 3T3 cells. Cytotoxic and bactericidal properties of these peptides matched with peptide-induced damage/permeabilization of mammalian cells and bacteria or their mimetic lipid vesicles suggesting cell membrane could be the target of these peptides. As evidenced by tryptophan fluorescence and acrylamide quenching studies the peptides showed similarities either in interaction or in their localization within the bacterial membrane mimetic negatively charged lipid vesicles. Only SLZP showed localization inside the mammalian membrane mimetic zwitterionic lipid vesicles. The results show

  1. Snake Cathelicidin NA-CATH and Smaller Helical Antimicrobial Peptides Are Effective against Burkholderia thailandensis

    PubMed Central

    Blower, Ryan J.; Barksdale, Stephanie M.; van Hoek, Monique L.

    2015-01-01

    Burkholderia thailandensis is a Gram-negative soil bacterium used as a model organism for B. pseudomallei, the causative agent of melioidosis and an organism classified category B priority pathogen and a Tier 1 select agent for its potential use as a biological weapon. Burkholderia species are reportedly “highly resistant” to antimicrobial agents, including cyclic peptide antibiotics, due to multiple resistance systems, a hypothesis we decided to test using antimicrobial (host defense) peptides. In this study, a number of cationic antimicrobial peptides (CAMPs) were tested in vitro against B. thailandensis for both antimicrobial activity and inhibition of biofilm formation. Here, we report that the Chinese cobra (Naja atra) cathelicidin NA-CATH was significantly antimicrobial against B. thailandensis. Additional cathelicidins, including the human cathelicidin LL-37, a sheep cathelicidin SMAP-29, and some smaller ATRA peptide derivatives of NA-CATH were also effective. The D-enantiomer of one small peptide (ATRA-1A) was found to be antimicrobial as well, with EC50 in the range of the L-enantiomer. Our results also demonstrate that human alpha-defensins (HNP-1 & -2) and a short beta-defensin-derived peptide (Peptide 4 of hBD-3) were not bactericidal against B. thailandensis. We also found that the cathelicidin peptides, including LL-37, NA-CATH, and SMAP-29, possessed significant ability to prevent biofilm formation of B. thailandensis. Additionally, we show that LL-37 and its D-enantiomer D-LL-37 can disperse pre-formed biofilms. These results demonstrate that although B. thailandensis is highly resistant to many antibiotics, cyclic peptide antibiotics such as polymyxin B, and defensing peptides, some antimicrobial peptides including the elapid snake cathelicidin NA-CATH exert significant antimicrobial and antibiofilm activity towards B. thailandensis. PMID:26196513

  2. Host Antimicrobial Peptides in Bacterial Homeostasis and Pathogenesis of Disease

    PubMed Central

    Heimlich, Derek R.; Harrison, Alistair; Mason, Kevin M.

    2014-01-01

    Innate immune responses function as a first line of host defense against the development of bacterial infection, and in some cases to preserve the sterility of privileged sites in the human host. Bacteria that enter these sites must counter host responses for colonization. From the host’s perspective, the innate immune system works expeditiously to minimize the bacterial threat before colonization and subsequent dysbiosis. The multifactorial nature of disease further challenges predictions of how each independent variable influences bacterial pathogenesis. From bacterial colonization to infection and through disease, the microenvironments of the host are in constant flux as bacterial and host factors contribute to changes at the host-pathogen interface, with the host attempting to eradicate bacteria and the bacteria fighting to maintain residency. A key component of this innate host response towards bacterial infection is the production of antimicrobial peptides (AMPs). As an early component of the host response, AMPs modulate bacterial load and prevent establishment of infection. Under quiescent conditions, some AMPs are constitutively expressed by the epithelium. Bacterial infection can subsequently induce production of other AMPs in an effort to maintain sterility, or to restrict colonization. As demonstrated in various studies, the absence of a single AMP can influence pathogenesis, highlighting the importance of AMP concentration in maintaining homeostasis. Yet, AMPs can increase bacterial virulence through the co-opting of the peptides or alteration of bacterial virulence gene expression. Further, bacterial factors used to subvert AMPs can modify host microenvironments and alter colonization of the residential flora that principally maintain homeostasis. Thus, the dynamic interplay between host defense peptides and bacterial factors produced to quell peptide activity play a critical role in the progression and outcome of disease. PMID:26029470

  3. LL-37: Cathelicidin-related antimicrobial peptide with pleiotropic activity.

    PubMed

    Fabisiak, Adam; Murawska, Natalia; Fichna, Jakub

    2016-08-01

    Antimicrobial peptides (AMPs) is a large family of compounds serving as natural antibiotics, widely distributed across the organism, mainly in mucus layers. They are designed to prevent pathogens from colonization. Among them, defensins and cathelicidins could be found. LL-37, the sole human cathelicidin draws particular attention because of its outstanding abilities. In addition to being a broad spectrum antibiotic, LL-37 has potent chemotactic and immunomodulatory properties. In this review, we discussed the potency of LL-37 as a therapeutic agent in four systems: immunological, respiratory, gastrointestinal and in the skin. We analyzed the main molecular pathways dependent on human cathelicidin and related them to specific diseases. We conclude that LL-37 shows a great potential to be further investigated and developed as a drug with clinical use. PMID:27117377

  4. New Milk Protein-Derived Peptides with Potential Antimicrobial Activity: An Approach Based on Bioinformatic Studies

    PubMed Central

    Dziuba, Bartłomiej; Dziuba, Marta

    2014-01-01

    New peptides with potential antimicrobial activity, encrypted in milk protein sequences, were searched for with the use of bioinformatic tools. The major milk proteins were hydrolyzed in silico by 28 enzymes. The obtained peptides were characterized by the following parameters: molecular weight, isoelectric point, composition and number of amino acid residues, net charge at pH 7.0, aliphatic index, instability index, Boman index, and GRAVY index, and compared with those calculated for known 416 antimicrobial peptides including 59 antimicrobial peptides (AMPs) from milk proteins listed in the BIOPEP database. A simple analysis of physico-chemical properties and the values of biological activity indicators were insufficient to select potentially antimicrobial peptides released in silico from milk proteins by proteolytic enzymes. The final selection was made based on the results of multidimensional statistical analysis such as support vector machines (SVM), random forest (RF), artificial neural networks (ANN) and discriminant analysis (DA) available in the Collection of Anti-Microbial Peptides (CAMP database). Eleven new peptides with potential antimicrobial activity were selected from all peptides released during in silico proteolysis of milk proteins. PMID:25141106

  5. Fungicidal mechanisms of the antimicrobial peptide Bac8c.

    PubMed

    Lee, Wonyoung; Lee, Dong Gun

    2015-02-01

    Bac8c (RIWVIWRR-NH2) is an analogue peptide derived through complete substitution analysis of the linear bovine host defense peptide variant Bac2A. In the present study, the antifungal mechanism of Bac8c against pathogenic fungi was investigated, with a particular focus on the effects of Bac8c on the cytoplasmic membrane. We used bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC4(3)] staining and 3,3'-dipropylthiacarbocyanine iodide [DiSC3(5)] assays to show that Bac8c induced disturbances in the membrane potential of Candida albicans. An increase in membrane permeability and suppression of cell wall regeneration were also observed in Bac8c-treated C. albicans. We studied the effects of Bac8c treatment on model membranes to elucidate its antifungal mechanism. Using calcein and FITC-labeled dextran leakage assays from Bac8c-treated large unilamellar vesicles (LUVs) and giant unilamellar vesicles (GUVs), we found that Bac8c has a pore-forming action on fungal membranes, with an estimated pore radius of between 2.3 and 3.3 nm. A membrane-targeted mechanism of action was also supported by the observation of potassium release from the cytosol of Bac8c-treated C. albicans. These results indicate that Bac8c is considered as a potential candidate to develop a novel antimicrobial agent because of its low-cost production characteristics and high antimicrobial activity via its ability to induce membrane perturbations in fungi. PMID:25434926

  6. Membrane selectivity and disordering mechanism of antimicrobial peptide protegrin-1

    NASA Astrophysics Data System (ADS)

    Ishitsuka, Yuji

    Protegrin-1 (PG-1) is a beta-sheet antimicrobial peptide (AMP), a class of peptides innate to various organisms and functions as a defense agent against harmful microorganisms by means of membrane disordering. Characteristic chemical and structural properties of AMPs allow selective interaction against invaders' cell membranes. Despite their enormous biomedical potential, progress towards developing them into therapeutic agents has been hampered by a lack of insight into their mechanism of action. AMP insertion assays using Langmuir monolayers reveal that both electrostatic properties of the lipid head group as well as the packing density of the lipid tail group play important roles in determining the membrane selectivity of AMPs. These results help elucidate how the AMP selectively targets the cell membrane of microorganisms over the cell membrane of the host. In addition, these results also explain the higher hemolytic ability of PG-1 against human red blood cells (RBCs) compared to the hemolytic ability of PG-1 against sheep and pig RBCs. Synchrotron X-ray reflectivity shows that PG-1 penetrates into the lipid layer. Grazing incidence X-ray diffraction and fluorescence microscopy indicate that the insertion of PG-1 disorders tail group packing. Membrane selectivity and insertion location information of AMPs with different primary sequence and secondary structure have been obtained by using a truncated version of PG-1: PC-17, and an alpha-helical AMP, LL-37, respectively. The similarity of the membrane disordering process across these various peptides motivated us to test the membrane disordering effect of molecules designed to mimic these peptides. Peptide-mimics based on meta-phenylene ethynylenes demonstrate similar membrane disordering effects, showing that the potency of AMPs is derived from their overall chemical and structural properties, rather than exact peptide sequence. Atomic force microscopy (AFM) was used to directly image first, the PG-1

  7. Molecular Design, Structures, and Activity of Antimicrobial Peptide-Mimetic Polymers

    PubMed Central

    Takahashi, Haruko; Palermo, Edmund F.; Yasuhara, Kazuma; Caputo, Gregory A.

    2014-01-01

    There is an urgent need for new antibiotics which are effective against drug-resistant bacteria without contributing to resistance development. We have designed and developed antimicrobial copolymers with cationic amphiphilic structures based on the mimicry of naturally occurring antimicrobial peptides. These copolymers exhibit potent antimicrobial activity against a broad spectrum of bacteria including methicillin-resistant Staphylococcus aureus with no adverse hemolytic activity. Notably, these polymers also did not result in any measurable resistance development in E. coli. The peptide-mimetic design principle offers significant flexibility and diversity in the creation of new antimicrobial materials and their potential biomedical applications. PMID:23832766

  8. The proteome targets of intracellular targeting antimicrobial peptides.

    PubMed

    Shah, Pramod; Hsiao, Felix Shih-Hsiang; Ho, Yu-Hsuan; Chen, Chien-Sheng

    2016-04-01

    Antimicrobial peptides have been considered well-deserving candidates to fight the battle against microorganisms due to their broad-spectrum antimicrobial activities. Several studies have suggested that membrane disruption is the basic mechanism of AMPs that leads to killing or inhibiting microorganisms. Also, AMPs have been reported to interact with macromolecules inside the microbial cells such as nucleic acids (DNA/RNA), protein synthesis, essential enzymes, membrane septum formation and cell wall synthesis. Proteins are associated with many intracellular mechanisms of cells, thus protein targets may be specifically involved in mechanisms of action of AMPs. AMPs like pyrrhocoricin, drosocin, apidecin and Bac 7 are documented to have protein targets, DnaK and GroEL. Moreover, the intracellular targeting AMPs are reported to influence more than one protein targets inside the cell, suggesting for the multiple modes of actions. This complex mechanism of intracellular targeting AMPs makes them more difficult for the development of resistance. Herein, we have summarized the current status of AMPs in terms of their mode of actions, entry to cytoplasm and inhibition of macromolecules. To reveal the mechanism of action, we have focused on AMPs with intracellular protein targets. We have also included the use of high-throughput proteome microarray to determine the unidentified AMP protein targets in this review. PMID:26648572

  9. Mechanism of bacterial membrane poration by Antimicrobial Peptides

    NASA Astrophysics Data System (ADS)

    Arora, Ankita; Mishra, Abhijit

    2015-03-01

    Bacterial resistance to conventional antibiotics is a major health concern. Antimicrobial peptides (AMPs), an important component of mammalian immune system, are thought to utilize non-specific interactions to target common features on the outer membranes of pathogens; hence development of resistance to such AMPs may be less pronounced. Most AMPs are amphiphilic and cationic in nature. Most AMPs form pores in the bacterial membranes causing them to lyse, however, the exact mechanism is unknown. Here, we study the AMP CHRG01 (KSSTRGRKSSRRKK), derived from human β defensin 3 (hBD3) with all Cysteine residues substituted with Serine. Circular Dichorism studies indicate that CHRG01 shows helicity and there is change in helicity as it interacts with the lipid membrane. The AMP was effective against different species of bacteria. Leakage of cellular components from bacterial cells observed by SEM and AFM indicates AMP action by pore formation. Confocal microscopy studies on giant vesicles incubated with AMP confirm poration. The effect of this AMP on model bacterial membranes is characterized using Small Angle X-ray scattering and Fluorescence spectroscopy to elucidate the mechanism behind antimicrobial activity.

  10. Selection on an antimicrobial peptide defensin in ants.

    PubMed

    Viljakainen, Lumi; Pamilo, Pekka

    2008-12-01

    Ants live in crowded nests with interacting individuals, which makes them particularly prone to infectious diseases. The question is, how do ants cope with the increased risk of pathogen transmission due to sociality? We have studied the molecular evolution of defensin, a gene encoding an antimicrobial protein, in ants. Defensin sequences from several ant species were analyzed with maximum likelihood models of codon substitution to infer selection. Positive selection was detected in the mature region of defensin, whereas the signal and pro regions seem to be evolving neutrally. We also found a significantly higher rate of nonsynonymous substitutions in some phylogenetic lineages, as well as dN/dS >1, suggesting varying selection pressures in different lineages. Earlier studies on the molecular evolution of insect antimicrobial peptide genes have focused on termites and dipteran species, and detected positive selection only in duplicated termicin genes in termites. These findings, together with our present results, provide an indication that the immune systems of social insects (ants and termites) and dipteran insects may have responded differently to the selection pressure caused by microbial pathogens. PMID:18956133

  11. Short antimicrobial peptides as cosmetic ingredients to deter dermatological pathogens.

    PubMed

    Rahnamaeian, Mohammad; Vilcinskas, Andreas

    2015-11-01

    Antimicrobial peptides (AMPs) are components of the innate immune system in many species of animals. Their diverse spectrum of activity against microbial pathogens, both as innate defense molecules and immunomodulators, makes them attractive candidates for the development of a new generation of antibiotics. Although the potential immunogenicity of AMPs means they are not suitable for injection and their susceptibility to digestive peptidases is likely to reduce their oral efficacy, they are ideal for topical formulations such as lotions, creams, shampoos, and wound dressings and could therefore be valuable products for the cosmetic industry. In this context, short AMPs (<20 amino acids) lacking disulfide bonds combine optimal antimicrobial activity with inexpensive chemical synthesis and are therefore more compatible with large-scale production and the modifications required to ensure stability, low toxicity, and microbial specificity. Proof-of-concept for the application of AMPs as novel anti-infectives has already been provided in clinical trials. This perspective considers the anti-infective properties of short AMPs lacking disulfide bonds, which are active against dermatologically important microflora. We consider the challenges that need to be addressed to facilitate the prophylactic application of AMPs in personal care products. PMID:26307444

  12. Relative free energy of binding between antimicrobial peptides and SDS or DPC micelles.

    PubMed

    Sayyed-Ahmad, Abdallah; Khandelia, Himanshu; Kaznessis, Yiannis N

    2009-09-01

    We present relative binding free energy calculations for six antimicrobial peptide-micelle systems, three peptides interacting with two types of micelles. The peptides are the scorpion derived antimicrobial peptide (AMP), IsCT and two of its analogues. The micelles are dodecylphosphatidylcholine (DPC) and sodium dodecylsulphate (SDS) micelles. The interfacial electrostatic properties of DPC and SDS micelles are assumed to be similar to those of zwitterionic mammalian and anionic bacterial membrane interfaces, respectively. We test the hypothesis that the binding strength between peptides and the anionic micelle SDS can provide information on peptide antimicrobial activity, since it is widely accepted that AMPs function by binding to and disrupting the predominantly anionic lipid bilayer of the bacterial cytoplasmic membrane. We also test the hypothesis that the binding strength between peptides and the zwitterionic micelle DPC can provide information on peptide haemolytic activities, since it is accepted that they also bind to and disrupt the zwitterionic membrane of mammalian cells. Equilibrium structures of the peptides, micelles and peptide-micelle complexes are obtained from more than 300 ns of molecular dynamics simulations. A thermodynamic cycle is introduced to compute the binding free energy from electrostatic, non-electrostatic and entropic contributions. We find relative binding free energy strengths between peptides and SDS to correlate with the experimentally measured rankings for peptide antimicrobial activities, and relative free energy binding strengths between peptides and DPC to correlate with the observed rankings for peptide haemolytic toxicities. These findings point to the importance of peptide-membrane binding strength for antimicrobial activity and haemolytic activity. PMID:21113423

  13. 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.

  14. Focal Targeting of the Bacterial Envelope by Antimicrobial Peptides.

    PubMed

    Rashid, Rafi; Veleba, Mark; Kline, Kimberly A

    2016-01-01

    Antimicrobial peptides (AMPs) are utilized by both eukaryotic and prokaryotic organisms. AMPs such as the human beta defensins, human neutrophil peptides, human cathelicidin, and many bacterial bacteriocins are cationic and capable of binding to anionic regions of the bacterial surface. Cationic AMPs (CAMPs) target anionic lipids [e.g., phosphatidylglycerol (PG) and cardiolipins (CL)] in the cell membrane and anionic components [e.g., lipopolysaccharide (LPS) and lipoteichoic acid (LTA)] of the cell envelope. Bacteria have evolved mechanisms to modify these same targets in order to resist CAMP killing, e.g., lysinylation of PG to yield cationic lysyl-PG and alanylation of LTA. Since CAMPs offer a promising therapeutic alternative to conventional antibiotics, which are becoming less effective due to rapidly emerging antibiotic resistance, there is a strong need to improve our understanding about the AMP mechanism of action. Recent literature suggests that AMPs often interact with the bacterial cell envelope at discrete foci. Here we review recent AMP literature, with an emphasis on focal interactions with bacteria, including (1) CAMP disruption mechanisms, (2) delocalization of membrane proteins and lipids by CAMPs, and (3) CAMP sensing systems and resistance mechanisms. We conclude with new approaches for studying the bacterial membrane, e.g., lipidomics, high resolution imaging, and non-detergent-based membrane domain extraction. PMID:27376064

  15. Focal Targeting of the Bacterial Envelope by Antimicrobial Peptides

    PubMed Central

    Rashid, Rafi; Veleba, Mark; Kline, Kimberly A.

    2016-01-01

    Antimicrobial peptides (AMPs) are utilized by both eukaryotic and prokaryotic organisms. AMPs such as the human beta defensins, human neutrophil peptides, human cathelicidin, and many bacterial bacteriocins are cationic and capable of binding to anionic regions of the bacterial surface. Cationic AMPs (CAMPs) target anionic lipids [e.g., phosphatidylglycerol (PG) and cardiolipins (CL)] in the cell membrane and anionic components [e.g., lipopolysaccharide (LPS) and lipoteichoic acid (LTA)] of the cell envelope. Bacteria have evolved mechanisms to modify these same targets in order to resist CAMP killing, e.g., lysinylation of PG to yield cationic lysyl-PG and alanylation of LTA. Since CAMPs offer a promising therapeutic alternative to conventional antibiotics, which are becoming less effective due to rapidly emerging antibiotic resistance, there is a strong need to improve our understanding about the AMP mechanism of action. Recent literature suggests that AMPs often interact with the bacterial cell envelope at discrete foci. Here we review recent AMP literature, with an emphasis on focal interactions with bacteria, including (1) CAMP disruption mechanisms, (2) delocalization of membrane proteins and lipids by CAMPs, and (3) CAMP sensing systems and resistance mechanisms. We conclude with new approaches for studying the bacterial membrane, e.g., lipidomics, high resolution imaging, and non-detergent-based membrane domain extraction. PMID:27376064

  16. Immune Signaling and Antimicrobial Peptide Expression in Lepidoptera

    PubMed Central

    Casanova-Torres, Ángel M.; Goodrich-Blair, Heidi

    2013-01-01

    Many lepidopteran insects are agricultural pests that affect stored grains, food and fiber crops. These insects have negative ecological and economic impacts since they lower crop yield, and pesticides are expensive and can have off-target effects on beneficial arthropods. A better understanding of lepidopteran immunity will aid in identifying new targets for the development of specific insect pest management compounds. A fundamental aspect of immunity, and therefore a logical target for control, is the induction of antimicrobial peptide (AMP) expression. These peptides insert into and disrupt microbial membranes, thereby promoting pathogen clearance and insect survival. Pathways leading to AMP expression have been extensively studied in the dipteran Drosophila melanogaster. However, Diptera are an important group of pollinators and pest management strategies that target their immune systems is not recommended. Recent advances have facilitated investigation of lepidopteran immunity, revealing both conserved and derived characteristics. Although the general pathways leading to AMP expression are conserved, specific components of these pathways, such as recognition proteins have diverged. In this review we highlight how such comparative immunology could aid in developing pest management strategies that are specific to agricultural insect pests. PMID:25861461

  17. Strategies and molecular tools to fight antimicrobial resistance: resistome, transcriptome, and antimicrobial peptides

    PubMed Central

    Tavares, Letícia S.; Silva, Carolina S. F.; de Souza, Vinicius C.; da Silva, Vânia L.; Diniz, Cláudio G.; Santos, Marcelo O.

    2013-01-01

    The increasing number of antibiotic resistant bacteria motivates prospective research toward discovery of new antimicrobial active substances. There are, however, controversies concerning the cost-effectiveness of such research with regards to the description of new substances with novel cellular interactions, or description of new uses of existing substances to overcome resistance. Although examination of bacteria isolated from remote locations with limited exposure to humans has revealed an absence of antibiotic resistance genes, it is accepted that these genes were both abundant and diverse in ancient living organisms, as detected in DNA recovered from Pleistocene deposits (30,000 years ago). Indeed, even before the first clinical use of antibiotics more than 60 years ago, resistant organisms had been isolated. Bacteria can exhibit different strategies for resistance against antibiotics. New genetic information may lead to the modification of protein structure affecting the antibiotic carriage into the cell, enzymatic inactivation of drugs, or even modification of cellular structure interfering in the drug-bacteria interaction. There are still plenty of new genes out there in the environment that can be appropriated by putative pathogenic bacteria to resist antimicrobial agents. On the other hand, there are several natural compounds with antibiotic activity that may be used to oppose them. Antimicrobial peptides (AMPs) are molecules which are wide-spread in all forms of life, from multi-cellular organisms to bacterial cells used to interfere with microbial growth. Several AMPs have been shown to be effective against multi-drug resistant bacteria and have low propensity to resistance development, probably due to their unique mode of action, different from well-known antimicrobial drugs. These substances may interact in different ways with bacterial cell membrane, protein synthesis, protein modulation, and protein folding. The analysis of bacterial transcriptome

  18. Novel antimicrobial peptide specifically active against Porphyromonas gingivalis.

    PubMed

    Suwandecha, T; Srichana, T; Balekar, N; Nakpheng, T; Pangsomboon, K

    2015-09-01

    Porphyromonas gingivalis, the major etiologic agent of chronic periodontitis, produces a broad spectrum of virulence factors, including outer membrane vesicles, lipopolysaccharides, hemolysins and proteinases. Antimicrobial peptides (AMPs) including bacteriocins have been found to inhibit the growth of P. gingivalis; however, these peptides are relatively large molecules. Hence, it is difficult to synthesize them by a scale-up production. Therefore, this study aimed to synthesize a shorter AMP that was still active against P. gingivalis. A peptide that contained three cationic amino acids (Arg, His and Lys), two anionic amino acids (Glu and Asp), hydrophobic amino acids residues (Leu, Ile, Val, Ala and Pro) and hydrophilic residues (Ser and Gly) was obtained and named Pep-7. Its bioactivity and stability were tested after various treatments. The mechanism of action of Pep-7 and its toxicity to human red blood cells were investigated. The Pep-7 inhibited two pathogenic P. gingivalis ATCC 33277 and P. gingivalis ATCC 53978 (wp50) strains at a minimum bactericidal concentration (MBC) of 1.7 µM, but was ineffective against other oral microorganisms (P. intermedia, Tannerella forsythensis, Streptococcus salivarius and Streptococcus sanguinis). From transmission electron microscopy studies, Pep-7 caused pore formation at the poles of the cytoplasmic membranes of P. gingivalis. A concentration of Pep-7 at four times that of its MBC induced some hemolysis but only at 0.3%. The Pep-7 was heat stable under pressure (autoclave at 110 and 121 °C) and possessed activity over a pH range of 6.8-8.5. It was not toxic to periodontal cells over a range of 70.8-4.4 μM and did not induce toxic pro-inflammatory cytokines. The Pep-7 showed selective activity against Porphyromonas sp. by altering the permeability barriers of P. gingivalis. The Pep-7 was not mutagenic in vitro. This work highlighted the potential for the use of this synthetic Pep-7 against P. gingivalis. PMID:26041027

  19. The Cooperative Behaviour of α-Helical Antimicrobial Peptides in Different Environments

    NASA Astrophysics Data System (ADS)

    Pinna, Marco; Wang, Janping; Mura, Manuela; Zhou, Yuhua; Zvelindovsky, Andrei; Dennison, Sarah; Phoenix, David

    2014-03-01

    A systematic analysis of the antimicrobial peptides (AMPs) cooperative action is performed by means of a full atomistic molecular dynamics simulation. The following peptide analogues: Aurein 2.5-COOH, Aurein 2.6-COOH and Aurein 3.1-COOH are investigated in different environments including aqueous solution, trifluoroethanol (TFE), palmitoyloleoylphosphatidylethanolamine (POPE), and palmitoyloleoylphosphatidylglycerol (POPG) lipid bilayers. Simulations conducted for monomer and trimer peptide highlight the importance of the cooperative behaviour and reveal the different mechanisms of antimicrobial peptides action in different lipid bilayers.

  20. Understanding bacterial resistance to antimicrobial peptides: From the surface to deep inside.

    PubMed

    Maria-Neto, Simone; de Almeida, Keyla Caroline; Macedo, Maria Ligia Rodrigues; Franco, Octávio Luiz

    2015-11-01

    Resistant bacterial infections are a major health problem in many parts of the world. The major commercial antibiotic classes often fail to combat common bacteria. Although antimicrobial peptides are able to control bacterial infections by interfering with microbial metabolism and physiological processes in several ways, a large number of cases of resistance to antibiotic peptide classes have also been reported. To gain a better understanding of the resistance process various technologies have been applied. Here we discuss multiple strategies by which bacteria could develop enhanced antimicrobial peptide resistance, focusing on sub-cellular regions from the surface to deep inside, evaluating bacterial membranes, cell walls and cytoplasmic metabolism. Moreover, some high-throughput methods for antimicrobial resistance detection and discrimination are also examined. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides. PMID:25724815

  1. Antimicrobial and antibiofilm activity of cathelicidins and short, synthetic peptides against Francisella.

    PubMed

    Amer, Lilian S; Bishop, Barney M; van Hoek, Monique L

    2010-05-28

    Francisella infects the lungs causing pneumonic tularemia. Focusing on the lung's host defense, we have examined antimicrobial peptides as part of the innate immune response to Francisella infection. Interest in antimicrobial peptides, such as the cathelicidins, has grown due their potential therapeutic applications and the increasing problem of bacterial resistance to commonly used antibiotics. Only one human cathelicidin, LL-37, has been characterized. Helical cathelicidins have also been discovered in snakes including the Chinese King Cobra, Naja atra (NA-CATH). Four synthetic 11-residue peptides (ATRA-1, -2, -1A and -1P) containing variations of a repeated motif within NA-CATH were designed. We hypothesized that these smaller synthetic peptides could have excellent antimicrobial effectiveness with shorter length (and less cost), making them strong potential candidates for development into broad-spectrum antimicrobial compounds. We tested the susceptibility of F. novicida to four ATRA peptides, LL-37, and NA-CATH. Two of the ATRA peptides had high antimicrobial activity (microM), while the two proline-containing ATRA peptides had low activity. The ATRA peptides did not show significant hemolytic activity even at high peptide concentration, indicating low cytotoxicity against host cells. NA-CATH killed Francisella bacteria more quickly than LL-37. However, LL-37 was the most effective peptide against F. novicida (EC50=50 nM). LL-37 mRNA was induced in A549 cells by Francisella infection. We recently demonstrated that F. novicida forms in vitro biofilms. LL-37 inhibited F. novicida biofilm formation at sub-antimicrobial concentrations. Understanding the properties of these peptides, and their endogenous expression in the lung could lead to potential future therapeutic interventions for this lung infection. PMID:20399752

  2. Inducible Resistance of Fish Bacterial Pathogens to the Antimicrobial Peptide Cecropin B

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cecropin B is a cationic antimicrobial peptide originally isolated from the diapausing pupae of the giant silk moth, Hylphora cecropia. Cecropin B elicits its antimicrobial effects through disruption of the anionic cell membranes of gram-negative bacteria. Previous work by our laboratory demonstra...

  3. Euler buckling, membrane corrugation and pore formation induced by antimicrobial peptide

    NASA Astrophysics Data System (ADS)

    Golubovic, Leonardo; Gao, Lianghui; Chen, Licui; Jia, Nana; Fang, Weihai

    2014-03-01

    Antimicrobial peptides serve as defense weapons against bacteria. They are secreted by organisms of plants and animals and have a wide variety in composition and structure. In this study, we theoretically explore the effects of the antimicrobial peptides on the lipid bilayer membrane by using analytic arguments and the coarse grained dissipative particle dynamics simulations. We study peptide/lipid membrane complexes by considering peptides with various structure, hydrophobicity and peptide/lipid interaction strength. The role of lipid/water interaction is also discussed. We discuss a rich variety of membrane morphological changes induced by peptides, such as pore formation, membrane corrugation and Euler buckling. Such buckled membrane states have been indeed seen in a number of experiments with bacteria affected by peptide, yet this is the first theoretical study addressing these phenomena more deeply.

  4. Staphylococcal antimicrobial peptides: relevant properties and potential biotechnological applications.

    PubMed

    Bastos, M C F; Ceotto, H; Coelho, M L V; Nascimento, J S

    2009-01-01

    Bacteriocins are bacterial antimicrobial peptides with bactericidal activity against other bacteria. Staphylococcins are bacteriocins produced by staphylococci, which are Gram-positive bacteria with medical and veterinary importance. Most bacteriocins produced by staphylococci are either lantibiotics (e.g., Pep5, epidermin, epilancin K7, epicidin 280, staphylococcin C55/BacR1, and nukacin ISK-1) or class II bacteriocins (e.g., aureocins A70 and 53). Only one staphylococcin belonging to class III, lysostaphin, has been described so far. Production of staphylococcins is a self-protection mechanism that helps staphylococci to survive in their natural habitats. However, since these substances generally have a broad spectrum of activity, inhibiting several human and animal pathogens, they have potential biotechnological applications either as food preservatives or therapeutic agents. Due to the increasing consumer awareness of the risks derived not only from food-borne pathogens, but also from the artificial chemical preservatives used to control them, the interest in the discovery of natural food preservatives has increased considerably. The emergence and dissemination of antibiotic resistance among human and animal pathogens and their association with the use of antibiotics constitute a serious problem worldwide requiring effective measures for controlling their spread. Staphylococcins may be used, solely or in combination with other chemical agents, to avoid food contamination or spoilage and to prevent or treat bacterial infectious diseases. The use of combinations of antimicrobials is common in the clinical setting and expands the spectrum of organisms that can be targeted, prevents the emergence of resistant organisms, decreases toxicity by allowing lower doses of both agents and can result in synergistic inhibition. PMID:19149589

  5. De Novo Transcriptome Analysis and Detection of Antimicrobial Peptides of the American Cockroach Periplaneta americana (Linnaeus).

    PubMed

    Kim, In-Woo; Lee, Joon Ha; Subramaniyam, Sathiyamoorthy; Yun, Eun-Young; Kim, Iksoo; Park, Junhyung; Hwang, Jae Sam

    2016-01-01

    Cockroaches are surrogate hosts for microbes that cause many human diseases. In spite of their generally destructive nature, cockroaches have recently been found to harbor potentially beneficial and medically useful substances such as drugs and allergens. However, genomic information for the American cockroach (Periplaneta americana) is currently unavailable; therefore, transcriptome and gene expression profiling is needed as an important resource to better understand the fundamental biological mechanisms of this species, which would be particularly useful for the selection of novel antimicrobial peptides. Thus, we performed de novo transcriptome analysis of P. americana that were or were not immunized with Escherichia coli. Using an Illumina HiSeq sequencer, we generated a total of 9.5 Gb of sequences, which were assembled into 85,984 contigs and functionally annotated using Basic Local Alignment Search Tool (BLAST), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) database terms. Finally, using an in silico antimicrobial peptide prediction method, 86 antimicrobial peptide candidates were predicted from the transcriptome, and 21 of these peptides were experimentally validated for their antimicrobial activity against yeast and gram positive and -negative bacteria by a radial diffusion assay. Notably, 11 peptides showed strong antimicrobial activities against these organisms and displayed little or no cytotoxic effects in the hemolysis and cell viability assay. This work provides prerequisite baseline data for the identification and development of novel antimicrobial peptides, which is expected to provide a better understanding of the phenomenon of innate immunity in similar species. PMID:27167617

  6. De Novo Transcriptome Analysis and Detection of Antimicrobial Peptides of the American Cockroach Periplaneta americana (Linnaeus)

    PubMed Central

    Subramaniyam, Sathiyamoorthy; Yun, Eun-Young; Kim, Iksoo; Park, Junhyung; Hwang, Jae Sam

    2016-01-01

    Cockroaches are surrogate hosts for microbes that cause many human diseases. In spite of their generally destructive nature, cockroaches have recently been found to harbor potentially beneficial and medically useful substances such as drugs and allergens. However, genomic information for the American cockroach (Periplaneta americana) is currently unavailable; therefore, transcriptome and gene expression profiling is needed as an important resource to better understand the fundamental biological mechanisms of this species, which would be particularly useful for the selection of novel antimicrobial peptides. Thus, we performed de novo transcriptome analysis of P. americana that were or were not immunized with Escherichia coli. Using an Illumina HiSeq sequencer, we generated a total of 9.5 Gb of sequences, which were assembled into 85,984 contigs and functionally annotated using Basic Local Alignment Search Tool (BLAST), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) database terms. Finally, using an in silico antimicrobial peptide prediction method, 86 antimicrobial peptide candidates were predicted from the transcriptome, and 21 of these peptides were experimentally validated for their antimicrobial activity against yeast and gram positive and -negative bacteria by a radial diffusion assay. Notably, 11 peptides showed strong antimicrobial activities against these organisms and displayed little or no cytotoxic effects in the hemolysis and cell viability assay. This work provides prerequisite baseline data for the identification and development of novel antimicrobial peptides, which is expected to provide a better understanding of the phenomenon of innate immunity in similar species. PMID:27167617

  7. Self-assembly of cationic multidomain peptide hydrogels: supramolecular nanostructure and rheological properties dictate antimicrobial activity†

    PubMed Central

    Jiang, Linhai; Xu, Dawei; Sellati, Timothy J.

    2016-01-01

    Hydrogels are an important class of biomaterials that have been widely utilized for a variety of biomedical/medical applications. The biological performance of hydrogels, particularly those used as wound dressing could be greatly advanced if imbued with inherent antimicrobial activity capable of staving off colonization of the wound site by opportunistic bacterial pathogens. Possessing such antimicrobial properties would also protect the hydrogel itself from being adversely affected by microbial attachment to its surface. We have previously demonstrated the broad-spectrum antimicrobial activity of supramolecular assemblies of cationic multi-domain peptides (MDPs) in solution. Here, we extend the 1-D soluble supramolecular assembly to 3-D hydrogels to investigate the effect of the supramolecular nanostructure and its rheological properties on the antimicrobial activity of self-assembled hydrogels. Among designed MDPs, the bactericidal activity of peptide hydrogels was found to follow an opposite trend to that in solution. Improved antimicrobial activity of self-assembled peptide hydrogels is dictated by the combined effect of supramolecular surface chemistry and storage modulus of the bulk materials, rather than the ability of individual peptides/peptide assemblies to penetrate bacterial cell membrane as observed in solution. The structure–property–activity relationship developed through this study will provide important guidelines for designing biocompatible peptide hydrogels with built-in antimicrobial activity for various biomedical applications. PMID:26524425

  8. Amyloidogenic amyloid-β-peptide variants induce microbial agglutination and exert antimicrobial activity.

    PubMed

    Spitzer, Philipp; Condic, Mateja; Herrmann, Martin; Oberstein, Timo Jan; Scharin-Mehlmann, Marina; Gilbert, Daniel F; Friedrich, Oliver; Grömer, Teja; Kornhuber, Johannes; Lang, Roland; Maler, Juan Manuel

    2016-01-01

    Amyloid-β (Aβ) peptides are the main components of the plaques found in the brains of patients with Alzheimer's disease. However, Aβ peptides are also detectable in secretory compartments and peripheral blood contains a complex mixture of more than 40 different modified and/or N- and C-terminally truncated Aβ peptides. Recently, anti-infective properties of Aβ peptides have been reported. Here, we investigated the interaction of Aβ peptides of different lengths with various bacterial strains and the yeast Candida albicans. The amyloidogenic peptides Aβ1-42, Aβ2-42, and Aβ3p-42 but not the non-amyloidogenic peptides Aβ1-40 and Aβ2-40 bound to microbial surfaces. As observed by immunocytochemistry, scanning electron microscopy and Gram staining, treatment of several bacterial strains and Candida albicans with Aβ peptide variants ending at position 42 (Aβx-42) caused the formation of large agglutinates. These aggregates were not detected after incubation with Aβx-40. Furthermore, Aβx-42 exerted an antimicrobial activity on all tested pathogens, killing up to 80% of microorganisms within 6 h. Aβ1-40 only had a moderate antimicrobial activity against C. albicans. Agglutination of Aβ1-42 was accelerated in the presence of microorganisms. These data demonstrate that the amyloidogenic Aβx-42 variants have antimicrobial activity and may therefore act as antimicrobial peptides in the immune system. PMID:27624303

  9. PFR peptide, one of the antimicrobial peptides identified from the derivatives of lactoferrin, induces necrosis in leukemia cells

    PubMed Central

    Lu, Yan; Zhang, Teng-Fei; Shi, Yue; Zhou, Han-Wei; Chen, Qi; Wei, Bu-Yun; Wang, Xi; Yang, Tian-Xin; Chinn, Y. Eugene; Kang, Jian; Fu, Cai-Yun

    2016-01-01

    LF11-322 (PFWRIRIRR-NH2) (PFR peptide), a nine amino acid-residue peptide fragment derived from human lactoferricin, possesses potent cytotoxicity against bacteria. We report here the discovery and characterization of its antitumor activity in leukemia cells. PFR peptide inhibited the proliferation of MEL and HL-60 leukemia cells by inducing cell death in the absence of the classical features of apoptosis, including chromatin condensation, Annexin V staining, Caspase activation and increase of abundance of pro-apoptotic proteins. Instead, necrotic cell death as evidenced by increasing intracellular PI staining and LDH release, inducing membrane disruption and up-regulating intracellular calcium level, was observed following PFR peptide treatment. In addition to necrotic cell death, PFR peptide also induced G0/G1 cell cycle arrest. Moreover, PFR peptide exhibited favorable antitumor activity and tolerability in vivo. These findings thus provide a new clue of antimicrobial peptides as a potential novel therapy for leukemia. PMID:26860588

  10. Simultaneous Antibiofilm and Antiviral Activities of an Engineered Antimicrobial Peptide during Virus-Bacterium Coinfection

    PubMed Central

    Melvin, Jeffrey A.; Lashua, Lauren P.; Kiedrowski, Megan R.; Yang, Guanyi; Deslouches, Berthony; Montelaro, Ronald C.

    2016-01-01

    ABSTRACT Antimicrobial-resistant infections are an urgent public health threat, and development of novel antimicrobial therapies has been painstakingly slow. Polymicrobial infections are increasingly recognized as a significant source of severe disease and also contribute to reduced susceptibility to antimicrobials. Chronic infections also are characterized by their ability to resist clearance, which is commonly linked to the development of biofilms that are notorious for antimicrobial resistance. The use of engineered cationic antimicrobial peptides (eCAPs) is attractive due to the slow development of resistance to these fast-acting antimicrobials and their ability to kill multidrug-resistant clinical isolates, key elements for the success of novel antimicrobial agents. Here, we tested the ability of an eCAP, WLBU2, to disrupt recalcitrant Pseudomonas aeruginosa biofilms. WLBU2 was capable of significantly reducing biomass and viability of P. aeruginosa biofilms formed on airway epithelium and maintained activity during viral coinfection, a condition that confers extraordinary levels of antibiotic resistance. Biofilm disruption was achieved in short treatment times by permeabilization of bacterial membranes. Additionally, we observed simultaneous reduction of infectivity of the viral pathogen respiratory syncytial virus (RSV). WLBU2 is notable for its ability to maintain activity across a broad range of physiological conditions and showed negligible toxicity toward the airway epithelium, expanding its potential applications as an antimicrobial therapeutic. IMPORTANCE Antimicrobial-resistant infections are an urgent public health threat, making development of novel antimicrobials able to effectively treat these infections extremely important. Chronic and polymicrobial infections further complicate antimicrobial therapy, often through the development of microbial biofilms. Here, we describe the ability of an engineered antimicrobial peptide to disrupt biofilms

  11. Simultaneous Antibiofilm and Antiviral Activities of an Engineered Antimicrobial Peptide during Virus-Bacterium Coinfection.

    PubMed

    Melvin, Jeffrey A; Lashua, Lauren P; Kiedrowski, Megan R; Yang, Guanyi; Deslouches, Berthony; Montelaro, Ronald C; Bomberger, Jennifer M

    2016-01-01

    Antimicrobial-resistant infections are an urgent public health threat, and development of novel antimicrobial therapies has been painstakingly slow. Polymicrobial infections are increasingly recognized as a significant source of severe disease and also contribute to reduced susceptibility to antimicrobials. Chronic infections also are characterized by their ability to resist clearance, which is commonly linked to the development of biofilms that are notorious for antimicrobial resistance. The use of engineered cationic antimicrobial peptides (eCAPs) is attractive due to the slow development of resistance to these fast-acting antimicrobials and their ability to kill multidrug-resistant clinical isolates, key elements for the success of novel antimicrobial agents. Here, we tested the ability of an eCAP, WLBU2, to disrupt recalcitrant Pseudomonas aeruginosa biofilms. WLBU2 was capable of significantly reducing biomass and viability of P. aeruginosa biofilms formed on airway epithelium and maintained activity during viral coinfection, a condition that confers extraordinary levels of antibiotic resistance. Biofilm disruption was achieved in short treatment times by permeabilization of bacterial membranes. Additionally, we observed simultaneous reduction of infectivity of the viral pathogen respiratory syncytial virus (RSV). WLBU2 is notable for its ability to maintain activity across a broad range of physiological conditions and showed negligible toxicity toward the airway epithelium, expanding its potential applications as an antimicrobial therapeutic. IMPORTANCE Antimicrobial-resistant infections are an urgent public health threat, making development of novel antimicrobials able to effectively treat these infections extremely important. Chronic and polymicrobial infections further complicate antimicrobial therapy, often through the development of microbial biofilms. Here, we describe the ability of an engineered antimicrobial peptide to disrupt biofilms formed by the

  12. Mechanisms and consequences of bacterial resistance to antimicrobial peptides.

    PubMed

    Andersson, D I; Hughes, D; Kubicek-Sutherland, J Z

    2016-05-01

    Cationic antimicrobial peptides (AMPs) are an intrinsic part of the human innate immune system. Over 100 different human AMPs are known to exhibit broad-spectrum antibacterial activity. Because of the increased frequency of resistance to conventional antibiotics there is an interest in developing AMPs as an alternative antibacterial therapy. Several cationic peptides that are derivatives of AMPs from the human innate immune system are currently in clinical development. There are also ongoing clinical studies aimed at modulating the expression of AMPs to boost the human innate immune response. In this review we discuss the potential problems associated with these therapeutic approaches. There is considerable experimental data describing mechanisms by which bacteria can develop resistance to AMPs. As for any type of drug resistance, the rate by which AMP resistance would emerge and spread in a population of bacteria in a natural setting will be determined by a complex interplay of several different factors, including the mutation supply rate, the fitness of the resistant mutant at different AMP concentrations, and the strength of the selective pressure. Several studies have already shown that AMP-resistant bacterial mutants display broad cross-resistance to a variety of AMPs with different structures and modes of action. Therefore, routine clinical administration of AMPs to treat bacterial infections may select for resistant bacterial pathogens capable of better evading the innate immune system. The ramifications of therapeutic levels of exposure on the development of AMP resistance and bacterial pathogenesis are not yet understood. This is something that needs to be carefully studied and monitored if AMPs are used in clinical settings. PMID:27180309

  13. Role of amphipathicity and hydrophobicity in the balance between hemolysis and peptide-membrane interactions of three related antimicrobial peptides.

    PubMed

    Hollmann, Axel; Martínez, Melina; Noguera, Martín E; Augusto, Marcelo T; Disalvo, Anibal; Santos, Nuno C; Semorile, Liliana; Maffía, Paulo C

    2016-05-01

    Cationic antimicrobial peptides (CAMPs) represent important self defense molecules in many organisms, including humans. These peptides have a broad spectrum of activities, killing or neutralizing many Gram-negative and Gram-positive bacteria. The emergence of multidrug resistant microbes has stimulated research on the development of alternative antibiotics. In the search for new antibiotics, cationic antimicrobial peptides (CAMPs) offer a viable alternative to conventional antibiotics, as they physically disrupt the bacterial membranes, leading to lysis of microbial membranes and eventually cell death. In particular, the group of linear α-helical cationic peptides has attracted increasing interest from clinical as well as basic research during the last decade. In this work, we studied the biophysical and microbiological characteristics of three new designed CAMPs. We modified a previously studied CAMP sequence, in order to increase or diminish the hydrophobic face, changing the position of two lysines or replacing three leucines, respectively. These mutations modified the hydrophobic moment of the resulting peptides and allowed us to study the importance of this parameter in the membrane interactions of the peptides. The structural properties of the peptides were also correlated with their membrane-disruptive abilities, antimicrobial activities and hemolysis of human red blood cells. PMID:26896660

  14. Toward Infection-Resistant Surfaces: Achieving High Antimicrobial Peptide Potency by Modulating the Functionality of Polymer Brush and Peptide.

    PubMed

    Yu, Kai; Lo, Joey C Y; Mei, Yan; Haney, Evan F; Siren, Erika; Kalathottukaren, Manu Thomas; Hancock, Robert E W; Lange, Dirk; Kizhakkedathu, Jayachandran N

    2015-12-30

    Bacterial infection associated with indwelling medical devices and implants is a major clinical issue, and the prevention or treatment of such infections is challenging. Antimicrobial coatings offer a significant step toward addressing this important clinical problem. Antimicrobial coatings based on tethered antimicrobial peptides (AMPs) on hydrophilic polymer brushes have been shown to be one of the most promising strategies to avoid bacterial colonization and have demonstrated broad spectrum activity. Optimal combinations of the functionality of the polymer-brush-tethered AMPs are essential to maintaining long-term AMP activity on the surface. However, there is limited knowledge currently available on this topic. Here we report the development of potent antimicrobial coatings on implant surfaces by elucidating the roles of polymer brush chemistry and peptide structure on the overall antimicrobial activity of the coatings. We screened several combinations of polymer brush coatings and AMPs constructed on nanoparticles, titanium surfaces, and quartz slides on their antimicrobial activity and bacterial adhesion against Gram-positive and Gram-negative bacteria. Highly efficient killing of planktonic bacteria by the antimicrobial coatings on nanoparticle surfaces, as well as potent killing of adhered bacteria in the case of coatings on titanium surfaces, was observed. Remarkably, the antimicrobial activity of AMP-conjugated brush coatings demonstrated a clear dependence on the polymer brush chemistry and peptide structure, and optimization of these parameters is critical to achieving infection-resistant surfaces. By analyzing the interaction of polymer-brush-tethered AMPs with model lipid membranes using circular dichroism spectroscopy, we determined that the polymer brush chemistry has an influence on the extent of secondary structure change of tethered peptides before and after interaction with biomembranes. The peptide structure also has an influence on the density

  15. Role of Antimicrobial Peptides in Amphibian Defense Against Trematode Infection

    PubMed Central

    Calhoun, Dana M.; Woodhams, Doug; Howard, Cierra; LaFonte, Bryan E.; Gregory, Jacklyn R.; Johnson, Pieter T. J.

    2016-01-01

    Antimicrobial peptides (AMPs) contribute to the immune defenses of many vertebrates, including amphibians. As larvae, amphibians are often exposed to the infectious stages of trematode parasites, many of which must penetrate the host’s skin, potentially interacting with host AMPs. We tested the effects of the natural AMPs repertoires on both the survival of trematode infectious stages as well as their ability to infect larval amphibians. All five trematode species exhibited decreased survival of cercariae in response to higher concentrations of adult bullfrog AMPs, but no effect when exposed to AMPs from larval bullfrogs. Similarly, the use of norepinephrine to remove AMPs from larval bullfrogs, Pacific chorus frogs, and gray treefrogs had only weak (gray treefrogs) or non-significant (other tested species) effects on infection success by Ribeiroia ondatrae. We nonetheless observed strong differences in parasite infection as a function of both host stage (first- versus second-year bullfrogs) and host species (Pacific chorus frogs versus gray treefrogs) that were apparently unrelated to AMPs. Taken together, our results suggest that AMPs do not play a significant role in defending larval amphibians against trematode cercariae, but that they could be one mechanism helping to prevent infection of post-metamorphic amphibians, particularly for highly aquatic species. PMID:26911920

  16. Potential Use of Antimicrobial Peptides as Vaginal Spermicides/Microbicides.

    PubMed

    Tanphaichitr, Nongnuj; Srakaew, Nopparat; Alonzi, Rhea; Kiattiburut, Wongsakorn; Kongmanas, Kessiri; Zhi, Ruina; Li, Weihua; Baker, Mark; Wang, Guanshun; Hickling, Duane

    2016-01-01

    The concurrent increases in global population and sexually transmitted infection (STI) demand a search for agents with dual spermicidal and microbicidal properties for topical vaginal application. Previous attempts to develop the surfactant spermicide, nonoxynol-9 (N-9), into a vaginal microbicide were unsuccessful largely due to its inefficiency to kill microbes. Furthermore, N-9 causes damage to the vaginal epithelium, thus accelerating microbes to enter the women's body. For this reason, antimicrobial peptides (AMPs), naturally secreted by all forms of life as part of innate immunity, deserve evaluation for their potential spermicidal effects. To date, twelve spermicidal AMPs have been described including LL-37, magainin 2 and nisin A. Human cathelicidin LL-37 is the most promising spermicidal AMP to be further developed for vaginal use for the following reasons. First, it is a human AMP naturally produced in the vagina after intercourse. Second, LL-37 exerts microbicidal effects to numerous microbes including those that cause STI. Third, its cytotoxicity is selective to sperm and not to the female reproductive tract. Furthermore, the spermicidal effects of LL-37 have been demonstrated in vivo in mice. Therefore, the availability of LL-37 as a vaginal spermicide/microbicide will empower women for self-protection against unwanted pregnancies and STI. PMID:26978373

  17. Do Antimicrobial Peptides and Complement Collaborate in the Intestinal Mucosa?

    PubMed Central

    Kopp, Zoë A.; Jain, Umang; Van Limbergen, Johan; Stadnyk, Andrew W.

    2015-01-01

    It is well understood that multiple antimicrobial peptides (AMPs) are constitutively deployed by the epithelium to bolster the innate defenses along the entire length of the intestines. In addition to this constitutive/homeostatic production, AMPs may be inducible and levels changed during disease. In contrast to this level of knowledge on AMP sources and roles in the intestines, our understanding of the complement cascade in the healthy and diseased intestines is rudimentary. Epithelial cells make many complement proteins and there is compelling evidence that complement becomes activated in the lumen. With the common goal of defending the host against microbes, the opportunities for cross-talk between these two processes is great, both in terms of actions on the target microbes but also on regulating the synthesis and secretion of the alternate family of molecules. This possibility is beginning to become apparent with the finding that colonic epithelial cells possess anaphylatoxin receptors. There still remains much to be learned about the possible points of collaboration between AMPs and complement, for example, whether there is reciprocal control over expression in the intestinal mucosa in homeostasis and restoring the balance following infection and inflammation. PMID:25688244

  18. The Antimicrobial Peptide Lysozyme Is Induced after Multiple Trauma

    PubMed Central

    Klüter, Tim; Fitschen-Oestern, Stefanie; Lippross, Sebastian; Weuster, Matthias; Pufe, Thomas; Tohidnezhad, Mersedeh; Beyer, Andreas; Seekamp, Andreas; Varoga, Deike

    2014-01-01

    The antimicrobial peptide lysozyme is an important factor of innate immunity and exerts high potential of antibacterial activity. In the present study we evaluated the lysozyme expression in serum of multiple injured patients and subsequently analyzed their possible sources and signaling pathways. Expression of lysozyme was examined in blood samples of multiple trauma patients from the day of trauma until 14 days after trauma by ELISA. To investigate major sources of lysozyme, its expression and regulation in serum samples, different blood cells, and tissue samples were analysed by ELISA and real-time PCR. Neutrophils and hepatocytes were stimulated with cytokines and supernatant of Staphylococcus aureus. The present study demonstrates the induction and release of lysozyme in serum of multiple injured patients. The highest lysozyme expression of all tested cells and tissues was detected in neutrophils. Stimulation with trauma-related factors such as interleukin-6 and S. aureus induced lysozyme expression. Liver tissue samples of patients without trauma show little lysozyme expression compared to neutrophils. After stimulation with bacterial fragments, lysozyme expression of hepatocytes is upregulated significantly. Toll-like receptor 2, a classic receptor of Gram-positive bacterial protein, was detected as a possible target for lysozyme induction. PMID:25258475

  19. Antimicrobial peptides and gut microbiota in homeostasis and pathology

    PubMed Central

    Ostaff, Maureen J; Stange, Eduard Friedrich; Wehkamp, Jan

    2013-01-01

    We survive because we adapted to a world of microorganisms. All our epithelial surfaces participate in keeping up an effective barrier against microbes while not initiating ongoing inflammatory processes and risking collateral damage to the host. Major players in this scenario are antimicrobial peptides (AMPs). Such broad-spectrum innate antibiotics are in part produced by specialized cells but also widely sourced from all epithelia as well as circulating inflammatory cells. AMPs belong to an ancient defense system found in all organisms and participated in a preservative co-evolution with a complex microbiome. Particularly interesting interactions between host barrier and microbiota can be found in the gut. The intestinal cell lining not only has to maintain a tightly regulated homeostasis during its high-throughput regeneration, but also a balanced relationship towards an extreme number of mutualistic or commensal inhabitants. Recent research suggests that advancing our understanding of the circumstances of such balanced and sometimes imbalanced interactions between gut microbiota and host AMPs should have therapeutic implications for different intestinal disorders. PMID:24039130

  20. Reactive Oxygen Species, Apoptosis, Antimicrobial Peptides and Human Inflammatory Diseases

    PubMed Central

    Oyinloye, Babatunji Emmanuel; Adenowo, Abiola Fatimah; Kappo, Abidemi Paul

    2015-01-01

    Excessive free radical generation, especially reactive oxygen species (ROS) leading to oxidative stress in the biological system, has been implicated in the pathogenesis and pathological conditions associated with diverse human inflammatory diseases (HIDs). Although inflammation which is considered advantageous is a defensive mechanism in response to xenobiotics and foreign pathogen; as a result of cellular damage arising from oxidative stress, if uncontrolled, it may degenerate to chronic inflammation when the ROS levels exceed the antioxidant capacity. Therefore, in the normal resolution of inflammatory reactions, apoptosis is acknowledged to play a crucial role, while on the other hand, dysregulation in the induction of apoptosis by enhanced ROS production could also result in excessive apoptosis identified in the pathogenesis of HIDs. Apparently, a careful balance must be maintained in this complex environment. Antimicrobial peptides (AMPs) have been proposed in this review as an excellent candidate capable of playing prominent roles in maintaining this balance. Consequently, in novel drug design for the treatment and management of HIDs, AMPs are promising candidates owing to their size and multidimensional properties as well as their wide spectrum of activities and indications of reduced rate of resistance. PMID:25850012

  1. The antimicrobial peptide lysozyme is induced after multiple trauma.

    PubMed

    Klüter, Tim; Fitschen-Oestern, Stefanie; Lippross, Sebastian; Weuster, Matthias; Mentlein, Rolf; Steubesand, Nadine; Neunaber, Claudia; Hildebrand, Frank; Pufe, Thomas; Tohidnezhad, Mersedeh; Beyer, Andreas; Seekamp, Andreas; Varoga, Deike

    2014-01-01

    The antimicrobial peptide lysozyme is an important factor of innate immunity and exerts high potential of antibacterial activity. In the present study we evaluated the lysozyme expression in serum of multiple injured patients and subsequently analyzed their possible sources and signaling pathways. Expression of lysozyme was examined in blood samples of multiple trauma patients from the day of trauma until 14 days after trauma by ELISA. To investigate major sources of lysozyme, its expression and regulation in serum samples, different blood cells, and tissue samples were analysed by ELISA and real-time PCR. Neutrophils and hepatocytes were stimulated with cytokines and supernatant of Staphylococcus aureus. The present study demonstrates the induction and release of lysozyme in serum of multiple injured patients. The highest lysozyme expression of all tested cells and tissues was detected in neutrophils. Stimulation with trauma-related factors such as interleukin-6 and S. aureus induced lysozyme expression. Liver tissue samples of patients without trauma show little lysozyme expression compared to neutrophils. After stimulation with bacterial fragments, lysozyme expression of hepatocytes is upregulated significantly. Toll-like receptor 2, a classic receptor of Gram-positive bacterial protein, was detected as a possible target for lysozyme induction. PMID:25258475

  2. Antimicrobial peptide genes in Bacillus strains from plant environments.

    PubMed

    Mora, Isabel; Cabrefiga, Jordi; Montesinos, Emilio

    2011-12-01

    The presence of the antimicrobial peptide (AMP) biosynthetic genes srfAA (surfactin), bacA (bacylisin), fenD (fengycin), bmyB (bacyllomicin), spaS (subtilin), and ituC (iturin) was examined in 184 isolates of Bacillus spp. obtained from plant environments (aerial, rhizosphere, soil) in the Mediterranean land area of Spain. Most strains had between two and four AMP genes whereas strains with five genes were seldom detected and none of the strains had six genes. The most frequent AMP gene markers were srfAA, bacA, bmyB, and fenD, and the most frequent genotypes srfAA-bacA-bmyB and srfAAbacA- bmyB-fenD. The dominance of these particular genes in Bacillus strains associated with plants reinforces the competitive role of surfactin, bacyllomicin, fengycin, and bacilysin in the fitness of strains in natural environments. The use of these AMP gene markers may assist in the selection of putative biological control agents of plant pathogens. PMID:22569759

  3. Potential Use of Antimicrobial Peptides as Vaginal Spermicides/Microbicides

    PubMed Central

    Tanphaichitr, Nongnuj; Srakaew, Nopparat; Alonzi, Rhea; Kiattiburut, Wongsakorn; Kongmanas, Kessiri; Zhi, Ruina; Li, Weihua; Baker, Mark; Wang, Guanshun; Hickling, Duane

    2016-01-01

    The concurrent increases in global population and sexually transmitted infection (STI) demand a search for agents with dual spermicidal and microbicidal properties for topical vaginal application. Previous attempts to develop the surfactant spermicide, nonoxynol-9 (N-9), into a vaginal microbicide were unsuccessful largely due to its inefficiency to kill microbes. Furthermore, N-9 causes damage to the vaginal epithelium, thus accelerating microbes to enter the women’s body. For this reason, antimicrobial peptides (AMPs), naturally secreted by all forms of life as part of innate immunity, deserve evaluation for their potential spermicidal effects. To date, twelve spermicidal AMPs have been described including LL-37, magainin 2 and nisin A. Human cathelicidin LL-37 is the most promising spermicidal AMP to be further developed for vaginal use for the following reasons. First, it is a human AMP naturally produced in the vagina after intercourse. Second, LL-37 exerts microbicidal effects to numerous microbes including those that cause STI. Third, its cytotoxicity is selective to sperm and not to the female reproductive tract. Furthermore, the spermicidal effects of LL-37 have been demonstrated in vivo in mice. Therefore, the availability of LL-37 as a vaginal spermicide/microbicide will empower women for self-protection against unwanted pregnancies and STI. PMID:26978373

  4. Rational Evolution of Antimicrobial Peptides Containing Unnatural Amino Acids to Combat Burn Wound Infections.

    PubMed

    Xiong, Meng; Chen, Ming; Zhang, Jue

    2016-09-01

    Antimicrobial peptides have long been raised as a promising strategy to combat bacterial infection in burn wounds. Here, we attempted to rationally design small antimicrobial peptides containing unnatural amino acids by integrating in silico analysis and in vitro assay. Predictive quantitative sequence-activity models were established and validated rigorously based on a large panel of nonamer antimicrobial peptides with known antibacterial activity. The best quantitative sequence-activity model predictor was employed to guide genetic evolution of a peptide population. In the evolution procedure, a number of unnatural amino acids with desired physicochemical properties were introduced, resulting in a genetic evolution-improved population, from which seven peptide candidates with top scores, containing 1-3 unnatural amino acids, and having diverse structures were successfully identified, and their antibacterial potencies against two antibiotic-resistant bacterial strains isolated from infected burn wounds were measured using in vitro susceptibility test. Consequently, four (WL-Orn-LARKIV-NH2 , ARKRWF-Dab-FL-NH2 , KFI-Hag-IWR-Orn-R-NH2 and YW-Hag-R-Cit-RF-Orn-N-NH2 ) of the seven tested peptides were found to be more potent than reference Bac2A, the smallest naturally occurring broad spectrum antimicrobial peptide. Molecular dynamics simulations revealed that the designed peptides can fold into amphipathic helical structure that allows them to interact directly with microbial membranes. PMID:27062533

  5. Biosynthesis of the Polycyclic Antimicrobial Peptides Lacticin 481, Haloduracin, and Cinnamycin

    ERIC Educational Resources Information Center

    Cooper, Lisa E.

    2009-01-01

    Lantibiotics are bacterial-derived polycyclic antimicrobial peptides. They are genetically encoded and ribosomally synthesized as precursor peptides containing a structural region that undergoes post-translational modification and a leader sequence that is not modified. Specific serine and threonine residues in the pre-lantibiotic structural…

  6. Antimicrobial peptide scolopendrasin VII, derived from the centipede Scolopendra subspinipes mutilans, stimulates macrophage chemotaxis via formyl peptide receptor 1.

    PubMed

    Park, Yoo Jung; Lee, Ha Young; Jung, Young Su; Park, Joon Seong; Hwang, Jae Sam; Bae, Yoe-Sik

    2015-08-01

    In this study, we report that one of the antimicrobial peptides scolopendrasin VII, derived from Scolopendra subspinipes mutilans, stimulates actin polymerization and the subsequent chemotactic migration of macrophages through the activation of ERK and protein kinase B (Akt) activity. The scolopendrasin VII-induced chemotactic migration of macrophages is inhibited by the formyl peptide receptor 1 (FPR1) antagonist cyclosporine H. We also found that scolopendrasin VII stimulate the chemotactic migration of FPR1-transfected RBL-2H3 cells, but not that of vector-transfected cells; moreover, scolopendrasin VII directly binds to FPR1. Our findings therefore suggest that the antimicrobial peptide scolopendrasin VII, derived from Scolopendra subspinipes mutilans, stimulates macrophages, resulting in chemotactic migration via FPR1 signaling, and the peptide can be useful in the study of FPR1-related biological responses. PMID:26129676

  7. Design, recombinant expression, and antibacterial activity of the cecropins-melittin hybrid antimicrobial peptides.

    PubMed

    Cao, Yu; Yu, Rong Qing; Liu, Yi; Zhou, Huo Xiang; Song, Ling Ling; Cao, Yi; Qiao, Dai Rong

    2010-09-01

    In order to evaluate their antibacterial activities and toxicities, the cecropins-melittin hybrid antimicrobial peptide, CA(1-7)-M(4-11) (CAM) and CB(1-7)-M(4-11) (CBM), were designed by APD2 database. The recombinant hybrid antimicrobial peptides were successfully expressed and purified in Pichia pastoris. Antimicrobial activity assay showed that both of the two hybrid antimicrobial peptides had strong antibacterial abilities against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus subtilis, Bacillus thuringiensis, and Salmonella derby. The potency of CAM and CBM to E. coli 25922 were 0.862 and 0.849, respectively, slightly lower than Amp's 0.957. The hemolytic assays indicated CAM and CBM had no hemolytic in vivo and in vitro, and so they had a good application prospect. PMID:20111863

  8. Alpha-Melanocyte Stimulating Hormone: An Emerging Anti-Inflammatory Antimicrobial Peptide

    PubMed Central

    Singh, Madhuri; Mukhopadhyay, Kasturi

    2014-01-01

    The alpha-melanocyte stimulating hormone (α-MSH) is a neuropeptide belonging to the melanocortin family. It is well known for its anti-inflammatory and antipyretic effects and shares several characteristics with antimicrobial peptides (AMPs). There have been some recent reports about the direct antimicrobial activity of α-MSH against various microbes belonging to both fungal and bacterial pathogens. Similar to α-MSH's anti-inflammatory properties, its C-terminal residues also exhibit antimicrobial activity parallel to that of the entire peptide. This review is focused on the current findings regarding the direct antimicrobial potential and immunomodulatory mechanism of α-MSH and its C-terminal fragments, with particular emphasis on the prospects of α-MSH based peptides as a strong anti-infective agent. PMID:25140322

  9. Contribution of Amphipathicity and Hydrophobicity to the Antimicrobial Activity and Cytotoxicity of β-Hairpin Peptides

    PubMed Central

    2016-01-01

    Bacteria have acquired extensive resistance mechanisms to protect themselves against antibiotic action. Today the bacterial membrane has become one of the “final frontiers” in the search for new compounds acting on novel targets to address the threat of multi-drug resistant (MDR) and XDR bacterial pathogens. β-Hairpin antimicrobial peptides are amphipathic, membrane-binding antibiotics that exhibit a broad range of activities against Gram-positive, Gram-negative, and fungal pathogens. However, most members of the class also possess adverse cytotoxicity and hemolytic activity that preclude their development as candidate antimicrobials. We examined peptide hydrophobicity, amphipathicity, and structure to better dissect and understand the correlation between antimicrobial activity and toxicity, membrane binding, and membrane permeability. The hydrophobicity, pI, net charge at physiological pH, and amphipathic moment for the β-hairpin antimicrobial peptides tachyplesin-1, polyphemusin-1, protegrin-1, gomesin, arenicin-3, and thanatin were determined and correlated with key antimicrobial activity and toxicity data. These included antimicrobial activity against five key bacterial pathogens and two fungi, cytotoxicity against human cell lines, and hemolytic activity in human erythrocytes. Observed antimicrobial activity trends correlated with compound amphipathicity and, to a lesser extent, with overall hydrophobicity. Antimicrobial activity increased with amphipathicity, but unfortunately so did toxicity. Of note, tachyplesin-1 was found to be 8-fold more amphipathic than gomesin. These analyses identify tachyplesin-1 as a promising scaffold for rational design and synthetic optimization toward an antibiotic candidate. PMID:27331141

  10. Engineered Chimeric Peptides as Antimicrobial Surface Coating Agents toward Infection-Free Implants.

    PubMed

    Yazici, Hilal; O'Neill, Mary B; Kacar, Turgay; Wilson, Brandon R; Oren, E Emre; Sarikaya, Mehmet; Tamerler, Candan

    2016-03-01

    Prevention of bacterial colonization and consequent biofilm formation remains a major challenge in implantable medical devices. Implant-associated infections are not only a major cause of implant failures but also their conventional treatment with antibiotics brings further complications due to the escalation in multidrug resistance to a variety of bacterial species. Owing to their unique properties, antimicrobial peptides (AMPs) have gained significant attention as effective agents to combat colonization of microorganisms. These peptides have been shown to exhibit a wide spectrum of activities with specificity to a target cell while having a low tendency for developing bacterial resistance. Engineering biomaterial surfaces that feature AMP properties, therefore, offer a promising approach to prevent implant infections. Here, we engineered a chimeric peptide with bifunctionality that both forms a robust solid-surface coating while presenting antimicrobial property. The individual domains of the chimeric peptides were evaluated for their solid-binding kinetics to titanium substrate as well as for their antimicrobial properties in solution. The antimicrobial efficacy of the chimeric peptide on the implant material was evaluated in vitro against infection by a variety of bacteria, including Streptococcus mutans, Staphylococcus. epidermidis, and Escherichia coli, which are commonly found in oral and orthopedic implant related surgeries. Our results demonstrate significant improvement in reducing bacterial colonization onto titanium surfaces below the detectable limit. Engineered chimeric peptides with freely displayed antimicrobial domains could be a potential solution for developing infection-free surfaces by engineering implant interfaces with highly reduced bacterial colonization property. PMID:26795060

  11. Dynamical and phase behavior of a phospholipid membrane altered by an antimicrobial peptide at low concentration

    DOE PAGESBeta

    Mamontov, Eugene; Tyagi, M.; Qian, Shuo; Rai, Durgesh K.; Urban, Volker S.; Sharma, V. K.

    2016-05-27

    Here we discuss that the mechanism of action of antimicrobial peptides is traditionally attributed to the formation of pores in the lipid cell membranes of pathogens, which requires a substantial peptide to lipid ratio. However, using incoherent neutron scattering, we show that even at a concentration too low for pore formation, an archetypal antimicrobial peptide, melittin, disrupts the regular phase behavior of the microscopic dynamics in a phospholipid membrane, dimyristoylphosphatidylcholine (DMPC). At the same time, another antimicrobial peptide, alamethicin, does not exert a similar effect on the DMPC microscopic dynamics. The melittin-altered lateral motion of DMPC at physiological temperature nomore » longer resembles the fluid-phase behavior characteristic of functional membranes of the living cells. The disruptive effect demonstrated by melittin even at low concentrations reveals a new mechanism of antimicrobial action relevant in more realistic scenarios, when peptide concentration is not as high as would be required for pore formation, which may facilitate treatment with antimicrobial peptides.« less

  12. Enhanced antimicrobial activity of peptide-cocktails against common bacterial contaminants of ex vivo stored platelets.

    PubMed

    Mohan, K V K; Rao, S Sainath; Gao, Y; Atreya, C D

    2014-01-01

    Bacterial contamination of blood components such as ex vivo-stored platelets is a major safety risk in transfusion medicine. We have recently shown that synthetic antimicrobial peptides named PD1-PD4 derived from the thrombin-induced human platelet-derived antimicrobial proteins, and repeats of Arg-Trp (RW1-RW5) demonstrate microbicidal activity against selected bacteria and viruses. In the present study, we selected PD3, PD4, RW2, RW3 and RW4 and evaluated each individual peptide and their various combinations to see whether the cocktail regimen enhances the antimicrobial activity above and over the individual peptides. Stored platelet or plasma samples spiked with known titres of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Bacillus cereus were treated with either individual peptides or with peptides in various combinations. Analyses revealed that individual peptides show moderate microbicidal activity (10- to 100-fold reduction) against the tested bacteria relative to their combined regimen. The peptide combinations (RW2 + RW4, RW2 + RW3 + RW4 and PD4 + RW3 + RW4) on the other hand enhanced the microbicidal activity (c.10 000-fold reduction) and revealed a minimal inhibitory concentration of 5 μM. Time-kill kinetics indicated that these three peptide combinations exhibited enhanced antimicrobial activity bringing about a 100-fold reduction of bacterial titres within 20 min of incubation. The present study therefore demonstrates the synergistic effect of antimicrobial peptides when used in combinations and provides a proof-of-concept of its potential application as a molecular tool towards pathogen reduction and further extends the possibility of using peptide combinatorial therapeutics as broad-spectrum antibiotics or as alternatives to combat drug-resistant bacteria. PMID:23926880

  13. The emerging role of peptides and lipids as antimicrobial epidermal barriers and modulators of local inflammation

    PubMed Central

    Brogden, N.K.; Mehalick, L.; Fischer, C.L.; Wertz, P.W.; Brogden, K.A.

    2012-01-01

    Skin is complex and comprised of distinct layers, each layer with unique architecture and immunologic functions. Cells within these layers produce differing amounts of antimicrobial peptides and lipids (sphingoid bases and sebaceous fatty acids) that limit colonization of commensal and opportunistic microorganisms. Furthermore, antimicrobial peptides and lipids have distinct, concentration-dependent ancillary innate and adaptive immune functions. At 0.1-2.0 μM, antimicrobial peptides induce cell migration and adaptive immune responses to co-administered antigens. At 2.0-6.0 μM, they induce cell proliferation and enhance wound healing. At 6.0-12.0 μM, antimicrobial peptides can regulate chemokine and cytokine production and at their highest concentrations of 15.0-30.0 μM, antimicrobial peptides can be cytotoxic. At 1-100 nM, lipids enhance cell migration induced by chemokines, suppress apoptosis, and optimize T cell cytotoxicity and at 0.3-1.0 μM, they inhibit cell migration and attenuate chemokine and pro-inflammatory cytokine responses. Recently many antimicrobial peptides and lipids at 0.1-2.0 μM have been found to attenuate the production of chemokines and pro-inflammatory cytokines to microbial antigens. Together, both the antimicrobial and the anti-inflammatory activities of these peptides and lipids may serve to create a strong, overlapping immunologic barrier that not only controls the concentrations of cutaneous commensal flora but also the extent to which they induce a localized inflammatory response. PMID:22538862

  14. Self-assembled cationic peptide nanoparticles as an efficient antimicrobial agent

    NASA Astrophysics Data System (ADS)

    Liu, Lihong; Xu, Kaijin; Wang, Huaying; Jeremy Tan, P. K.; Fan, Weimin; Venkatraman, Subbu S.; Li, Lanjuan; Yang, Yi-Yan

    2009-07-01

    Antimicrobial cationic peptides are of interest because they can combat multi-drug-resistant microbes. Most peptides form α-helices or β-sheet-like structures that can insert into and subsequently disintegrate negatively charged bacterial cell surfaces. Here, we show that a novel class of core-shell nanoparticles formed by self-assembly of an amphiphilic peptide have strong antimicrobial properties against a range of bacteria, yeasts and fungi. The nanoparticles show a high therapeutic index against Staphylococcus aureus infection in mice and are more potent than their unassembled peptide counterparts. Using Staphylococcus aureus-infected meningitis rabbits, we show that the nanoparticles can cross the blood-brain barrier and suppress bacterial growth in infected brains. Taken together, these nanoparticles are promising antimicrobial agents that can be used to treat brain infections and other infectious diseases.

  15. Antimicrobial peptide expression is developmentally regulated in the ovine gastrointestinal tract.

    PubMed

    Huttner, K M; Brezinski-Caliguri, D J; Mahoney, M M; Diamond, G

    1998-02-01

    Antimicrobial peptides are abundant components of the innate immune system present in species throughout the plant and animal kingdoms. In mammals, these immune peptides have been localized to epithelial tissues of the pig, mouse, rat, cow and human gastrointestinal tracts. We have identified in sheep two members of the beta-defensin antimicrobial peptide gene family that are expressed in a unique pattern throughout the gastrointestinal tract. Sheep beta-defensin 1 mRNA is the most prevalent from tongue to colon with the exception of the distal ileum, where beta-defensin 2 mRNA predominates. Sheep beta-defensin expression varies significantly between animals and is developmentally regulated both pre- and postnatally. These changes in antimicrobial peptide expression may correlate with anatomical differentiation as well as physiologic adaptations to extra-uterine life. PMID:9478010

  16. Enhanced stability and activity of an antimicrobial peptide in conjugation with silver nanoparticle.

    PubMed

    Pal, Indrani; Brahmkhatri, Varsha P; Bera, Swapna; Bhattacharyya, Dipita; Quirishi, Yasrib; Bhunia, Anirban; Atreya, Hanudatta S

    2016-12-01

    The conjugation of nanoparticles with antimicrobial peptides (AMP) is emerging as a promising route to achieve superior antimicrobial activity. However, the nature of peptide-nanoparticle interactions in these systems remains unclear. This study describes a system consisting of a cysteine containing antimicrobial peptide conjugated with silver nanoparticles, in which the two components exhibit a dynamic interaction resulting in a significantly enhanced stability and biological activity compared to that of the individual components. This was investigated using NMR spectroscopy in conjunction with other biophysical techniques. Using fluorescence assisted cell sorting and membrane mimics we carried out a quantitative comparison of the activity of the AMP-nanoparticle system and the free peptide. Taken together, the study provides new insights into nanoparticle-AMP interactions at a molecular level and brings out the factors that will be useful for consideration while designing new conjugates with enhanced functionality. PMID:27585423

  17. The contribution of skin antimicrobial peptides to the system of innate immunity in anurans.

    PubMed

    Conlon, J Michael

    2011-01-01

    Cationic peptides with the propensity to adopt an amphipathic α-helical conformation in a membrane-mimetic environment are synthesized in the skins of many species of anurans (frogs and toads). These peptides frequently display cytolytic activities against a range of pathogenic bacteria and fungi consistent with the idea that they play a role in the host's system of innate immunity. However, the importance of the peptides in the survival strategy of the animal is not clearly understood. It is a common misconception that antimicrobial peptides are synthesized in the skins of all anurans. In fact, the species distribution is sporadic suggesting that their production may confer some evolutionary advantage to the organism but is not necessary for survival. Although growth inhibitory activity against the chytrid fungus Batrachochytrium dendrobatidis, responsible for anuran population declines worldwide, has been demonstrated in vitro, the ability of frog skin antimicrobial peptides to protect the animal in the wild appears to be limited and there is no clear correlation between their production by a species and its resistance to fatal chytridiomycosis. The low potency of many frog skin antimicrobial peptides is consistent with the hypothesis that cutaneous symbiotic bacteria may provide the major system of defense against pathogenic microorganisms in the environment with antimicrobial peptides assuming a supplementary role in some species. PMID:20640445

  18. 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. PMID:25020259

  19. Development of Antimicrobial Peptide Prediction Tool for Aquaculture Industries.

    PubMed

    Gautam, Aditi; Sharma, Asuda; Jaiswal, Sarika; Fatma, Samar; Arora, Vasu; Iquebal, M A; Nandi, S; Sundaray, J K; Jayasankar, P; Rai, Anil; Kumar, Dinesh

    2016-09-01

    Microbial diseases in fish, plant, animal and human are rising constantly; thus, discovery of their antidote is imperative. The use of antibiotic in aquaculture further compounds the problem by development of resistance and consequent consumer health risk by bio-magnification. Antimicrobial peptides (AMPs) have been highly promising as natural alternative to chemical antibiotics. Though AMPs are molecules of innate immune defense of all advance eukaryotic organisms, fish being heavily dependent on their innate immune defense has been a good source of AMPs with much wider applicability. Machine learning-based prediction method using wet laboratory-validated fish AMP can accelerate the AMP discovery using available fish genomic and proteomic data. Earlier AMP prediction servers are based on multi-phyla/species data, and we report here the world's first AMP prediction server in fishes. It is freely accessible at http://webapp.cabgrid.res.in/fishamp/ . A total of 151 AMPs related to fish collected from various databases and published literature were taken for this study. For model development and prediction, N-terminus residues, C-terminus residues and full sequences were considered. Best models were with kernels polynomial-2, linear and radial basis function with accuracy of 97, 99 and 97 %, respectively. We found that performance of support vector machine-based models is superior to artificial neural network. This in silico approach can drastically reduce the time and cost of AMP discovery. This accelerated discovery of lead AMP molecules having potential wider applications in diverse area like fish and human health as substitute of antibiotics, immunomodulator, antitumor, vaccine adjuvant and inactivator, and also for packaged food can be of much importance for industries. PMID:27141850

  20. Antimicrobial peptide-based treatment for endodontic infections--biotechnological innovation in endodontics.

    PubMed

    Lima, Stella Maris de Freitas; de Pádua, Gabriela Martins; Sousa, Maurício Gonçalves da Costa; Freire, Mirna de Souza; Franco, Octávio Luiz; Rezende, Taia Maria Berto

    2015-01-01

    The presence/persistence of microorganisms in the pulp and periapical area corresponds to the maintenance of an exacerbated immune response that leads to the start of periradicular bone resorption and its perpetuation. In endodontic treatment, the available intracanal medications do not have all the desirable properties in the context of endodontic infection and apical periodontitis; they need to include not only strong antimicrobial performance but also an immunomodulatory and reparative activity, without host damage. In addition, there are various levels of resistance to root canal medications. Thus, antimicrobial agents that effectively eliminate resistant species in root canals could potentially improve endodontic treatment. In the emergence of new therapies, an increasing number of studies on antimicrobial peptides (AMPs) have been seen over the past few years. AMPs are defense biomolecules produced in response to infection, and they have a wide spectrum of action against many oral microorganisms. There are some studies that correlate peptides and oral infections, including oral peptides, neuropeptides, and bacterial, fish, bovine and synthetic peptides. So far, there are around 120 published studies correlating endodontic microbiota with AMPs but, according to our knowledge, there are no registered patents in the American patent database. There are a considerable number of AMPs that exhibit excellent antimicrobial activity against endodontic microbiota at a small inhibitory concentration and modulate an exacerbated immune response, down-regulating bone resorption. All these reasons indicate the antimicrobial peptide-based endodontic treatment as an emerging and promising option. PMID:25447423

  1. Prokaryotic expression and antimicrobial mechanism of XPF-St7-derived α-helical peptides.

    PubMed

    Yi, Tonghui; Huang, Yibing; Chen, Yuxin

    2015-01-01

    XPF-St7 (GLLSNVAGLLKQFAKGGVNAVLNPK) is an antimicrobial peptide isolated from Silurana tropicalis. We developed an α-helical segment of XPF-St7 termed as XPF2. Using the XPF2 as a framework, we increased the positive net charge of XPF2 by amino acid substitutions, and thus obtained two novel antimicrobial peptides XPF4 and XPF6. These were each fused with an ubiquitin tag and successfully expressed in Escherichia coli. This ubiquitin fusion system may present a viable alternative for industrial production of antimicrobial peptides. XPF4 and XPF6 showed much better overall antimicrobial activity against both Gram-negative and Gram-positive bacteria than XPF2. The therapeutic index of XPF4 and XPF6 was 5.6-fold and 6.7-fold of XPF2, respectively. Bacterial cell membrane permeabilization and genomic DNA interaction assays were utilized to explore the mechanism of action of XPF serial peptides. The results revealed that the target of these antimicrobial peptides was the bacterial cytoplasmic membrane. PMID:25421112

  2. On the Functional Overlap between Complement and Anti-Microbial Peptides

    PubMed Central

    Zimmer, Jana; Hobkirk, James; Mohamed, Fatima; Browning, Michael J.; Stover, Cordula M.

    2015-01-01

    Intriguingly, activated complement and anti-microbial peptides share certain functionalities; lytic, phagocytic, and chemo-attractant activities and each may, in addition, exert cell instructive roles. Each has been shown to have distinct LPS detoxifying activity and may play a role in the development of endotoxin tolerance. In search of the origin of complement, a functional homolog of complement C3 involved in opsonization has been identified in horseshoe crabs. Horseshoe crabs possess anti-microbial peptides able to bind to acyl chains or phosphate groups/saccharides of endotoxin, LPS. Complement activity as a whole is detectable in marine invertebrates. These are also a source of anti-microbial peptides with potential pharmaceutical applicability. Investigating the locality for the production of complement pathway proteins and their role in modulating cellular immune responses are emerging fields. The significance of local synthesis of complement components is becoming clearer from in vivo studies of parenchymatous disease involving specifically generated, complement-deficient mouse lines. Complement C3 is a central component of complement activation. Its provision by cells of the myeloid lineage varies. Their effector functions in turn are increased in the presence of anti-microbial peptides. This may point to a potentiating range of activities, which should serve the maintenance of health but may also cause disease. Because of the therapeutic implications, this review will consider closely studies dealing with complement activation and anti-microbial peptide activity in acute inflammation (e.g., dialysis-related peritonitis, appendicitis, and ischemia). PMID:25646095

  3. On the Functional Overlap between Complement and Anti-Microbial Peptides.

    PubMed

    Zimmer, Jana; Hobkirk, James; Mohamed, Fatima; Browning, Michael J; Stover, Cordula M

    2014-01-01

    Intriguingly, activated complement and anti-microbial peptides share certain functionalities; lytic, phagocytic, and chemo-attractant activities and each may, in addition, exert cell instructive roles. Each has been shown to have distinct LPS detoxifying activity and may play a role in the development of endotoxin tolerance. In search of the origin of complement, a functional homolog of complement C3 involved in opsonization has been identified in horseshoe crabs. Horseshoe crabs possess anti-microbial peptides able to bind to acyl chains or phosphate groups/saccharides of endotoxin, LPS. Complement activity as a whole is detectable in marine invertebrates. These are also a source of anti-microbial peptides with potential pharmaceutical applicability. Investigating the locality for the production of complement pathway proteins and their role in modulating cellular immune responses are emerging fields. The significance of local synthesis of complement components is becoming clearer from in vivo studies of parenchymatous disease involving specifically generated, complement-deficient mouse lines. Complement C3 is a central component of complement activation. Its provision by cells of the myeloid lineage varies. Their effector functions in turn are increased in the presence of anti-microbial peptides. This may point to a potentiating range of activities, which should serve the maintenance of health but may also cause disease. Because of the therapeutic implications, this review will consider closely studies dealing with complement activation and anti-microbial peptide activity in acute inflammation (e.g., dialysis-related peritonitis, appendicitis, and ischemia). PMID:25646095

  4. Dermaseptins as models for the elucidation of membrane-acting helical amphipathic antimicrobial peptides.

    PubMed

    Amiche, Mohamed; Galanth, Cécile

    2011-08-01

    Antimicrobial peptides (AMPs) produced by a wide variety of organisms are major actors of the host defense systems against invading pathogenic microorganisms. These peptides exhibit a broad spectrum of action against bacteria, yeasts, fungi, protozoa and viruses. It is widely believed that a large part of their antimicrobial effect derives from direct interactions with the lipid membrane surrounding the target cells, causing its permeabilization and cell lysis. However, the exact nature of these interactions is presently unclear. The skin of the amphibians has proved to be a remarkably rich storehouse of AMPs that encompass a wide variety of structural motifs. This natural AMP bank is used in combined approaches, based on biophysical and cellular biology methods, to elucidate how these peptides perturb the membrane and whether such membrane perturbations are related to the antimicrobial activity of these peptides. Here we review our current knowledge about the structure and the mechanism of action of the dermaseptin super-family, α-helical amphipathic AMPs isolated from the skin of frogs of the Phyllomedusa genus. Dermaseptins are genetically related, with a remarkable identity in signal sequences and acidic propieces of their preproforms but have clearly diverged to yield several families of microbicidal cationic peptides that are structurally distinct. Particularly, we focused on the orthologous peptides dermaseptin S and B of which the shortening from the carboxy terminal extremity causes a drastic change in their membrane disruption activity. These peptides could be good models to study the membrane-peptide interactions discussed in this review. PMID:21470155

  5. Characterization of unique amphipathic antimicrobial peptides from venom of the scorpion Pandinus imperator.

    PubMed Central

    Corzo, G; Escoubas, P; Villegas, E; Barnham, K J; He, W; Norton, R S; Nakajima, T

    2001-01-01

    Two novel antimicrobial peptides have been identified and characterized from venom of the African scorpion Pandinus imperator. The peptides, designated pandinin 1 and 2, are alpha-helical polycationic peptides, with pandinin 1 belonging to the group of antibacterial peptides previously described from scorpions, frogs and insects, and pandinin 2 to the group of short magainin-type helical peptides from frogs. Both peptides demonstrated high antimicrobial activity against a range of Gram-positive bacteria (2.4-5.2 microM), but were less active against Gram-negative bacteria (2.4-38.2 microM), and only pandinin 2 affected the yeast Candida albicans. Pandinin 2 also demonstrated strong haemolytic activity (11.1-44.5 microM) against sheep erythrocytes, in contrast with pandinin 1, which was not haemolytic. CD studies and a high-resolution structure of pandinin 2 determined by NMR, showed that the two peptides are both essentially helical, but differ in their overall structure. Pandinin 2 is composed of a single alpha-helix with a predominantly hydrophobic N-terminal sequence, whereas pandinin 1 consists of two distinct alpha-helices separated by a coil region of higher flexibility. This is the first report of magainin-type polycationic antimicrobial peptides in scorpion venom. Their presence brings new insights into the mode of action of scorpion venom and also opens new avenues for the discovery of novel antibiotic molecules from arthropod venoms. PMID:11563967

  6. Two novel antimicrobial peptides from skin venoms of spadefoot toad Megophrys minor.

    PubMed

    Yang, Hong-Ling; Shen, Zhi-Qiang; Liu, Xuan; Kong, Yi

    2016-04-01

    Amphibian skin contains rich bioactive peptides. Especially, a large amount of antimicrobial peptides have been identified from amphibian skin secretions. Antimicrobial peptides display potent cytolytic activities against a range of pathogenic bacteria and fungi and play important defense roles. No antimicrobial peptides have been reported from toads belonging to the family of Pelobatidae. In this work, two novel antimicrobial peptides (Megin 1 and Megin 2) were purified and characterized from the skin venoms of spadefoot toad Megophrys minor (Pelobatidae, Anura, Amphibia). Megin 1 had an amino acid sequence of FLKGCWTKWYSLKPKCPF-NH2, which was composed of 18 amino acid residues and contained an intra-molecular disulfide bridge and an amidated C-terminus. Megin 2 had an amino acid sequence of FFVLKFLLKWAGKVGLEHLACKFKNWC, which was composed of 27 amino acid residues and contained an intra-molecular disulfide bridge. Both Megin 1 and Megin 2 showed potential antimicrobial abilities against bacteria and fungi. The MICs of Megin 1 against Escherichia coli, Bacillus dysenteriae, Staphylococcus aureus, Bacillus subtilis, and Candida albicans were 25, 3, 6.25, 3, and 50 μg·mL(-1), respectively. The corresponding MICs for Megin 2 were 6.25, 1.5, 12.5, 1.5, and 12.5 μg·mL(-1), respectively. They also exerted strong hemolytic activity against human and rabbit red cells. The results suggested that megin peptides in the toad skin of M. minor displayed toxic effects on both eukaryotes and prokaryotes. This was the first report of antimicrobial peptides from amphibians belonging to the family of Pelobatidae. PMID:27114317

  7. Progressive Structuring of a Branched Antimicrobial Peptide on the Path to the Inner Membrane Target*

    PubMed Central

    Bai, Yang; Liu, Shouping; Li, Jianguo; Lakshminarayanan, Rajamani; Sarawathi, Padmanabhan; Tang, Charles; Ho, Duncun; Verma, Chandra; Beuerman, Roger W.; Pervushin, Konstantin

    2012-01-01

    In recent years, interest has grown in the antimicrobial properties of certain natural and non-natural peptides. The strategy of inserting a covalent branch point in a peptide can improve its antimicrobial properties while retaining host biocompatibility. However, little is known regarding possible structural transitions as the peptide moves on the access path to the presumed target, the inner membrane. Establishing the nature of the interactions with the complex bacterial outer and inner membranes is important for effective peptide design. Structure-activity relationships of an amphiphilic, branched antimicrobial peptide (B2088) are examined using environment-sensitive fluorescent probes, electron microscopy, molecular dynamics simulations, and high resolution NMR in solution and in condensed states. The peptide is reconstituted in bacterial outer membrane lipopolysaccharide extract as well as in a variety of lipid media mimicking the inner membrane of Gram-negative pathogens. Progressive structure accretion is observed for the peptide in water, LPS, and lipid environments. Despite inducing rapid aggregation of bacteria-derived lipopolysaccharides, the peptide remains highly mobile in the aggregated lattice. At the inner membranes, the peptide undergoes further structural compaction mediated by interactions with negatively charged lipids, probably causing redistribution of membrane lipids, which in turn results in increased membrane permeability and bacterial lysis. These findings suggest that peptides possessing both enhanced mobility in the bacterial outer membrane and spatial structure facilitating its interactions with the membrane-water interface may provide excellent structural motifs to develop new antimicrobials that can overcome antibiotic-resistant Gram-negative pathogens. PMID:22700968

  8. Expressing antimicrobial peptide cathelicidin-BF in Bacillus subtilis using SUMO technology.

    PubMed

    Luan, Chao; Zhang, Hai Wen; Song, De Guang; Xie, Yong Gang; Feng, Jie; Wang, Yi Zhen

    2014-04-01

    Small ubiquitin-related modifier (SUMO) technology has been widely used in Escherichia coli expression systems to produce antimicrobial peptides. However, E. coli is a pathogenic bacterium that produces endotoxins and can secrete proteins into the periplasm, forming inclusion bodies. In our work, cathelicidin-BF (CBF), an antimicrobial peptide purified from Bungarus fasciatus venom, was produced in a Bacillus subtilis expression system using SUMO technology. The chimeric genes his-SUMO-CBF and his-SUMO protease 1 were ligated into vector pHT43 and expressed in B. subtilis WB800N. Approximately 22 mg of recombinant fusion protein SUMO-CBF and 1 mg of SUMO protease 1 were purified per liter of culture supernatant. Purified SUMO protease 1 was highly active and cleaved his-SUMO-CBF with an enzyme-to-substrate ratio of 1:40. Following cleavage, recombinant CBF was further purified by affinity and cation exchange chromatography. Peptide yields of ~3 mg/l endotoxin-free CBF were achieved, and the peptide demonstrated antimicrobial activity. This is the first report of the production of an endotoxin-free antimicrobial peptide, CBF, by recombinant DNA technology, as well as the first time purified SUMO protease 1 with high activity has been produced from B. subtilis. This work has expanded the application of SUMO fusion technology and may represent a safe and efficient way to generate peptides and proteins in B. subtilis. PMID:24121930

  9. Influence of lipidation on the mode of action of a small RW-rich antimicrobial peptide.

    PubMed

    Wenzel, Michaela; Schriek, Patrick; Prochnow, Pascal; Albada, H Bauke; Metzler-Nolte, Nils; Bandow, Julia E

    2016-05-01

    Antimicrobial peptides are a potent class of antibiotics. In the Gram-positive model organism Bacillus subtilis the synthetic peptide RWRWRW-NH2 integrates into the bacterial membrane and delocalizes essential peripheral membrane proteins involved in cell wall biosynthesis and respiration. A lysine residue has been added to the hexapeptide core structure, either C or N-terminally. Lipidation of the lysine residues by a C8-acyl chain significantly improved antibacterial activity against both Gram-positive and Gram-negative bacteria. Here, we report a comparative proteomic study in B. subtilis on the mechanism of action of the lipidated and non-lipidated peptides. All derivatives depolarized the bacterial membrane without forming pores and all affected cell wall integrity. Proteomic profiling of the bacterial stress responses to the small RW-rich antimicrobial peptides was reflective of non-disruptive membrane integration. Overall, our results indicate that antimicrobial peptides can be derivatized with lipid chains enhancing antibacterial activity without significantly altering the mechanism of action. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert. PMID:26603779

  10. Expression analysis and identification of antimicrobial peptide transcripts from six North American frog species

    USGS Publications Warehouse

    Robertson, Laura S.; Fellers, Gary M.; Marranca, Jamie Marie; Kleeman, Patrick M.

    2013-01-01

    Frogs secrete antimicrobial peptides onto their skin. We describe an assay to preserve and analyze antimicrobial peptide transcripts from field-collected skin secretions that will complement existing methods for peptide analysis. We collected skin secretions from 4 North American species in the field in California and 2 species in the laboratory. Most frogs appeared healthy after release; however, Rana boylii in the Sierra Nevada foothills, but not the Coast Range, showed signs of morbidity and 2 died after handling. The amount of total RNA extracted from skin secretions was higher in R. boylii and R. sierrae compared to R. draytonii, and much higher compared to Pseudacris regilla. Interspecies variation in amount of RNA extracted was not explained by size, but for P. regilla it depended upon collection site and date. RNA extracted from skin secretions from frogs handled with bare hands had poor quality compared to frogs handled with gloves or plastic bags. Thirty-four putative antimicrobial peptide precursor transcripts were identified. This study demonstrates that RNA extracted from skin secretions collected in the field is of high quality suitable for use in sequencing or quantitative PCR (qPCR). However, some species do not secrete profusely, resulting in very little extracted RNA. The ability to measure transcript abundance of antimicrobial peptides in field-collected skin secretions complements proteomic analyses and may provide insight into transcriptional mechanisms that could affect peptide abundance.

  11. 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

  12. Purification and characterization of a plant antimicrobial peptide expressed in Escherichia coli.

    PubMed

    Harrison, S J; McManus, A M; Marcus, J P; Goulter, K C; Green, J L; Nielsen, K J; Craik, D J; Maclean, D J; Manners, J M

    1999-03-01

    MiAMP1 is a low-molecular-weight, cysteine-rich, antimicrobial peptide isolated from the nut kernel of Macadamia integrifolia. A DNA sequence encoding MiAMP1 with an additional ATG start codon was cloned into a modified pET vector under the control of the T7 RNA polymerase promoter. The pET vector was cotransformed together with the vector pSB161, which expresses a rare arginine tRNA. The peptide was readily isolated in high yield from the insoluble fraction of the Escherichia coli extract. The purified peptide was shown to have an identical molecular weight to the native peptide by mass spectroscopy indicating that the N-terminal methionine had been cleaved. Analysis by NMR spectroscopy indicated that the refolded recombinant peptide had a similar overall three-dimensional structure to that of the native peptide. The peptide inhibited the growth of phytopathogenic fungi in vitro in a similar manner to the native peptide. To our knowledge, MiAMP1 is the first antimicrobial peptide from plants to be functionally expressed in E. coli. This will permit a detailed structure-function analysis of the peptide and studies of its mode of action on phytopathogens. PMID:10049672

  13. Characterization of a highly potent antimicrobial peptide microcin N from uropathogenic Escherichia coli.

    PubMed

    Kaur, Kamaljit; Tarassova, Oxana; Dangeti, Ramana Venkata; Azmi, Sarfuddin; Wishart, David; McMullen, Lynn; Stiles, Michael

    2016-06-01

    Microcin N is a low-molecular weight, highly active antimicrobial peptide produced by uropathogenic Escherichia coli In this study, the native peptide was expressed and purified from pGOB18 plasmid carrying E. coli in low yield. The pure peptide was characterized using mass spectrometry, N-terminal sequencing by Edman degradation as well as trypsin digestion. We found that the peptide is 74-residue long, cationic (+2 total charge), highly hydrophobic and consists of glycine as the first N-terminal residue. The minimum inhibitory concentration of the peptide against Salmonella enteritidis was found to be 150 nM. Evaluation of the solution conformation of the peptide using circular dichroism spectroscopy showed that the peptide is well folded in 40% trifluoroethanol with helical structure whereas the folded structure is lost in aqueous solution. To increase the yield of this potent peptide, we overexpressed GST-tagged microcin N using E. coli BL21. Recombinant GST-tagged microcin N was successfully expressed in E. coli BL21; however, the cleaved mature microcin N did not show activity against the indicator strain (S. enterica) most likely due to the extreme hydrophobic nature of the peptide. Efforts to produce active microcin N in large scale are discussed as this peptide has huge potential to be the next generation antimicrobial agent. PMID:27190283

  14. A Review of Antimicrobial Peptides and Their Therapeutic Potential as Anti-Infective Drugs

    PubMed Central

    Gordon, Y. Jerold; Romanowski, Eric G.; McDermott, Alison M.

    2006-01-01

    Purpose. Antimicrobial peptides (AMPs) are an essential part of innate immunity that evolved in most living organisms over 2.6 billion years to combat microbial challenge. These small cationic peptides are multifunctional as effectors of innate immunity on skin and mucosal surfaces and have demonstrated direct antimicrobial activity against various bacteria, viruses, fungi, and parasites. This review summarizes their progress to date as commercial antimicrobial drugs for topical and systemic indications. Methods. Literature review. Results. Despite numerous clinical trials, no modified AMP has obtained Food & Drug Administration approval yet for any topical or systemic medical indications. Conclusions. While AMPs are recognized as essential components of natural host innate immunity against microbial challenge, their usefulness as a new class of antimicrobial drugs still remains to be proven. PMID:16020284

  15. Airway Epithelial Cells are the Site of Expression of a Mammalian Antimicrobial Peptide Gene

    NASA Astrophysics Data System (ADS)

    Diamond, Gill; Jones, Douglas E.; Bevins, Charles L.

    1993-05-01

    We previously reported the isolation and characterization of a broad-spectrum antimicrobial peptide from the bovine tracheal mucosa, which we called tracheal antimicrobial peptide (TAP). We now show the TAP gene is expressed throughout the adult conducting airway, from nasal to bronchiolar tissue, but not in tissues other than airway mucosa, as determined by Northern blot analysis. In situ hybridization of airway sections localizes TAP mRNA to columnar cells of the pseudostratified epithelium. We report the structural organization of the TAP gene and show that TAP is a member of a large family of related sequences with high nucleotide identity in the 5'exon. The data support the hypothesis that antimicrobial peptides contribute to host defense of the respiratory tract.

  16. Self-assembly of cationic multidomain peptide hydrogels: supramolecular nanostructure and rheological properties dictate antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Jiang, Linhai; Xu, Dawei; Sellati, Timothy J.; Dong, He

    2015-11-01

    Hydrogels are an important class of biomaterials that have been widely utilized for a variety of biomedical/medical applications. The biological performance of hydrogels, particularly those used as wound dressing could be greatly advanced if imbued with inherent antimicrobial activity capable of staving off colonization of the wound site by opportunistic bacterial pathogens. Possessing such antimicrobial properties would also protect the hydrogel itself from being adversely affected by microbial attachment to its surface. We have previously demonstrated the broad-spectrum antimicrobial activity of supramolecular assemblies of cationic multi-domain peptides (MDPs) in solution. Here, we extend the 1-D soluble supramolecular assembly to 3-D hydrogels to investigate the effect of the supramolecular nanostructure and its rheological properties on the antimicrobial activity of self-assembled hydrogels. Among designed MDPs, the bactericidal activity of peptide hydrogels was found to follow an opposite trend to that in solution. Improved antimicrobial activity of self-assembled peptide hydrogels is dictated by the combined effect of supramolecular surface chemistry and storage modulus of the bulk materials, rather than the ability of individual peptides/peptide assemblies to penetrate bacterial cell membrane as observed in solution. The structure-property-activity relationship developed through this study will provide important guidelines for designing biocompatible peptide hydrogels with built-in antimicrobial activity for various biomedical applications.Hydrogels are an important class of biomaterials that have been widely utilized for a variety of biomedical/medical applications. The biological performance of hydrogels, particularly those used as wound dressing could be greatly advanced if imbued with inherent antimicrobial activity capable of staving off colonization of the wound site by opportunistic bacterial pathogens. Possessing such antimicrobial properties would

  17. High Antimicrobial Activity and Low Human Cell Cytotoxicity of Core-Shell Magnetic Nanoparticles Functionalized with an Antimicrobial Peptide.

    PubMed

    Maleki, Hajar; Rai, Akhilesh; Pinto, Sandra; Evangelista, Marta; Cardoso, Renato M S; Paulo, Cristiana; Carvalheiro, Tiago; Paiva, Artur; Imani, Mohammad; Simchi, Abdolreza; Durães, Luísa; Portugal, António; Ferreira, Lino

    2016-05-11

    Superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with antimicrobial agents are promising infection-targeted therapeutic platforms when coupled with external magnetic stimuli. These antimicrobial nanoparticles (NPs) may offer advantages in fighting intracellular pathogens as well as biomaterial-associated infections. This requires the development of NPs with high antimicrobial activity without interfering with the biology of mammalian cells. Here, we report the preparation of biocompatible antimicrobial SPION@gold core-shell NPs based on covalent immobilization of the antimicrobial peptide (AMP) cecropin melittin (CM) (the conjugate is named AMP-NP). The minimal inhibitory concentration (MIC) of the AMP-NP for Escherichia coli was 0.4 μg/mL, 10-times lower than the MIC of soluble CM. The antimicrobial activity of CM depends on the length of the spacer between the CM and the NP. AMP-NPs are taken up by endothelial (between 60 and 170 pg of NPs per cell) and macrophage (between 18 and 36 pg of NPs per cell) cells and accumulate preferentially in endolysosomes. These NPs have no significant cytotoxic and pro-inflammatory activities for concentrations up to 200 μg/mL (at least 100 times higher than the MIC of soluble CM). Our results in membrane models suggest that the selectivity of AMP-NPs for bacteria and not eukaryotic membranes is due to their membrane compositions. The AMP-NPs developed here open new opportunities for infection-site targeting. PMID:27074633

  18. Antimicrobial functionalization of silicone surfaces with engineered short peptides having broad spectrum antimicrobial and salt-resistant properties.

    PubMed

    Li, Xiang; Li, Peng; Saravanan, Rathi; Basu, Anindya; Mishra, Biswajit; Lim, Suo Hon; Su, Xiaodi; Tambyah, Paul Anantharajah; Leong, Susanna Su Jan

    2014-01-01

    Catheter-associated urinary tract infections (CAUTIs) are often preceded by pathogen colonization on catheter surfaces and are a major health threat facing hospitals worldwide. Antimicrobial peptides (AMPs) are a class of new antibiotics that hold promise in curbing CAUTIs caused by antibiotic-resistant pathogens. This study aims to systematically evaluate the feasibility of immobilizing two newly engineered arginine/lysine/tryptophan-rich AMPs with broad antimicrobial spectra and salt-tolerant properties on silicone surfaces to address CAUTIs. The peptides were successfully immobilized on polydimethylsiloxane and urinary catheter surfaces via an allyl glycidyl ether (AGE) polymer brush interlayer, as confirmed by X-ray photoelectron spectroscopy and water contact angle analyses. The peptide-coated silicone surfaces exhibited excellent microbial killing activity towards bacteria and fungi in urine and in phosphate-buffered saline. Although both the soluble and immobilized peptides demonstrated membrane disruption capabilities, the latter showed a slower rate of kill, presumably due to reduced diffusivity and flexibility resulting from conjugation to the polymer brush. The synergistic effects of the AGE polymer brush and AMPs prevented biofilm formation by repelling cell adhesion. The peptide-coated surface showed no toxicity towards smooth muscle cells. The findings of this study clearly indicate the potential for the development of AMP-based coating platforms to prevent CAUTIs. PMID:24056098

  19. Antimicrobial properties of analgesic kyotorphin peptides unraveled through atomic force microscopy

    SciTech Connect

    Ribeiro, Marta M.B.; Franquelim, Henri G.; Torcato, Ines M.; Ramu, Vasanthakumar G.; Heras, Montserrat; Bardaji, Eduard R.; Castanho, Miguel A.R.B.

    2012-04-13

    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 defined 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

  20. 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

  1. The effect of thiol functional group incorporation into cationic helical peptides on antimicrobial activities and spectra.

    PubMed

    Wiradharma, Nikken; Khan, Majad; Yong, Lin-Kin; Hauser, Charlotte A E; Seow, See Voon; Zhang, Shuguang; Yang, Yi-Yan

    2011-12-01

    Antimicrobial peptides (AMP) have been proposed as blueprints for the development of new antimicrobial agents for the treatment of drug resistant infections. A series of synthetic AMPs capable of forming α-helical structures and containing free-sulfhydryl groups are designed in this study ((LLKK)(2)C, C(LLKK)(2)C, (LLKK)(3)C, C(LLKK)(3)C). In particular, the AMP with 2 cysteine residues at the terminal ends of the peptide and 2 repeat units of LLKK, i.e., C(LLKK)(2)C, has been demonstrated to have high selectivity towards a wide range of microbes from Gram-positive Bacillus subtilis, Gram-negative Escherichia coli, Pseudomonas aerogenosa, and yeast Candida albicans over red blood cells. At the MIC levels, this peptide does not induce significant hemolysis, and its MIC values occur at the concentration of more than 10 times of their corresponding 50% hemolysis concentrations (HC(50)). Microscopy studies suggest that this peptide kills microbial cells by inducing pores of ∼20-30 nm in size in microbial membrane on a short time scale, which further develops to grossly damaged membrane envelope on a longer time scale. Multiple treatments of microbes with this peptide at sub MIC concentration do not induce resistance, even up to passage 10. However, the same treatment with conventional antibiotics penicillin G or ciprofloxacin easily develop resistance in the treated microbes. In addition, the peptides are shown not to induce secretion of IFN-γ and TNF-α in human monocytes as compared to lipopolysaccharide, which implies additional safety aspects of the peptides to be used as both systemic and topical antimicrobial agents. Therefore, this study provides an excellent basis to develop promising antimicrobial agents that possess a broad range of antimicrobial activities with less susceptibility for development of drug resistance. PMID:21906803

  2. Obtaining antimicrobial peptides by controlled peptic hydrolysis of bovine hemoglobin.

    PubMed

    Adje, Estelle Yaba; Balti, Rafik; Kouach, Mostafa; Dhulster, Pascal; Guillochon, Didier; Nedjar-Arroume, Naïma

    2011-08-01

    Under standard conditions, the peptides and specially the active peptides were obtained from either the denatured hemoglobin that all structures are completely modified or either the native hemoglobin where all structures are intact. In these conditions, antibacterial peptides were isolated from a very complex peptidic hydrolysate which contains more than one hundred peptides having various sizes and characteristics, involving a complex purification process. The new hydrolysis conditions were obtained by using 40% methanol, 30% ethanol, 20% propanol or 10% butanol. These conditions, where only the secondary structure of hemoglobin retains intact, were followed in order to enrich the hydrolyzed hemoglobin by active peptides or obtain new antibacterial peptides. In these controlled peptic hydrolysis of hemoglobin, a selective and restrictive hydrolysate contained only 29 peptides was obtained. 26 peptides have an antibacterial activity against Micrococcus luteus, Listeria innocua, and Escherichia coli with MIC from 187.1 to 1 μM. Among these peptides, 13 new antibacterial peptides are obtained only in these new hydrolysis conditions. PMID:21510973

  3. Identification and Molecular Characterization of Molluskin, a Histone-H2A-Derived Antimicrobial Peptide from Molluscs

    PubMed Central

    Sathyan, Naveen; Philip, Rosamma; Chaithanya, E. R.; Anil Kumar, P. R.

    2012-01-01

    Antimicrobial peptides are humoral innate immune components of molluscs that provide protection against pathogenic microorganisms. Among these, histone-H2A-derived antimicrobial peptides are known to actively participate in host defense responses of molluscs. Present study deals with identification of putative antimicrobial sequences from the histone-H2A of back-water oyster Crassostrea madrasensis, rock oyster Saccostrea cucullata, grey clam Meretrix casta, fig shell Ficus gracilis, and ribbon bullia Bullia vittata. A 75 bp fragment encoding 25 amino acid residues was amplified from cDNA of these five bivalves and was named “Molluskin.” The 25 amino acid peptide exhibited high similarity to previously reported histone-H2A-derived AMPs from invertebrates indicating the presence of an antimicrobial sequence motif. Physicochemical properties of the peptides are in agreement with the characteristic features of antimicrobial peptides, indicating their potential role in innate immunity of molluscs.

  4. Modulation of the Activity of Secretory Phospholipase A2 by Antimicrobial Peptides

    PubMed Central

    Zhao, Hongxia; Kinnunen, Paavo K. J.

    2003-01-01

    The antimicrobial peptides magainin 2, indolicidin, and temporins B and L were found to modulate the hydrolytic activity of secretory phospholipase A2 (sPLA2) from bee venom and in human lacrimal fluid. More specifically, hydrolysis of phosphatidylcholine (PC) liposomes by bee venom sPLA2 at 10 μM Ca2+ was attenuated by these peptides while augmented product formation was observed in the presence of 5 mM Ca2+. The activity of sPLA2 towards anionic liposomes was significantly enhanced by the antimicrobial peptides at low [Ca2+] and was further enhanced in the presence of 5 mM Ca2+. Similarly, with 5 mM Ca2+ the hydrolysis of anionic liposomes was enhanced significantly by human lacrimal fluid sPLA2, while that of PC liposomes was attenuated. These results indicate that concerted action of antimicrobial peptides and sPLA2 could improve the efficiency of the innate response to infections. Interestingly, inclusion of a cationic gemini surfactant in the vesicles showed an essentially similar pattern on sPLA2 activity, suggesting that the modulation of the enzyme activity by the antimicrobial peptides may involve also charge properties of the substrate surface. PMID:12604528

  5. Conformational study of melectin and antapin antimicrobial peptides in model membrane environments.

    PubMed

    Kocourková, Lucie; Novotná, Pavlína; Čujová, Sabína; Čeřovský, Václav; Urbanová, Marie; Setnička, Vladimír

    2017-01-01

    Antimicrobial peptides have long been considered as promising compounds against drug-resistant pathogens. In this work, we studied the secondary structure of antimicrobial peptides melectin and antapin using electronic (ECD) and vibrational circular dichroism (VCD) spectroscopies that are sensitive to peptide secondary structures. The results from quantitative ECD spectral evaluation by Dichroweb and CDNN program and from the qualitative evaluation of the VCD spectra were compared. The antimicrobial activity of the selected peptides depends on their ability to adopt an amphipathic α-helical conformation on the surface of the bacterial membrane. Hence, solutions of different zwitterionic and negatively charged liposomes and micelles were used to mimic the eukaryotic and bacterial biological membranes. The results show a significant content of α-helical conformation in the solutions of negatively charged liposomes mimicking the bacterial membrane, thus correlating with the antimicrobial activity of the studied peptides. On the other hand in the solutions of zwitterionic liposomes used as models of the eukaryotic membranes, the fraction of α-helical conformation was lower, which corresponds with their moderate hemolytic activity. PMID:27450123

  6. Can antimicrobial peptides scavenge around a cell in less than a second?

    PubMed

    Chekmenev, Eduard Y; Vollmar, Breanna S; Cotten, Myriam

    2010-02-01

    Antimicrobial peptides, which play multiple host-defense roles, have garnered increased experimental focus because of their potential applications in the pharmaceutical and food production industries. While their mechanisms of action are richly debated, models that have been advanced share modes of peptide-lipid interactions that require peptide dynamics. Before the highly cooperative and specific events suggested in these models take place, peptides must undergo an important process of migration along the membrane surface and delivery from their site of binding on the membrane to the actual site of functional performance. This phenomenon, which contributes significantly to antimicrobial function, is poorly understood, largely due to a lack of experimental and computational tools needed to assess it. Here, we use (15)N solid-state nuclear magnetic resonance to obtain molecular level data on the motions of piscidin's amphipathic helices on the surface of phospholipid bilayers. The studies presented here may help contribute to a better understanding of the speed at which the events that lead to antimicrobial response take place. Specifically, from the perspective of the kinetics of cellular processes, we discuss the possibility that piscidins and perhaps many other amphipathic antimicrobial peptides active on the membrane surface may represent a class of fast scavengers rather than static polypeptides attached to the water-lipid interface. PMID:19735645

  7. Anticancer Activity of the Antimicrobial Peptide Scolopendrasin VII Derived from the Centipede, Scolopendra subspinipes mutilans.

    PubMed

    Lee, Joon Ha; Kim, In-Woo; Kim, Sang-Hee; Kim, Mi-Ae; Yun, Eun-Young; Nam, Sung-Hee; Ahn, Mi-Young; Kang, Dongchul; Hwang, Jae Sam

    2015-08-01

    Previously, we performed de novo RNA sequencing of Scolopendra subspinipes mutilans using high-throughput sequencing technology and identified several antimicrobial peptide candidates. Among them, a cationic antimicrobial peptide, scolopendrasin VII, was selected based on its physicochemical properties, such as length, charge, and isoelectric point. Here, we assessed the anticancer activities of scolopendrasin VII against U937 and Jurkat leukemia cell lines. The results showed that scolopendrasin VII decreased the viability of the leukemia cells in MTS assays. Furthermore, flow cytometric analysis and acridine orange/ethidium bromide staining revealed that scolopendrasin VII induced necrosis in the leukemia cells. Scolopendrasin VII-induced necrosis was mediated by specific interaction with phosphatidylserine, which is enriched in the membrane of cancer cells. Taken together, these data indicated that scolopendrasin VII induced necrotic cell death in leukemia cells, probably through interaction with phosphatidylserine. The results provide a useful anticancer peptide candidate and an efficient strategy for new anticancer peptide development. PMID:25907065

  8. Nanomechanical Response of Pseudomonas aeruginosa PAO1 Bacterial Cells to Cationic Antimicrobial Peptides

    NASA Astrophysics Data System (ADS)

    Lu, Shun; Walters, Grant; Dutcher, John

    2013-03-01

    We have used an atomic force microscopy (AFM)-based creep deformation technique to study changes to the viscoelastic properties of individual Gram-negative Pseudomonas aeruginosa PAO1 cells as a function of time of exposure to two cationic peptides: polymyxin B (PMB), a cyclic antimicrobial peptide, and the structurally-related compound, polymyxin B nonapeptide (PMBN). The measurements provide a direct measure of the mechanical integrity of the bacterial cell envelope, and the results can be understood in terms of simple viscoelastic models of arrangements of springs and dashpots, which can be ascribed to different components within the bacterial cell. Time-resolved creep deformation experiments reveal abrupt changes to the viscoelastic properties of P. aeruginosa bacterial cells after exposure to both PMB and PMBN, with quantitatively different changes for the two cationic peptides. These measurements provide new insights into the kinetics and mechanism of action of antimicrobial peptides on bacterial cells.

  9. Antimicrobial Peptide-Driven Colloidal Transformations in Liquid-Crystalline Nanocarriers.

    PubMed

    Gontsarik, Mark; Buhmann, Matthias T; Yaghmur, Anan; Ren, Qun; Maniura-Weber, Katharina; Salentinig, Stefan

    2016-09-01

    Designing efficient colloidal systems for the delivery of membrane active antimicrobial peptides requires in-depth understanding of their structural and morphological characteristics. Using dispersions of inverted type bicontinuous cubic phase (cubosomes), we examine the effect of integrating the amphiphilic peptide LL-37 at different concentrations on the self-assembled structure and evaluate its bactericidal ability against Escherichia coli. Small-angle X-ray scattering, dynamic light scattering, and cryogenic transmission electron microscopy show that LL-37 integrates into the bicontinuous cubic structure, inducing colloidal transformations to sponge and lamellar phases and micelles in a concentration-dependent manner. These investigations, together with in vitro evaluation studies using a clinically relevant bacterial strain, established the composition-nanostructure-activity relationship that can guide the design of new nanocarriers for antimicrobial peptides and may provide essential knowledge on the mechanisms underlying the bacterial membrane disruption with peptide-loaded nanostructures. PMID:27541048

  10. Scolopendin 2, a cationic antimicrobial peptide from centipede, and its membrane-active mechanism.

    PubMed

    Lee, Heejeong; Hwang, Jae-Sam; Lee, Jaeho; Kim, Jae Il; Lee, Dong Gun

    2015-02-01

    Scolopendin 2 is a 16-mer peptide (AGLQFPVGRIGRLLRK) derived from the centipede Scolopendra subspinipes mutilans. We observed that this peptide exhibited antimicrobial activity in a salt-dependent manner against various fungal and bacterial pathogens and showed no hemolytic effect in the range of 1.6 μM to 100 μM. Circular dichroism analysis showed that the peptide has an α-helical properties. Furthermore, we determined the mechanism(s) of action using flow cytometry and by investigating the release of intracellular potassium. The results showed that the peptide permeabilized the membranes of Escherichia coli O157 and Candida albicans, resulting in loss of intracellular potassium ions. Additionally, bis-(1,3-dibutylbarbituric acid) trimethine oxonol and 3,3'-dipropylthiacarbocyanine iodide assays showed that the peptide caused membrane depolarization. Using giant unilamellar vesicles encapsulating calcein and large unilamellar vesicles containing fluorescein isothiocyanate-dextran, which were similar in composition to typical E. coli O157 and C. albicans membranes, we demonstrated that scolopendin 2 disrupts membranes, resulting in a pore size between 4.8 nm and 5.0 nm. Thus, we have demonstrated that a cationic antimicrobial peptide, scolopendin 2, exerts its broad-spectrum antimicrobial effects by forming pores in the cell membrane. PMID:25462167