These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Photodynamic inactivation of recombinant bioluminescent Escherichia coli by cationic porphyrins under artificial and solar irradiation  

Microsoft Academic Search

A faster and simpler method to monitor the photoinactivation process of Escherichia coli involving the use of recombinant bioluminescent bacteria is described here. Escherichia coli cells were transformed with luxCDABE genes from the marine bioluminescent bacterium Vibrio fischeri and the recombinant bioluminescent indicator strain was used to assess, in real time, the effect of three cationic meso-substituted porphyrin derivatives on

Eliana Alves; Carla M. B. Carvalho; João P. C. Tomé; Maria A. F. Faustino; Maria G. P. M. S. Neves; Augusto C. Tomé; José A. S. Cavaleiro; Ângela Cunha; Sónia Mendo; Adelaide Almeida

2008-01-01

2

Antioxidant assay using genetically engineered bioluminescent Escherichia coli  

NASA Astrophysics Data System (ADS)

A new antioxidant activity assay based on the reactive oxygen species (ROS)-inducible bacterial strain (E. coli DPD2511) is described. The strain harbors the plasmid pKatG::luxCDABE and responds to hydrogen peroxide treatment by increasing light emission at 490 nm. Antioxidant capacity is evaluated through the ability of an agent to inhibit the hydrogen peroxide-induced bioluminescence of E. coli DPD2511. Applicability of the developed assay in detecting levels of antioxidants in various aqueous plant extracts is demonstrated. The assay was validated against 2,2-diphenylpicrylhydrazyl (DPPH) assay, a known antioxidant assay.

Bartolome, Amelita; Macalino, Bernadette; Pastoral, Ian Lemuel; Sevilla, Fortunato, III

2006-02-01

3

Photodynamic inactivation of bioluminescent Escherichia coli by neutral and cationic pyrrolidine-fused chlorins and isobacteriochlorins.  

PubMed

Photodynamic inactivation of bioluminescent Escherichia coli in the presence of cationic chlorin and isobacteriochlorin photosensitizers (PSs) obtained from 5,10,15,20-tetrakis(pentafluorophenyl)-porphyrin is described. The spectroscopic data for the neutral and cationic derivatives and their photophysical characterizations, especially fluorescence and singlet oxygen generation capacity are also reported. The results show that there is a direct relation between the inactivation efficiency and the increasing number of charges on the molecules. The combined effect of higher wavelength absorption and number of positive charges on the PS shows a 6.1 log reduction during the inactivation process. Overall this study shows that the cationic isobacteriochlorin has high potential to be used as PS for the inactivation of Gram (-) bacteria. PMID:24424133

Mesquita, Mariana Q; Menezes, José C J M D S; Neves, Maria G P M S; Tomé, Augusto C; Cavaleiro, José A S; Cunha, Ângela; Almeida, Adelaide; Hackbarth, Steffen; Röder, Beate; Faustino, M Amparo F

2014-02-01

4

Postantibiotic effect of beta-lactam antibiotics on Escherichia coli evaluated by bioluminescence assay of bacterial ATP.  

PubMed Central

The in vitro postantibiotic effects (PAE) of aztreonam, ceftazidime, cefuroxime, imipenem, and piperacillin on Escherichia coli ATCC 25922 were studied by a bioluminescence assay of bacterial ATP. In parallel with the PAE investigation, viability and morphology studies were performed. The strain was exposed for 2 h to different concentrations of beta-lactam antibiotics. The antibiotic activity was eliminated by 10(-4) dilutions, and regrowth of bacteria was monitored hourly by the bioluminescence assay of bacterial ATP. The length of PAE was dose dependent for ceftazidime (0.5 to 2.6 h), cefuroxime (0.4 to 2.6 h), and imipenem (0.3 to 4.5 h). The long PAE for these antibiotics at higher concentrations was associated with a potent initial killing and the presence of spheroplasts. Aztreonam and piperacillin produced a short, non-dose-dependent PAE (0.4 to 0.95 h). Short PAEs (below 1 h) were seen concomitantly with production of filaments, except in the case of imipenem, which only produced spheroplasts. The bioluminescence method was not jeopardized by filament formation, in contrast to the viable count assay which is normally used for PAE investigations. This makes it possible to study PAE for beta-lactam antibiotics on gram-negative bacteria with bioluminescence. PMID:2183707

Hanberger, H; Nilsson, L E; Kihlström, E; Maller, R

1990-01-01

5

Activation of bioluminescence of sensor Escherichia coli srains used to detect N -acyl-homoserine lactones in presence of nitrofurans and NO generators  

Microsoft Academic Search

Nitrofurans (nitrofurazone, nitrofurantoin, furazidin, nifuroxazide) and nitric oxide generators (sodium nitroprusside and\\u000a isosorbide mononitrate) in subinhibitory concentrations were shown to significantly increase the bioluminescence of the sensor\\u000a Escherichia coli strains used to detect N-acyl-homoserine lactones, which are signal molecules of quorum sensing (QS) regulatory systems. The highest activation of\\u000a bioluminescence (up to 250–400-fold) was observed in the presence of the

Yu. V. Zaitseva; V. G. Granik; A. S. Belik; O. A. Koksharova; I. A. Khmel

2010-01-01

6

LuxCDABE--transformed constitutively bioluminescent Escherichia coli for toxicity screening: comparison with naturally luminous Vibrio fischeri.  

PubMed

We show that in vitro toxicity assay based on inhibition of the bioluminescence of recombinant Escherichia coli encoding thermostable luciferase from Photorhabdus luminescens is a versatile alternative to Vibrio fischeri Microtox™ test. Performance of two luxCDABE-transformed E. coli MC1061 constructs (pDNlux) and (pSLlux) otherwise identical, but having 100-fold different background luminescence was compared with the performance of V. fischeri. The microplate luminometer and a kinetic Flash-Assay test format was used that differently from Microtox test is also applicable for high throughput analysis. Toxic effects (30-s till 30-min EC(50)) of four heavy metals (Zn, Cd, Hg, Cu) and three organic chemicals (aniline, 3,5-dichloroaniline and 3,5-dichlorophenol) were studied. Both E. coli strains had comparable sensitivity and the respective 30-min EC(50) values highly correlated (log-log R(2) = 0.99; p < 0.01) showing that the sensitivity of the recombinant bacteria towards chemicals analyzed did not depend on the bioluminescence level of the recombinant cells. The most toxic chemical for all used bacterial strains (E. coli, V. fischeri) was mercury whereas the lowest EC(50) values for Hg (0.04-0.05 mg/L) and highest EC(50) values for aniline (1,300-1,700 mg/L) were observed for E. coli strains. Despite of that, toxicity results obtained with both E. coli strains (pSLlux and pDNlux) significantly correlated with V. fischeri results (log-log R(2) = 0.70/0.75; p < 0.05/0.01). The use of amino acids (0.25%) and glucose (0.05%)-supplemented M9 medium instead of leucine-supplemented saline significantly (p < 0.05) reduced the apparent toxicity of heavy metals to both E. coli strains up to three orders of magnitude, but had little or no complexing effect on organic compounds. Thus, P. luminescens luxCDABE-transformed E. coli strains can be successfully used for the acute toxicity screening of various types of organic chemicals and heavy metals and can replace V. fischeri in certain cases where the thermostability of luciferase >30 °C is crucial. The kinetic Flash Assay test format of the bioluminescence inhibition assay facilitates high throughput analysis. The assay medium, especially in case of testing heavy metals should be a compromise: optimal for the viability/luminescence of the recombinant test strain and of minimum complexing potential. PMID:22164050

Kurvet, Imbi; Ivask, Angela; Bondarenko, Olesja; Sihtmäe, Mariliis; Kahru, Anne

2011-01-01

7

LuxCDABE—Transformed Constitutively Bioluminescent Escherichia coli for Toxicity Screening: Comparison with Naturally Luminous Vibrio fischeri  

PubMed Central

We show that in vitro toxicity assay based on inhibition of the bioluminescence of recombinant Escherichia coli encoding thermostable luciferase from Photorhabdus luminescens is a versatile alternative to Vibrio fischeri Microtox™ test. Performance of two luxCDABE-transformed E. coli MC1061 constructs (pDNlux) and (pSLlux) otherwise identical, but having 100-fold different background luminescence was compared with the performance of V. fischeri. The microplate luminometer and a kinetic Flash-Assay test format was used that differently from Microtox test is also applicable for high throughput analysis. Toxic effects (30-s till 30-min EC50) of four heavy metals (Zn, Cd, Hg, Cu) and three organic chemicals (aniline, 3,5-dichloroaniline and 3,5-dichlorophenol) were studied. Both E. coli strains had comparable sensitivity and the respective 30-min EC50 values highly correlated (log-log R2 = 0.99; p < 0.01) showing that the sensitivity of the recombinant bacteria towards chemicals analyzed did not depend on the bioluminescence level of the recombinant cells. The most toxic chemical for all used bacterial strains (E. coli, V. fischeri) was mercury whereas the lowest EC50 values for Hg (0.04–0.05 mg/L) and highest EC50 values for aniline (1,300–1,700 mg/L) were observed for E. coli strains. Despite of that, toxicity results obtained with both E. coli strains (pSLlux and pDNlux) significantly correlated with V. fischeri results (log-log R2 = 0.70/0.75; p < 0.05/0.01). The use of amino acids (0.25%) and glucose (0.05%)-supplemented M9 medium instead of leucine-supplemented saline significantly (p < 0.05) reduced the apparent toxicity of heavy metals to both E. coli strains up to three orders of magnitude, but had little or no complexing effect on organic compounds. Thus, P. luminescens luxCDABE-transformed E. coli strains can be successfully used for the acute toxicity screening of various types of organic chemicals and heavy metals and can replace V. fischeri in certain cases where the thermostability of luciferase >30 °C is crucial. The kinetic Flash Assay test format of the bioluminescence inhibition assay facilitates high throughput analysis. The assay medium, especially in case of testing heavy metals should be a compromise: optimal for the viability/luminescence of the recombinant test strain and of minimum complexing potential. PMID:22164050

Kurvet, Imbi; Ivask, Angela; Bondarenko, Olesja; Sihtmäe, Mariliis; Kahru, Anne

2011-01-01

8

[Activation of the bioluminescence of the sensor Escherichia coli strains used for detecting N-acyl-homoserine lactones in the presence of nitrofurans and NO generators].  

PubMed

Nitrofurans (nitrofurazone, nitrofurantoin, furazidin, nifuroxazide), and nitric oxide generators (sodium nitroprusside and isosorbide mononitrate) in subinhibitory concentrations were shown to significantly increase the bioluminescence of the sensor Escherichia coli strains used for detecting N-acyl-homoserine lactones, signaling molecules of Quorum Sensing (QS) regulatory systems. The highest activation of bioluminescence (up to 250-400 fold) was observed in the presence of nitrofurazone on E. coli DH5alpha biosensors containing lux-reporter plasmids pSB401 or pSB536. However, this activation was not specifically associated with the functioning of QS systems. We suggest that the effect observed results from a direct action of nitrofurans and NO donors on the process of bioluminescence. The data indicate the necessity of using the biosensors that make it possible to detect specific effects of substances tested on QS regulation. PMID:20540359

Za?tseva, Iu V; Granik, V G; Belik, A S; Koksharova, O A; Khmel', I A

2010-01-01

9

Some observations in freeze-drying of recombinant bioluminescent Escherichia coli for toxicity monitoring  

Microsoft Academic Search

A recombinant bioluminescent bacteria, containing a fabA::luxCDABE fusion gene, has been used to characterize freeze-drying methods, which may be conveniently used as a tool for the development of a portable biosensor. Through residual water, viability, biosensing activity and scanning electron microscopy analyses, the characteristics that four cryoprotectants, trehalose, sucrose, sorbitol, and mannitol, conferred on freeze-dried samples were elucidated, including the

Man Bock Gu; Sue Hyung Choi; Sung Woo Kim

2001-01-01

10

Ex Vivo Bioluminescence Imaging of Late Gestation Ewes Following Intra-uterine Inoculation With Lux-modified Escherichia coli  

Technology Transfer Automated Retrieval System (TEKTRAN)

Our objectives were to develop an ovine model for Escherichia coli-induced preterm delivery, and monitor E. coli (lux modified for photonic detection) invasion of the fetal environment—ewes (124 ± 18 d of gestation) received intrauterine inoculations using E. coli-lux as follows: control (n = 5), 1....

11

Escherichia Coli  

ERIC Educational Resources Information Center

Diverse biological data may be used to create illustrations of molecules in their cellular context. I describe the scientific results that support a recent textbook illustration of an "Escherichia coli cell". The image magnifies a portion of the bacterium at one million times, showing the location and form of individual macromolecules. Results…

Goodsell, David S.

2009-01-01

12

Diarrheagenic Escherichia coli  

PubMed Central

Escherichia coli is the predominant nonpathogenic facultative flora of the human intestine. Some E. coli strains, however, have developed the ability to cause disease of the gastrointestinal, urinary, or central nervous system in even the most robust human hosts. Diarrheagenic strains of E. coli can be divided into at least six different categories with corresponding distinct pathogenic schemes. Taken together, these organisms probably represent the most common cause of pediatric diarrhea worldwide. Several distinct clinical syndromes accompany infection with diarrheagenic E. coli categories, including traveler’s diarrhea (enterotoxigenic E. coli), hemorrhagic colitis and hemolytic-uremic syndrome (enterohemorrhagic E. coli), persistent diarrhea (enteroaggregative E. coli), and watery diarrhea of infants (enteropathogenic E. coli). This review discusses the current level of understanding of the pathogenesis of the diarrheagenic E. coli strains and describes how their pathogenic schemes underlie the clinical manifestations, diagnostic approach, and epidemiologic investigation of these important pathogens. PMID:9457432

Nataro, James P.; Kaper, James B.

1998-01-01

13

Pathogenic Escherichia coli  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli, a member of the Enterobacteriaceae family, is a part of the normal flora of the intestinal tract of humans and a variety of animals. E. coli strains are classified on the basis of antigenic differences in two surface components (serotyping), the somatic antigen (O) of the lipopoly...

14

Genetic recombination. [Escherichia coli  

SciTech Connect

The molecular pathways of gene recombination are explored and compared in studies of the model organisms, Escherichia coli and phase lambda. In the discussion of data from these studies it seems that recombination varies with the genetic idiosyncrasies of the organism and may also vary within a single organism.

Stahl, F.W.

1987-02-01

15

Recurrent Escherichia coli bacteremia.  

PubMed

Escherichia coli is the most common gram-negative organism associated with bacteremia. While recurrent E. coli urinary tract infections are well-described, recurrent E. coli bacteremia appears to be uncommon, with no episodes noted in multiple series of patients with gram-negative bacteremias. We report on 5 patients with recurrent bloodstream infections identified from a series of 163 patients with E. coli bacteremia. For each patient, the isolates from each episode were analyzed by pulsed-field gel electrophoresis (PFGE) and ribotyping and for the presence of E. coli virulence factors. For each of four patients, the index and recurrent episodes of bacteremia represented the same strain as defined by PFGE, and the strains were found to carry one or more virulence factors. The remaining patient, with two episodes of bloodstream infection separated by a 4-year interval, was infected with two isolates that did not carry any virulence factors and that were clonally related by ribotype analysis but differed by PFGE. All five patients had either a local host defense defect (three patients) or impaired systemic defenses (one patient) or both (one patient). Thus, recurrent E. coli bacteremia is likely to represent a multifactorial process that occurs in patients with impaired host defenses who are infected with virulent isolates. PMID:7910828

Maslow, J N; Mulligan, M E; Arbeit, R D

1994-03-01

16

Monitoring of bactericidal action of laser by in vivo imaging of bioluminescent E. coli in a cutaneous wound infection  

Microsoft Academic Search

The worldwide rise in antibiotic resistance necessitates the development of novel antimicrobial strategies. This study aimed to evaluate the bactericidal action of an 810-nm diode laser in a cutaneous wound infection. An Escherichia coli strain was transformed with a shuttle vector (pRB474) containing firefly luciferase gene from Photinus pyralis resulting in a bioluminescent phenotype. Because firefly luciferase is an enzyme

Samir Jawhara; Serge Mordon

2006-01-01

17

Aging of Escherichia coli  

PubMed Central

Clifton, C. E. (Stanford University, Stanford, Calif.). Aging of Escherichia coli. J. Bacteriol. 92:905–912. 1966.—The rates of endogenous and exogenous (glucose) respiration decreased much more rapidly than did the viable count during the first 24 hr of aging of washed, C14-labeled cells of Escherichia coli K-12 suspended in a basal salt medium devoid of ammonium salts. The rates of decrease of respiration and of death approached each other as the age of the cells increased, but death was not the only factor involved in decreased respiratory activity of the suspensions. The greatest decrease in cellular contents with aging was noted in the ribonucleic acid fraction, of which the ribose appeared to be oxidized, while uracil accumulated in the suspension medium. The viable count and respiratory activities remained higher in glucose-fed than in nonfed suspensions. Proline-labeled cells fed glucose tended to lose more of their proline and to convert more proline into C14O2 than in unfed controls. On the other hand, uracil-labeled cells fed glucose retained more of the uracil than did nonfed cells, but glucose elicited some oxidation of uracil. An exogenous energy source such as glucose aided in the maintenance of a population, but it was not the only factor needed for such maintenance. PMID:5332874

Clifton, C. E.

1966-01-01

18

PATHOGENIC ESCHERICHIA COLI IN FOODS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pathogenic Escherichia coli are defined as those E. coli strains that are capable of causing diarrhoeal disease in humans. Subdivision of the pathogenic forms is made on the basis of the mechanism underlying the illness. Presently, four types of pathogenic E. coli have been implicated in foodborne...

19

Biotyping of Escherichia coli.  

PubMed

We examined the results of tests with 22 substrates for their ability to discriminate a series of 917 strains of Escherichia coli collected from different sources. The tests with three of the substrates were discarded because of difficulties in performance or interpretation, and another nine substrates because they provided little discrimination. The tests used to obtain biotype profiles for strains were those for the fermentation of dulcitol, D-raffinose or sucrose or both, L-rhamnose and L-sorbose, the decarboxylation of L-lysine and L-ornithine, the hydrolysis of aesculin, motility, and prototrophy. Observations on several series of cultures from different sources showed that biotype characters were stable in vivo and after storage on non-selective medium. The biotype profiles obtained were as reliable as partial O serotyping for the routine subtyping of strains of E. coli isolated from the urine of patients with long-term urinary-tract infections and those from other sources in different patients. Biotyping and O serotyping used in conjuction offered a very fine degree of strain discrimination. PMID:390154

Crichton, P B; Old, D C

1979-11-01

20

Review article Enterotoxigenic Escherichia coli (ETEC)  

E-print Network

Review article Enterotoxigenic Escherichia coli (ETEC) in farm animals Béla Nagy* Péter Zs. Fekete to enterotoxigenic Escherichia coli (ETEC) typically appear as severe watery diarrhoea during the first few days a population of E. coli with a diverse genetic background. @ Inra/Elsevier, Paris. enterotoxin / fimbria

Paris-Sud XI, Université de

21

Bioluminescence  

NSDL National Science Digital Library

This Bioluminescence webpage is an entry in Kimball's online biology textbook. It discusses the ability of living things to emit light, the various molecules involved, how fireflies control their flashing, and bioluminescence in marine organisms.

Kimball, John W.; Pages, Kimball'S B.

22

Bioluminescence.  

ERIC Educational Resources Information Center

Describes bioluminescence and the chemistry of how it occurs. Presents information for conducting the following classroom activities: (1) firefly mimic; (2) modeling deep-sea fish; (3) sea fireflies; and (4) the chemistry of light. (PR)

Jones, M. Gail

1993-01-01

23

Cardiolipin synthase from Escherichia coli.  

PubMed

Escherichia coli cardiolipin synthase catalyzes reversible phosphatidyl group transfer from one phosphatidylglycerol molecule to another to form cardiolipin (CL) and glycerol. The enzyme is specified by the cls gene, located at min 28.02 of the E. coli genetic map. Cells with mutations in cls have longer doubling times, tend to lose viability in the stationary phase, are more resistant to 3,4-dihydroxybutyl-1-phosphonate, and have an altered sensitivity to novobiocin. Although cls null mutants appear to lack CL synthase activity, they are still able to form trace quantities of CL. The enzyme appears to be regulated at both the genetic and enzymatic levels. CL synthase's molecular mass is 45-46 kDa, or about 8 kDa less than the polypeptide predicted by the gene sequence, suggesting that posttranslational processing occurs. CL synthase can use various polyols such as mannitol and arabitol to convert CL to the corresponding phosphatidylglycerol analog. When the amino acid sequences of four bacterial CL synthases are compared, three highly conserved regions are apparent. One of these regions contains a conserved pentapeptide sequence, RN(Q)HRK, and another has a conserved HXK sequence. These two sequences may be part of the active site. E. coli CL synthase has been studied by using a mixed micelle assay. The enzyme is inhibited by CL, the product of the reaction, and by phosphatidate. Phosphatidylethanolamine partially offsets inhibition caused by CL but not by phosphatidate. CDP-diacylglycerol does not appear to affect the activity of the purified enzyme but does stimulate the activity associated with crude membrane preparations. PMID:9370333

Tropp, B E

1997-09-01

24

Recombinant collagen production optimization in Escherichia coli  

E-print Network

An Escherichia coli-based collagen-production process was used to investigate several process optimization objectives for use at the industrial scale. The effect of cooling on fermentation growth kinetics was studied, with ...

Whittemore, Brett A

2005-01-01

25

High level indole signalling in Escherichia coli  

E-print Network

Chapter 1 Introduction 16 1.1 Bacterial Communication and Signalling Bacteria are able to produce and use a wide variety of chemical signals to communicate. They are able to utilise these messages to better respond to changing environments... indole signalling in Escherichia coli Abstract Indole is a small signalling molecule, produced by many species of bacteria, including Escherichia coli. It is made by the enzyme tryptophanase, which converts tryptophan into indole, pyruvate and ammonia...

Gaimster, Hannah Dorne

2014-06-10

26

Strategies for Protein Overproduction in Escherichia coli.  

ERIC Educational Resources Information Center

Examines heterologous expression in Escherichia coli and the role of regulatory sequences which control gene expression at transcription resulting in abundant production of messenger RNA and regulatory sequences in mRNA which promote efficient translation. Also examines the role of E. coli cells in stabilizing mRNA and protein that is…

Mott, John E.

1984-01-01

27

Succinate production in Escherichia coli  

PubMed Central

Succinate has been recognized as an important platform chemical that can be produced from biomass. While a number of organisms are capable of succinate production naturally, this review focuses on the engineering of Escherichia coli for production of the four-carbon dicarboxylic acid. Important features of a succinate production system are to achieve optimal balance of reducing equivalents generated by consumption of the feedstock, while maximizing the amount of carbon that is channeled to the product. Aerobic and anaerobic production strains have been developed and applied to production from glucose as well as other abundant carbon sources. Metabolic engineering methods and strain evolution have been used and supplemented by the recent application of systems biology and in silico modeling tools to construct optimal production strains. The metabolic capacity of the production strain, as well as the requirement for efficient recovery of succinate and the reliability of the performance under scale-up are important in the overall process. The costs of the overall biorefinery compatible process will determine the economical commercialization of succinate and its impact in larger chemical markets. PMID:21932253

Thakker, Chandresh; Martínez, Irene; San, Ka-Yiu; Bennett, George N.

2012-01-01

28

Asparagine Utilization in Escherichia coli  

PubMed Central

Asparagine-requiring auxotrophs of Escherichia coli K-12 that have an active cytoplasmic asparaginase do not conserve asparagine supplements for use in protein synthesis. Asparagine molecules entering the cell in excess of the pool required for use of this amino acid in protein synthesis are rapidly degraded rather than accumulated. Supplements are conserved when asparagine degradation is inhibited by the asparagine analogue 5-diazo-4-oxo-l-norvaline (DONV) or mutation to cytoplasmic asparaginase deficiency. A strain deficient in cytoplasmic asparaginase required approximately 260 ?mol of asparagine for the synthesis of 1 g of cellular protein. The cytoplasmic asparaginase (asparaginase I) is required for growth of cells when asparagine is the nitrogen source. This enzyme has an apparent Km for l-asparagine of 3.5 mM, and asparaginase activity is competitively inhibited by DONV with an apparent Ki of 2 mM. The analogue provides a time-dependent, irreversible inhibition of cytoplasmic asparaginase activity in the absence of asparagine. PMID:4595199

Willis, R. C.; Woolfolk, C. A.

1974-01-01

29

Infection strategies of enteric pathogenic Escherichia coli  

PubMed Central

Enteric Escherichia coli (E. coli) are both natural flora of humans and important pathogens causing significant morbidity and mortality worldwide. Traditionally enteric E. coli have been divided into 6 pathotypes, with further pathotypes often proposed. In this review we suggest expansion of the enteric E. coli into 8 pathotypes to include the emerging pathotypes of adherent invasive E. coli (AIEC) and Shiga-toxin producing enteroaggregative E. coli (STEAEC). The molecular mechanisms that allow enteric E. coli to colonize and cause disease in the human host are examined and for two of the pathotypes that express a type 3 secretion system (T3SS) we discuss the complex interplay between translocated effectors and manipulation of host cell signaling pathways that occurs during infection. PMID:22555463

Clements, Abigail; Young, Joanna C.; Constantinou, Nicholas; Frankel, Gad

2012-01-01

30

Firefly luciferase as the reporter for transcriptional response to the environment in Escherichia coli.  

PubMed

We demonstrate that firefly luciferase is a good reporter in Escherichia coli for transcription dynamics in response to the environment. E. coli strains, carrying a fusion of the promoter of the ycgZ gene and the coding region of the luciferase gene, showed transient bioluminescence on receiving blue light. This response was compromised in mutants lacking known regulators in manners consistent with each regulator's function. We also show that relA, a gene encoding a (p)ppGpp synthetase, affects ycgZ dynamics when nullified. Moreover, two unstable luciferase variants showed improved response dynamics and should be useful to study quick changes of gene expression. PMID:24012794

Ryo, Masashi; Oshikoshi, Yuta; Doi, Shosei; Motoki, Shogo; Niimi, Atsuko; Aoki, Setsuyuki

2013-12-15

31

Native valve Escherichia coli endocarditis following urosepsis  

PubMed Central

Gram-negative organisms are a rare cause of infective endocarditis. Escherichia coli, the most common cause of urinary tract infection and gram-negative septicemia involves endocardium rarely. In this case report, we describe infection of native mitral valve by E. coli following septicemia of urinary tract origin in a diabetic male; subsequently, he required prosthetic tissue valve replacement indicated by persistent sepsis and congestive cardiac failure. PMID:23814428

Rangarajan, D.; Ramakrishnan, S.; Patro, K. C.; Devaraj, S.; Krishnamurthy, V.; Kothari, Y.; Satyaki, N.

2013-01-01

32

Chaperone-Usher Fimbriae of Escherichia coli  

PubMed Central

Chaperone-usher (CU) fimbriae are adhesive surface organelles common to many Gram-negative bacteria. Escherichia coli genomes contain a large variety of characterised and putative CU fimbrial operons, however, the classification and annotation of individual loci remains problematic. Here we describe a classification model based on usher phylogeny and genomic locus position to categorise the CU fimbrial types of E. coli. Using the BLASTp algorithm, an iterative usher protein search was performed to identify CU fimbrial operons from 35 E. coli (and one Escherichia fergusonnii) genomes representing different pathogenic and phylogenic lineages, as well as 132 Escherichia spp. plasmids. A total of 458 CU fimbrial operons were identified, which represent 38 distinct fimbrial types based on genomic locus position and usher phylogeny. The majority of fimbrial operon types occupied a specific locus position on the E. coli chromosome; exceptions were associated with mobile genetic elements. A group of core-associated E. coli CU fimbriae were defined and include the Type 1, Yad, Yeh, Yfc, Mat, F9 and Ybg fimbriae. These genes were present as intact or disrupted operons at the same genetic locus in almost all genomes examined. Evaluation of the distribution and prevalence of CU fimbrial types among different pathogenic and phylogenic groups provides an overview of group specific fimbrial profiles and insight into the ancestry and evolution of CU fimbriae in E. coli. PMID:23382825

Wurpel, Daniël J.; Beatson, Scott A.; Totsika, Makrina; Petty, Nicola K.; Schembri, Mark A.

2013-01-01

33

Beta-alanine synthesis in Escherichia coli.  

PubMed Central

The enzyme, aspartate 1-decarboxylase (L-aspartate 1-carboxy-lyase; EC 4.1.1.15), that catalyzes the reaction aspartate leads to beta-alanine + CO2 was found in extracts of Escherichia coli. panD mutants of E. coli are defective in beta-alanine biosynthesis and lack aspartate 1-decarboxylase. Therefore, the enzyme functions in the biosynthesis of the beta-alanine moiety of pantothenate. The genetic lesion in these mutants is closely linked to the other pantothenate (pan) loci of E. coli K-12. Images PMID:6767707

Cronan, J E

1980-01-01

34

Escherichia Coli--Key to Modern Genetics.  

ERIC Educational Resources Information Center

Mid-nineteenth century work by Mendel on plant hybrids and by Pasteur on fermentation gave birth by way of bacterial genetics to modern-day molecular biology. The bacterium Escherichia Coli has occupied a key position in genetic studies leading from early gene identification with DNA to current genetic engineering using recombinant DNA technology.…

Bregegere, Francois

1982-01-01

35

Maltoheptaose Promotes Nanoparticle Internalization by Escherichia coli  

PubMed Central

Nanoparticles conjugated with D-maltoheptaose (G7) showed a striking increase in the internalization by Escherichia coli. This applies to strains with and without the maltodextrin transport channel and particles ranging from a few to a hundred nanometers. PMID:23463337

Jayawardena, Surangi; Jayawardana, Kalana; Chen, Xuan

2013-01-01

36

Engineering ethanologenic Escherichia coli for levoglucosan utilization  

Microsoft Academic Search

Levoglucosan is a major product of biomass pyrolysis. While this pyrolyzed biomass, also known as bio-oil, contains sugars that are an attractive fermentation substrate, commonly-used biocatalysts, such as Escherichia coli, lack the ability to metabolize this anhydrosugar. It has previously been shown that recombinant expression of the levoglucosan kinase enzyme enables use of levoglucosan as carbon and energy source. Here,

Donovan S. Layton; Avanthi Ajjarapu; Dong Won Choi; Laura R. Jarboe

2011-01-01

37

Escherichia coli in Europe: An Overview  

PubMed Central

Escherichia coli remains one of the most frequent causes of several common bacterial infections in humans and animals. E. coli is the prominent cause of enteritis, urinary tract infection, septicaemia and other clinical infections, such as neonatal meningitis. E. coli is also prominently associated with diarrhoea in pet and farm animals. The therapeutic treatment of E. coli infections is threatened by the emergence of antimicrobial resistance. The prevalence of multidrug-resistant E. coli strains is increasing worldwide principally due to the spread of mobile genetic elements, such as plasmids. The rise of multidrug-resistant strains of E. coli also occurs in Europe. Therefore, the spread of resistance in E. coli is an increasing public health concern in European countries. This paper summarizes the current status of E. coli strains clinically relevant in European countries. Furthermore, therapeutic interventions and strategies to prevent and control infections are presented and discussed. The article also provides an overview of the current knowledge concerning promising alternative therapies against E. coli diseases. PMID:24287850

Allocati, Nerino; Masulli, Michele; Alexeyev, Mikhail F.; Di Ilio, Carmine

2013-01-01

38

Functional proteomics in Escherichia coli  

E-print Network

-state of E. coli corresponding to hundreds of unique gene products. The copurification of proteins when fractionated at varying pHs could suggest the components of higher order complexes. This non-denaturing proteomic approach should provide physiological...

Champion, Matthew Maurice

2006-04-12

39

Biosynthesis of 4-Aminobenzoate in Escherichia coli  

PubMed Central

Two different mutations (pabA and pabB) affecting 4-aminobenzoate biosynthesis were obtained in strains of Escherichia coli lacking chorismate mutase and anthranilate synthetase activity, thus allowing study of the pathway of biosynthesis of 4-aminobenzoate by use of cell extracts of strains carrying the pab mutations. Two components with approximate molecular weights of 9,000 (component A) and 48,000 (component B) are concerned in the biosynthesis of 4-aminobenzoate from chorismate by E. coli. No diffusible intermediate compound could be detected. PMID:4914080

Huang, Minta; Gibson, F.

1970-01-01

40

Rotation of Escherichia coli F 1ATPase  

Microsoft Academic Search

By applying the same method used for F1-ATPase (TF1) from thermophilic Bacillus PS3 (Noji, H., Yasuda, R., Yoshida, M., and Kinosita, K., Jr. (1997) Nature 386, 299–302), we observed ATP-driven rotation of a fluorescent actin filament attached to the ? subunit in Escherichia coli F1-ATPase. The torque value and the direction of the rotation were the same as those observed

Hiroyuki Noji; Katrin Häsler; Wolfgang Junge; Kazuhiko Kinosita; Masasuke Yoshida; Siegfried Engelbrecht

1999-01-01

41

Energetics of sodium efflux from Escherichia coli.  

PubMed

When energy-starved cells of Escherichia coli were passively loaded with 22Na+, efflux of sodium could be initiated by addition of a source of metabolic energy. Conditions were established where the source of energy was phosphate bond energy, an electrochemical proton gradient, or both. Only an electrochemical proton gradient was required for efflux from intact cells. These results are consistent with secondary exchange of Na+ for H+ catalyzed by a sodium/proton antiporter. PMID:6322694

Borbolla, M G; Rosen, B P

1984-02-15

42

Response of bioluminescent bacteria to sixteen azo dyes  

Microsoft Academic Search

Recombinant bioluminescent bacteria were used to monitor and classify the toxicity of azo dyes. Two constitutive bioluminescent\\u000a bacteria,Photobacterium phosphoreum andEscherichia coli, E. coli GC2 (lac::luxCDABE), were used to detect the cellular toxicity of the azo dyes. In addition, four stress-inducible bioluminescentE. coli, DPD2794 (recA::luxCDABE), a DNA damage sensitive strain; DPD2540 (fabA::luxCDABE), a membrane damage sensitive strain; DPD2511 (katG::luxCDABE), an oxidative

Hwa Young Lee; Sue Hyung Choi; Man Bock Gu

2003-01-01

43

Action of sodium deoxycholate on Escherichia coli  

SciTech Connect

Sodium deoxycholate is used in a number of bacteriological media for the isolation and classification of gram-negative bacteria from food and the environment. Initial experiments to study the effect of deoxycholate on the growth parameters of Escherichia coli showed an increase in the lag time constant and generation time and a decrease in the growth rate constant total cell yield of this microorganisms. Cell fractionation studies indicated that sodium deoxycholate at levels used in bacteriological media interferes with the incorporation of (U-/sup 14/C)glucose into the cold-trichloroacetic acid-soluble, ethanol-soluble, and trypsin-soluble cellular fractions of E. coli. Finally, sodium deoxycholate interfered with the flagellation and motility of Proteus mirabilis and E. coli. It would appear then that further improvement of the deoxycholate medium may be in order.

D'Mello, A.; Yotis, W.W.

1987-08-01

44

Biotyping of Escherichia coli in microwell plates.  

PubMed

A simple, inexpensive scheme of eight tests for biotyping strains of Escherichia coli in microwell plates is described. The tests comprise primary tests for the fermentation of raffinose, sorbose, ornithine, dulcitol and 2-deoxy-D-ribose, and secondary tests for rhamnose fermentation, lysine decarboxylation and motility. Among a collection of 75 clinical isolates of Esch. coli from 12 patients, 18 full biotypes designated according to their positive and negative reactions in the eight tests were distinguished. These biotypes gave an indication of the natural history of patients' infections. Because it provides excellent and reliable type discrimination, biotyping can be used in a combination with other typing techniques to resolve local epidemiological problems involving Esch. coli. PMID:8527993

Crichton, P B; Taylor, A

1995-09-01

45

Detection of DNA Damage by Use of Escherichia coli Carrying recA9::lux uvrA9::lux o ralkA9::lux Reporter Plasmids  

Microsoft Academic Search

Plasmids were constructed in which DNA damage-inducible promoters recA, uvrA, and alkA from Escherichia coli were fused to the Vibrio fischeri luxCDABE operon. Introduction of these plasmids into E. coli allowed the detection of a dose-dependent response to DNA-damaging agents, such as mitomycin and UV irradiation. Bioluminescence was measured in real time over extended periods. The fusion of the recA

Amy C. Vollmer; Shimshon Belkin; Dana R. Smulski; Tina K. Van Dyk; Robert A. Larossa

1997-01-01

46

Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance  

E-print Network

Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance Nicole Salmonella typhimurium increases its antibiotic toler- ance in response to indole, even though S. typhimurium

Collins, James J.

47

Survival of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi in Vembanadu  

E-print Network

Survival of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi the survival response of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi- otypes of Escherichia coli, Salmonella enterica typhi and paratyphi are highly endemic to India

Mazumder, Asit

48

Biodegradation of Aromatic Compounds by Escherichia coli  

PubMed Central

Although Escherichia coli has long been recognized as the best-understood living organism, little was known about its abilities to use aromatic compounds as sole carbon and energy sources. This review gives an extensive overview of the current knowledge of the catabolism of aromatic compounds by E. coli. After giving a general overview of the aromatic compounds that E. coli strains encounter and mineralize in the different habitats that they colonize, we provide an up-to-date status report on the genes and proteins involved in the catabolism of such compounds, namely, several aromatic acids (phenylacetic acid, 3- and 4-hydroxyphenylacetic acid, phenylpropionic acid, 3-hydroxyphenylpropionic acid, and 3-hydroxycinnamic acid) and amines (phenylethylamine, tyramine, and dopamine). Other enzymatic activities acting on aromatic compounds in E. coli are also reviewed and evaluated. The review also reflects the present impact of genomic research and how the analysis of the whole E. coli genome reveals novel aromatic catabolic functions. Moreover, evolutionary considerations derived from sequence comparisons between the aromatic catabolic clusters of E. coli and homologous clusters from an increasing number of bacteria are also discussed. The recent progress in the understanding of the fundamentals that govern the degradation of aromatic compounds in E. coli makes this bacterium a very useful model system to decipher biochemical, genetic, evolutionary, and ecological aspects of the catabolism of such compounds. In the last part of the review, we discuss strategies and concepts to metabolically engineer E. coli to suit specific needs for biodegradation and biotransformation of aromatics and we provide several examples based on selected studies. Finally, conclusions derived from this review may serve as a lead for future research and applications. PMID:11729263

Díaz, Eduardo; Ferrández, Abel; Prieto, María A.; García, José L.

2001-01-01

49

Escherichia coli fimbriae recognizing sialyl galactosides.  

PubMed Central

Fimbriae recognizing sialyl galactosides (S fimbriae) were purified from an Escherichia coli strain. The S fimbriae were morphologically identical to type 1 and P fimbriae of E. coli and showed a hemagglutination that was abolished when erythrocytes were treated with neuraminidase. Hemagglutination by the purified fimbriae was inhibited by orosomucoid but not by its desialylated derivative. Of the oligosaccharides tested, sialyl-(alpha 2-3)-lactose and sialyl-(alpha 2-3)-N-acetyllactosamine had the strongest inhibitory activities. It was concluded that S fimbriae have the strongest affinity for (alpha 2-3)-linked sialyl galactosides. In the enzyme-linked immunosorbent assay, the hyperimmune serum to the S fimbriae reacted strongly with the homologous antigen but not with type 1, P, or nonhemagglutinating KS71C fimbriae of E. coli. Analogously, the hyperimmune sera to the other E. coli fimbriae did not react with the purified S fimbriae. The immunoprecipitation assay showed that S fimbriae on different E. coli serotypes shared immunological cross-reactivity. Images PMID:6146600

Korhonen, T K; Väisänen-Rhen, V; Rhen, M; Pere, A; Parkkinen, J; Finne, J

1984-01-01

50

Escherichia coli fimbriae recognizing sialyl galactosides.  

PubMed

Fimbriae recognizing sialyl galactosides (S fimbriae) were purified from an Escherichia coli strain. The S fimbriae were morphologically identical to type 1 and P fimbriae of E. coli and showed a hemagglutination that was abolished when erythrocytes were treated with neuraminidase. Hemagglutination by the purified fimbriae was inhibited by orosomucoid but not by its desialylated derivative. Of the oligosaccharides tested, sialyl-(alpha 2-3)-lactose and sialyl-(alpha 2-3)-N-acetyllactosamine had the strongest inhibitory activities. It was concluded that S fimbriae have the strongest affinity for (alpha 2-3)-linked sialyl galactosides. In the enzyme-linked immunosorbent assay, the hyperimmune serum to the S fimbriae reacted strongly with the homologous antigen but not with type 1, P, or nonhemagglutinating KS71C fimbriae of E. coli. Analogously, the hyperimmune sera to the other E. coli fimbriae did not react with the purified S fimbriae. The immunoprecipitation assay showed that S fimbriae on different E. coli serotypes shared immunological cross-reactivity. PMID:6146600

Korhonen, T K; Väisänen-Rhen, V; Rhen, M; Pere, A; Parkkinen, J; Finne, J

1984-08-01

51

Core and Panmetabolism in Escherichia coli? †  

PubMed Central

Escherichia coli exhibits a wide range of lifestyles encompassing commensalism and various pathogenic behaviors which its highly dynamic genome contributes to develop. How environmental and host factors shape the genetic structure of E. coli strains remains, however, largely unknown. Following a previous study of E. coli genomic diversity, we investigated its diversity at the metabolic level by building and analyzing the genome-scale metabolic networks of 29 E. coli strains (8 commensal and 21 pathogenic strains, including 6 Shigella strains). Using a tailor-made reconstruction strategy, we significantly improved the completeness and accuracy of the metabolic networks over default automatic reconstruction processes. Among the 1,545 reactions forming E. coli panmetabolism, 885 reactions were common to all strains. This high proportion of core reactions (57%) was found to be in sharp contrast to the low proportion (13%) of core genes in the E. coli pangenome, suggesting less diversity of metabolic functions compared to that of all gene functions. Core reactions were significantly overrepresented among biosynthetic reactions compared to the more variable degradation processes. Differences between metabolic networks were found to follow E. coli phylogeny rather than pathogenic phenotypes, except for Shigella networks, which were significantly more distant from the others. This suggests that most metabolic changes in non-Shigella strains were not driven by their pathogenic phenotypes. Using a supervised method, we were yet able to identify small sets of reactions related to pathogenicity or commensalism. The quality of our reconstructed networks also makes them reliable bases for building metabolic models. PMID:21239590

Vieira, Gilles; Sabarly, Victor; Bourguignon, Pierre-Yves; Durot, Maxime; Le Fèvre, François; Mornico, Damien; Vallenet, David; Bouvet, Odile; Denamur, Erick; Schachter, Vincent; Médigue, Claudine

2011-01-01

52

Gas signatures from Escherichia coli and Escherichia coli-inoculated human whole blood  

PubMed Central

Background The gaseous headspace above naïve Escherichia Coli (E. coli) cultures and whole human blood inoculated with E. coli were collected and analyzed for the presence of trace gases that may have the potential to be used as novel, non-invasive markers of infectious disease. Methods The naïve E. coli culture, LB broth, and human whole blood or E. coli inoculated whole blood were incubated in hermetically sealable glass bioreactors at 37°C for 24 hrs. LB broth and whole human blood were used as controls for background volatile organic compounds (VOCs). The headspace gases were collected after incubation and analyzed using a gas chromatographic system with multiple column/detector combinations. Results Six VOCs were observed to be produced by E. coli-infected whole blood while there existed nearly zero to relatively negligible amounts of these gases in the whole blood alone, LB broth, or E. coli-inoculated LB broth. These VOCs included dimethyl sulfide (DMS), carbon disulfide (CS2), ethanol, acetaldehyde, methyl butanoate, and an unidentified gas S. In contrast, there were several VOCs significantly elevated in the headspace above the E. coli in LB broth, but not present in the E. coli/blood mixture. These VOCs included dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), methyl propanoate, 1-propanol, methylcyclohexane, and unidentified gases R2 and Q. Conclusions This study demonstrates 1) that cultivated E. coli in LB broth produce distinct gas profiles, 2) for the first time, the ability to modify E. coli-specific gas profiles by the addition of whole human blood, and 3) that E. coli-human whole blood interactions present different gas emission profiles that have the potential to be used as non-invasive volatile biomarkers of E. coli infection. PMID:23842518

2013-01-01

53

Engineering Desiccation Tolerance in Escherichia coli  

PubMed Central

Recombinant sucrose-6-phosphate synthase (SpsA) was synthesized in Escherichia coli BL21DE3 by using the spsA gene of the cyanobacterium Synechocystis sp. strain PCC 6803. Transformants exhibited a 10,000-fold increase in survival compared to wild-type cells following either freeze-drying, air drying, or desiccation over phosphorus pentoxide. The phase transition temperatures and vibration frequencies (P?O stretch) in phospholipids suggested that sucrose maintained membrane fluidity during cell dehydration. PMID:10742260

Billi, Daniela; Wright, Deborah J.; Helm, Richard F.; Prickett, Todd; Potts, Malcolm; Crowe, John H.

2000-01-01

54

Engineering ethanologenic Escherichia coli for levoglucosan utilization.  

PubMed

Levoglucosan is a major product of biomass pyrolysis. While this pyrolyzed biomass, also known as bio-oil, contains sugars that are an attractive fermentation substrate, commonly-used biocatalysts, such as Escherichia coli, lack the ability to metabolize this anhydrosugar. It has previously been shown that recombinant expression of the levoglucosan kinase enzyme enables use of levoglucosan as carbon and energy source. Here, ethanologenic E. coli KO11 was engineered for levoglucosan utilization by recombinant expression of levoglucosan kinase from Lipomyces starkeyi. Our engineering strategy uses a codon-optimized gene that has been chromosomally integrated within the pyruvate to ethanol (PET) operon and does not require additional antibiotics or inducers. Not only does this engineered strain use levoglucosan as sole carbon source, but it also ferments levoglucosan to ethanol. This work demonstrates that existing biocatalysts can be easily modified for levoglucosan utilization. PMID:21719279

Layton, Donovan S; Ajjarapu, Avanthi; Choi, Dong Won; Jarboe, Laura R

2011-09-01

55

Automatic Tracking of Escherichia Coli Bacteria , Shahid Khan2 3  

E-print Network

of choice for elucidation of the design principles of transmembrane and intracellular signal transductionAutomatic Tracking of Escherichia Coli Bacteria Jun Xie1 , Shahid Khan2 3 , and Mubarak Shah4 1. In this paper, we present an automatic method for estimating the tra- jectories of Escherichia coli bacteria

Central Florida, University of

56

Monitoring and classification of PAH toxicity using an immobilized bioluminescent bacteria  

Microsoft Academic Search

An immobilized recombinant bioluminescent Escherichia coli strain, harboring a lac::luxCDABE fused plasmid, which shows lower bioluminescence levels when cellular metabolism is inhibited, was used to monitor the cellular toxicity of polycyclic aromatic hydrocarbons (PAHs). PAHs, classified as pericondensed (PCPAHs) or catacondensed (CCPAHs) according to their molecular structures, were differentiable according to the response of this biosensor. Only CCPAHs were found

Hyun Joo Lee; Julien Villaume; David C. Cullen; Byoung Chan Kim; Man Bock Gu

2003-01-01

57

Production of glycoprotein vaccines in Escherichia coli  

PubMed Central

Background Conjugate vaccines in which polysaccharide antigens are covalently linked to carrier proteins belong to the most effective and safest vaccines against bacterial pathogens. State-of-the art production of conjugate vaccines using chemical methods is a laborious, multi-step process. In vivo enzymatic coupling using the general glycosylation pathway of Campylobacter jejuni in recombinant Escherichia coli has been suggested as a simpler method for producing conjugate vaccines. In this study we describe the in vivo biosynthesis of two novel conjugate vaccine candidates against Shigella dysenteriae type 1, an important bacterial pathogen causing severe gastro-intestinal disease states mainly in developing countries. Results Two different periplasmic carrier proteins, AcrA from C. jejuni and a toxoid form of Pseudomonas aeruginosa exotoxin were glycosylated with Shigella O antigens in E. coli. Starting from shake flask cultivation in standard complex medium a lab-scale fed-batch process was developed for glycoconjugate production. It was found that efficiency of glycosylation but not carrier protein expression was highly susceptible to the physiological state at induction. After induction glycoconjugates generally appeared later than unglycosylated carrier protein, suggesting that glycosylation was the rate-limiting step for synthesis of conjugate vaccines in E. coli. Glycoconjugate synthesis, in particular expression of oligosaccharyltransferase PglB, strongly inhibited growth of E. coli cells after induction, making it necessary to separate biomass growth and recombinant protein expression phases. With a simple pulse and linear feed strategy and the use of semi-defined glycerol medium, volumetric glycoconjugate yield was increased 30 to 50-fold. Conclusions The presented data demonstrate that glycosylated proteins can be produced in recombinant E. coli at a larger scale. The described methodologies constitute an important step towards cost-effective in vivo production of conjugate vaccines, which in future may be used for combating severe infectious diseases, particularly in developing countries. PMID:20701771

2010-01-01

58

Sources of Escherichia coli in a Coastal Subtropical Environment  

Microsoft Academic Search

Sources of Escherichia coli in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in E. coli concentrations as well as experiments conducted under laboratory-controlled conditions. E. coli from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling

HELENA M. SOLO-GABRIELE; MELINDA A. WOLFERT; TIMOTHY R. DESMARAIS; CAROL J. PALMER

2000-01-01

59

Engineering a Reduced Escherichia coli Genome  

PubMed Central

Our goal is to construct an improved Escherichia coli to serve both as a better model organism and as a more useful technological tool for genome science. We developed techniques for precise genomic surgery and applied them to deleting the largest K-islands of E. coli, identified by comparative genomics as recent horizontal acquisitions to the genome. They are loaded with cryptic prophages, transposons, damaged genes, and genes of unknown function. Our method leaves no scars or markers behind and can be applied sequentially. Twelve K-islands were successfully deleted, resulting in an 8.1% reduced genome size, a 9.3% reduction of gene count, and elimination of 24 of the 44 transposable elements of E. coli. These are particularly detrimental because they can mutagenize the genome or transpose into clones being propagated for sequencing, as happened in 18 places of the draft human genome sequence. We found no change in the growth rate on minimal medium, confirming the nonessential nature of these islands. This demonstration of feasibility opens the way for constructing a maximally reduced strain, which will provide a clean background for functional genomics studies, a more efficient background for use in biotechnology applications, and a unique tool for studies of genome stability and evolution. [Sequence data described in this paper have been submitted to the DNA Data Bank of Japan, European Molecular Biology Laboratory, and GenBank databases under accession nos. AF402780, AF402779, and AF406953, respectively.] PMID:11932248

Kolisnychenko, Vitaliy; Plunkett, Guy; Herring, Christopher D.; Fehér, Tamás; Pósfai, János; Blattner, Frederick R.; Pósfai, György

2002-01-01

60

Autophosphorylation of phosphoglucosamine mutase from Escherichia coli.  

PubMed

Phosphoglucosamine mutase (GlmM) catalyzes the formation of glucosamine-1-phosphate from glucosamine-6-phosphate, an essential step in the pathway for UDP-N-acetylglucosamine biosynthesis in bacteria. This enzyme must be phosphorylated to be active and acts according to a ping-pong mechanism involving glucosamine-1, 6-diphosphate as an intermediate (L. Jolly, P. Ferrari, D. Blanot, J. van Heijenoort, F. Fassy, and D. Mengin-Lecreulx, Eur. J. Biochem. 262:202-210, 1999). However, the process by which the initial phosphorylation of the enzyme is achieved in vivo remains unknown. Here we show that the phosphoglucosamine mutase from Escherichia coli autophosphorylates in vitro in the presence of [(32)P]ATP. The same is observed with phosphoglucosamine mutases from other bacterial species, yeast N-acetylglucosamine-phosphate mutase, and rabbit muscle phosphoglucomutase. Labeling of the E. coli GlmM enzyme with [(32)P]ATP requires the presence of a divalent cation, and the label is subsequently lost when the enzyme is incubated with either of its substrates. Analysis of enzyme phosphorylation by high-pressure liquid chromatography and coupled mass spectrometry confirms that only one phosphate has been covalently linked to the enzyme. Only phosphoserine could be detected after acid hydrolysis of the labeled protein, and site-directed mutagenesis of serine residues located in or near the active site identifies the serine residue at position 102 as the site of autophosphorylation of E. coli GlmM. PMID:10671448

Jolly, L; Pompeo, F; van Heijenoort, J; Fassy, F; Mengin-Lecreulx, D

2000-03-01

61

Characterization of molybdenum cofactor from Escherichia coli.  

PubMed Central

Molybdenum cofactor activity was found in the soluble fraction of cell-free extracts of Escherichia coli grown aerobically in media supplemented with molybdate. Cofactor was detected by its ability to complement the nitrate reductase-deficient mutant of Neurospora crossa, nit-1, resulting in the vitro formation of nitrate reductase activity. Acid treatment of E. coli extracts was not required for release of cofactor activity. Cofactor was able to diffuse through a membrane of nominal 2,000-molecular-weight cutoff and was insensitive to trypsin. The cofactor was associated with a carrier molecule (approximately 40,000 daltons) during gel filtration and sucrose gradient centrifugation, but was easily removed from the carrier by dialysis. The carrier molecule protected the cofactor from inactivation by heat or oxygen. E. coli grown in molybdenum-free media, without and with tungsten, synthesized a metal-free "empty" cofactor and its tungsten analog, respectively, both of which were subsequently activated by the addition of molybdate. Empty and tungsten-containing cofactor complemented the nitrate reductase subunits in the nit-1 extract, forming inactive, but intact, 7.9S nitrate reductase. Addition of molybdate to the enzyme complemented in this manner restored nitrate reductase activity. PMID:387715

Amy, N K; Rajagopalan, K V

1979-01-01

62

Vibrio parahaemolyticus, enterotoxigenic Escherichia coli, enterohemorrhagic Escherichia coli and Vibrio cholerae  

PubMed Central

This review highlighted the following: (i) pathogenic mechanism of the thermostable direct hemolysin produced by Vibrio parahaemolyticus, especially on its cardiotoxicity, (ii) heat-labile and heat-stable enterotoxins produced by enterotoxigenic Escherichia coli, especially structure–activity relationship of heat-stable enterotoxin, (iii) RNA N-glycosidase activity of Vero toxins (VT1 and VT2) produced by enterohemorrhagic Escherichia coli O157:H7, (iv) discovery of Vibrio cholerae O139, (v) isolation of new variant of Vibrio cholerae O1 El Tor that carries classical ctxB, and production of high concentration of cholera toxin by these strains, and (vi) conversion of viable but nonculturable (VBNC) Vibrio cholerae to culturable state by co-culture with eukaryotic cells. PMID:21233598

TAKEDA, Yoshifumi

2011-01-01

63

Indole transport across Escherichia coli membranes.  

PubMed

Indole has many, diverse roles in bacterial signaling. It regulates the transition from exponential to stationary phase, it is involved in the control of plasmid stability, and it influences biofilm formation, virulence, and stress responses (including antibiotic resistance). Its role is not restricted to bacteria, and recently it has been shown to include mutually beneficial signaling between enteric bacteria and their mammalian hosts. In many respects indole behaves like the signaling component of a quorum-sensing system. Indole synthesized within the producer bacterium is exported into the surroundings where its accumulation is detected by sensitive cells. A view often repeated in the literature is that in Escherichia coli the AcrEF-TolC and Mtr transporter proteins are involved in the export and import, respectively, of indole. However, the evidence for their involvement is indirect, and it has been known for a long time that indole can pass directly through a lipid bilayer. We have combined in vivo and in vitro approaches to examine the relative importance of protein-mediated transport and direct passage across the E. coli membrane. We conclude that the movement of indole across the E. coli membrane under normal physiological conditions is independent of AcrEF-TolC and Mtr. Furthermore, direct observation of individual liposomes shows that indole can rapidly cross an E. coli lipid membrane without the aid of any proteinaceous transporter. These observations not only enhance our understanding of indole signaling in bacteria but also provide a simple explanation for the ability of indole to signal between biological kingdoms. PMID:21296966

Piñero-Fernandez, S; Chimerel, C; Keyser, U F; Summers, D K

2011-04-01

64

Dispensability of Escherichia coli's latent pathways  

E-print Network

Gene-knockout experiments on single-cell organisms have established that expression of a substantial fraction of genes is not needed for optimal growth. This problem acquired a new dimension with the recent discovery that environmental and genetic perturbations of the bacterium Escherichia coli are followed by the temporary activation of a large number of latent metabolic pathways, which suggests the hypothesis that temporarily activated reactions impact growth and hence facilitate adaptation in the presence of perturbations. Here we test this hypothesis computationally and find, surprisingly, that the availability of latent pathways consistently offers no growth advantage, and tends in fact to inhibit growth after genetic perturbations. This is shown to be true even for latent pathways with a known function in alternate conditions, thus extending the significance of this adverse effect beyond apparently nonessential genes. These findings raise the possibility that latent pathway activation is in fact derivat...

Cornelius, Sean P; Motter, Adilson E; 10.1073/pnas.1009772108

2011-01-01

65

Mechanism of Escherichia coli Resistance to Pyrrhocoricin  

PubMed Central

Due to their lack of toxicity to mammalian cells and good serum stability, proline-rich antimicrobial peptides (PR-AMPs) have been proposed as promising candidates for the treatment of infections caused by antimicrobial-resistant bacterial pathogens. It has been hypothesized that these peptides act on multiple targets within bacterial cells, and therefore the likelihood of the emergence of resistance was considered to be low. Here, we show that spontaneous Escherichia coli mutants resistant to pyrrhocoricin arise at a frequency of approximately 6 × 10?7. Multiple independently derived mutants all contained a deletion in a nonessential gene that encodes the putative peptide uptake permease SbmA. Sensitivity could be restored to the mutants by complementation with an intact copy of the sbmA gene. These findings question the viability of the development of insect PR-AMPs as antimicrobials. PMID:24590485

Narayanan, Shalini; Modak, Joyanta K.; Ryan, Catherine S.; Garcia-Bustos, Jose; Davies, John K.

2014-01-01

66

Electrokinetically induced flocculation of Enteroaggregative Escherichia coli  

NASA Astrophysics Data System (ADS)

Enteroaggregative Escherichia coli (EAEC) is a diarrheal microbe, whose aggregative dynamics is involved in its pathogenic behavior. We investigated EAEC's electrokinetic response in miniaturized and microfluidic devices. We found a novel response of the microbe under low magnitude, uniform and oscillating electric fields. In this electrokinetically induced response, microbial adhesion to a glass substrate decreases significantly, leading to a loss of EAEC's biofilm forming abilities. Some earlier studies had indicated that that microbial adhesion and detachment at surfaces can be prompted only by charge-transfer processes at the electrode and not applied electrical potentials - such an inference is not corroborated by our work. Instead, we found that electric fields promote the formation of large mesoscopic microbial aggregations (flocs) in the solution. The presence of frequency dependent relaxation phenomena is explored and the observed results are extended to other microbes.

Kumar, Aloke; Mortensen, Ninell; Harris, Mansueta; Mukherjee, Partha; Retterer, Scott; Doktycz, Mitchel

2011-11-01

67

Animal models of enteroaggregative Escherichia coli infection  

PubMed Central

Enteroaggregative Escherichia coli (EAEC) has been acknowledged as an emerging cause of gastroenteritis worldwide for over two decades. Epidemiologists are revealing the role of EAEC in diarrheal outbreaks as a more common occurrence than ever suggested before. EAEC induced diarrhea is most commonly associated with travelers, children and immunocompromised individuals however its afflictions are not limited to any particular demographic. Many attributes have been discovered and characterized surrounding the capability of EAEC to provoke a potent pro-inflammatory immune response, however cellular and molecular mechanisms underlying initiation, progression and outcomes are largely unknown. This limited understanding can be attributed to heterogeneity in strains and the lack of adequate animal models. This review aims to summarize current knowledge about EAEC etiology, pathogenesis and clinical manifestation. Additionally, current animal models and their limitations will be discussed along with the value of applying systems-wide approaches such as computational modeling to study host-EAEC interactions. PMID:23680797

Philipson, Casandra W.; Bassaganya-Riera, Josep; Hontecillas, Raquel

2013-01-01

68

Genetic Analysis of an Escherichia coli Syndrome  

PubMed Central

A mutant strain of Escherichia coli that fails to recover from prolonged (72 hr) starvation also fails to grow at 43 C. Extracts of this mutant strain show an increased ribonuclease II activity as compared to extracts of the parental strain, and stable ribonucleic acid is degraded to a larger extent in this strain during starvation. Ts+ transductants and revertants were tested for all the above-mentioned phenotypes. All the Ts+ transductants and revertants tested behaved like the Ts+ parental strain, which suggests that all the observed phenotypes are caused by a single sts (starvation-temperature sensitivity) mutation. The reversion rate from sts? to sts+ is rather low but is within the range of reversion rates for other single-site mutations. Three-point transduction crosses located this sts mutation between the ilv and rbs genes. The properties of sts+/sts? merozygotes suggested that the Ts? phenotype of this mutation is recessive. PMID:4945197

Lennette, Evelyne T.; Apirion, David

1971-01-01

69

Direct Upstream Motility in Escherichia coli  

PubMed Central

We provide an experimental demonstration of positive rheotaxis (rapid and continuous upstream motility) in wild-type Escherichia coli freely swimming over a surface. This hydrodynamic phenomenon is dominant below a critical shear rate and robust against Brownian motion and cell tumbling. We deduce that individual bacteria entering a flow system can rapidly migrate upstream (>20 ?m/s) much faster than a gradually advancing biofilm. Given a bacterial population with a distribution of sizes and swim speeds, local shear rate near the surface determines the dominant hydrodynamic mode for motility, i.e., circular or random trajectories for low shear rates, positive rheotaxis for moderate flow, and sideways swimming at higher shear rates. Faster swimmers can move upstream more rapidly and at higher shear rates, as expected. Interestingly, we also find on average that both swim speed and upstream motility are independent of cell aspect ratio. PMID:22500751

Kaya, Tolga; Koser, Hur

2012-01-01

70

Evolution of transcription factors and the gene regulatory network in Escherichia coli  

E-print Network

Evolution of transcription factors and the gene regulatory network in Escherichia coli M. Madan Escherichia coli. In order to gain insight into the evolution of the E.coli regula- tory network, we analysed

Babu, M. Madan

71

Chemotaxis Toward Amino Acids in Escherichia coli  

PubMed Central

Escherichia coli cells are shown to be attracted to the l-amino acids alanine, asparagine, aspartate, cysteine, glutamate, glycine, methionine, serine, and threonine, but not to arginine, cystine, glutamine, histidine, isoleucine, leucine, lysine, phenylalanine, tryptophan, tyrosine, or valine. Bacteria grown in a proline-containing medium were, in addition, attracted to proline. Chemotaxis toward amino acids is shown to be mediated by at least two detection systems, the aspartate and serine chemoreceptors. The aspartate chemoreceptor was nonfunctional in the aspartate taxis mutant, which showed virtually no chemotaxis toward aspartate, glutamate, or methionine, and reduced taxis toward alanine, asparagine, cysteine, glycine, and serine. The serine chemoreceptor was nonfunctional in the serine taxis mutant, which was defective in taxis toward alanine, asparagine, cysteine, glycine, and serine, and which showed no chemotaxis toward threonine. Additional data concerning the specificities of the amino acid chemoreceptors with regard to amino acid analogues are also presented. Finally, two essentially nonoxidizable amino acid analogues, ?-aminoisobutyrate and ?-methylaspartate, are shown to be attractants for E. coli, demonstrating that extensive metabolism of attractants is not required for amino acid taxis. PMID:4562400

Mesibov, Robert; Adler, Julius

1972-01-01

72

Uropathogenic Escherichia coli Induces Chronic Pelvic Pain ?  

PubMed Central

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a debilitating syndrome of unknown etiology often postulated, but not proven, to be associated with microbial infection of the prostate gland. We hypothesized that infection of the prostate by clinically relevant uropathogenic Escherichia coli (UPEC) can initiate and establish chronic pain. We utilized an E. coli strain newly isolated from a patient with CP/CPPS (strain CP1) and examined its molecular pathogenesis in cell culture and in a murine model of bacterial prostatitis. We found that CP1 is an atypical isolate distinct from most UPEC in its phylotype and virulence factor profile. CP1 adhered to, invaded, and proliferated within prostate epithelia and colonized the prostate and bladder of NOD and C57BL/6J mice. Using behavioral measures of pelvic pain, we showed that CP1 induced and sustained chronic pelvic pain in NOD mice, an attribute not exhibited by a clinical cystitis strain. Furthermore, pain was observed to persist even after bacterial clearance from genitourinary tissues. CP1 induced pelvic pain behavior exclusively in NOD mice and not in C57BL/6J mice, despite comparable levels of colonization and inflammation. Microbial infections can thus serve as initiating agents for chronic pelvic pain through mechanisms that are dependent on both the virulence of the bacterial strain and the genetic background of the host. PMID:21078846

Rudick, Charles N.; Berry, Ruth E.; Johnson, James R.; Johnston, Brian; Klumpp, David J.; Schaeffer, Anthony J.; Thumbikat, Praveen

2011-01-01

73

Nucleotide excision repair in Escherichia coli.  

PubMed Central

One of the best-studied DNA repair pathways is nucleotide excision repair, a process consisting of DNA damage recognition, incision, excision, repair resynthesis, and DNA ligation. Escherichia coli has served as a model organism for the study of this process. Recently, many of the proteins that mediate E. coli nucleotide excision have been purified to homogeneity; this had led to a molecular description of this repair pathway. One of the key repair enzymes of this pathway is the UvrABC nuclease complex. The individual subunits of this enzyme cooperate in a complex series of partial reactions to bind to and incise the DNA near a damaged nucleotide. The UvrABC complex displays a remarkable substrate diversity. Defining the structural features of DNA lesions that provide the specificity for damage recognition by the UvrABC complex is of great importance, since it represents a unique form of protein-DNA interaction. Using a number of in vitro assays, researchers have been able to elucidate the action mechanism of the UvrABC nuclease complex. Current research is devoted to understanding how these complex events are mediated within the living cell. PMID:2181258

Van Houten, B

1990-01-01

74

Chemotaxis toward sugars in Escherichia coli.  

PubMed

Using a quantitative assay for measuring chemotaxis, we tested a variety of sugars and sugar derivatives for their ability to attract Escherichia coli bacteria. The most effective attractants, i.e., those that have thresholds near 10(-5) M or below, are N-acetyl-d-glucosamine, 6-deoxy-d-glucose, d-fructose, d-fucose, 1-d-glycerol-beta-d-galactoside, galactitol, d-galactose, d-glucosamine, d-glucose, alpha-d-glucose-1-phosphate, lactose, maltose, d-mannitol, d-mannose, methyl-beta-d-galactoside, methyl-beta-d-glucoside, d-ribose, d-sorbitol, and trehalose. Lactose, and probably d-glucose-1-phosphate, are attractive only after conversion to the free monosaccharide, while the other attractants do not require breakdown for taxis. Nine different chemoreceptors are involved in detecting these various attractants. They are called the N-acetyl-glucosamine, fructose, galactose, glucose, maltose, mannitol, ribose, sorbitol, and trehalose chemoreceptors; the specificity of each was studied. The chemoreceptors, with the exception of the one for d-glucose, are inducible. The galactose-binding protein serves as the recognition component of the galactose chemoreceptor. E. coli also has osmotically shockable binding activities for maltose and d-ribose, and these appear to serve as the recognition components for the corresponding chemoreceptors. PMID:4580570

Adler, J; Hazelbauer, G L; Dahl, M M

1973-09-01

75

Independence of replisomes in Escherichia coli chromosomalreplication  

SciTech Connect

In Escherichia coli DNA replication is carried out by the coordinated action of the proteins within a replisome. After replication initiation, the two bidirectionally oriented replisomes from a single origin are colocalized into higher-order structures termed replication factories. The factory model postulated that the two replisomes are also functionally coupled. We tested this hypothesis by using DNA combing and whole-genome microarrays. Nascent DNA surrounding oriC in single, combed chromosomes showed instead that one replisome, usually the leftward one, was significantly ahead of the other 70% of the time. We next used microarrays to follow replication throughout the genome by measuring DNA copy number. We found in multiple E. coli strains that the replisomes are independent, with the leftward replisome ahead of the rightward one. The size of the bias was strain-specific, varying from 50 to 130 kb in the array results. When we artificially blocked one replisome, the other continued unabated, again demonstrating independence. We suggest an improved version of the factory model that retains the advantages of threading DNA through colocalized replisomes at about equal rates, but allows the cell flexibility to overcome obstacles encountered during elongation.

Breier, Adam M.; Weier, Heinz-Ulrich G.; Cozzarelli, Nicholas R.

2005-03-13

76

Cyclomodulins in Urosepsis Strains of Escherichia coli?  

PubMed Central

Determinants of urosepsis in Escherichia coli remain incompletely defined. Cyclomodulins (CMs) are a growing functional family of toxins that hijack the eukaryotic cell cycle. Four cyclomodulin types are actually known in E. coli: cytotoxic necrotizing factors (CNFs), cycle-inhibiting factor (Cif), cytolethal distending toxins (CDTs), and the pks-encoded toxin. In the present study, the distribution of CM-encoding genes and the functionality of these toxins were investigated in 197 E. coli strains isolated from patients with community-acquired urosepsis (n = 146) and from uninfected subjects (n = 51). This distribution was analyzed in relation to the phylogenetic background, clinical origin, and antibiotic resistance of the strains. It emerged from this study that strains harboring the pks island and the cnf1 gene (i) were strongly associated with the B2 phylogroup (P, <0.001), (ii) frequently harbored both toxin-encoded genes in phylogroup B2 (33%), and (iii) were predictive of a urosepsis origin (P, <0.001 to 0.005). However, the prevalences of the pks island among phylogroup B2 strains, in contrast to those of the cnf1 gene, were not significantly different between fecal and urosepsis groups, suggesting that the pks island is more important for the colonization process and the cnf1 gene for virulence. pks- or cnf1-harboring strains were significantly associated with susceptibility to antibiotics (amoxicillin, cotrimoxazole, and quinolones [P, <0.001 to 0.043]). Otherwise, only 6% and 1% of all strains harbored the cdtB and cif genes, respectively, with no particular distribution by phylogenetic background, antimicrobial susceptibility, or clinical origin. PMID:20375237

Dubois, Damien; Delmas, Julien; Cady, Anne; Robin, Frédéric; Sivignon, Adeline; Oswald, Eric; Bonnet, Richard

2010-01-01

77

Cyclomodulins in urosepsis strains of Escherichia coli.  

PubMed

Determinants of urosepsis in Escherichia coli remain incompletely defined. Cyclomodulins (CMs) are a growing functional family of toxins that hijack the eukaryotic cell cycle. Four cyclomodulin types are actually known in E. coli: cytotoxic necrotizing factors (CNFs), cycle-inhibiting factor (Cif), cytolethal distending toxins (CDTs), and the pks-encoded toxin. In the present study, the distribution of CM-encoding genes and the functionality of these toxins were investigated in 197 E. coli strains isolated from patients with community-acquired urosepsis (n = 146) and from uninfected subjects (n = 51). This distribution was analyzed in relation to the phylogenetic background, clinical origin, and antibiotic resistance of the strains. It emerged from this study that strains harboring the pks island and the cnf1 gene (i) were strongly associated with the B2 phylogroup (P, <0.001), (ii) frequently harbored both toxin-encoded genes in phylogroup B2 (33%), and (iii) were predictive of a urosepsis origin (P, <0.001 to 0.005). However, the prevalences of the pks island among phylogroup B2 strains, in contrast to those of the cnf1 gene, were not significantly different between fecal and urosepsis groups, suggesting that the pks island is more important for the colonization process and the cnf1 gene for virulence. pks- or cnf1-harboring strains were significantly associated with susceptibility to antibiotics (amoxicillin, cotrimoxazole, and quinolones [P, <0.001 to 0.043]). Otherwise, only 6% and 1% of all strains harbored the cdtB and cif genes, respectively, with no particular distribution by phylogenetic background, antimicrobial susceptibility, or clinical origin. PMID:20375237

Dubois, Damien; Delmas, Julien; Cady, Anne; Robin, Frédéric; Sivignon, Adeline; Oswald, Eric; Bonnet, Richard

2010-06-01

78

COMMUNICATION Escherichia coli tatC Mutations that Suppress Defective  

E-print Network

COMMUNICATION Escherichia coli tatC Mutations that Suppress Defective Twin-Arginine Transporter of the membrane pro- teins TatA, TatB and TatC. Among Gram-positive bacteria, a few organisms can be found

Georgiou, George

79

Repair System for Noncanonical Purines in Escherichia coli  

Microsoft Academic Search

Exposure of Escherichia coli strains deficient in molybdopterin biosynthesis (moa) to the purine base N-6-hydroxylaminopurine (HAP) is mutagenic and toxic. We show that moa mutants exposed to HAP also exhibit elevated mutagenesis, a hyperrecombination phenotype, and increased SOS induction. The E. coli rdgB gene encodes a protein homologous to a deoxyribonucleotide triphosphate pyrophosphatase from Methanococ- cus jannaschii that shows a

Nicholas E. Burgis; Jason J. Brucker; Richard P. Cunningham

2003-01-01

80

Escherichia coli Response to Exogenous Pyrophosphate and Analogs  

Microsoft Academic Search

The addition of exogenous pyrophosphate increases the growth yield and cAMP synthesis in stationary phase when Escherichia coli is grown in minimal medium. Pyrophosphate increases the yield by altering the enterobactin uptake system. We studied the physiological effects and examined how the E. coli transcriptome was modified when two structural analogs of pyrophosphate were added to the growth medium. Methylenediphosphonic

Francis Biville; Taku Oshima; Hirotada Mori; Yuya Kawagoe; Odile Bouvet; Marie-Noëlle Rager; Marina Perrotte-Piquemal; Antoine Danchin

2003-01-01

81

ORIGINAL ARTICLE Escherichia coli transcription factor YncC  

E-print Network

, USA Quorum-sensing signal autoinducer 2 (AI-2) stimulates Escherichia coli biofilm formation through is partially reduced by the b3023 mutation. Therefore, AI-2 quorum-sensing control of biofilm formation, which represses biofilm formation of E. coli by repressing motility, inducing the sensor of the quorum-sensing

Wood, Thomas K.

82

Genetic engineering of ethanol production in Escherichia coli  

Microsoft Academic Search

The genes encoding essential enzymes of the fermentative pathway for ethanol production in Zymomonas mobilis, an obligately ethanologenic bacterium, were inserted into Escherichia coli under the control of a common promoter. Alcohol dehydrogenase II and pyruvate decarboxylase from Z. mobilis were expressed at high levels in E. coli, resulting in increased cell growth and the production of ethanol as the

L. O. Ingram; T. Conway; D. P. Clark; G. W. Sewell; J. F. Preston

1987-01-01

83

Molecular Serotyping of Escherichia coli O111:H8  

Technology Transfer Automated Retrieval System (TEKTRAN)

Accurate Escherichia coli serotyping is critical for pathogen diagnosis and surveillance of non-O157 shiga-toxigenic strains, however, few laboratories have this capacity. The molecular serotyping protocol described in this paper targets the somatic and flagellar antigens of E. coli O111:H8 used in...

84

RAPID GLUTAMATE DECARBOXYLASE ASSAY FOR THE DETECTION OF ESCHERICHIA COLI  

EPA Science Inventory

A rapid test procedure for the enzyme glutamate decarboxylase was developed for the detection of Escherichia coli. he assay procedure was able to confirm the presence of E. coli in enteric broth cultures with a 95 percent specificity for both pure cultures and environmental sampl...

85

Multidimensional annotation of the Escherichia coli K-12 genome  

Microsoft Academic Search

The annotation of the Escherichia coli K-12 genome in the EcoCyc database is one of the most accurate, complete and multidimensional genome annota- tions. Of the 4460 E. coli genes, EcoCyc assigns biochemical functions to 76%, and 66% of all genes had their functions determined experimentally. EcoCyc assigns E. coli genes to Gene Ontology and to MultiFun. Seventy-five percent of

Peter D. Karp; Ingrid M. Keseler; Alexander Shearer; Mario Latendresse; Markus Krummenacker; Suzanne M. Paley; Ian Paulsen; Julio Collado-Vides; Socorro Gama-Castro; Martin Peralta-Gil; Alberto Santos-Zavaleta; M. I. Penaloza-Spinola; C. Bonavides-Martinez; J. Ingraham

2007-01-01

86

Biocontrol of Escherichia coli O157  

PubMed Central

The effect of a bacteriophage cocktail (EcoShield™) that is specific against Escherichia coli O157:H7 was evaluated against a nalidixic acid-resistant enterohemorrhagic E. coli O157:H7 RM4407 (EHEC) strain on leafy greens stored under either (1) ambient air or (2) modified atmosphere (MA; 5% O2/35% CO2/60% N2). Pieces (~2 × 2 cm2) of leafy greens (lettuce and spinach) inoculated with 4.5 log CFU/cm2 EHEC were sprayed with EcoShield™ (6.5 log PFU/cm2). Samples were stored at 4 or 10°C for up to 15 d. On spinach, the level of EHEC declined by 2.38 and 2.49 log CFU/cm2 at 4 and 10°C, respectively, 30 min after phage application (p ? 0.05). EcoShield™ was also effective in reducing EHEC on the surface of green leaf lettuce stored at 4°C by 2.49 and 3.28 log units in 30 min and 2 h, respectively (p ? 0.05). At 4°C under atmospheric air, the phage cocktail significantly (p ? 0.05) lowered the EHEC counts in one day by 1.19, 3.21 and 3.25 log CFU/cm2 on spinach, green leaf and romaine lettuce, respectively compared with control (no bacteriophage) treatments. When stored under MA at 4°C, phages reduced (p ? 0.05) EHEC populations by 2.18, 3.50 and 3.13 log CFU/cm2, on spinach, green leaf and romaine lettuce. At 10°C, EHEC reductions under atmospheric air storage were 1.99, 3.90 and 3.99 log CFU/cm2 (p ? 0.05), while population reductions under MA were 3.08, 3.89 and 4.34 logs on spinach, green leaf and romaine lettuce, respectively, compared with controls (p ? 0.05). The results of this study showed that bacteriophages were effective in reducing the levels of E. coli O157:H7 on fresh leafy produce, and that the reduction was further improved when produce was stored under the MA conditions. PMID:23819107

Boyacioglu, Olcay; Sharma, Manan; Sulakvelidze, Alexander; Goktepe, Ipek

2013-01-01

87

Escherichia coli challenge in newborn pigs.  

PubMed

Escherichia coli F18 is a common porcine enteric pathogen causing diarrhea and edema in weaned pigs. An essential step in the pathogenesis of this enteric colibacillosis is a fimbria-receptor interaction in the small intestine, involving the ?(1,2)-fucosyltransferase gene (FUT1) enzyme for bacterial receptor binding to the epithelium. Enzyme expression is genetically determined and increases after weaning at 3 to5 wk, probably due to age- and/or diet-related intestinal maturation. We hypothesized that artificially reared piglets, deprived of sow's milk from birth, show susceptibility to F18 already in the neonatal period. First we verified the intestinal expression of FUT1 in preterm, term, and weaned pigs by quantitative real-time polymerase chain reaction. Then age-related F18 susceptibility (degree of diarrhea) was evaluated in 3-, 10-, and 20-d-old pigs after inoculation of 10(10) cfu E. coli F18 per day for 12 d. Finally, F18 susceptibility was evaluated in caesarean-delivered 0- to 7-d-old piglets inoculated daily with F18 as above. For all pigs, their sows were genotyped to ensure expression of the FUT1 enzyme. FUT1 expression was detected in the proximal and distal small intestine with no apparent differences in levels among preterm, term, and weaned pigs. No consistent F18-induced diarrhea was detected in any of the 3 groups of 3- to 20-d-old pigs. In contrast, 0- to 7-d-old caesarean-delivered pigs showed a higher score of diarrhea in pigs inoculated with F18 compared with controls (2.4 ± 0.1 vs. 1.8 ± 0.1 respectively; P < 0.001). Caesarean-delivered piglets deprived of sow milk are highly susceptible to diarrhea induced by E. coli F18. Lack of the protective effects of birth colonization and sow milk may contribute to high intestinal F18 sensitivity. The newborn pig may be a useful model to investigate factors in maternal milk that protect against F18 diarrhea. PMID:23365279

Jensen, M L; Cilieborg, M S; Østergaard, M V; Bering, S B; Jørgensen, C B; Sangild, P T

2012-12-01

88

Regulation of alcohol fermentation by Escherichia coli  

SciTech Connect

The purpose of this project is to elucidate the way in which the fermentative synthesis of ethanol is regulated in the facultative anaerobe Escherichia coli. Focus is on the two final steps in alcohol synthesis, which are catalyzed by alcohol dehydrogenase and acetaldehyde CoA dehydrogenase. We have isolated a series of mutations affecting the expression of these enzymes. Some of these mutations are in the structural genes for these enzymes; others affect the regulation of the adh operon. We have recently cloned the genes coding for these enzymes and are now studying the effect of multiple copies of the adh gene on fermentative growth and its regulation. A recently invented technique, proton suicide has allowed the selection of a variety of novel mutants affecting fermentation which are presently being characterized. We have isolated a comprehensive collection of operon fusions in which the lacZ structural gene is fused to promoters that are inactive aerobically but active anaerobically. Although these genes (like adh) are only expressed under anaerobic conditions, the level of induction varies from two-fold to nearly 100-fold. The nitrogen source, medium pH, nature of the buffer, presence of alternative electron acceptors (e.g., nitrate), and other factors exert a great effect on the expression of many of these genes. In the near future we will investigate control mechanisms common to the adh operon and other anaerobically regulated genes.

Clark, D.P.

1986-03-01

89

Biochemistry of homologous recombination in Escherichia coli.  

PubMed Central

Homologous recombination is a fundamental biological process. Biochemical understanding of this process is most advanced for Escherichia coli. At least 25 gene products are involved in promoting genetic exchange. At present, this includes the RecA, RecBCD (exonuclease V), RecE (exonuclease VIII), RecF, RecG, RecJ, RecN, RecOR, RecQ, RecT, RuvAB, RuvC, SbcCD, and SSB proteins, as well as DNA polymerase I, DNA gyrase, DNA topoisomerase I, DNA ligase, and DNA helicases. The activities displayed by these enzymes include homologous DNA pairing and strand exchange, helicase, branch migration, Holliday junction binding and cleavage, nuclease, ATPase, topoisomerase, DNA binding, ATP binding, polymerase, and ligase, and, collectively, they define biochemical events that are essential for efficient recombination. In addition to these needed proteins, a cis-acting recombination hot spot known as Chi (chi: 5'-GCTGGTGG-3') plays a crucial regulatory function. The biochemical steps that comprise homologous recombination can be formally divided into four parts: (i) processing of DNA molecules into suitable recombination substrates, (ii) homologous pairing of the DNA partners and the exchange of DNA strands, (iii) extension of the nascent DNA heteroduplex; and (iv) resolution of the resulting crossover structure. This review focuses on the biochemical mechanisms underlying these steps, with particular emphases on the activities of the proteins involved and on the integration of these activities into likely biochemical pathways for recombination. Images PMID:7968921

Kowalczykowski, S C; Dixon, D A; Eggleston, A K; Lauder, S D; Rehrauer, W M

1994-01-01

90

Membrane topology of Escherichia coli diacylglycerol kinase.  

PubMed Central

The topology of Escherichia coli diacylglycerol kinase (DAGK) within the cytoplasmic membrane was elucidated by a combined approach involving both multiple aligned sequence analysis and fusion protein experiments. Hydropathy plots of the five prokaryotic DAGK sequences available were uniform in their prediction of three transmembrane segments. The hydropathy predictions were experimentally tested genetically by fusing C-terminal deletion derivatives of DAGK to beta-lactamase and beta-galactosidase. Following expression, the enzymatic activities of the chimeric proteins were measured and used to determine the cellular location of the fusion junction. These studies confirmed the hydropathy predictions for DAGK with respect to the number and approximate sequence locations of the transmembrane segments. Further analysis of the aligned DAGK sequences detected probable alpha-helical N-terminal capping motifs and two amphipathic alpha-helices within the enzyme. The combined fusion and sequence data indicate that DAGK is a polytopic integral membrane protein with three transmembrane segments with the N terminus of the protein in the cytoplasm, the C terminus in the periplasmic space, and two amphipathic helices near the cytoplasmic surface. Images PMID:8071224

Smith, R L; O'Toole, J F; Maguire, M E; Sanders, C R

1994-01-01

91

Antimicrobial-resistant Invasive Escherichia coli, Spain  

PubMed Central

To address the public health problem of antimicrobial resistance, the European Union founded the European Antimicrobial Resistance Surveillance System. A network of 32 Spanish hospitals, serving ?9.6 million persons, submitted antimicrobial-susceptibility data on 7,098 invasive Escherichia coli species (2001–2003). Resistance to ampicillin, cotrimoxazole, ciprofloxacin, gentamicin, and tobramycin was found at rates of 59.9%, 32.6%, 19.3%, 6.8%, and 5.3%, respectively. Resistance to multiple drugs increased from 13.8% in 2001 to 20.6% in 2003 (p <0.0001). Antimicrobial consumption data were obtained from the Spanish National Health System. In spite of decreased cephalosporin and ?-lactam use, overall extended-spectrum ?-lactamase production increased from 1.6% (2001) to 4.1% (2003) (p <0.0001), mainly due to the rising prevalence of cefotaximases. Resistance to ciprofloxacin significantly increased, mostly in community-onset infections, which coincided with a rise in community quinolone use. Cotrimoxazole resistance remained stable at ?30%, even though its use was dramatically reduced. PMID:15829192

Oteo, Jesús; Lázaro, Edurne; de Abajo, Francisco J.; Baquero, Fernando; Campos, José

2005-01-01

92

Escherichia coli mutants impaired in maltodextrin transport.  

PubMed Central

Wild-type Escherichia coli K-12 was found to grow equally well on maltose and on maltodextrins containing up to seven glucose residues. Three classes of mutants unable to grow on maltodextrins, but still able to grow on maltose, were investigated in detail. The first class, already known, was composed of phage lambda-resistant mutants, which lack the outer membrane protein coded by gene lamB. These mutants grow on maltose and maltotriose but not at all on maltotetraose and longer maltodextrins which cannot cross the outer membrane. A second class of mutants were affected in malE, the structural gene of the periplasmic maltose binding protein. The maltose binding proteins isolated from the new mutants were altered in their substrate binding properties, but not in a way that could account for the mutant phenotypes. Rather, the results of growth experiments and transport studies suggest that these malE mutants are impaired in their ability to transport maltodextrins across the outer membrane. This implies that the maltose binding protein (in wild-type strains) cooperates with the lambda receptor in permeation through the outer membrane. The last class of mutants described in this paper were affected in malG, or perhaps in an as yet undetected gene close to malG. They were defective in the transfer of maltodextrins from the periplasmic space to the cytoplasm but only slightly affected in the transport of maltose. Images PMID:387714

Wandersman, C; Schwartz, M; Ferenci, T

1979-01-01

93

Incomplete flagellar structures in Escherichia coli mutants.  

PubMed Central

Escherichia coli mutants with defects in 29 flagellar genes identified so far were examined by electron microscopy for possession of incomplete flagellar structures in membrane-associated fractions. The results are discussed in consideration of the known transcriptional interaction of flagellar genes. Hook-basal body structures were detected in flaD, flaS, flaT, flbC, and hag mutants. The flaE mutant had a polyhook-basal body structure. An intact basal body appeared in flaK mutants. Putative precursors of the basal body were detected in mutants with defects in flaM, flaU, flaV, and flaY. No structures homologous to the flagellar basal body or its parts were detected in mutants with defects in flaA, flaB, flaC, flaG, flaH, flaI, flaL, flaN, flaO, flaP, flaQ, flaR, flaW, flaX, flbA, flbB, and flbD. One flaZ mutant had an incomplete flagellar basal body structure and another formed no significant structure, suggesting that flaZ is responsible for both basal body assembly and the transcription of the hag gene. Images PMID:7007337

Suzuki, T; Komeda, Y

1981-01-01

94

Virulence regulons of enterotoxigenic Escherichia coli.  

PubMed

Enterotoxigenic Escherichia coli is frequently associated with travelers' diarrhea and is a leading cause of infant and childhood mortality in developing countries. Disease is dependent upon the orchestrated expression of enterotoxins, flexible adhesive pili, and other virulence factors. Both the heat-labile (LT) and heat-stable (ST-H) enterotoxins are regulated at the level of transcription by cAMP-receptor protein which represses the expression of LT while activating expression of ST-H. The expression of many different serotypes of adhesive pili is regulated by Rns, a member of the AraC family that represents a subgroup of conserved virulence regulators from several enteric pathogens. These Rns-like regulators recognize similar DNA binding sites, and a compiled sequence logo suggests they may bind DNA through both major and minor groove interactions. These regulators are also tempting targets for novel therapeutics because they play pivotal roles during infection. To that end, high-throughput screens have begun to identify compounds that inhibit the activity of these regulators, predominately by interfering with DNA binding. PMID:24203442

Munson, George P

2013-12-01

95

The Escherichia coli divisome: born to divide.  

PubMed

Septation in Escherichia coli involves complex molecular mechanisms that contribute to the accuracy of bacterial division. The proto-ring, a complex made up by the FtsZ, FtsA and ZipA proteins, forms at the beginning of the process and directs the assembly of the full divisome. Central to this complex is the FtsZ protein, a GTPase able to assemble into a ring-like structure that responds to several modulatory inputs including mechanisms to position the septum at midcell. The connection with the cell wall synthesising machinery stabilizes the constriction of the cytoplasmic membrane. Although a substantial amount of evidence supports this description, many details on how individual divisome elements are structured or how they function are subjected to controversial interpretations. We discuss these discrepancies arising from incomplete data and from technical difficulties imposed by the small size of bacteria. Future work, including more powerful imaging and reconstruction technologies, will help to clarify the missing details on the architecture and function of the bacterial division machinery. PMID:23962168

Natale, Paolo; Pazos, Manuel; Vicente, Miguel

2013-12-01

96

Transcription of the Escherichia coli fliC gene is regulated by metal ions  

SciTech Connect

luxAB gene fusions in the Escherichia coli genome were used to screen for clones displaying transcriptional changes in the presence of aluminum. One clone was found that contained a luciferase gene fusion in which transcription was increased in the presence of aluminum and which was subsequently shown to be induced by copper, iron, and nickel. Cloning of the metal-regulated gene, hybridization to the ordered phage {lambda} bank of the E. coli chromosome, and sequencing of DNA adjacent to the luxAB fusion revealed that the insertion occurred within the fliC (hag) gene of E. coli. This gene encodes flagellin the filament subunit of the bacterial motility organ, and is under the control of several regulatory cascades. These results suggest that environmental metals may play a role in the regulation of the motility potential of E. coli and that this bioluminescent gene fusion clone (or derivatives thereof) may be used to prepare a biosensor for the rapid detection of metal contamination in water samples.

Guzzo, A.; Diorio, C.; DuBow, M.S. (McGill Univ., Montreal, Quebec (Canada))

1991-08-01

97

Shiga toxin-producing Escherichia coli.  

PubMed

In the United States, it is estimated that non-O157 Shiga toxin-producing Escherichia coli (STEC) cause more illnesses than STEC O157:H7, and the majority of cases of non-O157 STEC infections are due to serogroups O26, O45, O103, O111, O121, and O145, referred to as the top six non-O157 STEC. The diseases caused by non-O157 STEC are generally milder than those induced by O157 STEC; nonetheless, non-O157 STEC strains have also been associated with serious illnesses such as hemorrhagic colitis and hemolytic uremic syndrome, as well as death. Ruminants, particularly cattle, are reservoirs for both O157 and non-O157 STEC, which are transmitted to humans by person-to-person or animal contact and by ingestion of food or water contaminated with animal feces. Improved strategies to control STEC colonization and shedding in cattle and contamination of meat and produce are needed. In general, non-O157 STEC respond to stresses such as acid, heat, and other stresses induced during food preparation similar to O157 STEC. Similar to O157:H7, the top six non-O157 STEC are classified as adulterants in beef by the USDA Food Safety and Inspection Service, and regulatory testing for these pathogens began in June 2012. Due to the genetic and phenotypic variability of non-O157 STEC strains, the development of accurate and reliable methods for detection and isolation of these pathogens has been challenging. Since the non-O157 STEC are responsible for a large portion of STEC-related illnesses, more extensive studies on their physiology, genetics, pathogenicity, and evolution are needed in order to develop more effective control strategies. PMID:24377855

Smith, James L; Fratamico, Pina M; Gunther, Nereus W

2014-01-01

98

Severe Zinc Depletion of Escherichia coli  

PubMed Central

Zinc ions play indispensable roles in biological chemistry. However, bacteria have an impressive ability to acquire Zn2+ from the environment, making it exceptionally difficult to achieve Zn2+ deficiency, and so a comprehensive understanding of the importance of Zn2+ has not been attained. Reduction of the Zn2+ content of Escherichia coli growth medium to 60 nm or less is reported here for the first time, without recourse to chelators of poor specificity. Cells grown in Zn2+-deficient medium had a reduced growth rate and contained up to five times less cellular Zn2+. To understand global responses to Zn2+ deficiency, microarray analysis was conducted of cells grown under Zn2+-replete and Zn2+-depleted conditions in chemostat cultures. Nine genes were up-regulated more than 2-fold (p < 0.05) in cells from Zn2+-deficient chemostats, including zinT (yodA). zinT is shown to be regulated by Zur (zinc uptake regulator). A mutant lacking zinT displayed a growth defect and a 3-fold lowered cellular Zn2+ level under Zn2+ limitation. The purified ZinT protein possessed a single, high affinity metal-binding site that can accommodate Zn2+ or Cd2+. A further up-regulated gene, ykgM, is believed to encode a non-Zn2+ finger-containing paralogue of the Zn2+ finger ribosomal protein L31. The gene encoding the periplasmic Zn2+-binding protein znuA showed increased expression. During both batch and chemostat growth, cells “found” more Zn2+ than was originally added to the culture, presumably because of leaching from the culture vessel. Zn2+ elimination is shown to be a more precise method of depleting Zn2+ than by using the chelator N,N,N?,N?-tetrakis(2-pyridylmethyl)ethylenediamine. PMID:19377097

Graham, Alison I.; Hunt, Stuart; Stokes, Sarah L.; Bramall, Neil; Bunch, Josephine; Cox, Alan G.; McLeod, Cameron W.; Poole, Robert K.

2009-01-01

99

Comparison of the PhoPQ Regulon in Escherichia coli and Salmonella typhimurium  

E-print Network

Comparison of the PhoPQ Regulon in Escherichia coli and Salmonella typhimurium Pieter Monsieurs,1 as a transcriptional regulator that responds to Mg2+ starvation both in Escherichia coli and Salmonella typhimurium.g., pathogenesis in S. typhimurium). Key words: PhoPQ regulon -- Escherichia coli -- Salmonella typhimirium

100

Obscured phylogeny and possible recombinational dormancy in Escherichia coli  

PubMed Central

Background Escherichia coli is one of the best studied organisms in all of biology, but its phylogenetic structure has been difficult to resolve with current data and analytical techniques. We analyzed single nucleotide polymorphisms in chromosomes of representative strains to reconstruct the topology of its emergence. Results The phylogeny of E. coli varies according to the segment of chromosome analyzed. Recombination between extant E. coli groups is largely limited to only three intergroup pairings. Conclusions Segment-dependent phylogenies most likely are legacies of a complex recombination history. However, E. coli are now in an epoch in which they no longer broadly share DNA. Using the definition of species as organisms that freely exchange genetic material, this recombinational dormancy could reflect either the end of E. coli as a species, or herald the coalescence of E. coli groups into new species. PMID:21708031

2011-01-01

101

Pathogenomics of the Virulence Plasmids of Escherichia coli  

PubMed Central

Summary: Bacterial plasmids are self-replicating, extrachromosomal elements that are key agents of change in microbial populations. They promote the dissemination of a variety of traits, including virulence, enhanced fitness, resistance to antimicrobial agents, and metabolism of rare substances. Escherichia coli, perhaps the most studied of microorganisms, has been found to possess a variety of plasmid types. Included among these are plasmids associated with virulence. Several types of E. coli virulence plasmids exist, including those essential for the virulence of enterotoxigenic E. coli, enteroinvasive E. coli, enteropathogenic E. coli, enterohemorrhagic E. coli, enteroaggregative E. coli, and extraintestinal pathogenic E. coli. Despite their diversity, these plasmids belong to a few plasmid backbones that present themselves in a conserved and syntenic manner. Thanks to some recent research, including sequence analysis of several representative plasmid genomes and molecular pathogenesis studies, the evolution of these virulence plasmids and the implications of their acquisition by E. coli are now better understood and appreciated. Here, work involving each of the E. coli virulence plasmid types is summarized, with the available plasmid genomic sequences for several E. coli pathotypes being compared in an effort to understand the evolution of these plasmid types and define their core and accessory components. PMID:19946140

Johnson, Timothy J.; Nolan, Lisa K.

2009-01-01

102

Recombinational Construction in Escherichia coli of Infectious Adenoviral Genomes  

Microsoft Academic Search

A two-step gene replacement procedure was developed that generates infectious adenoviral genomes through homologous recombination in Escherichia coli. As a prerequisite, a human adenovirus serotype 5 (Ad5)-derived genome was first introduced as a PacI restriction fragment into an incP-derived replicon which, in contrast to ColE1-derivatives (e.g., pBR322 or pUC plasmids), is functional in a polA mutant of E. coli. Any

Joel Crouzet; Laurent Naudin; Cecile Orsini; Emmanuelle Vigne; Lucy Ferrero; Aude Le Roux; Patrick Benoit; Martine Latta; Christophe Torrent; Didier Branellec; Patrice Denefle; Jean-Francois Mayaux; Michel Perricaudet; Patrice Yeh

1997-01-01

103

EcoCyc: a comprehensive database resource for Escherichia coli  

Microsoft Academic Search

The EcoCyc database (http:\\/\\/EcoCyc.org\\/) is a com- prehensivesourceofinformationonthebiologyofthe prototypical model organism Escherichia coli K12. ThemissionforEcoCycistocontainbothcomputable descriptions of, and detailed comments describing, all genes, proteins, pathways and molecular interac- tions in E.coli. Through ongoing manual curation, extensive information such as summary comments, regulatory information, literature citations and evi- dence types has been extracted from 8862 publica- tions and added to Version

Ingrid M. Keseler; Julio Collado-vides; Socorro Gama-castro; John Ingraham; Suzanne M. Paley; Ian T. Paulsen; Martín Peralta-gil; Peter D. Karp

2005-01-01

104

EcoCyc: a comprehensive database resource for Escherichia coli  

Microsoft Academic Search

The EcoCyc database (http:\\/\\/EcoCyc. org\\/) is a com-prehensive source of information on the biology of the prototypical model organism Escherichia coli K12.The mission for EcoCyc is to contain both computable descriptions of, and detailed comments describing, all genes, proteins, pathways and molecular interac-tions in E. coli. Through ongoing manual curation, extensive information such as summary comments, regulatory information, literature citations

Ingrid M. Keseler; Julio Collado-vides; Socorro Gama-castro; John Ingraham

2006-01-01

105

YeeO from Escherichia coli exports flavins.  

PubMed

Multidrug and toxic compound extrusion (MATE) proteins help maintain cellular homeostasis by secreting metabolic wastes. Flavins may occur as cellular waste products, with their production and secretion providing potential benefit for industrial applications related to biofuel cells. Here we find that MATE protein YeeO from Escherichia coli exports both flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Significant amounts of flavins were trapped intracellularly when YeeO was produced indicating transport limits secretion of flavins. Wild-type E. coli secreted 3 flavins (riboflavin, FMN, and FAD), so E. coli likely produces additional flavin transporters. PMID:25482085

McAnulty, Michael J; Wood, Thomas K

2014-11-01

106

Sources of Escherichia coli in a coastal subtropical environment.  

PubMed

Sources of Escherichia coli in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in E. coli concentrations as well as experiments conducted under laboratory-controlled conditions. E. coli from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling tasks included sampling the length of the North Fork to identify the river reach contributing high E. coli levels, autosampler experiments at two locations, and spatially intense sampling efforts at hot spots. Laboratory experiments were designed to simulate tidal conditions within the riverbank soils. The results showed that E. coli entered the river in a large pulse during storm conditions. After the storm, E. coli levels returned to baseline levels and varied in a cyclical pattern which correlated with tidal cycles. The highest concentrations were observed during high tide, whereas the lowest were observed at low tide. This peculiar pattern of E. coli concentrations between storm events was caused by the growth of E. coli within riverbank soils which were subsequently washed in during high tide. Laboratory analysis of soil collected from the riverbanks showed increases of several orders of magnitude in soil E. coli concentrations. The ability of E. coli to multiply in the soil was found to be a function of soil moisture content, presumably due to the ability of E. coli to outcompete predators in relatively dry soil. The importance of soil moisture in regulating the multiplication of E. coli was found to be critical in tidally influenced areas due to periodic wetting and drying of soils in contact with water bodies. Given the potential for growth in such systems, E. coli concentrations can be artificially elevated above that expected from fecal impacts alone. Such results challenge the use of E. coli as a suitable indicator of water quality in tidally influenced areas located within tropical and subtropical environments. PMID:10618229

Solo-Gabriele, H M; Wolfert, M A; Desmarais, T R; Palmer, C J

2000-01-01

107

Slugs: Potential Novel Vectors of Escherichia coli O157  

PubMed Central

Field and laboratory studies were performed to determine whether slugs could act as novel vectors for pathogen (e.g., Escherichia coli O157) transfer from animal feces to salad vegetables. Escherichia coli O157 was isolated from 0.21% of field slugs from an Aberdeenshire sheep farm. These isolates carried the verocytotoxin genes (vt1 and vt2) and the attaching and effacing gene (eae), suggesting that they are potentially pathogenic to humans. Strain typing using multilocus variable number tandem repeats analysis showed that slug and sheep isolates were indistinguishable. Laboratory experiments using an E. coli mutant resistant to nalidixic acid showed that the ubiquitous slug species Deroceras reticulatum could carry viable E. coli on its external surface for up to 14 days. Slugs that had been fed E. coli shed viable bacteria in their feces with numbers showing a short but statistically significant linear log decline. Further, it was found that E. coli persisted for up to 3 weeks in excreted slug feces, and hence, we conclude that slugs have the potential to act as novel vectors of E. coli O157. PMID:16391036

Sproston, Emma L.; Macrae, M.; Ogden, Iain D.; Wilson, Michael J.; Strachan, Norval J. C.

2006-01-01

108

Naturalized Escherichia coli from New Zealand wetland and stream environments.  

PubMed

This research investigates the presence of a naturalized clade of Escherichia coli in wetland and stream biofilms. Escherichia coli is used as a faecal indicator in water quality monitoring programmes worldwide, with the assumption that this bacterium is exclusively a commensal of the vertebrate gut. However, recent findings indicate growth and multiplication of E. coli in water and soils. This study seeks to clarify the relationships between environmental and commensal E. coli strains retrieved from New Zealand streams by evaluating fundamental genetic differences using the multilocus sequence typing (MLST) method. Environmental and commensal strains showed a high diversity of MLST profiles. Genetic analyses of linkage disequilibrium, index of association and rates of synonymous and nonsynonymous substitutions were used to investigate sequence variability and nature of change. Phylogenetic trees based on the concatenated sequences of the seven MLST housekeeping genes displayed distinct clustering of environmental strains. Comparison of the New Zealand sequences with worldwide E. coli strains retrieved from the Shigatox MLST database online did not allow the identification of a clear environmental genotype. However, some New Zealand aquatic E. coli isolates showed close relationships with strains from human and bovine origins, suggesting that environmental isolates were originally derived from subpopulations of commensal E. coli from these sources. PMID:22974403

Perchec-Merien, Anne-Marie; Lewis, Gillian D

2013-02-01

109

Expression of enteropathogenic Escherichia coli map is significantly different than that of other type III secreted effectors in vivo.  

PubMed

The enteropathogenic Escherichia coli (EPEC) locus of enterocyte effacement (LEE)-encoded effectors EspF and Map are multifunctional and have an impact on the tight junction barrier while the non-LEE-encoded proteins NleH1 and NleH2 possess significant anti-inflammatory activity. In order to address the temporal expression of these important genes in vivo, their promoters were cloned upstream of the luxCDABE operon, and luciferase expression was measured in EPEC-infected mice by bioluminescence using an in vivo imaging system (IVIS). Bioluminescent images of living mice, of excised whole intestines, and of whole intestines longitudinally opened and washed were assessed. The majority of bioluminescent bacteria localized in the cecum by 3 h postinfection, indicating that the cecum is not only a major colonization site of EPEC but also a site of EPEC effector gene expression in mice. espF, nleH1, and nleH2 were abundantly expressed over the course of infection. In contrast, map expression was suppressed at 2 days postinfection, and at 4 days postinfection it was totally abolished. After 2 to 4 days postinfection, when map is suppressed, EPEC colonization is significantly reduced, indicating that map may be one of the factors required to maintain EPEC colonization. This was confirmed in a competitive colonization study and in two models of chronic infection, repeated exposure to ketamine and Citrobacter rodentium infection. Our data suggest that map expression contributes to the maintenance of EPEC colonization. PMID:25312947

Nguyen, Mai; Rizvi, Jason; Hecht, Gail

2015-01-01

110

The hydrogenases and formate dehydrogenases of Escherichia coli  

Microsoft Academic Search

Escherichia coli has the capacity to synthesise three distinct formate dehydrogenase isoenzymes and three hydrogenase isoenzymes. All six are multisubunit, membrane-associated proteins that are functional in the anaerobic metabolism of the organism. One of the formate dehydrogenase isoenzymes is also synthesised in aerobic cells. Two of the formate dehydrogenase enzymes and two hydrogenases have a respiratory function while the formate

Gary Sawers

1994-01-01

111

Synthesis of Calf Prochymosin (Prorennin) in Escherichia coli  

Microsoft Academic Search

A gene for calf prochymosin (prorennin) has been reconstructed from chemically synthesized oligodeoxyribonucleotides and cloned DNA copies of preprochymosin mRNA. This gene has been inserted into a bacterial expression plasmid containing the Escherichia coli tryptophan promoter and a bacterial ribosome binding site. Induction of transcription from the tryptophan promoter results in prochymosin synthesis at a level of up to 5%

J. S. Emtage; S. Angal; M. T. Doel; T. J. R. Harris; B. Jenkins; G. Lilley; P. A. Lowe

1983-01-01

112

Escherichia coli bacteraemia in Canberra: incidence and clinical features  

Microsoft Academic Search

Objective: To determine the population incidence and clinical features of Escherichia coli bacteraemia in Canberra, Australia. Design, setting and participants: Canberra (including the nearby local government areas of Queanbeyan and Yarrowlumla) has a geographically isolated population of about 366 000 people. Its six hospitals also provide tertiary medical services for the surrounding region. Confining our analysis (by residential postcodes) to

Karina J Kennedy; Jan L Roberts; Peter J Collignon

2008-01-01

113

Combating enteropathogenic Escherichia coli (EPEC) infections: the way forward  

PubMed Central

Enteropathogenic Escherichia coli (EPEC) strains continue to cause severe and sometimes fatal infantile diarrhea, particularly in Africa. Increased efforts at diagnosis, defining the clinical spectrum of disease, understanding pathogenic mechanisms, and delineating immune responses are desperately needed to develop new strategies to combat EPEC. PMID:23815982

Donnenberg, Michael S.; Finlay, B. Brett

2015-01-01

114

Why the Phosphotransferase System of Escherichia coli Escapes Diffusion Limitation  

Microsoft Academic Search

We calculated the implications of diffusion for the phosphoenolpyruvate:glucose phosphotransferase system (glucose-PTS) of Escherichia coli in silicon cells of various magnitudes. For a cell of bacterial size, diffusion limitation of glucose influx was negligible. Nevertheless, a significant concentration gradient for one of the enzyme species, nonphosphorylated IIAGlc, was found. This should have consequences because the phosphorylation state of IIAGlc is

Christof Francke; Pieter W. Postma; Hans V. Westerhoff; Joke G. Blom; Mark A. Peletier

2003-01-01

115

Escherichia coli and other Enterobacteriaceae: Food poisoning and health effects  

Technology Transfer Automated Retrieval System (TEKTRAN)

The family Enterobactericeae consists of rod-shaped, Gram-negative, facultatively anaerobic, non-spore forming bacteria and also includes the food-borne pathogens, Cronobacter spp., Escherichia coli, Salmonella enterica, Shigella spp., and Yersinia spp. Illness caused by these pathogens is acquired...

116

Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation.  

EPA Science Inventory

Titanium dioxide in the anatase crystalline form was used as a photocatalyst to generate hydroxyl radicals in a flowthrough water reactor. Experiments were performed on pure cultures of Escherichia coli in dechlorinated tap water and a surface water sample to evaluate the disinfe...

117

Global Incidence of Carbapenemase-Producing Escherichia coli ST131  

PubMed Central

We characterized Escherichia coli ST131 isolates among 116 carbapenemase-producing strains. Of isolates from 16 countries collected during 2008–2013, 35% belonged to ST131 and were associated with blaKPC, H30 lineage, and virotype C. This study documents worldwide incidents of resistance to “last resort” antimicrobial drugs among a common pathogen in a successful sequence type. PMID:25340464

Peirano, Gisele; Bradford, Patricia A.; Kazmierczak, Krystyna M.; Badal, Robert E.; Hackel, Meredith; Hoban, Daryl J.

2014-01-01

118

Biological Costs and Mechanisms of Fosfomycin Resistance in Escherichia coli  

Microsoft Academic Search

Fosfomycin is a cell wall inhibitor used mainly for the treatment of uncomplicated lower urinary tract infections. As shown here, resistance to fosfomycin develops rapidly in Escherichia coli under experimental conditions, but in spite of the relatively high mutation rate in vitro, resistance in clinical isolates is rare. To examine this apparent contradiction, we mathematically modeled the probability of resistance

Annika I. Nilsson; Otto G. Berg; Olle Aspevall; Gunnar Kahlmeter; Dan I. Andersson

2003-01-01

119

Lactuca indica extract interferes with uroepithelial infection by Escherichia coli  

Microsoft Academic Search

Ethnopharmacological relevanceUropathogenic Escherichia coli is the major cause for urinary tract infections (UTI). Due to emerging antimicrobial resistances treatment of UTI is becoming increasingly difficult. Therefore, alternative treatment strategies are required. We sought to investigate the molecular mechanisms of a traditionally used decoction from Vietnamese dandelion (Lactuca indica L.) mediating local protection of the bladder epithelium.

Petra Lüthje; Dang Ngoc Dzung; Annelie Brauner

2011-01-01

120

Structure and Mechanism of the Lactose Permease of Escherichia coli  

Microsoft Academic Search

Membrane transport proteins that transduce free energy stored in electrochemical ion gradients into a concentration gradient are a major class of membrane proteins. We report the crystal structure at 3.5 angstroms of the Escherichia coli lactose permease, an intensively studied member of the major facilitator superfamily of transporters. The molecule is composed of N- and C-terminal domains, each with six

Jeff Abramson; Irina Smirnova; Vladimir Kasho; Gillian Verner; H. Ronald Kaback; So Iwata

2003-01-01

121

Bactericidal activity of human serum against Escherichia coli chi1776.  

PubMed Central

Escherichia coli chi1776 is a host strain providing the EK2 level of biological containment. Laboratories equipped to use this strain may be located near medical care facilities where patients prone to infection may be found. We have therefore documented the marked susceptibility of chi1776 to killing by human serum from normal as well as ill individuals. PMID:6995323

Alexander, W J; Alexander, L S; Curtiss, R

1980-01-01

122

Recombinant protein folding and misfolding in Escherichia coli  

Microsoft Academic Search

The past 20 years have seen enormous progress in the understanding of the mechanisms used by the enteric bacterium Escherichia coli to promote protein folding, support protein translocation and handle protein misfolding. Insights from these studies have been exploited to tackle the problems of inclusion body formation, proteolytic degradation and disulfide bond generation that have long impeded the production of

Mirna Mujacic; François Baneyx

2004-01-01

123

Changes in Escherichia coli transcriptome during acclimatization at low temperature  

Microsoft Academic Search

Upon cold shock Escherichia coli transiently stops growing and adapts to the new temperature (acclimatization phase). The major physiological effects of cold temperature are a decrease in membrane fluidity and the stabilization of secondary structures of RNA and DNA, which may affect the efficiencies of translation, transcription, and replication. Specific proteins are transiently induced in the acclimatization phase. mRNA stabilization

Alessandra Polissi; Walter De Laurentis; Sandro Zangrossi; Federica Briani; Vera Longhi; Graziano Pesole; Gianni Dehò

2003-01-01

124

Quorum sensing in Escherichia coli and Salmonella typhimurium  

Microsoft Academic Search

Escherichia coli and Salmonella typhimurium strains grown in Luria-Bertani medium containing glucose secrete a small soluble heat labile organic molecule that is involved in intercellular communication. The factor is not produced when the strains are grown in Luria-Bertani me- dium in the absence of glucose. Maximal secretion of the substance occurs in midexponential phase, and the extracel- lular activity is

MICHAEL G. SURETTE; BONNIE L. BASSLER

1998-01-01

125

Genetics of ribosomal protein methylation in Escherichia coli  

Microsoft Academic Search

Two genes governing ribosomal protein methylation have been located on the map of Escherichia coli by conjugation and transduction crosses between wild-type and prm (protein methylation) mutants. The Prm phenotype of recombinants was determined by an in vitro assay of methylgroups incorporation into protein.

Charles Colson; Jacques Lhoest; Colette Urlings

1979-01-01

126

Carbon nutrition of Escherichia coli in the mouse intestine  

E-print Network

Carbon nutrition of Escherichia coli in the mouse intestine Dong-Eun Chang*, Darren J. Smalley in the mammalian intestine. Most were nutritional genes corresponding to catabolic pathways for nutrients found of the mouse intestine in competition with their wild-type parent. We found that only mutations in sugar

Conway, Tyrrell

127

Budget Analysis of Escherichia coli at a Southern Lake Michigan  

E-print Network

Budget Analysis of Escherichia coli at a Southern Lake Michigan Beach P R A M O D T H U P A K I and the Environment, University of Michigan, Ann Arbor, Michigan, NOAA Great Lakes Environmental Research Laboratory (GLERL), Ann Arbor, Michigan, and Lake Michigan Ecological Research Station, U.S. Geological Survey

128

Original article Resistance of Escherichia coli growing as biofilms  

E-print Network

Original article Resistance of Escherichia coli growing as biofilms to disinfectants C Ntsama) Summary ― The bactericidal activity of various disinfectants (cationic or amphoteric surfactants in a continuous culture system. The bacteria tested on germ-carriers or included in biofilms were more resistant

Boyer, Edmond

129

The deoxycytidine pathway for thymidylate synthesis in Escherichia coli.  

PubMed

When thymidylate production is diminished by a mutation affecting dCTP deaminase, Escherichia coli is known to use an alternate pathway involving deoxycytidine as an intermediate. The pathway requires the gene for any of three nucleoside diphosphate kinases (ndk, pykA, or pykF) and the gene for a 5'-nucleotidase (yfbR). PMID:17827303

Weiss, Bernard

2007-11-01

130

Kinetics of Bacteriophage ? Deoxyribonucleic Acid Infection of Escherichia coli  

PubMed Central

Barnhart, Benjamin J. (Los Alamos Scientific Laboratory, University of California, Los Alamos, N.M.). Kinetics of bacteriophage ? deoxyribonucleic acid infection of Escherichia coli. J. Bacteriol. 90:1617–1623. 1965.—The kinetics of Escherichia coli K-12 infection by phage ? deoxyribonucleic acid (DNA) were determined. An initial lag of 55 to 80 sec was found to be the time required for infecting DNA to become deoxyribonuclease-insensitive at 33 C. When cell-DNA interactions were stopped by washing away unbound DNA, the already bound DNA continued to infect the cell at rates described by linear kinetics with no apparent lag. Whereas the lag period was relatively insensitive to DNA and cell concentrations, both the lag and the subsequent linear portions of the rate curves were temperature-sensitive. Cell and DNA dose-response curves prescribed hyperbolic functions. Similarities between ? DNA infection of E. coli and bacterial transformation systems are discussed. PMID:5322721

Barnhart, Benjamin J.

1965-01-01

131

Novel phage-based bio-processing of pathogenic Escherichia coli and its biofilms  

Microsoft Academic Search

To explore new approaches of phage-based bio-process of specifically pathogenic Escherichia coli bacteria in food products within a short period. One hundred and forty highly lytic designed coliphages were used. Escherichia coli naturally contaminated and Enterohemorrhagic Escherichia coli experimentally inoculated samples of lettuce, cabbage, meat, and egg were used. In addition, experimentally produced biofilms\\u000a of E. coli were tested. A

S. A. A. Jassim; A. S. Abdulamir; F. Abu Bakar

132

Cloning, expression and bioinformatics analysis of ATP sulfurylase from Acidithiobacillus ferrooxidans ATCC 23270 in Escherichia coli.  

PubMed

Molecular studies of enzymes involved in sulfite oxidation in Acidithiobacillus ferrooxidans have not yet been developed, especially in the ATP sulfurylase (ATPS) of these acidophilus tiobacilli that have importance in biomining. This enzyme synthesizes ATP and sulfate from adenosine phosphosulfate (APS) and pyrophosphate (PPi), final stage of the sulfite oxidation by these organisms in order to obtain energy. The atpS gene (1674 bp) encoding the ATPS from Acidithiobacillus ferrooxidans ATCC 23270 was amplified using PCR, cloned in the pET101-TOPO plasmid, sequenced and expressed in Escherichia coli obtaining a 63.5 kDa ATPS recombinant protein according to SDS-PAGE analysis. The bioinformatics and phylogenetic analyses determined that the ATPS from A. ferrooxidans presents ATP sulfurylase (ATS) and APS kinase (ASK) domains similar to ATPS of Aquifex aeolicus, probably of a more ancestral origin. Enzyme activity towards ATP formation was determined by quantification of ATP formed from E. coli cell extracts, using a bioluminescence assay based on light emission by the luciferase enzyme. Our results demonstrate that the recombinant ATP sulfurylase from A. ferrooxidans presents an enzymatic activity for the formation of ATP and sulfate, and possibly is a bifunctional enzyme due to its high homology to the ASK domain from A. aeolicus and true kinases. PMID:23055613

Jaramillo, Michael L; Abanto, Michel; Quispe, Ruth L; Calderón, Julio; Del Valle, Luís J; Talledo, Miguel; Ramírez, Pablo

2012-01-01

133

Lytic bacteriophages reduce Escherichia coli O157  

PubMed Central

The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield™) or a control (phosphate buffered saline, PBS) was applied to lettuce by either; (1) immersion of lettuce in 500 ml of EcoShield™ 8.3 log PFU/ml or 9.8 log PFU/ml for up to 2 min before inoculation with E. coli O157:H7; (2) spray-application of EcoShield™ (9.3 log PFU/ml) to lettuce after inoculation with E. coli O157:H7 (4.10 CFU/cm2) following exposure to 50 ?g/ml chlorine for 30 sec. After immersion studies, lettuce was spot-inoculated with E. coli O157:H7 (2.38 CFU/cm2). Phage-treated, inoculated lettuce pieces were stored at 4°C for and analyzed for E. coli O157:H7 populations for up to 7 d. Immersion of lettuce in 9.8 log PFU/ml EcoShield™ for 2 min significantly (p < 0.05) reduced E. coli O157:H7 populations after 24 h when stored at 4°C compared with controls. Immersion of lettuce in suspensions containing high concentrations of EcoShield™ (9.8 log PFU/ml) resulted in the deposition of high concentrations (7.8 log log PFU/cm2) of bacteriophages on the surface of fresh cut lettuce, potentially contributing to the efficacy of the lytic phages on lettuce. Spraying phages on to inoculated fresh cut lettuce after being washed in hypochlorite solution was significantly more effective in reducing E. coli O157:H7 populations (2.22 log CFU/cm2) on day 0 compared with control treatments (4.10 log CFU/cm2). Both immersion and spray treatments provided protection from E. coli O157:H7 contamination on lettuce, but spray application of lytic bacteriophages to lettuce was more effective in immediately reducing E. coli O157:H7 populations fresh cut lettuce. PMID:23819106

Ferguson, Sean; Roberts, Cheryl; Handy, Eric; Sharma, Manan

2013-01-01

134

[Acute diarrheal disease caused by enteropathogenic Escherichia coli in Colombia].  

PubMed

Intestinal Escherichia coli pathogens are leading causes of acute diarrheal disease in children less than 5 years in Latin America, Africa and Asia and a leading cause of death in children living in poorest communities in Africa and South East Asia. Studies on the role of E. coli pathogens in childhood diarrhea in Colombia and other countries in Latin America are limited due to the lack of detection assays in clinical laboratories at the main urban medical centers. Recent studies report that enterotoxigenic E. coli is the most common E. coli pathogens associated with diarrhea in children less than 5 years of age. Other E. coli pathotypes have been detected in children with diarrhea including enteropathogenic, enteroaggregative, shiga-toxin producing and diffusely adherent E. coli. It was also found that meat and vegetables at retail stores are contaminated with Shiga-toxin producing E. coli and enteroaggregative E. coli, suggesting that food products are involved in transmission and infection of the susceptible host. More studies are necessary to evaluate the mechanisms of transmission, the impact on the epidemiology of diarrheal disease, and management strategies and prevention of these pathogens affecting the pediatric population in Colombia. PMID:25491457

Gómez-Duarte, Oscar G

2014-10-01

135

Toxicity monitoring and classification of endocrine disrupting chemicals (EDCs) using recombinant bioluminescent bacteria  

Microsoft Academic Search

A recombinant bioluminescent Escherichia coli, DPD2794, containing the recA promoter region fused to luxCDABE originating from Vibrio fischeri was used for detecting genotoxicity caused by endocrine disrupting chemicals (EDCs) to cells. As well, several other recombinant bioluminescent bacteria, including TV1061, which is sensitive to protein damage (grpE::luxCDABE), DPD2511, sensitive to oxidative damage (katG::luxCDABE), and DPD2540, sensitive to membrane damage (fabA::luxCDABE),

Man Bock Gu; Jiho Min; Eun Jin Kim

2002-01-01

136

Biosynthesis of bioactive O-methylated flavonoids in Escherichia coli.  

PubMed

Two bioactive O-methylflavonoids, sakuranetin (7-O-methylnaringenin) and ponciretin (7-O-methylnaringenin), were synthesized in Escherichia coli. Sakuranetin inhibits germination of Magnaporthe grisea, and ponciretin is a potential inhibitor of Helicobacter pylori. To achieve this, we reconstructed the naringenin biosynthesis pathway in E. coli. First, the shikimic acid pathway, which leads to the biosynthesis of tyrosine, was engineered in E. coli to increase the amount of available tyrosine. Second, several genes for the biosynthesis of ponciretin and sakuranetin such as tyrosine ammonia lyase (TAL), 4-coumaroyl CoA ligase (4CL), chalcone synthase (CHS), and O-methyltransferase (OMT) were overexpressed. In order to increase the supply the Coenzyme A (CoA), one gene (icdA, isocitrate dehydrogenase) was deleted. Using these strategies, we synthesized ponciretin and sakuranetin from glucose in E. coli at the concentration of 42.5 mg/L and 40.1 mg/L, respectively. PMID:23771780

Kim, Min-Ji; Kim, Bong-Gyu; Ahn, Joong-Hoon

2013-08-01

137

BIOSYNTHESIS AND BIOSYNTHETIC PATHWAYS OF PENTOSES IN ESCHERICHIA COLI  

PubMed Central

Sable, Henry Z. (Western Reserve University, Cleveland, Ohio) and Elayne E. Cassisi. Biosynthesis and biosynthetic pathways of pentoses in Escherichia coli. J. Bacteriol. 84:1169–1172. 1962.—Resting glucose-adapted Escherichia coli supplied with glucose continues to synthesize pentose by the oxidative pathway characteristic of logarithmically growing glucose-adapted cells. This behavior is unlike that of acetate-adapted resting E. coli supplied with glucose, which continues to synthesize most of its pentose by the nonoxidative pathway characteristic of acetate-adapted cells. When infected with bacteriophage T2H, E. coli continues to use the oxidative pathway predominantly. This finding is in contrast to reports that infection with T6r+ bacteriophage increases the participation of a nonoxidative pathway. Resting glucose-adapted E. coli supplied with acetate-1-C14 as sole carbon source synthesizes pentose by a pathway or pathways which cannot be assessed completely by methods previously developed (which are based on the relative labeling of C-1, C-2, and C-3 of the pentose) but which is most probably predominantly nonoxidative. PMID:13975889

Sable, Henry Z.; Cassisi, Elayne E.

1962-01-01

138

Uncoupler Resistance in Escherichia coli: the Role of Cellular Respiration  

Microsoft Academic Search

Bioenergetic properties of a mutant strain of Escherichia coli K12 designated TUV, which is resistant to the protonophoric uncoupling agent 4,5,6,7-tetrachloro-2-trifluoromethylbenzimid- azole (TTFB) have been compared with those of its non-resistant parent, E. coli K12 Doc-S. Strain TUV grew and respired some 20-30% faster than strain Doc-S, and was cross-resistant to carbonylcyanide p-(trifluoromethoxy)phenylhydrazone and triphenyltin, but not to 2,4- dinitrophenol.

PHILIP G. QUIRK; MICHAEL R. JONES; ROBERT S. HAWORTH; R. BRIAN BEECHEY; IAIN D. CAMPBELL

1989-01-01

139

[Reactive arthritis due to Escherichia coli urinary tract infection].  

PubMed

Reactive arthritis following Escherichia coli urinary tract infection is very rare. We report a 25-year-old woman with acute oligoarthritis associated with bilateral anterior uveitis after an episode of urinary tract infection due to E. coli. The diagnosis of reactive arthritis was considered and the patient treated with non-steroidal anti-inflammatory agents. Disease course was rapidly successful and at 6-month follow-up the patient was asymptomatic. Reactive arthritis is associated with intestinal infection but also with common urinary tract infection. PMID:20605282

Renou, F; Wartel, G; Raffray, L; Kuli, B; Fayeulle, S; Yvin, J-L

2011-01-01

140

Functional Role of bdm During Flagella Biogenesis in Escherichia coli.  

PubMed

The biofilm-dependent modulation gene (bdm) has recently been shown to play a role in osmotic-induced formation of biofilm in Escherichia coli. In this study, we demonstrated that deletion of bdm results in down-regulation of flagella biosynthesis genes and, consequently, a defect in E. coli motility. In addition, we employed atomic force microscopy to confirm the absence of flagella-like structures on the surface of bdm-null cells. These findings indicate that bdm plays a key role in regulatory pathway for the formation of flagella. PMID:25398323

Kim, Ji-Sun; Kim, Yu Jin; Seo, Sojin; Seong, Maeng-Je; Lee, Kangseok

2015-03-01

141

Inactivation of Escherichia coli using atmospheric-pressure plasma jet  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure argon (Ar) plasma jet was applied to the inactivation of Escherichia coli. The Ar plasma jet was generated at a frequency of 10 kHz, an applied voltage of 10 kV, and an Ar gas flow rate of 10 L/min at atmospheric pressure. E. coli cells seeded on an agar medium in a Petri dish were inactivated by Ar plasma jet irradiation for 1 s. Scanning electron microscopy (SEM) revealed that E. coli cells were killed because their cell wall and membrane were disrupted. To determine the causes of the disruption of the cell wall and membrane of E. coli, we performed the following experiments: the measurement of the surface temperature of an agar medium using a thermograph, the analysis of an emission spectrum of a plasma jet obtained using a multichannel spectrometer, and the determination of the distribution of the concentration of hydrogen peroxide (H2O2) generated on an agar medium by plasma jet irradiation using semiquantitative test strips. Moreover, H2O2 solutions of different concentrations were dropped onto an agar medium seeded with E. coli cells to examine the contribution of H2O2 to the death of E. coli. The results of these experiments showed that the cell wall and membrane of E. coli were disrupted by electrons in the plasma jet, as well as by electroneutral excited nitrogen molecules (N2) and hydroxyl (OH) radicals in the periphery of the plasma jet.

Kuwahata, Hiroshi; Yamaguchi, Takeshi; Ohyama, Ryu-ichiro; Ito, Atsushi

2015-01-01

142

Determination and quantification of Escherichia coli by capillary electrophoresis.  

PubMed

Capillary electrophoresis (CE) is widely employed for the separation of nucleic acids or protein, but it is rarely applied in the quantification of Escherichia coli (E. coli). Here, we have analysed E. coli by CE with mercury lamp induced fluorescence, and demonstrated the relationship between its fluorescence intensity with the concentration of E. coli for the first time. The gradient concentration of E. coli was obtained by polymerase chain reaction (PCR) with different amplification cycles and dilution certain PCR products of E. coli, respectively. Results show that the peak area was linearly related to the logarithm of the concentration of E. coli and the logarithm of PCR replication numbers. The correlation coefficients R(2) are 0.957 and 0.966, respectively. The limit of detection (LOD) was found to be about 8.913 × 10(-15) mol ?l(-1). The reproducibility of capillary electrophoresis may make this technique possible for quantitative measurement of bacteria in bio-analytical science. PMID:25307062

Li, Zhenqing; Li, De; Zhang, Dawei; Yamaguchi, Yoshinori

2014-12-01

143

Enterotoxigenic Escherichia coli infection in captive black-footed ferrets.  

PubMed

Enterotoxigenic Escherichia coli with genes for heat stabile toxins Sta and STb was isolated from the gastrointestinal tract and multiple visceral organs of three adult and three juvenile black-footed ferrets (Mustela nigripes) that died in a captive breeding colony between 24 May 1998 and 2 July 1998. Similar isolates were obtained from rectal swabs of one adult and one juvenile that were clinically ill. All were fed a diet composed of mink chow, raw rabbit meat, beef liver powder, blood meal and lard. Escherichia coli of the same toxin genotype was isolated from the mixed ration. Clinical signs included sudden death, dehydration, anorexia and diarrhea. Necropsy lesions included acute enteritis with large numbers of rod shaped bacteria microscopically visible on intestinal villi. PMID:11504237

Bradley, G A; Orr, K; Reggiardo, C; Glock, R D

2001-07-01

144

Expression of soluble cloned porcine pepsinogen A in Escherichia coli.  

PubMed Central

A system for the production of soluble porcine pepsinogen A (EC 3.4.23.1) was developed by fusing the pepsinogen and thioredoxin genes and then expressing the fused product (Trx-PG) in Escherichia coli. The expressed fusion protein was purified using a combination of ion-exchange and hydrophobic chromatography. Trypsin digestion of the fusion protein yielded pepsinogen which was one residue longer than the intrinsic length. Acidification of either the fusion protein or pepsinogen (tryptic digestion of Trx-PG) yielded recombinant pepsin A (r-pepsin). When compared with commercial porcine pepsin A, r-pepsin had similar milk-clotting and proteolytic activities, kinetic parameters and pH dependency. The above results indicate that an expression system was developed which yielded fully active soluble pepsin(ogen) from Escherichia coli. PMID:8615812

Tanaka, T; Yada, R Y

1996-01-01

145

Development of functionalised polyelectrolyte capsules using filamentous Escherichia coli cells  

PubMed Central

Background Escherichia coli is one of the best studied microorganisms and finds multiple applications especially as tool in the heterologous production of interesting proteins of other organisms. The heterologous expression of special surface (S-) layer proteins caused the formation of extremely long E. coli cells which leave transparent tubes when they divide into single E. coli cells. Such natural structures are of high value as bio-templates for the development of bio-inorganic composites for many applications. In this study we used genetically modified filamentous Escherichia coli cells as template for the design of polyelectrolyte tubes that can be used as carrier for functional molecules or particles. Diversity of structures of biogenic materials has the potential to be used to construct inorganic or polymeric superior hybrid materials that reflect the form of the bio-template. Such bio-inspired materials are of great interest in diverse scientific fields like Biology, Chemistry and Material Science and can find application for the construction of functional materials or the bio-inspired synthesis of inorganic nanoparticles. Results Genetically modified filamentous E. coli cells were fixed in 2% glutaraldehyde and coated with alternating six layers of the polyanion polyelectrolyte poly(sodium-4styrenesulfonate) (PSS) and polycation polyelectrolyte poly(allylamine-hydrochloride) (PAH). Afterwards we dissolved the E. coli cells with 1.2% sodium hypochlorite, thus obtaining hollow polyelectrolyte tubes of 0.7 ?m in diameter and 5–50 ?m in length. For functionalisation the polyelectrolyte tubes were coated with S-layer protein polymers followed by metallisation with Pd(0) particles. These assemblies were analysed with light microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. Conclusion The thus constructed new material offers possibilities for diverse applications like novel catalysts or metal nanowires for electrical devices. The novelty of this work is the use of filamentous E. coli templates and the use of S-layer proteins in a new material construct. PMID:23259586

2012-01-01

146

Escherichia coli and Salmonella 2000: the view from here.  

PubMed

Five years after the publication of the second edition of the reference book Escherichia coli and Salmonella: Cellular and Molecular Biology, and on the eve of launching a successor venture, the editors and colleagues examine where we stand in our quest for an understanding of these organisms. The main areas selected for this brief inquiry are genomics, evolution, molecular multifunctionality, functional backups, regulation of gene expression, cell biology, sensing of the environment, and ecology. PMID:11238988

Schaechter, M

2001-03-01

147

Escherichia coli acid resistance: tales of an amateur acidophile  

Microsoft Academic Search

Gastrointestinal pathogens are faced with an extremely acidic environment. Within moments, a pathogen such as Escherichia coli O157:H7 can move from the nurturing pH 7 environment of a hamburger to the harsh pH 2 milieu of the stomach. Surprisingly, certain microorganisms that grow at neutral pH have elegantly regulated systems that enable survival during excursions into acidic environments. The best-characterized

John W. Foster

2004-01-01

148

Expression of the Human Erythrocyte Glucose Transporter in Escherichia coli  

Microsoft Academic Search

The gene encoding the human erythrocyte glucose transporter, cloned from HepG2 hepatoma cells, was expressed in Escherichia coli by introducing a prokaryote-type ribosome binding site, subcloning the gene into the T7 promoter\\/T7 polymerase expression system, and transforming a strain that is defective in glucose transport. Cells bearing plasmids with the transporter gene take up 2-deoxy-D-glucose and D-glucose, unlike cells bearing

Hemanta K. Sarkar; Bernard Thorens; Harvey F. Lodish; H. Ronald Kaback

1988-01-01

149

Electric field induced bacterial flocculation of enteroaggregative Escherichia coli 042  

NASA Astrophysics Data System (ADS)

A response of the aggregation dynamics of enteroaggregative Escherichia coli under low magnitude steady and oscillating electric fields is presented. The presence of uniform electric fields hampered microbial adhesion and biofilm formation on a transverse glass surface, but instead promoted the formation of flocs. Extremely heterogenous distribution of live and dead cells was observed among the flocs. Moreover, floc formation was largely observed to be independent of the frequency of alternating electric fields.

Kumar, Aloke; Mortensen, Ninell P.; Mukherjee, Partha P.; Retterer, Scott T.; Doktycz, Mitchel J.

2011-06-01

150

Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation  

Microsoft Academic Search

Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes\\u000a including Fe–S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we\\u000a present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin\\u000a IX

Tomas Majtan; Frank E. Frerman; Jan P. Kraus

2011-01-01

151

Polymorphous crystallization and diffraction of threonine deaminase from Escherichia coli.  

PubMed

The biosynthetic threonine deaminase from Escherichia coli, an allosteric tetramer with key regulatory functions, has been crystallized in several crystal forms. Two distinct forms, both belonging to either space group P3121 or P3221, with different sized asymmetric units that both contain a tetramer, grow under identical conditions. Diffraction data sets to 2.8 A resolution (native) and 2. 9 A resolution (isomorphous uranyl derivative) have been collected from a third crystal form in space group I222. PMID:9761930

Gallagher, D T; Eisenstein, E; Fisher, K E; Zondlo, J; Chinchilla, D; Yu, H D; Dill, J; Winborne, E; Ducote, K; Xiao, G; Gilliland, G L

1998-05-01

152

Solar radiation induces sublethal injury in Escherichia coli in seawater.  

PubMed Central

Sublethal injury was noted in Escherichia coli after cells were exposed to solar radiation. Injury was detected by differential plate counts between complete and minimal media that were observed with sunlight-exposed cells but not with cells kept in the dark. Since addition of catalase or pyruvate to minimal medium overcame or repaired this injury, the catalase system appeared to be the site of injury. PMID:7013708

Kapuscinski, R B; Mitchell, R

1981-01-01

153

Depression of adenosylmethionine content of Escherichia coli by thioglycerol.  

PubMed Central

The mechanism of growth inhibition of Escherichia coli by thioglycerol was probed. The extent of growth inhibition depended on the ratio of thioglycerol to initial cell concentration. Exogenously added methionine and several methionine analogues reversed the inhibition of 2 to 40 mM thioglycerol. Exposure to thioglycerol elevated the intracellular concentration of methionine, but the level of S-adenosylmethionine was depressed. Thioglycerol was methylated in vivo to 3-methylthio-1,2-propanediol. PMID:6362560

Javor, G T

1983-01-01

154

Transcriptional Regulation of the esp Genes of Enterohemorrhagic Escherichia coli  

Microsoft Academic Search

We have determined that the genes encoding the secreted proteins EspA, EspD, and EspB of enterohemor- rhagic Escherichia coli (EHEC) are organized in a single operon. The esp operon is controlled by a promoter located 94 bp upstream from the ATG start codon of the espA gene. The promoter is activated in the early logarithmic growth phase, upon bacterial contact

FABRIZIO BELTRAMETTI; ANDREAS U. KRESSE; CARLOS A. GUZMAN

1999-01-01

155

Occurrence of Escherichia coli in Wild Cottontail Rabbits.  

PubMed

Free-ranging cottontail rabbits (Sylvilagus floridanus) from two areas in central Pennsylvania were sampled over a 4-year period. Large numbers of coliforms were isolated from the intestinal tracts of these animals; in 136 of the 141 rabbits sampled, Escherichia coli was found to be a major component of the alimentary flora. Four serogroups (O7, O77, O73, and O103) were predominant among the isolates and were considered resistant coliflora of this species of cottontail rabbit. PMID:16345208

Kozlowski, R; Glantz, P J; Anthony, R G

1977-03-01

156

Genome sequence of enterohaemorrhagic Escherichia coli O157:H7  

Microsoft Academic Search

The bacterium Escherichia coli O157:H7 is a worldwide threat to public health and has been implicated in many outbreaks of haemorrhagic colitis, some of which included fatalities caused by haemolytic uraemic syndrome. Close to 75,000 cases of O157:H7 infection are now estimated to occur annually in the United States. The severity of disease, the lack of effective treatment and the

Nicole T. Perna; Guy Plunkett; Valerie Burland; Bob Mau; Jeremy D. Glasner; Debra J. Rose; George F. Mayhew; Peter S. Evans; Jason Gregor; Heather A. Kirkpatrick; György Pósfai; Jeremiah Hackett; Sara Klink; Adam Boutin; Ying Shao; Leslie Miller; Erik J. Grotbeck; N. Wayne Davis; Alex Lim; Eileen T. Dimalanta; Konstantinos D. Potamousis; Jennifer Apodaca; Thomas S. Anantharaman; Jieyi Lin; Galex Yen; David C. Schwartz; Rodney A. Welch; Frederick R. Blattner

2001-01-01

157

Functional requirements for heat induced genome amplification in Escherichia coli  

Microsoft Academic Search

A temperature shift-up induces extra rounds of fully replicated chromosomes in Escherichia coli and leads to an increase in DNA\\/mass ratio. In the present work we characterize the requirements for this heat-induced replication (HIR) with respect to replisome components, replication restart, and recombination functions. We found that HIR requires Klenow and 5?–3? exonuclease activities from Pol I and Pol III,

Rocío González-Soltero; Alfonso Jiménez-Sánchez; Emilia Botello

2008-01-01

158

Escherichia coli as a pathogen in dogs and cats.  

PubMed

Certain strains of Escherichia coli behave as pathogens in dogs and cats causing gastro-intestinal and extra-intestinal diseases. Among the five known groups of diarrhoeagenic E. coli, namely enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), shiga-toxin producing E. coli (STEC) and enteroaggregative E. coli (EAggEC), only EPEC and ETEC were clearly associated with enteric disease in young dogs. ETEC isolates from diarrhoeic dogs were found to be positive for the heat-stable enterotoxins STa and STb but negative for heat-labile enterotoxin (LT). Canine ETEC were found to be different from those of other animals and humans by their serotypes, production of alpha-haemolysin and adhesive factors and by the production of uncharacterized types of enterotoxins by some ETEC. Canine EPEC could be distinguished from EPEC of humans or other animals by their serotypes and by the eae-protein intimin which mediates intimate adherence of EPEC to intestinal mucosa cells. STEC were occasionally isolated from faeces of healthy and diarrhoeic dogs but their role in canine diarrhoea is not yet well known. EIEC and EAggEC were not reported to occur in dogs or cats. Very little is known on diarrhoegenic E. coli in cats and further epidemiological investigations on this subject are needed. Besides its role in gastro-intestinal infections, E. coli can cause infections of the urogenital tract and systemic disease in dogs and cats. Extra-intestinal pathogenic E. coli strains from dogs and cats belong to a limited number of serotypes and clonal groups and are frequently found as a part of the normal gut flora of these animals. Many of these E. coli strains carry P-fimbriae and produce alpha-haemolysin and a necrotizing cytotoxin (CNF1). Some of the frequently isolated types of extra-intestinal pathogenic E. coli from dogs, cats and humans were found to be highly genetically related but showed differences in their P-fimbrial adhesins which determine host specificity. Transmission of extra-intestinal and enteral pathogenic E. coli between dogs and humans was reported. Further research is needed, however, to determine the role of dogs and cats as transmission vectors of pathogenic E. coli strains to other animals and humans. PMID:10367359

Beutin, L

1999-01-01

159

Fluorogenic assays for immediate confirmation of Escherichia coli.  

PubMed

Rapid assays for Escherichia coli were developed by using the compound 4-methylumbelliferone glucuronide (MUG), which is hydrolyzed by glucuronidase to yield a fluorogenic product. The production of glucuronidase was limited to strains of E. coli and some Salmonella and Shigella strains in the family Enterobacteriaceae. For immediate confirmation of the presence of E. coli in most-probable-number tubes, MUG was incorporated into lauryl tryptose broth at a final concentration of 100 micrograms/ml. Results of both the presumptive test (gas production) and the confirmed test (fluorescence) for E. coli were obtained from a variety of food, water, and milk samples after incubation for only 24 h at 35 degrees C. Approximately 90% of the tubes showing both gas production and fluorescence contained fecal coliforms (they were positive in EC broth incubated at 45 degrees C). Few false-positive reactions were observed. The lauryl tryptose broth-MUG-most-probable-number assay was superior to violet red bile agar for the detection of heat- and chlorine-injured E. coli cells. Anaerogenic strains produced positive reactions, and small numbers of E. coli could be detected in the presence of large numbers of competing bacteria. The fluorogenic assay was sensitive and rapid; the presence of one viable cell was detected within 20 h. E. coli colonies could be distinguished from other coliforms on membrane filters and plates of violet red bile agar if MUG was incorporated into the culture media. A rapid confirmatory test for E. coli that is amenable to automation was developed by using microtitration plates filled with a nonselective medium containing MUG. Pure or mixed cultures containing E. coli produced fluorescence within 4 h (most strains) to 24 h (a few weakly positive strains). PMID:7049088

Feng, P C; Hartman, P A

1982-06-01

160

Survival of Escherichia coli on strawberries grown under greenhouse conditions.  

PubMed

Strawberries are soft fruit that are not recommended to have a post-harvest wash due to quality concerns. Escherichia coli O157:H7 has been linked to outbreaks with strawberries but little is known about the survival of E. coli during the growth cycle of strawberries. The survival of E. coli on strawberry plants during growing under greenhouses conditions was evaluated. Soil, leaves, and strawberries (if present) were artificially contaminated with an E. coli surrogate either at the time of planting, first runner removal (4 wk), second runner removal (8 wk), or one week prior to harvest. At harvest E. coli was recovered from the leaves, soil, and strawberries regardless of the contamination time. Time of contamination influenced (P < 0.05) numbers of viable E. coli on the plant. The highest survival of E. coli (P < 0.0001) was detected in soil that was contaminated at planting (4.27 log10 CFU g soil(-1)), whereas, the survival of E. coli was maximal at later contamination times (8 wk and 1 wk prior to harvest) for the leaves (4.40 and 4.68 log10 CFU g leaves(-1)) and strawberries (3.37 and 3.53 log10 CFU strawberry(-1)). Cross contamination from leaves to fruit was observed during this study, with the presence of E. coli on strawberries which had not been present at the time of contamination. These results indicate that good agricultural best practices to avoid contamination are necessary to minimize the risk of contamination of these popular fruit with enteric pathogens. Practices should include soil testing prior to harvest and avoiding contamination of the leaves. PMID:25475285

Shaw, Angela Laury; Svoboda, Amanda; Jie, Beatrice; Nonnecke, Gail; Mendonca, Aubrey

2015-04-01

161

Expression of the Serratia marcescens lipoproteins gene in Escherichia coli.  

PubMed Central

The lipoprotein gene (lpp) of Serratia marcescens was cloned in a lambda phage vector (K. Nakamura and M. Inouye, Proc. Natl. Acad. Sci. U.S.A. 77: 1369-1373, 1980). This lpp gene was recloned in plasmid vectors pBR322 and pSC101. When a lipoprotein-deficient (lpp) mutant of Escherichia coli was transformed with pBR322 carrying the S. marcescens lpp gene, cells became nonleaky for ribonuclease, resistant to ethylenediaminetetraacetic acid, and sensitive to globomycin. The lipoprotein was found exclusively in the outer membrane fraction. These results indicate that the S. marcescens lipoprotein was normally secreted across the cytoplasmic membrane, modified, and assembled in the E. coli outer membrane. The amount of the free-form lipoprotein produced in this system was three times higher than that produced in lpp + C. coli cells, whereas there was no difference in the amount of the bound-form lipoprotein. On the other hand, lpp E. coli cells which harbored pSC101 carrying the S. marcescens lpp gene produced only one-third of the free-form lipoprotein produced in lpp E. coli cells which harbored pSC101 carrying the E. coli lpp gene. One of the major factors causing this difference in efficiency of gene expression between the lpp genes of S. marcescens and E. coli appears to be a deletion mutation at the transcription termination region found in the cloned S. marcescens lpp gene. The functional half-life of the S. marcescens lpp messenger ribonucleic acid in E. coli was found to be found half that of the E. coli lpp messenger ribonucleic acid. Images PMID:7016834

Lee, N; Nakamura, K; Inouye, M

1981-01-01

162

Bacteriophage cocktail significantly reduces Escherichia coli O157  

PubMed Central

Foods contaminated with Escherichia coli O157:H7 cause more than 63,000 foodborne illnesses in the United States every year, resulting in a significant economic impact on medical costs and product liabilities. Efforts to reduce contamination with E. coli O157:H7 have largely focused on washing, application of various antibacterial chemicals, and gamma-irradiation, each of which has practical and environmental drawbacks. A relatively recent, environmentally-friendly approach proposed for eliminating or significantly reducing E. coli O157:H7 contamination of foods is the use of lytic bacteriophages as biocontrol agents. We found that EcoShield™, a commercially available preparation composed of three lytic bacteriophages specific for E. coli O157:H7, significantly (p < 0.05) reduced the levels of the bacterium in experimentally contaminated beef by ? 94% and in lettuce by 87% after a five minute contact time. The reduced levels of bacteria were maintained for at least one week at refrigerated temperatures. However, the one-time application of EcoShield™ did not protect the foods from recontamination with E. coli O157:H7. Our results demonstrate that EcoShield™ is effective in significantly reducing contamination of beef and lettuce with E. coli O157:H7, but does not protect against potential later contamination due to, for example, unsanitary handling of the foods post processing. PMID:23275869

Carter, Chandi D.; Parks, Adam; Abuladze, Tamar; Li, Manrong; Woolston, Joelle; Magnone, Joshua; Senecal, Andre; Kropinski, Andrew M.; Sulakvelidze, Alexander

2012-01-01

163

Escherichia coli sequence type 131: epidemiology and challenges in treatment.  

PubMed

Escherichia coli ST131 has emerged as a global epidemic, multidrug-resistant clone of E. coli causing extra-intestinal infections. It is now highly prevalent among fluoroquinolone-resistant and CTX-M ESBL-producing E. coli isolates worldwide. Humans are likely the primary reservoir of ST131. Factors associated with its acquisition include residence in long-term care facilities and recent receipt of antimicrobial agents. E. coli ST131 causes a wide array of infections ranging from cystitis to life-threatening sepsis. Fluoroquinolones and trimethoprim-sulfamethoxazole are no longer adequate options for empiric therapy when E. coli ST131 is suspected from risk factors and local epidemiology. Expanded-spectrum cephalosporins, piperacillin-tazobactam and carbapenems are options to treat serious non-ESBL-producing E. coli ST131 infections, while carbapenems are indicated for ESBL-producing infections. There is a growing interest in reevaluating oral agents including fosfomycin and pivmecillinam for less serious infections such as uncomplicated cystitis. PMID:24694052

Qureshi, Zubair A; Doi, Yohei

2014-05-01

164

A miniaturized biotyping system for strain discrimination in Escherichia coli.  

PubMed

A two-tier miniaturized scheme of eight tests was devised for biotyping strains of Escherichia coli in microwell plates. Primary biotypes were defined by positive and negative reactions in tests for fermentation of raffinose, sorbose, dulcitol and 2-deoxy-D-ribose and for decarboxylation of ornithine when read after specified periods of incubation; subtypes were identified within primary biotypes according to results in secondary tests for rhamnose fermentation, lysine decarboxylation and motility. The method gave reproducible results on different occasions of testing. Among 100 E. coli strains from various sources, 26 of the 32 possible primary biotypes and 56 full biotypes, as defined by results in both primary and secondary tests, were identified, thus demonstrating a high index of strain discrimination (D = 0.98). The scheme is recommended as a simple, reliable, inexpensive and efficient method of differentiating strains of E. coli. PMID:8348935

Crichton, P B; Logan, J M; Old, D C

1993-08-01

165

Bronchopneumonia associated with extraintestinal pathogenic Escherichia coli in a horse.  

PubMed

Extraintestinal pathogenic Escherichia coli (ExPEC) strains carrying distinct virulence attributes are known to cause diseases in humans and animals and infect organs other than the gastrointestinal tract. A fatal case of bronchopneumonia in a 12-year-old female Quarterhorse was investigated. Following postmortem examination, E. coli, Enterococcus sp., and Klebsiella pneumonia were isolated from the lungs, which contained multifocal intra-alveolar accumulations of neutrophils and macrophages with edema, hemorrhage, and fibrin. The strain of E. coli belonged to O2H21 and carried virulence genes cnf1, sfa, foc, fimA, and papG allele I that are known to be associated with ExPEC strains. The strain was resistant to several antimicrobials including clindamycin, erythromycin, oxacillin, penicillin, and rifampin. This is the first report, to the authors' knowledge, in which ExPEC O2H21 has been associated with fatal bronchopneumonia in a horse. PMID:18776106

DebRoy, Chitrita; Roberts, Elisabeth; Jayarao, Bhushan M; Brooks, Jason W

2008-09-01

166

Engineering Escherichia coli K12 MG1655 to use starch  

PubMed Central

Background To attain a sustainable bioeconomy, fuel, or valuable product, production must use biomass as substrate. Starch is one of the most abundant biomass resources and is present as waste or as a food and agroindustry by-product. Unfortunately, Escherichia coli, one of the most widely used microorganisms in biotechnological processes, cannot use starch as a carbon source. Results We engineered an E. coli strain capable of using starch as a substrate. The genetic design employed the native capability of the bacterium to use maltodextrins as a carbon source plus expression and secretion of its endogenous ?-amylase, AmyA, in an adapted background. Biomass production improved using 35% dissolved oxygen and pH 7.2 in a controlled bioreactor. Conclusion The engineered E. coli strain can use starch from the milieu and open the possibility of optimize the process to use agroindustrial wastes to produce biofuels and other valuable chemicals. PMID:24886307

2014-01-01

167

Functions of the gene products of Escherichia coli.  

PubMed Central

A list of currently identified gene products of Escherichia coli is given, together with a bibliography that provides pointers to the literature on each gene product. A scheme to categorize cellular functions is used to classify the gene products of E. coli so far identified. A count shows that the numbers of genes concerned with small-molecule metabolism are on the same order as the numbers concerned with macromolecule biosynthesis and degradation. One large category is the category of tRNAs and their synthetases. Another is the category of transport elements. The categories of cell structure and cellular processes other than metabolism are smaller. Other subjects discussed are the occurrence in the E. coli genome of redundant pairs and groups of genes of identical or closely similar function, as well as variation in the degree of density of genetic information in different parts of the genome. PMID:7508076

Riley, M

1993-01-01

168

Effect of tannins on the in viro growth of Escherichia coli O157:H7 and in vivo growth of generic Escherichia coli excreted from steers  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effect of commercially available chestnut and mimosa tannins in vitro (experiment 1) or in vivo (experiment 2) on the growth or recovery of Escherichia coli O157:H7 or generic fecal E. coli was evaluated. In experiment 1, the mean growth rate of E. coli O157:H7, determined via the measurement o...

169

Prevalence and virulence gene profiles of Shiga toxin-producing Escherichia coli and enteropathogenic Escherichia coli from diarrhoeic and healthy lambs in India  

Microsoft Academic Search

This communication describes the prevalence and virulence attributes of Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) isolates in lambs with and without diarrhoea in Kashmir, India. One hundred twenty and 164 E. coli isolates belonging to 56 different ‘O’ serogroups were isolated from 101 diarrhoeic and 135 healthy lambs, respectively. All the 284 isolates were screened for

M. A. Bhat; Y. Nishikawa; S. A. Wani

2008-01-01

170

EXPERIMENTAL MASTITIS WITH ESCHERICHIA COLI: SEQUENTIAL RESPONSE OF LEUKOCYTES AND OPSONIC ACTIVITY  

E-print Network

EXPERIMENTAL MASTITIS WITH ESCHERICHIA COLI: SEQUENTIAL RESPONSE OF LEUKOCYTES AND OPSONIC ACTIVITY infusion of bacteria (Hill, 1979); b) opsonic activity is required in milk to enable polymorphonuclear

Paris-Sud XI, Université de

171

Analysis of O-island deletions in Escherichia coli O157:H7   

E-print Network

Escherichia coli (E. coli) are a diverse species of bacteria that reside, often harmoniously and beneficially, in the gastrointestinal tracts of humans and other mammals. However, some strains are associated with serious ...

Flockhart, Allen Forrest

2012-11-30

172

Global dissemination of a multidrug resistant Escherichia coli clone.  

PubMed

Escherichia coli sequence type 131 (ST131) is a globally disseminated, multidrug resistant (MDR) clone responsible for a high proportion of urinary tract and bloodstream infections. The rapid emergence and successful spread of E. coli ST131 is strongly associated with several factors, including resistance to fluoroquinolones, high virulence gene content, the possession of the type 1 fimbriae FimH30 allele, and the production of the CTX-M-15 extended spectrum ?-lactamase (ESBL). Here, we used genome sequencing to examine the molecular epidemiology of a collection of E. coli ST131 strains isolated from six distinct geographical locations across the world spanning 2000-2011. The global phylogeny of E. coli ST131, determined from whole-genome sequence data, revealed a single lineage of E. coli ST131 distinct from other extraintestinal E. coli strains within the B2 phylogroup. Three closely related E. coli ST131 sublineages were identified, with little association to geographic origin. The majority of single-nucleotide variants associated with each of the sublineages were due to recombination in regions adjacent to mobile genetic elements (MGEs). The most prevalent sublineage of ST131 strains was characterized by fluoroquinolone resistance, and a distinct virulence factor and MGE profile. Four different variants of the CTX-M ESBL-resistance gene were identified in our ST131 strains, with acquisition of CTX-M-15 representing a defining feature of a discrete but geographically dispersed ST131 sublineage. This study confirms the global dispersal of a single E. coli ST131 clone and demonstrates the role of MGEs and recombination in the evolution of this important MDR pathogen. PMID:24706808

Petty, Nicola K; Ben Zakour, Nouri L; Stanton-Cook, Mitchell; Skippington, Elizabeth; Totsika, Makrina; Forde, Brian M; Phan, Minh-Duy; Gomes Moriel, Danilo; Peters, Kate M; Davies, Mark; Rogers, Benjamin A; Dougan, Gordon; Rodriguez-Baño, Jesús; Pascual, Alvaro; Pitout, Johann D D; Upton, Mathew; Paterson, David L; Walsh, Timothy R; Schembri, Mark A; Beatson, Scott A

2014-04-15

173

The metabolism of isocytidine in Escherichia coli  

PubMed Central

Intact cells and cell-free extracts of E. coli convert isocytidine to isocytosine and uracil. The radioactive label of 5-[3H]isocytidine is incorporated into RNA and, DNA of growing bacteria at a rate equal to about 1.4% of that of cytidine under similar conditions; the radioactivity is found in uridylic, cytidylic and 2?-deoxythymidylic acids, while less than 0.4% of incorporated radioactive material might be due to possible incorporation of intact isocytidine. Uridine phosphorylase and cytidine deaminase apparently do not participate in the metabolic conversion of isocytidine. 5-[3H]isocytidine was prepared by platinum-catalyzed dehalogenation of 5-bromoisocytidine in the presence of tritium. The 5-bromo derivative was obtained from 2?,3?-0- -isopropylideneisocytidine by N-bromsuccinimide bromination followed by acidic hydrolysis. PMID:10793683

Dosko?il, J.; Holý, A.; Filip, J.

1974-01-01

174

Predicting non-coding RNA genes in Escherichia coli with boosted genetic programming  

E-print Network

Several methods exist for predicting non-coding RNA (ncRNA) genes in Escherichia coli (E.coli therefore speculate that E.coli contains more ncRNA genes than previously estimated. INTRODUCTION Non. We describe a method that uses automatic discovery of sequence patterns to predict ncRNA genes in E.coli

Fernandez, Thomas

175

The distribution and genetic structure of Escherichia coli in Australian vertebrates: host and geographic effects  

Microsoft Academic Search

Escherichia coli was isolated from more than 2300 non-domesticated vertebrate hosts living in Australia. E. coli was most prevalent in mammals, less prevalent in birds and uncommon in fish, frogs and reptiles. Mammals were unlikely to harbour E. coli if they lived in regions with a desert climate and less likely to have E. coli if they lived in the

David M. Gordon; Ann Cowling

2003-01-01

176

Enteropathogenic Escherichia coli translocated intimin receptor, Tir, requires a specic chaperone for stable  

E-print Network

. Summary Enteropathogenic Escherichia coli (EPEC) secretes several Esps (E. coli-secreted proteins, 1992). Related pathogens that cause disease using similar mechanisms include enterohaemorrhagic E. coli (EHEC) O157:H7 (Francis et al., 1986; Tzipori et al., 1987, 1988), rabbit enteropathogenic E. coli

Strynadka, Natalie

177

Persistence of cellulitis-associated Escherichia coli DNA ngerprints in successive broiler  

E-print Network

is primarily caused by Escherichia coli. Previous research found that the E. coli isolates of cellulitis origin were unique to each ranch, suggesting that these E. coli were endemic within the ranch environment. To test the hypothesis that the E. coli associated with cellulitis are endemic in the litter

Singer, Randall

178

The Pangenome Structure of Escherichia coli: Comparative Genomic Analysis of E. coli Commensal and Pathogenic Isolates? †  

PubMed Central

Whole-genome sequencing has been skewed toward bacterial pathogens as a consequence of the prioritization of medical and veterinary diseases. However, it is becoming clear that in order to accurately measure genetic variation within and between pathogenic groups, multiple isolates, as well as commensal species, must be sequenced. This study examined the pangenomic content of Escherichia coli. Six distinct E. coli pathovars can be distinguished using molecular or phenotypic markers, but only two of the six pathovars have been subjected to any genome sequencing previously. Thus, this report provides a seminal description of the genomic contents and unique features of three unsequenced pathovars, enterotoxigenic E. coli, enteropathogenic E. coli, and enteroaggregative E. coli. We also determined the first genome sequence of a human commensal E. coli isolate, E. coli HS, which will undoubtedly provide a new baseline from which workers can examine the evolution of pathogenic E. coli. Comparison of 17 E. coli genomes, 8 of which are new, resulted in identification of ?2,200 genes conserved in all isolates. We were also able to identify genes that were isolate and pathovar specific. Fewer pathovar-specific genes were identified than anticipated, suggesting that each isolate may have independently developed virulence capabilities. Pangenome calculations indicate that E. coli genomic diversity represents an open pangenome model containing a reservoir of more than 13,000 genes, many of which may be uncharacterized but important virulence factors. This comparative study of the species E. coli, while descriptive, should provide the basis for future functional work on this important group of pathogens. PMID:18676672

Rasko, David A.; Rosovitz, M. J.; Myers, Garry S. A.; Mongodin, Emmanuel F.; Fricke, W. Florian; Gajer, Pawel; Crabtree, Jonathan; Sebaihia, Mohammed; Thomson, Nicholas R.; Chaudhuri, Roy; Henderson, Ian R.; Sperandio, Vanessa; Ravel, Jacques

2008-01-01

179

Recent Advances in Understanding Enteric Pathogenic Escherichia coli  

PubMed Central

SUMMARY Although Escherichia coli can be an innocuous resident of the gastrointestinal tract, it also has the pathogenic capacity to cause significant diarrheal and extraintestinal diseases. Pathogenic variants of E. coli (pathovars or pathotypes) cause much morbidity and mortality worldwide. Consequently, pathogenic E. coli is widely studied in humans, animals, food, and the environment. While there are many common features that these pathotypes employ to colonize the intestinal mucosa and cause disease, the course, onset, and complications vary significantly. Outbreaks are common in developed and developing countries, and they sometimes have fatal consequences. Many of these pathotypes are a major public health concern as they have low infectious doses and are transmitted through ubiquitous mediums, including food and water. The seriousness of pathogenic E. coli is exemplified by dedicated national and international surveillance programs that monitor and track outbreaks; unfortunately, this surveillance is often lacking in developing countries. While not all pathotypes carry the same public health profile, they all carry an enormous potential to cause disease and continue to present challenges to human health. This comprehensive review highlights recent advances in our understanding of the intestinal pathotypes of E. coli. PMID:24092857

Croxen, Matthew A.; Law, Robyn J.; Scholz, Roland; Keeney, Kristie M.; Wlodarska, Marta

2013-01-01

180

The Genetic Basis of Escherichia coli Pathoadaptation to Macrophages  

PubMed Central

Antagonistic interactions are likely important driving forces of the evolutionary process underlying bacterial genome complexity and diversity. We hypothesized that the ability of evolved bacteria to escape specific components of host innate immunity, such as phagocytosis and killing by macrophages (M?), is a critical trait relevant in the acquisition of bacterial virulence. Here, we used a combination of experimental evolution, phenotypic characterization, genome sequencing and mathematical modeling to address how fast, and through how many adaptive steps, a commensal Escherichia coli (E. coli) acquire this virulence trait. We show that when maintained in vitro under the selective pressure of host M? commensal E. coli can evolve, in less than 500 generations, virulent clones that escape phagocytosis and M? killing in vitro, while increasing their pathogenicity in vivo, as assessed in mice. This pathoadaptive process is driven by a mechanism involving the insertion of a single transposable element into the promoter region of the E. coli yrfF gene. Moreover, transposition of the IS186 element into the promoter of Lon gene, encoding an ATP-dependent serine protease, is likely to accelerate this pathoadaptive process. Competition between clones carrying distinct beneficial mutations dominates the dynamics of the pathoadaptive process, as suggested from a mathematical model, which reproduces the observed experimental dynamics of E. coli evolution towards virulence. In conclusion, we reveal a molecular mechanism explaining how a specific component of host innate immunity can modulate microbial evolution towards pathogenicity. PMID:24348252

Miskinyte, Migla; Sousa, Ana; Ramiro, Ricardo S.; de Sousa, Jorge A. Moura; Kotlinowski, Jerzy; Caramalho, Iris; Magalhães, Sara; Soares, Miguel P.; Gordo, Isabel

2013-01-01

181

The biotyping of Escherichia coli isolated from healthy farm animals.  

PubMed

A total of 2973 Escherichia coli, isolated from six different groups of animals, were examined for their ability to ferment adonitol, dulcitol, raffinose, rhamnose and sorbose in solid media. Twenty-nine fermentation patterns were recorded although 2443 (82%) of the E. coli belonged to seven of the 32 possible biotypes. Ninety-six O-serotypes were identified within the 2973 E. coli. The number of O-serotypes represented in the 15 most common biotypes ranged from three to 15. Serotypes O8 and O9 were found most commonly in the different groups of animals and several biotypes amongst these two O-serotypes were identified in two or more groups of the animals. The ability of the E. coli to metabolize aesculin, ornithine, salicin and sucrose was also assessed. These test proved less reproducible and were not included in the primary biotyping scheme although their use allowed the enumeration of additional biotypes. The application of biotyping to the study of the ecology of drug-resistant strains of E. coli in five situations is briefly presented. PMID:7045219

Hinton, M; Allen, V; Linton, A H

1982-06-01

182

Unusual “Flesh-Eating” Strains of Escherichia coli  

PubMed Central

Monomicrobial necrotizing fasciitis (type II) is typically caused by group A streptococcus alone or in combination with Staphylococcus aureus. Escherichia coli has been isolated from polymicrobial or Fournier's gangrene but has rarely been reported in monomicrobial necrotizing fasciitis. We describe the clinical characteristics and outcomes of seven cases of monomicrobial E. coli necrotizing fasciitis and/or severe soft tissue infection diagnosed at a single institution during an 18-month period. Four isolates from three patients and two isolates from two patients with type I polymicrobial severe soft tissue infection (controls) were assayed by the randomly amplified polymorphic DNA (RAPD) analysis for fingerprinting and PCR amplification of primers in order to detect cytotoxic necrotizing factor 1 and 2 (cnf1 and cnf2) genes. All patients had some type of immune suppression. The limb was the most commonly involved organ. In all cases, E. coli was isolated as a monomicrobial pathogen from blood, fascia, or both. All patients died during hospitalization, three within the first 48 h. The RAPD amplification assay showed a high degree of genetic diversity among the “flesh-eating” strains and controls. The cnf1 toxin gene was identified in two out of three cases, but not in the controls. cnf2 was not detected in any of the patients. E. coli may be responsible for life-threatening necrotizing fasciitis. Further research is needed to reveal relevant risk factors, reservoirs, and modes of transmission of cnf1 E. coli. PMID:23035196

Shaked, Hila; Samra, Zmira; Paul, Michal; Madar-Shapiro, Liora; Cohen, Jonathan; Pitlik, Silvio

2012-01-01

183

CNF producing Escherichia coli isolated from cattle in Northern Ireland.  

PubMed

Tissue culture assays were used to investigate the incidence of cytotoxic necrotising factors (CNFs) 1 and 2 in Escherichia coli strains from cattle. E. coli cultures were obtained from faeces collected from 223 cases of diarrhoea and from 113 healthy animals. In addition, strains cultured from 62 cases of mastitis, 66 cases of septicaemia and 68 cases of abortion were also investigated. E. coli producing CNF 1 or 2 were identified in all sample groups except for the abortion cases. Comparable levels of CNF1 strains were present in E. coli from the faces of diarrhoeic (4%) and healthy faeces (4.4%) whereas lower levels of CNF2 were identified in the faeces from diarrhoeic animals (19.3%) in comparison with healthy animals (30.9%). One CNF1 producing strain was identified among the E. coli isolated from mastitis samples, while 3% and 10.6% of septicaemic strains were positive for CNF1 and 2, respectively. Serogrouping of CNF isolates did not reveal the association of any particular serogroups with the different conditions. PMID:8734640

Burns, A L; Ball, H J; Finlay, D A

1996-04-01

184

Unusual "flesh-eating" strains of Escherichia coli.  

PubMed

Monomicrobial necrotizing fasciitis (type II) is typically caused by group A streptococcus alone or in combination with Staphylococcus aureus. Escherichia coli has been isolated from polymicrobial or Fournier's gangrene but has rarely been reported in monomicrobial necrotizing fasciitis. We describe the clinical characteristics and outcomes of seven cases of monomicrobial E. coli necrotizing fasciitis and/or severe soft tissue infection diagnosed at a single institution during an 18-month period. Four isolates from three patients and two isolates from two patients with type I polymicrobial severe soft tissue infection (controls) were assayed by the randomly amplified polymorphic DNA (RAPD) analysis for fingerprinting and PCR amplification of primers in order to detect cytotoxic necrotizing factor 1 and 2 (cnf1 and cnf2) genes. All patients had some type of immune suppression. The limb was the most commonly involved organ. In all cases, E. coli was isolated as a monomicrobial pathogen from blood, fascia, or both. All patients died during hospitalization, three within the first 48 h. The RAPD amplification assay showed a high degree of genetic diversity among the "flesh-eating" strains and controls. The cnf1 toxin gene was identified in two out of three cases, but not in the controls. cnf2 was not detected in any of the patients. E. coli may be responsible for life-threatening necrotizing fasciitis. Further research is needed to reveal relevant risk factors, reservoirs, and modes of transmission of cnf1 E. coli. PMID:23035196

Shaked, Hila; Samra, Zmira; Paul, Michal; Madar-Shapiro, Liora; Cohen, Jonathan; Pitlik, Silvio; Bishara, Jihad

2012-12-01

185

Environmental Factors Affecting Indole Production in Escherichia coli  

PubMed Central

A variety of both Gram-positive and Gram-negative bacteria produce large quantities of indole as an intracellular signal in microbial communities. Biosynthesis of indole is well-studied, and while carbon sources and amino acids are important environmental cues for indole production in Escherichia coli, other environmental factors affecting indole production for this strain are less clear. This study demonstrates that the environmental cue pH is an important factor for indole production that further controls biofilm formation of E. coli. Moreover, E. coli produced a higher level of extracellular indole in the presence of the antibiotics ampicillin and kanamycin, and the increased indole enhanced cell survival during antibiotic stress. Additionally, we found here that temperature is another important factor for indole production; E. coli produces and accumulates a large amount of indole at 50°C, even at low cell densities. Overall, our results suggest that indole is a stable biological compound, and E. coli may utilize indole to protect itself against other microorganisms. PMID:21145393

Han, Thi Hiep; Lee, Jin-Hyung; Cho, Moo Hwan; Wood, Thomas K.; Lee, Jintae

2011-01-01

186

Immune complex glomerulonephritis in mice infected with Escherichia coli.  

PubMed Central

C57Bl/6 mice were injected intraperitoneally with 10(8) to 2 x 10(8) living K 38 Escherichia coli (E. coli) and serological changes and kidney involvement were studied. E. coli were found in the blood 45 min to 24 hr after injection. In serum, large amounts of deoxyribonucleic acid (DNA) were present 24 hr after E. coli injection, and thereafter disappeared. Seven days after infection, antibodies directed against E. coli, anti-DNA antibodies and C1q-binding substances were found in serum and the kinetics of the variations of these parameters were studied until day 35. Kidney lesions were evaluated immunochemically and by optical and electron microscopy. In the glomeruli, heavy granular deposits of IgG and IgM were constantly found in mesangium and along capillary walls. In most kidneys slight granular deposits of IgG and IgM were also found in the tubules. Histological studies revealed in the glomeruli mild endocapillary cell proliferation, focal thickening of glomerular basement membrane and dense deposits in mesangial and subendothelial areas and inside the glomerular basement membrane; in the tubules dense deposits were focally observed inside the tubular basement membrane. Images Fig. 6 Fig. 7 PMID:6450654

Fournié, G J; Mignon-Conté, M A; Lulé, J; Gayral-Ta Minh, M; Haas, S; Bauriaud, R; Conté, J J

1980-01-01

187

Bio-affecting mercury detection using mercury resistance gene module fused with bioluminescence reporter genes.  

PubMed

Bioluminescence sensor systems were developed for monitoring environmental mercury contamination. The biological mercury measurement sensor systems were constructed by DNA recombination technique. A bacterial mercury-resistant operon (meroperon) from Pseudomonas sp. K-6y4 and a bacterial bioluminescence operon (lux operon) from an ocean bacterium Vibrio fischeri were fused in avector plasmid. The resulting recombinant plasmids were cloned in Escherichia coli cells. The bioluminescence sensor systems responded to mercury chloride of 0.1 nM to 100 nM. The mercury bioluminescence sensor developed in this study can be used for monitoring of the bio-affecting mercury instead of total mercury that is measured by conventional analytical equipment. The fundamental feature of the bioluminescence sensor system is attractive for use as a monitoring system for bio-affecting environmental mercury contamination. PMID:12523762

Yamagata, T; Ishii, M; Narita, M; Huang, G C; Endo, G

2002-01-01

188

Role of Enteroaggregative Escherichia coli Virulence Factors in Uropathogenesis  

PubMed Central

A multiresistant clonal Escherichia coli O78:H10 strain qualifying molecularly as enteroaggregative Escherichia coli (EAEC) was recently shown to be the cause of a community-acquired outbreak of urinary tract infection (UTI) in greater Copenhagen, Denmark, in 1991. This marks the first time EAEC has been associated with an extraintestinal disease outbreak. Importantly, the outbreak isolates were recovered from the urine of patients with symptomatic UTI, strongly implying urovirulence. Here, we sought to determine the uropathogenic properties of the Copenhagen outbreak strain and whether these properties are conferred by the EAEC-specific virulence factors. We demonstrated that through expression of aggregative adherence fimbriae, the principal adhesins of EAEC, the outbreak strain exhibited pronouncedly increased adherence to human bladder epithelial cells compared to prototype uropathogenic strains. Moreover, the strain was able to produce distinct biofilms on abiotic surfaces, including urethral catheters. These findings suggest that EAEC-specific virulence factors increase uropathogenicity and may have played a significant role in the ability of the strain to cause a community-acquired outbreak of UTI. Thus, inclusion of EAEC-specific virulence factors is warranted in future detection and characterization of uropathogenic E. coli. PMID:23357383

Boll, Erik J.; Struve, Carsten; Boisen, Nadia; Olesen, Bente; Stahlhut, Steen G.

2013-01-01

189

Isolation of Enteropathogenic Escherichia coli from lettuce samples in Tehran  

PubMed Central

Aim The purpose of this study was to find the isolation rate of enteropathogenic Escherichia coli (EPEC) from lettuce samples collected in Tehran. Background During the last decade, the prevalence of infectious diarrheal diseases due to consumption of contaminated food especially raw vegetable has been increasingly reported. Enteropathogenic Escherichia coli strains are an important group of diarrheagenic E. coli that can cause infant diarrhea especially in the developing world. Material and Methods One hundred lettuce samples collected in Tehran were transported to the laboratory, homogenized by a stomacher in EC broth containing cefixime, and cultured on MacConkey agar plates. Bacterial DNA was extracted by boiling method and PCR was performed using three pairs of primers targeting stx1, stx2 and eaeA genes. Results Screening of 100 lettuce samples by PCR showed four samples were positive for the presence of EPEC. Conclusion This study suggests contamination of the lettuce by the EPEC and its possible role as the source of infection in this region. PMID:25436096

Mazaheri, Somayeh; Salmanzadeh-Ahrabi, Siavosh; Aslani, Mohammad-Mehdi

2014-01-01

190

Widespread antibiotic resistance of diarrheagenic Escherichia coli and Shigella species  

PubMed Central

Background: Antibiotic resistance of enteric pathogens particularly Shigella species, is a critical world-wide problem and monitoring their resistant pattern is essential, because the choice of antibiotics is absolutely dependent on regional antibiotic susceptibility patterns. During summer 2013, an unusual increase in number of diarrheal diseases was noticed in Isfahan, a central province of Iran. Therefore, the antibiotic resistance of diarrheagenic Escherichia coli and Shigella species isolated were evaluated. Materials and Methods: According to the guideline on National Surveillance System for Foodborn Diseases, random samples from patients with acute diarrhea were examined in local laboratories of health centers and samples suspicious of Shigella spp. were further assessed in referral laboratory. Isolated pathogens were identified by standard biochemical and serologic tests and antibiotic susceptibility testing was carried out by disc diffusion method. Results: A total of 1086 specimens were obtained and 58 samples suspicious of Shigella were specifically evaluated. The most prevalent isolated pathogen was Shigella sonnei (26/58) followed by E. coli (25/58) and Shigella flexneri (3/58). A large number of isolated bacteria were resistant to co-trimoxazole (Shigella spp: 100%, E. coli: 80%), azithromycin (Shigella spp: 70.4%, E. coli: 44.0%), ceftriaxone (Shigella spp: 88.9%, E. coli: 56.0%) and cefixime (Shigella spp: 85.2%, E. coli: 68.0%). About88.3% of S. sonnei isolates, one S. flexneri isolate, and 56% of E. coli strains were resistant to at least three antibiotic classes (multidrug resistant). Conclusion: Due to high levels of resistance to recommended and commonly used antibiotics for diarrhea, continuous monitoring of antibiotic resistance seems essential for determining best options of empirical therapy. PMID:25002896

Sadeghabadi, Azam Fatahi; Ajami, Ali; Fadaei, Reza; Zandieh, Masoud; Heidari, Elham; Sadeghi, Mahmoud; Ataei, Behrooz; Hoseini, Shervin Ghaffari

2014-01-01

191

Towards rapid on-site phage-mediated detection of generic Escherichia coli in water using luminescent and visual readout.  

PubMed

Wild-type T4 bacteriophage and recombinant reporter lac Z T4 bacteriophage carrying the ?-galactosidase gene were used for detection of generic Escherichia coli by monitoring the release of ?-galactosidase upon phage-mediated cell lysis. The reaction was performed on a paper-based portable culture device to limit the diffusion of reagents and, hence, increase the sensitivity of the assay, and to avoid handling large sample volumes, making the assay suitable for on-site analysis. Chromogenic (chlorophenol red-?-D-galactopyranoside, CPRG) and bioluminescent (6-O-?-galactopyranosyl-luciferin, Beta-Glo(®)) ?-galactosidase substrates were tested in the assay. Water samples were first filtered through 0.45-?m pore size filters to concentrate bacteria. The filters were then placed into the paper-based device containing nutrient medium and incubated at 37 °C for 4 h. Bacteriophage with the respective indicator substrate was added to the device, and signal (color, luminescence) development was recorded with a digital camera, luminometer, or luminescence imaging device. It was demonstrated that as low as 40 or <10 colony-forming units (cfu)?ml(-1) of E. coli can be detected visually within 8 h when wild-type T4 bacteriophage or recombinant lacZ T4 bacteriophage were used in the assay, respectively. Application of the bioluminescent ?-galactosidase substrate allowed reliable detection of <10 cfu ml(-1) within 5.5 h. The specificity of the assay was demonstrated using a panel of microorganisms including Aeromonas hydrophila, Enterobacter cloacae, E. coli, and Salmonella Typhimurium. PMID:24969469

Burnham, Sean; Hu, Jing; Anany, Hany; Brovko, Lubov; Deiss, Frederique; Derda, Ratmir; Griffiths, Mansel W

2014-09-01

192

Kinetic measurement of the membranolytic activity of serum complement using bioluminescent bacteria  

Microsoft Academic Search

A method for studying the kinetics of serum complement activity is presented. The assay utilises Escherichia coli and Bacillus subtilis cells which have been made bioluminescent by expressing an insect luciferase gene from Pyrophorus plagiophthalamus. The diffusion of the luciferase enzyme substrate through the cell membranes is very slow, and therefore a change in membrane permeability is seen as a

Marko Virta; Matti Karp; Sanna Rönnemaa; Esa-Matti Lilius

1997-01-01

193

Glucosylation of Isoflavonoids in Engineered Escherichia coli  

PubMed Central

A glycosyltransferase, YjiC, from Bacillus licheniformis has been used for the modification of the commercially available isoflavonoids genistein, daidzein, biochanin A and formononetin. The in vitro glycosylation reaction, using UDP-?-D-glucose as a donor for the glucose moiety and aforementioned four acceptor molecules, showed the prominent glycosylation at 4? and 7 hydroxyl groups, but not at the 5th hydroxyl group of the A-ring, resulting in the production of genistein 4?-O-?-D-glucoside, genistein 7-O-?-D-glucoside (genistin), genistein 4?,7-O-?-D-diglucoside, biochanin A-7-O-?-D-glucoside (sissotrin), daidzein 4?-O-?-D-glucoside, daidzein 7-O-?-D-glucoside (daidzin), daidzein 4?, 7-O-?-D-diglucoside, and formononetin 7-O-?-D-glucoside (ononin). The structures of all the products were elucidated using high performance liquid chromatography-photo diode array and high resolution quadrupole time-of-flight electrospray ionization mass spectrometry (HR QTOFESI/MS) analysis, and were compared with commercially available standard compounds. Significantly higher bioconversion rates of all four isoflavonoids was observed in both in vitro as well as in vivo bioconversion reactions. The in vivo fermentation of the isoflavonoids by applying engineered E. coli BL21(DE3)/?pgi?zwf?ushA overexpressing phosphoglucomutase (pgm) and glucose 1-phosphate uridyltransferase (galU), along with YjiC, found more than 60% average conversion of 200 ?M of supplemented isoflavonoids, without any additional UDP-?-D-glucose added in fermentation medium, which could be very beneficial to large scale industrial production of isoflavonoid glucosides. PMID:24599002

Pandey, Ramesh Prasad; Parajuli, Prakash; Koirala, Niranjan; Lee, Joo Ho; Park, Yong Il; Sohng, Jae Kyung

2014-01-01

194

A second Escherichia coli protein with CL synthase activity.  

PubMed

The Escherichia coli open reading frame f413, which has the potential to code for a polypeptide homologous to cardiolipin (CL) synthase, has been cloned. Its polypeptide product has a molecular mass of 48 kDa, is membrane-bound, and catalyzes CL formation but does not hydrolyze CL. A comparison of the sequences predicted for the polypeptides encoded by f413 and cls indicates that the N-terminal residues specified by cls may be unnecessary for CL synthase activity. Construction of a truncated cls gene and characterization of its polypeptide product have confirmed this conclusion. PMID:10634942

Guo, D; Tropp, B E

2000-01-17

195

L Tyrosine production by deregulated strains of Escherichia coli  

Microsoft Academic Search

The excretion of the aromatic amino acid l-tyrosine was achieved by manipulating three gene targets in the wild-type Escherichia coli K12: The feedback-inhibition-resistant (fbr) derivatives of aroG and tyrA were expressed on a low-copy-number vector, and the TyrR-mediated regulation of the aromatic amino acid biosynthesis was\\u000a eliminated by deleting the tyrR gene. The generation of this l-tyrosine producer, strain T1,

Tina Lütke-Eversloh; Gregory Stephanopoulos

2007-01-01

196

[Characterization of Escherichia coli esterase B after separation by chromatography].  

PubMed

Esterase B of Escherichia coli has been purified 56 fold with recovery of 39%. The apparent molecular weight as determined by gel filtration was approximately 57000. The pI as determined by isoelectric focusing was 4.6. This enzyme exhibited Michaelis-Menton kinetics with apparent Km of 0.25 mM for l-naphtyl acetate. It remained stable at 60 degrees C but was sensitive to pH values below 6. The esterase activity was completely inhibited by Di-isopropyl-fluorophosphate (DFP) but was resistant to iodoacetamide and to EDTA. PMID:6405981

Goullet, P; Picard, B; Hieng, H S

1983-01-31

197

Urinary-tract infection: localisation and virulence of Escherichia coli.  

PubMed

Virulence of 15 strains of Escherichia coli from the human upper urinary tract was compared with that of 16 strains from the lower urinary tract, using an ascending infection in the mouse. No significant difference was found. There was no significant difference in frequency of K antigen and ability to ferment dulcitol between 32 lower strains and 31 upper strains. However, 22 strains containing K antigen, regardless of anatomical site of localisation, were more significantly likely to cause infection than 9 strains with no antigen. Similarly, 23 dulcitolfermenting strains, regardless of site of localisation, were significantly more likely to cause infection than 8 non-fermenting strains. PMID:46051

Kalmanson, G M; Harwick, H J; Turck, M; Guze, L B

1975-01-18

198

Contact-dependent inhibition of growth in Escherichia coli.  

PubMed

Bacteria have developed mechanisms to communicate and compete with each other for limited environmental resources. We found that certain Escherichia coli, including uropathogenic strains, contained a bacterial growth-inhibition system that uses direct cell-to-cell contact. Inhibition was conditional, dependent upon the growth state of the inhibitory cell and the pili expression state of the target cell. Both a large cell-surface protein designated Contact-dependent inhibitor A (CdiA) and two-partner secretion family member CdiB were required for growth inhibition. The CdiAB system may function to regulate the growth of specific cells within a differentiated bacterial population. PMID:16109881

Aoki, Stephanie K; Pamma, Rupinderjit; Hernday, Aaron D; Bickham, Jessica E; Braaten, Bruce A; Low, David A

2005-08-19

199

Mounting of Escherichia coli spheroplasts for AFM imaging.  

SciTech Connect

The cytoplasmic membrane of Escherichia coli (E. coli) is the location of numerous, chemically specific transporters and recognition elements. Investigation of this membrane in vivo by atomic force microscopy (AFM) requires removal of the cell wall and stable immobilization of the spheroplast. AFM images demonstrate that spheroplasts can be secured with warm gelatin applied to the mica substrate just before the addition of a spheroplast suspension. The resulting preparation can be repeatedly imaged by AFM over the course of several hours. Confocal fluorescence imaging confirms the association of the spheroplasts with the gelatin layer. Gelatin molecules are known to reorder into a network after heating. Entrapment within this gelatin network is believed to be responsible for the immobilization of spheroplasts on mica.

Sullivan, Claretta J [ORNL; Morrell-Falvey, Jennifer L [ORNL; Allison, David P [ORNL; Doktycz, Mitchel John [ORNL

2005-11-01

200

Impact of cranberry on Escherichia coli cellular surface characteristics  

SciTech Connect

The anti-adhesive effects of cranberry have been attributed to both interactions of its components with the surface of bacterial cells and to inhibition of p-fimbriae expression. Previous reports also suggested that the presence of cranberry juice changed the Gram stain characteristics of Escherichia coli. Here, we show that the morphology of E. coli is changed when grown in the presence of juice or extract from Vaccinium macrocarpon (cranberry). Gene expression analysis indicates the down regulation of flagellar basal body rod and motor proteins. Consistent with this finding and previous reports, the SEM images indicate a decrease in the visible p-fimbriae. The iodine used in Gram-staining protocols was found to interact differently with the bacterial membrane when cells were cultured in spiked media. Slight alterations in the Gram stain protocol demonstrated that culturing in the presence of cranberry juice does not change the Gram stain characteristics contradicting other reports.

Johnson, Brandy J. [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Code 6900, Washington, DC 20375 (United States)], E-mail: brandy.white@nrl.navy.mil; Lin Baochuan; Dinderman, Michael A. [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Code 6900, Washington, DC 20375 (United States); Rubin, Robert A. [Independent Researcher, 8620 Portafino Place, Whittier, CA 90603 (United States); Malanoski, Anthony P.; Ligler, Frances S. [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Code 6900, Washington, DC 20375 (United States)

2008-12-19

201

Cellulosic hydrolysate toxicity and tolerance mechanisms in Escherichia coli  

PubMed Central

The sustainable production of biofuels will require the efficient utilization of lignocellulosic biomass. A key barrier involves the creation of growth-inhibitory compounds by chemical pretreatment steps, which ultimately reduce the efficiency of fermentative microbial biocatalysts. The primary toxins include organic acids, furan derivatives, and phenolic compounds. Weak acids enter the cell and dissociate, resulting in a drop in intracellular pH as well as various anion-specific effects on metabolism. Furan derivatives, dehydration products of hexose and pentose sugars, have been shown to hinder fermentative enzyme function. Phenolic compounds, formed from lignin, can disrupt membranes and are hypothesized to interfere with the function of intracellular hydrophobic targets. This review covers mechanisms of toxicity and tolerance for these compounds with a specific focus on the important industrial organism Escherichia coli. Recent efforts to engineer E. coli for improved tolerance to these toxins are also discussed. PMID:19832972

Mills, Tirzah Y; Sandoval, Nicholas R; Gill, Ryan T

2009-01-01

202

Involvement of DNA superhelicity in minichromosome maintenance in Escherichia coli.  

PubMed Central

Evidence is presented that Escherichia coli minichromosomes are harbored at superhelical densities which are lower than those measured for other E. coli plasmids but are comparable to that of the chromosome. When introduced into gyrB decreased-supercoiling mutants, minichromosomes were much more unstable than in strains with normal or increased supercoiling properties; in fact, certain minichromosome derivatives could not be introduced into top gyrB decreased-supercoiling mutants. These observations were unique to minichromosomes, since the maintenance of plasmids which did not replicate from oriC was not altered in these mutants. Analyses of minichromosomes of identical sizes but with different restriction fragment orientations suggested that supercoiling-dependent alterations in promoter-terminator functions, as well as direct effects of supercoiling on replication, may play a role in the observed minichromosome instability. Images PMID:2981821

Leonard, A C; Whitford, W G; Helmstetter, C E

1985-01-01

203

Continuous-sterilization system that uses photosemiconductor powders. [Escherichia coli  

SciTech Connect

We report a novel photochemical sterilization system in which Escherichia coli cells were sterilized with photosemiconductor powders (titanium oxide). For sterilization that could be used in practice, it was necessary to separate the TiO/sub 2/ powders from the cell suspension. Therefore, semiconductor powders were immobilized on acetylcellulose membranes. We constructed a continuous-sterilization system consisting of TiO/sub 2/-immobilized acetylcellulose membrane reactor, a mercury lamp, and a masterflex pump. As a result, under the various sterilization conditions examined, E.coli (10/sup 2/ cells per ml) was sterilized to < 1% survival when the cell suspension flowed in this system at a mean residence time of 16.0 min under irradiation (1800 microeinsteins/m/sup 2/ per s). We found that this system was reusable.

Matsunaga, T.; Tomoda, R.; Nakajima, T.; Nakamura, N.; Komine, T.

1988-06-01

204

Escherichia coli response to exogenous pyrophosphate and analogs.  

PubMed

The addition of exogenous pyrophosphate increases the growth yield and cAMP synthesis in stationary phase when Escherichia coli is grown in minimal medium. Pyrophosphate increases the yield by altering the enterobactin uptake system. We studied the physiological effects and examined how the E. coli transcriptome was modified when two structural analogs of pyrophosphate were added to the growth medium. Methylenediphosphonic acid or a high concentration of iron had the same positive effects as pyrophosphate on growth yield, cAMP synthesis and the repression of Fur-regulated genes. In contrast, imidodiphosphate did not affect these cellular processes significantly. The transcriptome modifications generated by pyrophosphate or methylenediphosphonic acid were more similar than those generated by imidodiphosphate or excess iron. The transcriptome data also indicated that processes other than iron uptake might be involved in the cellular response to exogenous pyrophosphate or methylenediphosphonic acid. PMID:12673060

Biville, Francis; Oshima, Taku; Mori, Hirotada; Kawagoe, Yuya; Bouvet, Odile; Rager, Marie-Noëlle; Perrotte-Piquemal, Marina; Danchin, Antoine

2003-01-01

205

Four products from Escherichia coli pseudogenes increase hydrogen production.  

PubMed

Pseudogenes are considered to be nonfunctional genes that lack a physiological role. By screening 3985 Escherichia coli mutants using chemochromic membranes, we found four pseudogenes involved in hydrogen metabolism. Knockouts of pseudogenes ydfW and ypdJ had a defective hydrogen phenotype on glucose and formate, respectively. Also, the knockout of pseudogene yqiG formed hydrogen from formate but not from glucose. For the yqiG mutant, 100% hydrogen recovery was obtained by the complementation of YqiG via a plasmid. The knockout of pseudogene ylcE showed hydrogen deficiency in minimal media which suggested that the role of YlcE is associated with cell growth. Hence, the products of these four pseudogenes play an important physiological role in hydrogen production in E. coli. PMID:24025676

Mohd Yusoff, Mohd Zulkhairi; Hashiguchi, Yuya; Maeda, Toshinari; Wood, Thomas K

2013-10-01

206

A biotyping scheme for the subspecific discrimination of Escherichia coli.  

PubMed

A two-tier system for biotyping Escherichia coli gave a fine and reliable differentiation of strains and is capable of future extension by the addition of new types and new tests. Strains were allocated to a primary biotype (1-16) by their reactions in four primary tests in culture media containing raffinose, sorbose, ornithine or dulcitol. Subtypes were distinguished within the primary biotypes by reactions in six secondary tests for rhamnose fermentation, lysine decarboxylation, aesculin hydrolysis, motility, type-1 fimbriation and prototrophy. Full biotypes were designated by letters indicating subtype reactions appended to primary type numbers. A series of 599 strains (1242 cultures) of E. coli from diverse sources was classified into 16 primary biotypes and into 213 full biotypes. The biotype characters of a strain were generally stable during its spread in the natural environment and in non-selective media used for storage. PMID:6754944

Crichton, P B; Old, D C

1982-05-01

207

A concise biotyping system for differentiating strains of Escherichia coli.  

PubMed

A six test biotyping system comprising fermentation of dulcitol, sorbose, raffinose, and 5 ketogluconate, motility and production of beta-haemolysis was used to obtain biotype profiles for 514 strains of Escherichia coli isolated from the urinary tract. This profile was suffixed to the API-20E code, recorded when the strains were originally identified. An expanded and reliable biotyping system was thus created giving a greater number of possible biotypes than with either system alone. The sensitivity in terms of distinguishing the organisms studied was therefore greatly increased. The use of O-serotyping in combination with biotyping is discussed. Biotyping can also be usefully supplemented by the determination of the eight commonest E coli O-serotypes. This is of value in many clinical situations where differentiation of organisms is vital to the proper analysis of results. PMID:6757274

Gargan, R; Brumfitt, W; Hamilton-Miller, J M

1982-12-01

208

Genetic characterization of moaB mutants of Escherichia coli  

PubMed Central

The moaABCDE operon of Escherichia coli encodes enzymes essential for the biosynthesis of the molybdenum cofactor (Moco). However, the role of the moaB gene within this operon has remained enigmatic. Here, we have investigated the effect of moaB defects on two phenotypes diagnostic for Moco-deficiency: chlorate-resistance and sensitivity to the base analog 6-N-hydroxylaminopurine (HAP). We found that transposon insertions in moaB caused partial Moco-deficiency associated with chlorate-resistance, but not for HAP-sensitivity. On the other hand, in-frame deletions of moaB, or moaB overexpression, had no effect on either phenotype. Our combined data are consistent with the lack of any role for MoaB in Moco biosynthesis in E. coli. PMID:23680484

Kozmin, Stanislav G.; Schaaper, Roel M.

2013-01-01

209

Enterotoxigenic and necrotizing Escherichia coli in human diarrhoea in Spain.  

PubMed

Enterotoxigenic Escherichia coli (ETEC) strains of serotype 0153: K-:H45 CFA/I+ STa+ were associated with two outbreaks of neonatal diarrhoea that occurred in two different hospitals of Madrid, in one of which several children died. Two other outbreaks were associated with ETEC strains of serotypes 0159: K-:H21 (LT+) and 0159: K-:H4 (LT+ STa+) without CFA/I and CFA/II colonization factors. Necrotizing E. coli (NTEC) strains of serotype 06:K13, producing the cytotoxic necrotizing factor CNF1 and alpha-haemolysin, were also associated with two outbreaks of neonatal diarrhoea that occurred in a hospital in Madrid and in a hospital in Talavera de la Reina. The results of the characterization of some ETEC and NTEC strains isolated from sporadic cases of diarrhoea are also discussed. PMID:1397224

Blanco, J; González, E A; Espinosa, P; Blanco, M; Garabal, J I; Alonso, M P

1992-07-01

210

Deer sausage: a newly identified vehicle of transmission of Escherichia coli O157:H7.  

PubMed

Five Missouri patients infected with Escherichia coli O157:H7 were studied for an epidemiologically plausible association. Case isolates, case interviews, and pathogen and meat XbaI pulsed field electrophoresis patterns were consistent with the common source being contaminated, fermented deer sausage, a previously unrecognized mode of transmission for Escherichia coli O157:H7. PMID:19773004

Ahn, Christina K; Russo, Anthony J; Howell, Karla R; Holt, Nicholas J; Sellenriek, Patricia L; Rothbaum, Robert J; Beck, Anne M; Luebbering, Leon J; Tarr, Phillip I

2009-10-01

211

FACTORS INFLUENCING THE SHEDDING OF ESCHERICHIA COLI AND SALMONELLA SPP. IN HOLSTEIN CATTLE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fecal samples were obtained in replicate from lactating (LAC; n = 60) and non-lactating (NLAC; n = 60) Holstein cows to determine the influence of time of day (AM vs PM), parity, and lactation phase [ 60 d in milk (DIM)] on shedding of Escherichia coli O157:H7 (EHEC), Escherichia coli (EC),...

212

Antibiotics Susceptibility Pattern of Escherichia coli Strains Isolated from Chickens with Colisepticemia in Tabriz Province, Iran  

Microsoft Academic Search

Antimicrobial agents are used extremely in order to reducing the enormous losses caused by Escherichia coli infections (colibacillosis) in Iran poultry industry. In this investigation fifty avian pathogenic Escherichia coli (APEC) strains isolated from broiler chickens with colisepticemia and examined for susceptibility to antimicrobials of veterinary and human significance. In vitro antibiotic activities of 3 2 antibiotic substances against the

2006-01-01

213

Structural and Biochemical Characterization of a Quinol Binding Site of Escherichia coli Nitrate Reductase A*  

E-print Network

Structural and Biochemical Characterization of a Quinol Binding Site of Escherichia coli Nitrate of Escherichia coli nitrate re- ductase A (NarGHI) in complex with pentachlorophenol has been determined to 2.0 Ã? of resolution. We have shown that pentachlorophenol is a potent inhibitor of quinol:nitrate oxidoreductase

Strynadka, Natalie

214

The human Pif1 helicase, a potential Escherichia coli RecD homologue, inhibits telomerase activity  

E-print Network

act as an adjuvant therapy for the treatment of human cancer (17). In most human tumor cells, telomereThe human Pif1 helicase, a potential Escherichia coli RecD homologue, inhibits telomerase activity is a potential homologue of Escherichia coli RecD, an ATP-dependent 50 to 30 DNA helicase. Ectopic expression

Tian, Weidong

215

Escherichia coli Bacteriocins: Antimicrobial Efficacy and Prevalence among Isolates from Patients with Bacteraemia  

Microsoft Academic Search

Bacteriocins are antimicrobial peptides generally active against bacteria closely related to the producer. Escherichia coli produces two types of bacteriocins, colicins and microcins. The in vitro efficacy of isolated colicins E1, E6, E7, K and M, was assessed against Escherichia coli strains from patients with bacteraemia of urinary tract origin. Colicin E7 was most effective, as only 13% of the

Maruška Budi?; Matija Rijavec; Živa Petkovšek; Darja Žgur-Bertok

2011-01-01

216

Structure of the Heme d of Penicillium vitale and Escherichia coli Catalases*  

E-print Network

Structure of the Heme d of Penicillium vitale and Escherichia coli Catalases* (Received-hydroxychlorin -spirolactone has been found in the crystal structures of Penicillium vitale catalase and Escherichia coli catalase hydroperoxidase II (HPII). The absolute stereochemistry of the two heme d chiral car- bon atoms

217

The RecA proteins of Deinococcus radiodurans and Escherichia coli promote DNA strand exchange  

E-print Network

-binding properties of the Ec RecA protein, and led us to examine the pathway for Dr RecA-mediated DNA strand exchangeThe RecA proteins of Deinococcus radiodurans and Escherichia coli promote DNA strand exchange via of Escherichia coli, and all filament-forming homologues identified to date, promote DNA strand exchange

Cox, Michael M.

218

MOLECULAR PROCESSING OF REPLICATION INTERMEDIATES IN ESCHERICHIA COLI AFTER DNA DAMAGE  

E-print Network

, such as dnaB266. We measured the amount of nascent DNA degradation, allowing us to determine how the newlyMOLECULAR PROCESSING OF REPLICATION INTERMEDIATES IN ESCHERICHIA COLI AFTER DNA DAMAGE By Jerilyn OF REPLICATION INTERMEDIATES IN ESCHERICHIA COLI AFTER DNA DAMAGE By Jerilyn Jalana Belle Approved

Courcelle, Justin

219

Review article Escherichia coli as a pathogen in dogs and cats  

E-print Network

Review article Escherichia coli as a pathogen in dogs and cats Lothar Beutin Robert Koch; accepted 17December 1998) Abstraet-Certain strains of Escherichia coli behave as pathogens in dogs and cats were clearly associated with enteric disease in young dogs. ETEC isolates from diar- rhoeic dogs were

Paris-Sud XI, Université de

220

Inhibition of the ATPase activity of Escherichia coli ATP synthase by magnesium fluoride  

E-print Network

Inhibition of the ATPase activity of Escherichia coli ATP synthase by magnesium fluoride Zulfiqar activity of Escherichia coli ATP synthase by magnesium fluoride (MgFx) was studied. Wild-type F1-ATPase synthesis mechanism; Magnesium fluoride; ATPase inhibition; Transition state analog 1. Introduction ATP

Zulfiqar Ahmad

221

Pathogenic Escherichia coli in rural household container waters.  

PubMed

Plastic containers in the range of 5-20 L are widely used - especially in rural African settings - to collect, transport and store water for domestic use, including drinking, bathing and hygiene. The pathogen content of the waters in these containers has not been adequately characterized as yet. This paper presents the primary findings of a synoptic survey of drinking water quality samples from these containers and involved collection of bacterial indicator and pathogenicity gene data. In total, 571 samples of a variety of waters were taken in rural communities in South Africa and the Escherichia coli numbers measured. Of the E. coli positive samples, 46% (n = 148) were screened for the presence of E. coli pathogen gene markers. Though synoptic, the survey provided many insights into the issues that drove the study. Container use markedly degraded water quality as judged by indicator counts, even where improved water supply services were in place. Household container use also appeared to promote regrowth or contamination of containers with pathogenic E. coli strains. Polymerase chain reaction (PCR) analysis also showed that the diversity of potential pathogenic E. coli carrying virulence genes was great. All seven genes screened for (Ial, Stx1, Stx2, EaeA, Eagg, ST, LT) were found in the waters, alone or as mixtures (number of different combinations = 31) including those characteristic of the more dangerous invasive and haemorrhagic E. coli strains. Given the central role of containers in the management of water supply to rural communities, it is clear the microbiology of these waters requires much further characterization. PMID:23508146

Jagals, P; Barnard, T G; Mokoena, M M; Ashbolt, N; Roser, D J

2013-01-01

222

The Modular Organization of Protein Interactions in Escherichia coli  

PubMed Central

Escherichia coli serves as an excellent model for the study of fundamental cellular processes such as metabolism, signalling and gene expression. Understanding the function and organization of proteins within these processes is an important step towards a ‘systems’ view of E. coli. Integrating experimental and computational interaction data, we present a reliable network of 3,989 functional interactions between 1,941 E. coli proteins (?45% of its proteome). These were combined with a recently generated set of 3,888 high-quality physical interactions between 918 proteins and clustered to reveal 316 discrete modules. In addition to known protein complexes (e.g., RNA and DNA polymerases), we identified modules that represent biochemical pathways (e.g., nitrate regulation and cell wall biosynthesis) as well as batteries of functionally and evolutionarily related processes. To aid the interpretation of modular relationships, several case examples are presented, including both well characterized and novel biochemical systems. Together these data provide a global view of the modular organization of the E. coli proteome and yield unique insights into structural and evolutionary relationships in bacterial networks. PMID:19798435

Peregrín-Alvarez, José M.; Xiong, Xuejian; Su, Chong; Parkinson, John

2009-01-01

223

A second DNA methyltransferase repair enzyme in Escherichia coli.  

PubMed Central

The Escherichia coli ada-alkB operon encodes a 39-kDa protein (Ada) that is a DNA-repair methyltransferase and a 27-kDa protein (AlkB) of unknown function. By DNA blot hybridization analysis we show that the alkylation-sensitive E. coli mutant BS23 [Sedgwick, B. & Lindahl, T. (1982) J. Mol. Biol. 154, 169-175] is a deletion mutant lacking the entire ada-alkB operon. Despite the absence of the ada gene and its product, the cells contain detectable levels of a DNA-repair methyltransferase activity. We conclude that the methyltransferase in BS23 cells is the product of a gene other than ada. A similar activity was detected in extracts of an ada-10::Tn10 insertion mutant of E. coli AB1157. This DNA methyltransferase has a molecular mass of about 19 kDa and transfers the methyl groups from O6-methylguanine and O4-methylthymine in DNA, but not those from methyl phosphotriester lesions. This enzyme was not induced by low doses of alkylating agent and is expressed at low levels in ada+ and a number of ada- E. coli strains. Images PMID:3283737

Rebeck, G W; Coons, S; Carroll, P; Samson, L

1988-01-01

224

Enteroaggregative Escherichia coli associated with a foodborne outbreak of gastroenteritis.  

PubMed

This study investigated two foodborne outbreaks of gastroenteritis that occurred 10 days apart among individuals who had meals at the restaurant of a farm holiday resort. Mild gastrointestinal symptoms were reported and none of the patients needed hospitalization. Mean incubation times were 45 and 33 h, and the overall attack rates were 43.5 and 58.3%, respectively. Stool sample examination was negative for common enteric pathogens in both outbreaks. Specimens from 13 people involved in the second outbreak and 3 restaurant staff were examined for diarrhoeagenic Escherichia coli. An enteroaggregative E. coli (EAEC) strain of serotype O92:H33 was isolated from six participants and one member of staff. In particular, the EAEC strain was isolated from five of the six cases of diarrhoea examined. The strain showed an aggregative pattern of adherence to HEp-2 cells, did not produce a biofilm and possessed the virulence-related genes aat, aggR, aap and set1A, but not the astA gene. A retrospective cohort study indicated a pecorino cheese made with unpasteurized sheep milk as the possible source (P<0.001). Samples of the cheese had E. coli counts higher than 10(6) c.f.u. g(-1), but the outbreak EAEC strain was not isolated. This report confirms that EAEC infections are probably underdiagnosed because of the limited availability of laboratories capable of identifying this group of pathogenic E. coli. PMID:18719185

Scavia, Gaia; Staffolani, Monica; Fisichella, Stefano; Striano, Gianluca; Colletta, Stefano; Ferri, Giovanni; Escher, Martina; Minelli, Fabio; Caprioli, Alfredo

2008-09-01

225

Low intensity infrared laser induces filamentation in Escherichia coli cells  

NASA Astrophysics Data System (ADS)

Low intensity continuous wave and pulsed emission modes laser is used in treating many diseases and the resulting biostimulative effect on tissues has been described, yet the photobiological basis is not well understood. The aim of this wok was to evaluate, using bacterial filamentation assay, effects of laser on Escherichia coli cultures in exponential and stationary growth phase. E. coli cultures, proficient and deficient on DNA repair, in exponential and stationary growth phase, were exposed to low intensity infrared laser, aliquots were spread onto microscopic slides, stained by Gram method, visualized by optical microscopy, photographed and percentage of bacterial filamentation were determined. Low intensity infrared laser with therapeutic fluencies and different emission modes can induce bacterial filamentation in cultures of E. coli wild type, fpg/ mutM, endonuclease III and exonuclease III mutants in exponential and stationary growth phase. This study showed induction of bacterial, filamentation in E. coli cultures expose to low intensity infrared laser and attention to laser therapy protocols, which should take into account fluencies, wavelengths, tissue conditions, and genetic characteristics of cells before beginning treatment.

Fonseca, A. S.; Presta, G. A.; Geller, M.; Paoli, F.

2011-10-01

226

Activity map of the Escherichia coli RNA polymerase bridge helix.  

PubMed

Transcription, the synthesis of RNA from a DNA template, is performed by multisubunit RNA polymerases (RNAPs) in all cellular organisms. The bridge helix (BH) is a distinct feature of all multisubunit RNAPs and makes direct interactions with several active site-associated mobile features implicated in the nucleotide addition cycle and RNA and DNA binding. Because the BH has been captured in both kinked and straight conformations in different crystals structures of RNAP, recently supported by molecular dynamics studies, it has been proposed that cycling between these conformations is an integral part of the nucleotide addition cycle. To further evaluate the role of the BH, we conducted systematic alanine scanning mutagenesis of the Escherichia coli RNAP BH to determine its contributions to activities required for transcription. Combining our data with an atomic model of E. coli RNAP, we suggest that alterations in the interactions between the BH and (i) the trigger loop, (ii) fork loop 2, and (iii) switch 2 can help explain the observed changes in RNAP functionality associated with some of the BH variants. Additionally, we show that extensive defects in E. coli RNAP functionality depend upon a single previously not studied lysine residue (Lys-781) that is strictly conserved in all bacteria. It appears that direct interactions made by the BH with other conserved features of RNAP are lost in some of the E. coli alanine substitution variants, which we infer results in conformational changes in RNAP that modify RNAP functionality. PMID:21357417

Jovanovic, Milija; Burrows, Patricia C; Bose, Daniel; Cámara, Beatriz; Wiesler, Simone; Zhang, Xiaodong; Wigneshweraraj, Sivaramesh; Weinzierl, Robert O J; Buck, Martin

2011-04-22

227

CRISPR-Cas Functional Module Exchange in Escherichia coli  

PubMed Central

ABSTRACT Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (cas) genes constitute the CRISPR-Cas systems found in the Bacteria and Archaea domains. At least in some strains they provide an efficient barrier against transmissible genetic elements such as plasmids and viruses. Two CRISPR-Cas systems have been identified in Escherichia coli, pertaining to subtypes I-E (cas-E genes) and I-F (cas-F genes), respectively. In order to unveil the evolutionary dynamics of such systems, we analyzed the sequence variations in the CRISPR-Cas loci of a collection of 131 E. coli strains. Our results show that the strain grouping inferred from these CRISPR data slightly differs from the phylogeny of the species, suggesting the occurrence of recombinational events between CRISPR arrays. Moreover, we determined that the primary cas-E genes of E. coli were altogether replaced with a substantially different variant in a minor group of strains that include K-12. Insertion elements play an important role in this variability. This result underlines the interchange capacity of CRISPR-Cas constituents and hints that at least some functional aspects documented for the K-12 system may not apply to the vast majority of E. coli strains. PMID:24473126

Almendros, Cristóbal; Mojica, Francisco J. M.; Díez-Villaseñor, César; Guzmán, Noemí M.; García-Martínez, Jesús

2014-01-01

228

Marine macroalgae as a source for osmoprotection for Escherichia coli.  

PubMed

At elevated osmolarity of the mineral medium M63, marine macroalgae constitute important osmoprotectants and nutrients sources for Escherichia coli. Growth of bacterial population (16 strains) was improved by supplementing M63 salts medium with either aqueous or ethanolic algal extracts obtained from Ascophyllum nodosum, Fucus serratus, Enteromorpha ramulosa, Ulva lactuca, and Palmaria palmata. In their presence, growth was still observed even at 1.02 M NaCl. Furthermore, the E. coli ZB400 growth in presence of whole macroalgae thalli in M63/0.85 M NaCI reached its maximum within 24 h (5 × 10(7) - 5 × 10(8) colony-forming units [CFU] per milliliter). In the presence of A. nodosum, bacterial growth was inhibited. In the same experimental conditions, ethanolic extracts improved E. coli growth significantly, because the yield reached 10(11) CFU per milliliter. Ulva lactuca and P. palmata allowed the better growth. The Dragendorff-positive compounds extracted from bacterial cells growing on each ethanolic extract exhibited an osmoprotective effect as proved by a disk-diffusion assay. On the other hand, the -onium compounds (quaternary ammonium [betaines] and tertiary sulphonium) and total free amino acid contents of U. lactuca ethanolic extracts were higher than in others. Fucaceae extracts demonstrated especially high protein content. Algal extracts constitute not only an appreciable osmoprotection source for E. coli but also nutrient sources. PMID:24185483

Ghoul, M; Minet, J; Bernard, T; Dupray, E; Cormier, M

1995-09-01

229

Metabolic Flux Responses to Pyruvate Kinase Knockout in Escherichia coli  

PubMed Central

The intracellular carbon flux distribution in wild-type and pyruvate kinase-deficient Escherichia coli was estimated using biosynthetically directed fractional 13C labeling experiments with [U-13C6]glucose in glucose- or ammonia-limited chemostats, two-dimensional nuclear magnetic resonance (NMR) spectroscopy of cellular amino acids, and a comprehensive isotopomer model. The general response to disruption of both pyruvate kinase isoenzymes in E. coli was a local flux rerouting via the combined reactions of phosphoenolpyruvate (PEP) carboxylase and malic enzyme. Responses in the pentose phosphate pathway and the tricarboxylic acid cycle were strongly dependent on the environmental conditions. In addition, high futile cycling activity via the gluconeogenic PEP carboxykinase was identified at a low dilution rate in glucose-limited chemostat culture of pyruvate kinase-deficient E. coli, with a turnover that is comparable to the specific glucose uptake rate. Furthermore, flux analysis in mutant cultures indicates that glucose uptake in E. coli is not catalyzed exclusively by the phosphotransferase system in glucose-limited cultures at a low dilution rate. Reliability of the flux estimates thus obtained was verified by statistical error analysis and by comparison to intracellular carbon flux ratios that were independently calculated from the same NMR data by metabolic flux ratio analysis. PMID:11741855

Emmerling, Marcel; Dauner, Michael; Ponti, Aaron; Fiaux, Jocelyne; Hochuli, Michel; Szyperski, Thomas; Wüthrich, Kurt; Bailey, J. E.; Sauer, Uwe

2002-01-01

230

Characterization of a second lysine decarboxylase isolated from Escherichia coli.  

PubMed Central

We report here on the existence of a new gene for lysine decarboxylase in Escherichia coli K-12. The hybridization experiments with a cadA probe at low stringency showed that the homologous region of cadA was located in lambda Kohara phage clone 6F5 at 4.7 min on the E. coli chromosome. We cloned the 5.0-kb HindIII fragment of this phage clone and sequenced the homologous region of cadA. This region contained a 2,139-nucleotide open reading frame encoding a 713-amino-acid protein with a calculated molecular weight of 80,589. Overexpression of the protein and determination of its N-terminal amino acid sequence defined the translational start site of this gene. The deduced amino acid sequence showed 69.4% identity to that of lysine decarboxylase encoded by cadA at 93.7 min on the E. coli chromosome. In addition, the level of lysine decarboxylase activity increased in strains carrying multiple copies of the gene. Therefore, the gene encoding this lysine decarboxylase was designated Idc. Analysis of the lysine decarboxylase activity of strains containing cadA, ldc, or cadA ldc mutations indicated that ldc was weakly expressed under various conditions but is a functional gene in E. coli. PMID:9226257

Kikuchi, Y; Kojima, H; Tanaka, T; Takatsuka, Y; Kamio, Y

1997-01-01

231

Virulence characteristics and antimicrobial susceptibility of uropathogenic Escherichia coli strains.  

PubMed

Eight virulence factors associated with uropathogenic Escherichia coli (UPEC) were investigated in 204 clinical isolates of E. coli recovered from urine cultures at counts ?10(5). The bacteria were classified into two groups according to the number of leukocytes in urine samples from which they were isolated: group I ?8 leukocytes/hpf, 104 strains; group II >8 leukocytes/hpf, 100 strains. Two multiplex PCR systems were used to detect genes encoding adhesin P (pap), adhesin S (sfa), afimbrial adhesin I (afa), siderophore aerobactin (aer), alpha-hemolysin (hly), cytotoxic necrotizing factor type 1 (cnf1), and traT associated with serum resistance. The PAI marker for the virulence island identified in strains CFT072 and CVD432, a marker of enteroaggregative E. coli, was also investigated using PCR. The susceptibility profile of E. coli strains was determined by disk diffusion method. Ninety percent UPEC showed at least one of the virulence genes, the prevalence being traT (76%), aer (41%), PAI (32%), sfa (26%), pap (25%), cnf1 (18%), afa (6%), and hly (5%). There was no significant difference in the distribution of virulence genes between groups I and II. A significantly higher degree of virulence was detected in UPEC group II. The CVD432 gene was not detected in any of the UPECs. Fifty-nine percent of the strains were resistant to at least one of the antimicrobials that we tested; the most common being resistance to ampicillin (51%) and trimethoprim-sulfamethoxazole (44%). PMID:22057993

Oliveira, F A; Paludo, K S; Arend, L N V S; Farah, S M S S; Pedrosa, F O; Souza, E M; Surek, M; Picheth, G; Fadel-Picheth, C M T

2011-01-01

232

Three-dimensional solution structure of Escherichia coli periplasmic cyclophilin.  

PubMed

The solution structure of the periplasmic cyclophilin type cis-trans peptidyl-prolyl isomerase from Escherichia coli (167 residues, MW > 18.200) has been determined using multidimensional heteronuclear NMR spectroscopy and distance geometry calculations. The structure determination is based on a total of 1720 NMR-derived restraints (1566 distance and 101 phi and 53 chi 1 torsion angle restraints). Twelve distance geometry structures were calculated, and the average root-mean-square (rms) deviation about the mean backbone coordinate positions is 0.84 +/- 0.18 A for the backbone atoms of residues 5-165 of the ensemble. The three-dimensional structure of E. coli cyclophilin consists of an eight-stranded antiparallel beta-sheet barrel capped by alpha-helices. The average coordinates of the backbone atoms of the core residues of E. coli cyclophilin have an rms deviation of 1.44 A, with conserved regions in the crystal structure of unligated human T cell cyclophilin [Ke, H. (1992) J. Mol. Biol. 228, 539-550]. Four regions proximal to the active site differ substantially and may determine protein substrate specificity, sensitivity to cyclosporin A, and the composite drug:protein surface required to inhibit calcineurin. A residue essential for isomerase activity in human T cell cyclophilin (His126) is replaced by Tyr122 in E. coli cyclophilin without affecting enzymatic activity. PMID:8130188

Clubb, R T; Ferguson, S B; Walsh, C T; Wagner, G

1994-03-15

233

Structural analysis of full-length Hfq from Escherichia coli  

PubMed Central

The structure of full-length host factor Q? (Hfq) from Escherichia coli obtained from a crystal belonging to space group P1, with unit-cell parameters a = 61.91, b = 62.15, c = 81.26?Å, ? = 78.6, ? = 86.2, ? = 59.9°, was solved by molecular replacement to a resolution of 2.85?Å and refined to R work and R free values of 20.7% and 25.0%, respectively. Hfq from E. coli has previously been crystallized and the structure has been solved for the N-terminal 72 amino acids, which cover ?65% of the full-length sequence. Here, the purification, crystallization and structural data of the full 102-amino-acid protein are presented. These data revealed that the presence of the C-terminus changes the crystal packing of E. coli Hfq. The crystal structure is discussed in the context of the recently published solution structure of Hfq from E. coli. PMID:21543856

Beich-Frandsen, Mads; Ve?erek, Branislav; Sjöblom, Björn; Bläsi, Udo; Djinovi?-Carugo, Kristina

2011-01-01

234

A second prepilin peptidase gene in Escherichia coli K-12.  

PubMed

Escherichia coli K-12 strains grown at 37 degrees C or 42 degrees C, but not at 30 degrees C, process the precursors of the Neisseria gonorrhoeae type IV pilin PilE and the Klebsiella oxytoca type IV pseudopilin PulG in a manner reminiscent of the prepilin peptidase-dependent processing of these proteins that occurs in these bacteria. Processing of prePulG in Escherichia coli requires a glycine at position -1, as does processing by the cognate prepilin peptidase (PulO), and is unaffected by mutations that inactivate several non-specific proteases. These data suggested that E. coli K-12 has a functional prepilin peptidase, despite the fact that it does not itself appear to express either type IV pilin or pseudopilin genes under the conditions that allow prePilE and prePulG processing. The E. coli K-12 genome contains two genes encoding proteins with significant sequence similarity to prepilin peptidases: gspO at minute 74.5 and pppA (f310c) at minute 67 on the genetic map. We have previously obtained evidence that gspO encodes an active enzyme but is not transcribed. pppA was cloned and shown to code for a functional prepilin peptidase capable of processing typical prepilin peptidase substrates. Inactivation of pppA eliminated the endogenous, thermoinducible prepilin peptidase activity. PppA was able to replace PulO prepilin peptidase in a pullulanase secretion system reconstituted in E. coli when expressed from high-copy-number plasmids but not when present in a single chromosomal copy. The analysis of pppA-lacZ fusions indicated that pppA expression was very low and regulated by the growth temperature at the level of translation, in agreement with the observed temperature dependence of PppA activity. Polymerase chain reaction and Southern hybridization analyses revealed the presence of the pppA gene in 12 out of 15 E. coli isolates. PMID:9515702

Franceti?, O; Lory, S; Pugsley, A P

1998-02-01

235

Characterization of recombinant human chymase expressed in Escherichia coli.  

PubMed

We compared recombinant human chymase expressed in Escherichia coli with human chymase purified from vascular tissues. The recombinant chymase, the structure of which was NH2-enterokinase cleavage site-chymase-COOH, was expressed in Escherichia coli and then was solubilized and renatured. The protein did not have a chymase activity, but gained this activity after the cleavage of the N-terminal site by enterokinase. The enzyme was purified by heparin affinity and gel filtration columns. The N-terminal sequence of the protein was identical to the sequence for human chymase. The molecular weights of the recombinant chymase and chymase purified from human vascular tissues were 26 and 30 kDa, respectively, and the 4 kDa difference was thought to be due to the presence or absence of glycan. The optimum pH of the recombinant enzyme activity was between 7.5 and 9.0. The activity of the recombinant enzyme was inhibited by chymostatin, soybean trypsin inhibitor and phenylmethylsulfonyl fluoride, but not by ethylenediaminetetraacetic acid and aprotinin. This enzyme cleaved specifically the Phe8-His9 bond of angiotensin (Ang) I to form Ang II and that of big endothelin (ET)-1 to form ET-1-(1-31). These findings demonstrated that the enzymatic characteristics of the recombinant enzyme were identical to that of native human chymase. PMID:10877533

Takai, S; Sumi, S; Aoike, M; Sakaguchi, M; Itoh, Y; Jin, D; Matsumura, E; Miyazaki, M

2000-02-01

236

Characterization of Escherichia coli serotype O157:H7.  

PubMed

A total of 174 strains of Escherichia coli serotype O157:H7 representing human isolates obtained from outbreaks and sporadic cases of hemorrhagic colitis, hemolytic-uremic syndrome, and nonbloody diarrheal illnesses as well as from asymptomatic carriers across Canada and the United States were examined. E. coli serotype O157:H7 possessed distinct biochemical markers, a 100% negative reaction for beta-glucuronidase and sorbitol, and a 100% positive reaction for raffinose and dulcitol; all strains otherwise were biochemically typical of E. coli. The vast majority (97%) of the strains were susceptible to commonly used antimicrobial agents. All strains produced readily detectable levels of Verotoxin; however, with polymyxin extraction, nearly 50% of the strains showed up to a 10-fold increase in the toxin level. None were found to mediate hemagglutination of human group A erythrocytes with or without D-mannose. The majority (approximately 70%) of the strains showed localized and diffuse adherence to HEp-2 cells and Henle 407 cells, and the adherence patterns were not very different from those observed among other E. coli strains. Twenty phage types were recognized, with phage types 1 and 2 accounting for 65% of the test strains. Plasmid analysis indicated three basic plasmid profiles: profile I was characterized by 68.7- and 4.2-megadalton (MDa) plasmids (62% of strains), profile II was characterized by 66.2- and 1.8-MDa plasmids (20% of strains), and profile III was characterized by a 62.5-MDa plasmid (18% of strains). A small number (19%) of the strains carried at least one additional plasmid over the basic complements, and these could be considered to constitute a miscellaneous category. None of the above-described characteristics of E. coli serotype O157:H7 could be directly correlated with one another, with the nature of infection, or with the geographical distribution of strains. PMID:3053758

Ratnam, S; March, S B; Ahmed, R; Bezanson, G S; Kasatiya, S

1988-10-01

237

Phenotypic and genotypic properties of Escherichia coli isolated from colisepticemic cases of Japanese quail  

Microsoft Academic Search

This study was conducted to characterize the Escherichia coli isolates from colisepticemic Japanese quails. One hundred and nine E. coli were isolated in pure culture from heart blood of dead Japanese quails. The sampled birds were originated from four different\\u000a farms. Antibiotic resistance pattern of E. coli isolates were determined against nine antibacterial agents. Phylotype and virulence genes of the

Mahmood Salehi; Reza Ghanbarpour

2010-01-01

238

Mouse in vivo neutralization of Escherichia coli Shiga toxin 2 with monoclonal antibodies  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli (E. coli) food contaminations pose serious health and food safety concerns, and have been the subject of massive food recalls. Shiga toxin 2 (Stx2)-producing E. coli has been identified as the major cause of hemorrhagic colitis and hemolytic uremic syndrome (HUS), the most severe di...

239

Localization of protein aggregation in Escherichia coli is governed by diffusion and nucleoid macromolecular crowding effect  

E-print Network

1 Localization of protein aggregation in Escherichia coli is governed by diffusion and nucleoid. coli is purely diffusive (Brownian). Using single-particle tracking of protein aggregates in live E. coli cells, we estimated the average size and diffusion constant of the aggregates. Our results

Paris-Sud XI, Université de

240

A homolog of an Escherichia coli phosphate-binding protein gene from Xanthomonas oryzae pv. oryzae  

NASA Technical Reports Server (NTRS)

A Xanthomonas oryzae pv. oryzae gene with sequence similarity to an Escherichia coli phosphate-binding protein gene (phoS) produces a periplasmic protein of apparent M(r) 35,000 when expressed in E. coli. Amino terminal sequencing revealed that a signal peptide is removed during transport to the periplasm in E. coli.

Hopkins, C. M.; White, F. F.; Heaton, L. A.; Guikema, J. A.; Leach, J. E.; Spooner, B. S. (Principal Investigator)

1995-01-01

241

Finished Genome Sequence of Escherichia coli K-12 Strain HMS174 (ATCC 47011)  

PubMed Central

Escherichia coli strain K-12 substrain HMS174 is an engineered descendant of the E. coli K-12 wild-type strain. Like its ancestor, it is an important organism in biotechnological research and is used in fermentation processes for heterologous protein production. Here, we report the complete genome sequence of E. coli HMS174 (ATCC 47011). PMID:25414489

Mairhofer, Juergen; Krempl, Peter M.; Thallinger, Gerhard G.

2014-01-01

242

ON-CHIP PARALLEL DETECTION OF SHIGA TOXIN PRODUCING ESCHERICHIA COLI USING  

E-print Network

ON-CHIP PARALLEL DETECTION OF SHIGA TOXIN PRODUCING ESCHERICHIA COLI USING LOOP-MEDIATED ISOTHERMAL AMPLIFICATION Carlos Duarte Guevara, Rashid Bashir Shiga toxin-producing Escheria coli (STEC) strains amplification based detection of E.coli using a system that creates a nano-droplet array and then amplify target

Bashir, Rashid

243

SENSITIVE DETECTION OF ESCHERICHIA COLI 0157:H7 BY THE USE OF IMMUNOMAGNETIC AND FLUORESCENT BEADS  

Technology Transfer Automated Retrieval System (TEKTRAN)

To meet the needs of food safety, a rapid and sensitive fluorescent sandwich method for the detection of Escherichia coli O157:H7 in ground beef was developed. Immunomagnetic beads (IMBs) coated with anti-E. coli O157:H7 antibodies were used to capture and concentrate E. coli O157:H7 present in gro...

244

Diet, Escherichia coli 0157:H7, and cattle, a review after 10 years  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli are commensal bacteria that can account for up to 1% of the bacterial population of the gut. Ruminant animals are reservoirs of the pathogenic bacteria E. coli strain O157:H7 and approximately 30% of feedlot cattle shed E. coli O157:H7. Feedlot and high-producing dairy cattle are ...

245

Recombinant expression of bioactive peptide lunasin in Escherichia coli.  

PubMed

Lunasin, a cancer-preventive peptide, was isolated from soybean, barley, and wheat. Previous studies showed that this 43-amino acid peptide has the ability to suppress chemical carcinogen-induced transformation in mammalian cells and skin carcinogenesis in mice. In this study, we attempted to use the Escherichia coli T7 expression system for expression of lunasin. The lunasin gene was synthesized by overlapping extension polymerase chain reaction and expressed in E. coli BL21(DE3) with the use of vector pET29a. The recombinant lunasin containing his-tag at the C-terminus was expressed in soluble form which could be purified by immobilized metal affinity chromatography. After 4 h, the expression level is above 4.73 mg of recombinant his-tagged lunasin/L of Luria-Bertani broth. It does not affect the bacterial growth and expression levels. This is the first study that successfully uses E. coli as a host to produce valuable bioactive lunasin. The result of in vitro bioassay showed that the purified recombinant lunasin can inhibit histone acetylation. Recombinant lunasin also inhibits the release of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, and nitric oxide production). Compared with other research methods on extraction or chemical synthesis to produce lunasin, our method is very efficient in saving time and cost. In the future, it could be applied in medicine and structure-function determination. PMID:20625716

Liu, Chin-Feng; Pan, Tzu-Ming

2010-09-01

246

The binary protein-protein interaction landscape of Escherichia coli.  

PubMed

Efforts to map the Escherichia coli interactome have identified several hundred macromolecular complexes, but direct binary protein-protein interactions (PPIs) have not been surveyed on a large scale. Here we performed yeast two-hybrid screens of 3,305 baits against 3,606 preys (?70% of the E. coli proteome) in duplicate to generate a map of 2,234 interactions, which approximately doubles the number of known binary PPIs in E. coli. Integration of binary PPI and genetic-interaction data revealed functional dependencies among components involved in cellular processes, including envelope integrity, flagellum assembly and protein quality control. Many of the binary interactions that we could map in multiprotein complexes were informative regarding internal topology of complexes and indicated that interactions in complexes are substantially more conserved than those interactions connecting different complexes. This resource will be useful for inferring bacterial gene function and provides a draft reference of the basic physical wiring network of this evolutionarily important model microbe. PMID:24561554

Rajagopala, Seesandra V; Sikorski, Patricia; Kumar, Ashwani; Mosca, Roberto; Vlasblom, James; Arnold, Roland; Franca-Koh, Jonathan; Pakala, Suman B; Phanse, Sadhna; Ceol, Arnaud; Häuser, Roman; Siszler, Gabriella; Wuchty, Stefan; Emili, Andrew; Babu, Mohan; Aloy, Patrick; Pieper, Rembert; Uetz, Peter

2014-03-01

247

Engineered biosynthesis of medium-chain esters in Escherichia coli.  

PubMed

Medium-chain esters such as isobutyl acetate (IBAc) and isoamyl acetate (IAAc) are high-volume solvents, flavors and fragrances. In this work, we engineered synthetic metabolic pathways in Escherichia coli for the total biosynthesis of IBAc and IAAc directly from glucose. Our pathways harnessed the power of natural amino acid biosynthesis. In particular, the native valine and leucine pathways in E. coli were utilized to supply the precursors. Then alcohol acyltransferases from various organisms were investigated on their capability to catalyze esterification reactions. It was discovered that ATF1 from Saccharomyces cerevisiae was the best enzyme for the formation of both IBAc and IAAc in E. coli. In vitro biochemical characterization of ATF1 confirmed the fermentation results and provided rational guidance for future enzyme engineering. We also performed strain improvement by removing byproduct pathways (?ldh, ?poxB, ?pta) and increased the production of both target chemicals. Then the best IBAc producing strain was used for scale-up fermentation in a 1.3-L benchtop bioreactor. 36g/L of IBAc was produced after 72h fermentation. This work demonstrates the feasibility of total biosynthesis of medium-chain esters as renewable chemicals. PMID:25447641

Tai, Yi-Shu; Xiong, Mingyong; Zhang, Kechun

2015-01-01

248

Characterization of Pyruvate Uptake in Escherichia coli K-12  

PubMed Central

The monocarboxylate pyruvate is an important metabolite and can serve as sole carbon source for Escherichia coli. Although specific pyruvate transporters have been identified in two bacterial species, pyruvate transport is not well understood in E. coli. In the present study, pyruvate transport was investigated under different growth conditions. The transport of pyruvate shows specific activities depending on the growth substrate used as sole carbon source, suggesting the existence of at least two systems for pyruvate uptake: i) one inducible system and probably highly specific for pyruvate and ii) one system active under non-induced conditions. Using the toxic pyruvate analog 3-fluoropyruvate, a mutant was isolated unable to grow on and transport pyruvate. Further investigation revealed that a revertant selected for growth on pyruvate regained the inducible pyruvate transport activity. Characterization of pyruvate excretion showed that the pyruvate transport negative mutant accumulated pyruvate in the growth medium suggesting an additional transport system for pyruvate excretion. The here presented data give valuable insight into the pyruvate metabolism and transport of E. coli suggesting the presence of at least two uptake systems and one excretion system to balance the intracellular level of pyruvate. PMID:23818977

Kreth, Jens; Lengeler, Joseph W.; Jahreis, Knut

2013-01-01

249

Fluorine-19 nuclear magnetic resonance studies of Escherichia coli membranes.  

PubMed Central

Several fluorinated fatty acids of the general structure CH3(CH2)13--mCF2(CH2)m--2COOH are incorporated biosynthetically as unsaturated fatty acid analogues into the phospholipids of Escherichia coli. Under optimum conditions an unsaturated fatty acid autotroph, K1060B5, can be grown so that 50% of the total phospholipid fatty acids are 8,8-difluoromyristate. Conditions are found for which more than 20% of the fatty acids are fluorinated before a decrease in growth rate is observed. We have used 19F nuclear magnetic resonance to examine membranes isolated from E. coli grown under the latter conditions. A comparison is made with spectra of aqueous dispersions of extracted E. coli phospholipids and model multilayer phospholipid membranes. An explanation of the 19F resonance line shape in these membrane systems and the relationship to a molecular order parameter is given. It is apparent that 19F nuclear magnetic resonance is more sensitive to the degree of ordering or fluidity of phospholipids than spin labels or fluorescent probes. For instance, a dramatic effect of membrane protein on lipid fluidity can be seen. Finally, this method can be used to measure the proportion of frozen and fluid lipid in biological membranes at temperatures within the span of the gel-to-lipid phase transition. PMID:345274

Gent, M P; Cottam, P F; Ho, C

1978-01-01

250

Fitness, Stress Resistance, and Extraintestinal Virulence in Escherichia coli  

PubMed Central

The extraintestinal virulence of Escherichia coli is dependent on numerous virulence genes. However, there is growing evidence for a role of the metabolic properties and stress responses of strains in pathogenesis. We assessed the respective roles of these factors in strain virulence by developing phenotypic assays for measuring in vitro individual and competitive fitness and the general stress response, which we applied to 82 commensal and extraintestinal pathogenic E. coli strains previously tested in a mouse model of sepsis. Individual fitness properties, in terms of maximum growth rates in various media (Luria-Bertani broth with and without iron chelator, minimal medium supplemented with gluconate, and human urine) and competitive fitness properties, estimated as the mean relative growth rate per generation in mixed cultures with a reference fluorescent E. coli strain, were highly diverse between strains. The activity of the main general stress response regulator, RpoS, as determined by iodine staining of the colonies, H2O2 resistance, and rpoS sequencing, was also highly variable. No correlation between strain fitness and stress resistance and virulence in the mouse model was found, except that the maximum growth rate in urine was higher for virulent strains. Multivariate analysis showed that the number of virulence factors was the only independent factor explaining the virulence in mice. At the species level, growth capacity and stress resistance are heterogeneous properties that do not contribute significantly to the intrinsic virulence of the strains. PMID:23690401

Bleibtreu, Alexandre; Gros, Pierre-Alexis; Laouénan, Cédric; Clermont, Olivier; Le Nagard, Hervé; Picard, Bertrand; Tenaillon, Olivier

2013-01-01

251

Binding of type 1-piliated Escherichia coli to vaginal mucus.  

PubMed Central

To better understand the interactions involved in bacterial adherence and the role of mucus in the pathogenesis of urinary tract infections, we developed a system to study the binding of a recombinant Escherichia coli strain, HB101/pWRS1-17, expressing type 1 pili, to vaginal mucus collected from 28 women. Bacteria bound to differing extents to all specimens examined, and preincubation of bacteria with mannose inhibited binding by 50 to 89%. Additionally, all mucus samples showed reactivity with anti-mannose antibody, and the levels of reactivity correlated with the levels of bacterial binding, suggesting that the mannose-terminal saccharides present on these glycoproteins are the receptors for the binding of type 1-piliated bacteria. Mucus specimens collected over periods of 5 days and 12 weeks exhibited significant variation in bacterial binding, indicating temporal differences in the ability of vaginal mucus to act as a receptor for type 1-piliated E. coli. The results show that vaginal mucus can bind bacteria and may thus influence the initial attachment and subsequent colonization of the vaginal and urinary tract epithelium by E. coli. PMID:7822005

Venegas, M F; Navas, E L; Gaffney, R A; Duncan, J L; Anderson, B E; Schaeffer, A J

1995-01-01

252

Colibri: a functional data base for the Escherichia coli genome.  

PubMed Central

Several data libraries have been created to organize all the data obtained worldwide about the Escherichia coli genome. Because the known data now amount to more than 40% of the whole genome sequence, it has become necessary to organize the data in such a way that appropriate procedures can associate knowledge produced by experiments about each gene to its position on the chromosome and its relation to other relevant genes, for example. In addition, global properties of genes, affected by the introduction of new entries, should be present as appropriate description fields. A data base, implemented on Macintosh by using the data base management system 4th Dimension, is described. It is constructed around a core constituted by known contigs of E. coli sequences and links data collected in general libraries (unmodified) to data associated with evolving knowledge (with modifiable fields). Biologically significant results obtained through the coupling of appropriate procedures (learning or statistical data analysis) are presented. The data base is available through a 4th Dimension runtime and through FTP on Internet. It has been regularly updated and will be systematically linked to other E. coli data bases (M. Kroger, R. Wahl, G. Schachtel, and P. Rice, Nucleic Acids Res. 20(Suppl.):2119-2144, 1992; K. E. Rudd, W. Miller, C. Werner, J. Ostell, C. Tolstoshev, and S. G. Satterfield, Nucleic Acids Res. 19:637-647, 1991) in the near future. Images PMID:8246843

Médigue, C; Viari, A; Hénaut, A; Danchin, A

1993-01-01

253

Biofilm and fluoroquinolone resistance of canine Escherichia coli uropathogenic isolates  

PubMed Central

Background Escherichia coli is the most common uropathogen involved in urinary tract infection (UTI). Virulence of strains may differ, and may be enhanced by antimicrobial resistance and biofilm formation, resulting in increased morbidity and recurrent infections. The aim of this study was to evaluate the in vitro biofilm forming capacity of E. coli isolates from dogs with UTI, by using fluorescent in situ hybridization, and its association with virulence genes and antimicrobial resistance. Findings The proportion of biofilm-producing isolates significantly increased with the length of incubation time (P??0.05), but was significantly associated with afa, aer and the ?-lactamase genes (P?coli isolates from dogs with UTI. Biofilm formation may contribute to UTI treatment failure in dogs, through the development of bacterial reservoirs inside bladder cells, allowing them to overcome host immune defenses and to establish recurrent infections. PMID:25099929

2014-01-01

254

Characterization of the YdeO Regulon in Escherichia coli  

PubMed Central

Enterobacteria are able to survive under stressful conditions within animals, such as acidic conditions in the stomach, bile salts during transfer to the intestine and anaerobic conditions within the intestine. The glutamate-dependent (GAD) system plays a major role in acid resistance in Escherichia coli, and expression of the GAD system is controlled by the regulatory cascade consisting of EvgAS > YdeO > GadE. To understand the YdeO regulon in vivo, we used ChIP-chip to interrogate the E. coli genome for candidate YdeO binding sites. All of the seven operons identified by ChIP-chip as being potentially regulated by YdeO were confirmed as being under the direct control of YdeO using RT-qPCR, EMSA, DNaseI-footprinting and reporter assays. Within this YdeO regulon, we identified four stress-response transcription factors, DctR, NhaR, GadE, and GadW and enzymes for anaerobic respiration. Both GadE and GadW are involved in regulation of the GAD system and NhaR is an activator for the sodium/proton antiporter gene. In conjunction with co-transcribed Slp, DctR is involved in protection against metabolic endoproducts under acidic conditions. Taken all together, we suggest that YdeO is a key regulator of E. coli survival in both acidic and anaerobic conditions. PMID:25375160

Yamanaka, Yuki; Oshima, Taku; Ishihama, Akira; Yamamoto, Kaneyoshi

2014-01-01

255

Potential production platform of n-butanol in Escherichia coli.  

PubMed

We proposed a potential production platform of n-butanol in Escherichia coli. First, a butyrate-conversion strain was developed by removal of undesired genes and recruiting endogenous atoDA and Clostridium adhE2. Consequently, this E. coli strain grown on the M9 mineral salt with yeast extract (M9Y) was shown to produce 6.2g/L n-butanol from supplemented butyrate at 36h. The molar conversion yield of n-butanol on butyrate reaches 92%. Moreover, the production platform was advanced by additional inclusion of a butyrate-producing strain. This strain was equipped with a pathway comprising atoDA and heterologous genes for the synthesis of butyrate. Without butyrate, the butyrate-conversion and the butyrate-producing strains were co-cultured in M9Y medium and produced 5.5g/L n-butanol from glucose at 24h. The production yield on glucose accounts for 69% of the theoretical yield. Overall, it indicates a promise of the developed platform for n-butanol production in E. coli. PMID:25461833

Saini, Mukesh; Hong Chen, Min; Chiang, Chung-Jen; Chao, Yun-Peng

2015-01-01

256

Identification of Diarrheagenic Escherichia coli Strains from Avian Organic Fertilizers  

PubMed Central

The Brazilian poultry industry generates large amounts of organic waste, such as chicken litter, which is often used in agriculture. Among the bacteria present in organic fertilizer are members of the Enterobacteriaceae family. The objective of this study was to detect the presence of diarrheagenic Escherichia coli (DEC) strains in avian organic fertilizer, and assess the potential damage they can cause in humans due to antimicrobial resistance. The presence of DEC pathotypes and phylogenetic groups were detected by multiplex-PCR. Phenotypic assays, such as tests for adhesion, cytotoxicity activity, biofilm formation and especially antimicrobial susceptibility, were performed. Fifteen DEC strains from 64 E. coli were isolated. Among these, four strains were classified as enteropathogenic (EPEC; 6.2%), three strains as Shiga toxin-producing (STEC; 4.7%), 10 strains as enteroaggregative (EAEC; 12.5%), but two of these harbored the eaeA gene too. The low number of isolated strains was most likely due to the composting process, which reduces the number of microorganisms. These strains were able to adhere to HEp-2 and HeLa cells and produce Shiga-toxins and biofilms; in addition, some of the strains showed antimicrobial resistance, which indicates a risk of the transfer of resistance genes to human E. coli. These results showed that DEC strains isolated from avian organic fertilizers can cause human infections. PMID:25170683

Puño-Sarmiento, Juan; Gazal, Luis Eduardo; Medeiros, Leonardo P.; Nishio, Erick K.; Kobayashi, Renata K. T.; Nakazato, Gerson

2014-01-01

257

Comprehensive Mapping of the Escherichia coli Flagellar Regulatory Network  

PubMed Central

Flagellar synthesis is a highly regulated process in all motile bacteria. In Escherichia coli and related species, the transcription factor FlhDC is the master regulator of a multi-tiered transcription network. FlhDC activates transcription of a number of genes, including some flagellar genes and the gene encoding the alternative Sigma factor FliA. Genes whose expression is required late in flagellar assembly are primarily transcribed by FliA, imparting temporal regulation of transcription and coupling expression to flagellar assembly. In this study, we use ChIP-seq and RNA-seq to comprehensively map the E. coli FlhDC and FliA regulons. We define a surprisingly restricted FlhDC regulon, including two novel regulated targets and two binding sites not associated with detectable regulation of surrounding genes. In contrast, we greatly expand the known FliA regulon. Surprisingly, 30 of the 52 FliA binding sites are located inside genes. Two of these intragenic promoters are associated with detectable noncoding RNAs, while the others either produce highly unstable RNAs or are inactive under these conditions. Together, our data redefine the E. coli flagellar regulatory network, and provide new insight into the temporal orchestration of gene expression that coordinates the flagellar assembly process. PMID:25275371

Fitzgerald, Devon M.; Bonocora, Richard P.; Wade, Joseph T.

2014-01-01

258

Virulence genes of Escherichia coli strains isolated from mastitic milk.  

PubMed

Escherichia coli, a Gram-negative environmental pathogen associated with bovine mastitis was isolated from the milk of 34 symptomatic cows that had been diagnosed with clinical mastitis. Eighty isolates were obtained over a 17-month period and these isolates were screened by DNA amplification for the following E. coli virulence genes: cnf1, cnf2, eaeA, eagg, einv, ltx1, stx1, stx2 and vt2e. Thirty of the bacterial isolates, obtained from 23 different cows, had toxin genes identified in their DNA. The most common virulence gene detected was stx1, with a prevalence of 31%, followed by cnf2 (7.5%), vt2e (6.25%) and eaeA (4%). The possession of different virulence genes by the bacterial isolates had no discernable impact on the health status of the cows as there was no correlation between the potential for toxin production by the E. coli isolates and the systemic clinical condition of the respective infected cows. PMID:15458491

Bean, A; Williamson, J; Cursons, R T

2004-08-01

259

Epithelial cell invasion by bovine septicemic Escherichia coli.  

PubMed Central

Little is known regarding the pathogenesis of Escherichia coli-induced septicemic colibacillosis of calves. To understand the mechanism by which these strains penetrate the intestinal epithelium and gain access to the bloodstream, we examined the potential of bovine septicemic E. coli to invade cultured epithelial cells. By using a gentamicin survival assay, we demonstrated bacterial invasion of Madin-Darby canine kidney (MDCK) cells. Transcytosis of polarized MDCK cell monolayers was also observed, but only when bacteria were added to the basolateral surface. Electron microscopy confirmed the presence of intracellular organisms which appeared to be within membrane-bound vacuoles. The bovine septicemic isolate used in this study expressed the fimbrial adhesion CS31A. To examine the role of CS31A-mediated adherence in invasion and transcytosis of MDCK cell monolayers, a CS31A-deficient mutant was constructed by suicide vector-mediated insertional mutagenesis. Although nonadherent, the mutant showed a level of invasion similar to that of the wild-type parent. E. coli DH5 alpha carrying the cloned CS31A determinant was noninvasive. These findings suggest that expression of CS31A is neither required nor sufficient to mediate invasion. Images PMID:7903284

Korth, M J; Lara, J C; Moseley, S L

1994-01-01

260

Rapid microarray-based DNA genoserotyping of Escherichia coli.  

PubMed

In this study, an improvement in the oligonucleotide-based DNA microarray for the genoserotyping of Escherichia coli is presented. Primer and probes for additional 70 O antigen groups were developed. The microarray was transferred to a new platform, the ArrayStrip format, which allows high through-put tests in 96-well formats and fully automated microarray analysis. Thus, starting from a single colony, it is possible to determine within a few hours and a single experiment, 94 of the over 180 known O antigen groups as well as 47 of the 53 different H antigens. The microarray was initially validated with a set of defined reference strains that had previously been serotyped by conventional agglutination in various reference centers. For further validation of the microarray, 180 clinical E. coli isolates of human origin (from urine samples, blood cultures, bronchial secretions, and wound swabs) and 53 E. coli isolates from cattle, pigs, and poultry were used. A high degree of concordance between the results of classical antibody-based serotyping and DNA-based genoserotyping was demonstrated during validation of the new 70 O antigen groups as well as for the field strains of human and animal origin. Therefore, this oligonucleotide array is a diagnostic tool that is user-friendly and more efficient than classical serotyping by agglutination. Furthermore, the tests can be performed in almost every routine lab and are easily expanded and standardized. PMID:24298918

Geue, Lutz; Monecke, Stefan; Engelmann, Ines; Braun, Sascha; Slickers, Peter; Ehricht, Ralf

2014-02-01

261

Regulation of neutrophil phagocytosis of Escherichia coli by antipsychotic drugs.  

PubMed

Antipsychotic drugs (APDs) have been used to ease the symptoms of schizophrenia. APDs have recently been reported to regulate the immune response. Our previous studies revealed that the atypical APDs risperidone and clozapine and the typical APD haloperidol can inhibit the phagocytic ability of macrophages. Our research next determined the effects of APDs on the phagocytic ability of neutrophils, which are the most abundant type of white blood cells in mammals. Here we provide evidence that clozapine and haloperidol can induce increased phagocytic uptake of Escherichia coli by differentiated HL-60 cells and by purified human neutrophils. Furthermore, clozapine and haloperidol can increase the myeloperoxidase activity and IL-8 production in neutrophils. Our results also show that clozapine can inhibit E. coli survival within differentiated HL-60 cells. Furthermore, clozapine and haloperidol are shown to enhance cell surface Mac-1 expression and the activated AKT signaling pathway in purified neutrophils exposed to E. coli. These results indicate that clozapine and haloperidol can increase the phagocytic ability of neutrophils by increasing AKT activation when cells are exposed to bacteria. PMID:25448498

Chen, Mao-Liang; Wu, Semon; Tsai, Tzung-Chieh; Wang, Lu-Kai; Tsai, Fu-Ming

2014-12-01

262

Opposite effects of cefoperazone and ceftazidime on S-ribosylhomocysteine lyase/autoinducer-2 quorum sensing and biofilm formation by an Escherichia coli clinical isolate  

PubMed Central

To investigate the effects of subminimum inhibitory concentrations of cephalosporins on bacterial biofilm formation, the biofilm production of 52 Escherichia (E.) coli strains was examined following treatment with cephalosporin compounds at 1/4 minimum inhibitory concentrations (MICs). Ceftazidime (CAZ) inhibited biofilm formation in seven isolates, while cefoperazone (CFP) enhanced biofilm formation in 18 isolates. Biofilm formation of E. coli E42 was inhibited by CAZ and induced by CFP. Therefore, using reverse transcription-polymerase chain reaction, the expression of the biofilm-modulating genes of this isolate was investigated. To monitor the production of the autoinducer of quorum sensing in E. coli, autoinducer-2 (AI-2) production was detected by measuring the bioluminescence response of Vibrio harveyi BB170. Antisense oligonucleotides (AS-ODNs) targeting S-ribosylhomocysteine lyase (luxS) inhibited the expression of the luxS gene in E. coli. CAZ at 1/4 MIC reduced luxS mRNA levels and the production of AI-2, whereas CFP at 1/4 MIC had the opposite effect. AS-ODNs targeting luxS significantly decreased the aforementioned inhibitory effects of CAZ and the induction effects of CFP on E. coli biofilm formation. Therefore, biofilm formation by the E. coli clinical isolate E42 was evoked by CFP but attenuated by CAZ at sub-MICs, via a luxS/AI-2-based quorum sensing system. PMID:25189202

SHI, HUI-QING; SUN, FENG-JUN; CHEN, JIAN-HONG; YONG, XIAO-LAN; OU, QIAN-YI; FENG, WEI; XIA, PEI-YUAN

2014-01-01

263

Opposite effects of cefoperazone and ceftazidime on S?ribosylhomocysteine lyase/autoinducer-2 quorum sensing and biofilm formation by an Escherichia coli clinical isolate.  

PubMed

To investigate the effects of subminimum inhibitory concentrations of cephalosporins on bacterial biofilm formation, the biofilm production of 52 Escherichia (E.) coli strains was examined following treatment with cephalosporin compounds at 1/4 minimum inhibitory concentrations (MICs). Ceftazidime (CAZ) inhibited biofilm formation in seven isolates, while cefoperazone (CFP) enhanced biofilm formation in 18 isolates. Biofilm formation of E. coli E42 was inhibited by CAZ and induced by CFP. Therefore, using reverse transcription?polymerase chain reaction, the expression of the biofilm?modulating genes of this isolate was investigated. To monitor the production of the autoinducer of quorum sensing in E. coli, autoinducer?2 (AI?2) production was detected by measuring the bioluminescence response of Vibrio harveyi BB170. Antisense oligonucleotides (AS?ODNs) targeting S?ribosylhomocysteine lyase (luxS) inhibited the expression of the luxS gene in E. coli. CAZ at 1/4 MIC reduced luxS mRNA levels and the production of AI?2, whereas CFP at 1/4 MIC had the opposite effect. AS?ODNs targeting luxS significantly decreased the aforementioned inhibitory effects of CAZ and the induction effects of CFP on E. coli biofilm formation. Therefore, biofilm formation by the E. coli clinical isolate E42 was evoked by CFP but attenuated by CAZ at sub?MICs, via a luxS/AI?2?based quorum sensing system. PMID:25189202

Shi, Hui-Qing; Sun, Feng-Jun; Chen, Jian-Hong; Yong, Xiao-Lan; Ou, Qian-Yi; Feng, Wei; Xia, Pei-Yuan

2014-11-01

264

Some evidences on the mode of action of Cinnamomum verum bark essential oil, alone and in combination with piperacillin against a multi-drug resistant Escherichia coli strain.  

PubMed

The purpose of this study was to investigate the mode of action of the cinnamon bark essential oil (CB) when use singly and in combination with piperacillin on its antimicrobial and synergistic activity against plasmid-conferred multi-drug resistant Escherichia coli J53 R1. Viable count of this combination showed a complete killing profile at 20 h and further confirmed its synergistic effect by reducing the bacteria cell numbers. Analysis of the membrane permeabilizing effects of CB on treated cultures through their stability against sodium dodecyl sulfate (SDS) revealed that the essential oils played a role in disrupting the bacterial cell membrane. Scanning electron microscopy analysis and zeta potential measurement also revealed that CB causes irreversible membrane damage and reduces the bacterial surface charge. In addition, reduction in bioluminescence expression of Escherichia coli [pSB1075] and E. coli [pSB401] by CB showed the presence of potential quorum sensing (QS) inhibitors. Gas-chromatography and mass spectrometry (GC-MS) of the essential oil of Cinnamomum verum showed that trans-cinnamaldehyde (72.81%), benzyl alcohol (12.5%) and eugenol (6.57%) were found to be the major components in the essential oil. These findings suggest that CB has the potential to reverse bacteria resistance to piperacillin in E. coli J53 R1 and may operate via two mechanisms: alteration of outer membrane permeability and inhibition of bacterial QS. PMID:25381741

Yap, Polly Soo Xi; Krishnan, Thiba; Chan, Kok-Gan; Lim, Swee Hua Erin

2014-11-10

265

Evolution of Enterohemorrhagic Escherichia coli Hemolysin Plasmids and the Locus for Enterocyte Effacement in Shiga Toxin-Producing E. coli  

Microsoft Academic Search

This study assessed the diversity of the enterohemorrhagic Escherichia coli (EHEC) hemolysin gene (ehxA) in a variety of Shiga toxin-producing E. coli (STEC) serotypes and the relationship between ehxA types and virulence markers on the locus for enterocyte effacement (LEE). Restriction fragment length polymorphism of the ehxA gene and flanking sequences and of the E. coli attaching and effacing (eae)

PATRICK BOERLIN; SHU CHEN; JOHN K. COLBOURNE; ROGER JOHNSON; STEPHANIE DE GRANDIS; CARLTON GYLES

1998-01-01

266

Engineered biosynthesis of bacterial aromatic polyketides in Escherichia coli  

PubMed Central

Bacterial aromatic polyketides are important therapeutic compounds including front line antibiotics and anticancer drugs. It is one of the last remaining major classes of natural products of which the biosynthesis has not been reconstituted in the genetically superior host Escherichia coli. Here, we demonstrate the engineered biosynthesis of bacterial aromatic polyketides in E. coli by using a dissected and reassembled fungal polyketide synthase (PKS). The minimal PKS of the megasynthase PKS4 from Gibberella fujikuroi was extracted by using two approaches. The first approach yielded a stand-alone Ketosynthase (KS)_malonyl-CoA:ACP transferase (MAT) didomain and an acyl-carrier protein (ACP) domain, whereas the second approach yielded a compact PKS (PKS_WJ) that consists of KS, MAT, and ACP on a single polypeptide. Both minimal PKSs produced nonfungal polyketides cyclized via different regioselectivity, whereas the fungal-specific C2-C7 cyclization mode was not observed. The kinetic properties of the two minimal PKSs were characterized to confirm both PKSs can synthesize polyketides with similar efficiency as the parent PKS4 megasynthase. Both minimal PKSs interacted effectively with exogenous polyketide cyclases as demonstrated by the synthesis of predominantly PK8 3 or NonaSEK4 6 in the presence of a C9-C14 or a C7-C12 cyclase, respectively. When PKS_WJ and downstream tailoring enzymes were expressed in E. coli, the expected nonaketide anthraquinone SEK26 was recovered in good titer. High-cell density fermentation was performed to demonstrate the scale-up potential of the in vivo platform for the biosynthesis of bacterial polyketides. Using engineered fungal PKSs can therefore be a general approach toward the heterologous biosynthesis of bacterial aromatic polyketides in E. coli. PMID:19075227

Zhang, Wenjun; Li, Yanran; Tang, Yi

2008-01-01

267

Specific electromagnetic effects of microwave radiation on Escherichia coli.  

PubMed

The present study investigated the effects of microwave (MW) radiation applied under a sublethal temperature on Escherichia coli. The experiments were conducted at a frequency of 18 GHz and at a temperature below 40°C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m(3), and the electric field was determined to be 300 V/m. Both values were theoretically confirmed using CST Microwave Studio 3D Electromagnetic Simulation Software. As a negative control, E. coli cells were also thermally heated to temperatures up to 40°C using Peltier plate heating. Scanning electron microscopy (SEM) analysis performed immediately after MW exposure revealed that the E. coli cells exhibited a cell morphology significantly different from that of the negative controls. This MW effect, however, appeared to be temporary, as following a further 10-min elapsed period, the cell morphology appeared to revert to a state that was identical to that of the untreated controls. Confocal laser scanning microscopy (CLSM) revealed that fluorescein isothiocyanate (FITC)-conjugated dextran (150 kDa) was taken up by the MW-treated cells, suggesting that pores had formed within the cell membrane. Cell viability experiments revealed that the MW treatment was not bactericidal, since 88% of the cells were recovered after radiation. It is proposed that one of the effects of exposing E. coli cells to MW radiation under sublethal temperature conditions is that the cell surface undergoes a modification that is electrokinetic in nature, resulting in a reversible MW-induced poration of the cell membrane. PMID:21378041

Shamis, Yury; Taube, Alex; Mitik-Dineva, Natasa; Croft, Rodney; Crawford, Russell J; Ivanova, Elena P

2011-05-01

268

Azorean wild rabbits as reservoirs of antimicrobial resistant Escherichia coli.  

PubMed

Antibiotic resistance in bacteria is an increasing problem that is not only constrained to the clinical setting but also to other environments that can lodge antibiotic resistant bacteria and therefore they may serve as reservoirs of genetic determinants of antibiotic resistance. One hundred and thirty-six faecal samples from European wild rabbits (Oryctolagus cuniculus algirus) were collected on São Jorge Island in Azores Archipelago, and analysed for Escherichia coli isolates. Seventy-seven isolates (56.6%) were recovered and studied for antimicrobial resistance, one isolate per positive sample. Thirteen (16.9%), 19 (24.7%), 25 (32.4%) and 20 (26%) isolates were ascribed to A, B1, B2 and D phylogenetic groups, respectively, by specific primer polymerase chain reaction. Different E. coli isolates were found to be resistant to ampicillin (16.9%), tetracycline (1.3%), streptomycin (42.9%), sulfamethoxazole-trimethoprim (1.3%), amikacin (1.3%), tobramycin (2.6%) and nalidixic acid (1.3%). Additionally, the blaTEM, tetA, strA/strB, aadA, sul1, intI, intI2 and qacE? + sul1 genes were found in most resistant isolates. This study showed that E. coli from the intestinal tract of wild rabbits from Azores Archipelago are resistant to widely prescribed antibiotics in medicine and they constitute a reservoir of antimicrobial resistant genes, which may play a significant role in the spread of antimicrobial resistance. Therefore, antibiotic resistant E. coli from Azorean wild rabbits may represent an ecological and public health problem. PMID:25246166

Marinho, Catarina; Igrejas, Gilberto; Gonçalves, Alexandre; Silva, Nuno; Santos, Tiago; Monteiro, Ricardo; Gonçalves, David; Rodrigues, Tiago; Poeta, Patrícia

2014-12-01

269

Engineering a homobutanol fermentation pathway in Escherichia coli EG03.  

PubMed

A homobutanol fermentation pathway was engineered in a derivative of Escherichia coli B (glucose [glycolysis] => 2 pyruvate + 2 NADH; pyruvate [pyruvate dehydrogenase] => acetyl-CoA + NADH; 2 acetyl-CoA [butanol pathway enzymes] + 4 NADH => butanol; summary stoichiometry: glucose => butanol). Initially, the native fermentation pathways were eliminated from E. coli B by deleting the genes encoding for lactate dehydrogenase (ldhA), acetate kinase (ackA), fumarate reductase (frdABCD), pyruvate formate lyase (pflB), and alcohol dehydrogenase (adhE), and the pyruvate dehydrogenase complex (aceEF-lpd) was anaerobically expressed through promoter replacement. The resulting strain, E. coli EG03 (?frdABCD ?ldhA ?ackA ?pflB ? adhE ?pdhR ::pflBp6-aceEF-lpd ?mgsA), could generate 4 NADH for every glucose oxidized to two acetyl-CoA through glycolysis and the pyruvate dehydrogenase complex. However, EG03 lost its ability for anaerobic growth due to the lack of NADH oxidation pathways. When the butanol pathway genes that encode for acetyl-CoA acetyltransferase (thiL), 3-hydroxybutyryl-CoA dehydrogenase (hbd), crotonase (crt), butyryl-CoA dehydrogenase (bcd, etfA, etfB), and butyraldehyde dehydrogenase (adheII) were cloned from Clostridium acetobutylicum ATCC 824, and expressed in E. coli EG03, a balanced NADH oxidation pathway was established for homobutanol fermentation (glucose => 4 NADH + 2 acetyl-CoA => butanol). This strain was able to convert glucose to butanol (1,254 mg l(-1)) under anaerobic condition. PMID:22776992

Garza, Erin; Zhao, Jinfang; Wang, Yongze; Wang, Jinhua; Iverson, Andrew; Manow, Ryan; Finan, Chris; Zhou, Shengde

2012-08-01

270

Specific Electromagnetic Effects of Microwave Radiation on Escherichia coli?  

PubMed Central

The present study investigated the effects of microwave (MW) radiation applied under a sublethal temperature on Escherichia coli. The experiments were conducted at a frequency of 18 GHz and at a temperature below 40°C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m3, and the electric field was determined to be 300 V/m. Both values were theoretically confirmed using CST Microwave Studio 3D Electromagnetic Simulation Software. As a negative control, E. coli cells were also thermally heated to temperatures up to 40°C using Peltier plate heating. Scanning electron microscopy (SEM) analysis performed immediately after MW exposure revealed that the E. coli cells exhibited a cell morphology significantly different from that of the negative controls. This MW effect, however, appeared to be temporary, as following a further 10-min elapsed period, the cell morphology appeared to revert to a state that was identical to that of the untreated controls. Confocal laser scanning microscopy (CLSM) revealed that fluorescein isothiocyanate (FITC)-conjugated dextran (150 kDa) was taken up by the MW-treated cells, suggesting that pores had formed within the cell membrane. Cell viability experiments revealed that the MW treatment was not bactericidal, since 88% of the cells were recovered after radiation. It is proposed that one of the effects of exposing E. coli cells to MW radiation under sublethal temperature conditions is that the cell surface undergoes a modification that is electrokinetic in nature, resulting in a reversible MW-induced poration of the cell membrane. PMID:21378041

Shamis, Yury; Taube, Alex; Mitik-Dineva, Natasa; Croft, Rodney; Crawford, Russell J.; Ivanova, Elena P.

2011-01-01

271

Isobutyraldehyde production from Escherichia coli by removing aldehyde reductase activity  

PubMed Central

Background Increasing global demand and reliance on petroleum-derived chemicals will necessitate alternative sources for chemical feedstocks. Currently, 99% of chemical feedstocks are derived from petroleum and natural gas. Renewable methods for producing important chemical feedstocks largely remain unaddressed. Synthetic biology enables the renewable production of various chemicals from microorganisms by constructing unique metabolic pathways. Here, we engineer Escherichia coli for the production of isobutyraldehyde, which can be readily converted to various hydrocarbons currently derived from petroleum such as isobutyric acid, acetal, oxime and imine using existing chemical catalysis. Isobutyraldehyde can be readily stripped from cultures during production, which reduces toxic effects of isobutyraldehyde. Results We adopted the isobutanol pathway previously constructed in E. coli, neglecting the last step in the pathway where isobutyraldehyde is converted to isobutanol. However, this strain still overwhelmingly produced isobutanol (1.5?g/L/OD600 (isobutanol) vs 0.14?g/L/OD600 (isobutyraldehyde)). Next, we deleted yqhD which encodes a broad-substrate range aldehyde reductase known to be active toward isobutyraldehyde. This strain produced isobutanol and isobutyraldehyde at a near 1:1 ratio, indicating further native isobutyraldehyde reductase (IBR) activity in E. coli. To further eliminate isobutanol formation, we set out to identify and remove the remaining IBRs from the E. coli genome. We identified 7 annotated genes coding for IBRs that could be active toward isobutyraldehyde: adhP, eutG, yiaY, yjgB, betA, fucO, eutE. Individual deletions of the genes yielded only marginal improvements. Therefore, we sequentially deleted all seven of the genes and assessed production. The combined deletions greatly increased isobutyraldehyde production (1.5?g/L/OD600) and decreased isobutanol production (0.4?g/L/OD600). By assessing production by overexpression of each candidate IBR, we reveal that AdhP, EutG, YjgB, and FucO are active toward isobutyraldehyde. Finally, we assessed long-term isobutyraldehyde production of our best strain containing a total of 15 gene deletions using a gas stripping system with in situ product removal, resulting in a final titer of 35?g/L after 5?days. Conclusions In this work, we optimized E. coli for the production of the important chemical feedstock isobutyraldehyde by the removal of IBRs. Long-term production yielded industrially relevant titers of isobutyraldehyde with in situ product removal. The mutational load imparted on E. coli in this work demonstrates the versatility of metabolic engineering for strain improvements. PMID:22731523

2012-01-01

272

Clonal relationships among bovine pathogenic Escherichia coli producing surface antigen CS31A.  

PubMed

Forty-two Escherichia coli strains producing surface antigen CS31A isolated from bovine infections were characterized with respect to OKH serotypes, outer membrane protein (OMP) electrophoretic patterns, allozymes for esterases A, B, C, I and biotypes. A large majority of the strains could be clustered in a limited number of groups of clonally related strains with diverse O serogroups. CS31A producing Escherichia coli strains thus appear to have a common genetic background and are representative of an important part of bovine pathogenic Escherichia coli. PMID:8095911

Contrepois, M; Bertin, Y; Girardeau, J P; Picard, B; Goullet, P

1993-01-15

273

An Unusual Case of Early Onset Persistent Escherichia coli Septicemia Associated with Endocarditis  

PubMed Central

Escherichia coli infection is very common cause of early onset septicemia especially in very low-birth-weight newborns, but E. coli endocarditis has not been described in newborns. E. coli endocarditis, even in the adult population, is a rare and not well-characterized disease and is associated with high mortality. We report a very unusual presentation of persistent E. coli infection associated with endocarditis. PMID:24147246

Gupta, Sachin K.; Nanda, Vishakha; Malviya, Prashant; Jacobs, Norman; Naheed, Z.; Joseph, Tessy

2013-01-01

274

Refolding of denatured lactate dehydrogenase by Escherichia coli ribosomes.  

PubMed Central

Escherichia coli ribosomes were used to refold denatured lactate dehydrogenase from porcine muscle. This activity of ribosomes, unlike most of the chaperons, did not require the presence of ATP. The molar concentration of ribosomes required for this refolding was comparable with that of the enzyme. Restoration of the enzyme activity was demonstrated using assays for both the forward and backward reactions. Binding of the denatured enzyme to ribosomes and its refolding were fairly rapid processes as revealed by the time course of the reaction and inhibition of folding when the denatured enzyme was allowed to refold spontaneously for short times before the addition of ribosomes. This protein-folding activity was detected in 70 S ribosomes as well as its RNA, in 50 S particles and in 23 S rRNA. However, 30 S particles failed to refold the enzyme. PMID:8010952

Chattopadhyay, S; Das, B; Bera, A K; Dasgupta, D; Dasgupta, C

1994-01-01

275

Active dimeric form of inorganic pyrophosphatase from Escherichia coli.  

PubMed

A dimeric form can be obtained from native hexameric Escherichia coli inorganic pyrophosphatase (E-PPase) by destroying the hydrophobic intersubunit contacts, and it has been shown earlier to consist of the subunits of different trimers. The present paper is devoted to the kinetic characterization of such a "double-decked" dimer obtained by the dissociation of either the native enzyme or the mutant variant Glu145Gln. The dimeric form of the native inorganic pyrophosphatase was shown to retain high catalytic efficiency that is in sharp contrast to the dimers obtained as a result of the mutations at the intertrimeric interface. The dimeric enzymes described in the present paper, however, have lost the regulatory properties, in contrast to the hexameric and trimeric forms of the enzyme. PMID:14640961

Vainonen, Yu P; Vorobyeva, N N; Kurilova, S A; Nazarova, T I; Rodina, E V; Avaeva, S M

2003-11-01

276

Enterotoxigenic Escherichia coli infection induces intestinal epithelial cell autophagy.  

PubMed

The morbidity and mortality in piglets caused by enterotoxigenic Escherichia coli (ETEC) results in large economic losses to the swine industry, but the precise pathogenesis of ETEC-associated diseases remains unknown. Intestinal epithelial cell autophagy serves as a host defense against pathogens. We found that ETEC induced autophagy, as measured by both the increased punctae distribution of GFP-LC3 and the enhanced conversion of LC3-I to LC3-II. Inhibiting autophagy resulted in decreased survival of IPEC-1 cells infected with ETEC. ETEC triggered autophagy in IPEC-1 cells through a pathway involving the mammalian target of rapamycin (mTOR), the extracellular signal-regulated kinases 1/2 (ERK1/2), and the AMP-activated protein kinase (AMPK). PMID:24742948

Tang, Yulong; Li, Fengna; Tan, Bie; Liu, Gang; Kong, Xiangfeng; Hardwidge, Philip R; Yin, Yulong

2014-06-25

277

Intimate host attachment: enteropathogenic and enterohaemorrhagic Escherichia coli  

PubMed Central

Enteropathogenic and enterohaemorrhagic Escherichia coli use a novel infection strategy to colonize the gut epithelium, involving translocation of their own receptor, Tir, via a type III secretion system and subsequent formation of attaching and effecting (A/E) lesions. Following integration into the host cell plasma membrane of cultured cells, and clustering by the outer membrane adhesin intimin, Tir triggers multiple actin polymerization pathways involving host and bacterial adaptor proteins that converge on the host Arp2/3 actin nucleator. Although initially thought to be involved in A/E lesion formation, recent data have shown that the known Tir-induced actin polymerization pathways are dispensable for this activity, but can play other major roles in colonization efficiency, in vivo fitness and systemic disease. In this review we summarize the roadmap leading from the discovery of Tir, through the different actin polymerization pathways it triggers, to our current understanding of their physiological functions. PMID:23927593

Lai, YuShuan; Rosenshine, Ilan; Leong, John M.; Frankel, Gad

2013-01-01

278

Production of l-Asparaginase II by Escherichia coli  

PubMed Central

l-Asparaginase II was synthesized at constant rates by Escherichia coli under anaerobic conditions. The enzyme was produced optimally by bacteria grown between pH 7 and 8 at 37 C. Although some enzyme was formed aerobically, between 100 and 1,000 times more asparaginase II was produced during anaerobic growth in media enriched with high concentrations of a variety of amino acids. Bacteria grown under these conditions should provide a rich starting material for the large-scale production of the enzyme. No single amino acid specifically induced the synthesis of the asparaginase, nor did l-asparagine, even when it was used as the only source of nitrogen. The enzyme was produced at lower rates in the presence of sugars; glucose was the most inhibitory. PMID:4881701

Cedar, Howard; Schwartz, James H.

1968-01-01

279

Novel Antigens for enterotoxigenic Escherichia coli (ETEC) Vaccines  

PubMed Central

Enterotoxigenic Escherichia coli (ETEC) are the most common bacterial pathogens-causing diarrhea in developing countries where they cause hundreds of thousands of deaths, mostly in children. These organisms are leading cause of diarrheal illness in travelers to endemic countries. ETEC pathogenesis, and consequently vaccine approaches, have largely focused on plasmid-encoded enterotoxins or fimbrial colonization factors. To date these approaches have not yielded a broadly protective vaccine. However, recent studies suggest that ETEC pathogenesis is more complex than previously appreciated and involves additional plasmid and chromosomally-encoded virulence molecules that can be targeted in vaccines. Here, we review recent novel antigen discovery efforts, potential contribution of these proteins to the molecular pathogenesis of ETEC and protective immunity, and the potential implications for development of next generation vaccines for important pathogens. These proteins may help to improve the effectiveness of future vaccines by making simpler and possibly broadly protective because of their conserved nature. PMID:24702311

Fleckenstein, James M.; Sheikh, Alaullah; Qadri, Firdausi

2014-01-01

280

Streptomycin-Suppressible Lethal Mutations in Escherichia coli1  

PubMed Central

Forty-one mutants have been isolated which require streptomycin for growth on complete medium. These streptomycin-suppressible lethal mutations are located randomly around the Escherichia coli genetic map; during growth in liquid culture, they exhibit a variety of responses to the removal of streptomycin as judged by turbidity, cell morphology, and macromolecular synthesis. In particular, some mutants are primarily affected in protein or ribonucleic acid (RNA) synthesis (or both), one in deoxyribonucleic acid synthesis, and two in lipid synthesis. Ten mutants affected in protein synthesis were examined for the activities of all twenty aminoacyl-transfer RNA synthetases, and three were found to have altered glutamyl-transfer RNA synthetase activities. The advantages of this method for isolating a wide variety of conditional lethal mutants are discussed. PMID:4912524

Murgola, E. J.; Adelberg, E. A.

1970-01-01

281

Intracellular location of the histonelike protein HU in Escherichia coli.  

PubMed Central

Immunocytochemical labeling of thin sections of cryosubstituted, Lowicryl-embedded Escherichia coli cells with protein A-colloidal gold was used to study the structural organization of the bacterial nucleoid. We found that the histonelike protein HU was not associated with the bulk DNA in the nucleoid but was located in areas of the cell where metabolically active DNA is associated with ribosomes and where single-stranded DNA, RNA polymerase, and DNA topoisomerase I were also located. The resolution of the methods used did not allow us to decide whether HU was associated either with ribosomes or with transcriptionally active DNA, nor could we demonstrate interaction of HU with either. Images PMID:2844727

Dürrenberger, M; Bjornsti, M A; Uetz, T; Hobot, J A; Kellenberger, E

1988-01-01

282

Metabolic flux analysis for Escherichia coli by flux balance analysis.  

PubMed

Conventional metabolic flux analysis (MFA) of Escherichia coli wild type and of pathway gene knockout mutants cultivated under anaerobic condition is explained in detail in this chapter. To place the MFA results into the context of the literature, the regulation of central carbon metabolism in terms of catabolite regulation by the phosphotransferase system (PTS) and the response to oxygen limitations via global regulators is reviewed. The effects of gene deletions such as pflA, pta, ppc, pykF, adhE, and ldhA on the metabolic network are presented. Moreover, for the pflA mutant the effects of various carbon sources were quantified. The chapter thereby contributes to the discussion of metabolic network function and the design of microbial cell factories. PMID:25178795

Matsuoka, Yu; Shimizu, Kazuyuki

2014-01-01

283

Engineering Escherichia coli for fumaric acid production from glycerol.  

PubMed

The evolved mutant Escherichia coli E2 previously developed for succinate production from glycerol was engineered in this study for fumaric acid production under aerobic conditions. Through deletion of three fumarases, 3.65g/L fumaric acid was produced with the yield of 0.25mol/mol glycerol and a large amount of acetate was accumulated as the main byproduct. In order to reduce acetate production several strategies were attempted, among which increasing the flux of the anaplerotic pathways through overexpression of phosphoenolpyruvate carboxylase gene ppc or the glyoxylate shunt operon aceBA effectively reduced acetate and improved fumaric acid production. In fed-batch culture, the resulting strain EF02(pSCppc) produced 41.5g/L fumaric acid from glycerol with 70% of the maximum theoretical yield and an overall productivity of 0.51g/L/h. PMID:25463785

Li, Ning; Zhang, Bo; Wang, Zhiwen; Tang, Ya-Jie; Chen, Tao; Zhao, Xueming

2014-10-01

284

The multisubunit active site of fumarase C from escherichia coli.  

SciTech Connect

The crystal structure of the tetrameric enzyme, fumarase C from Escherichia coli, has been determined to a resolution of 2.0 Angstroms. A tungstate derivative used in the X-ray analysis is a competitive inhibitor and places the active site of fumarase in a region which includes atoms from three of the four subunits. The polypeptide conformation is similar to that of {delta}-crystallin and is comprised of three domains. The central domain, D2, is a unique five-helix bundle. The association of the D2 domains results in a tetramer which has a core of 20 {alpha}-helices. The other two domains, D1 and D3, cap the helical bundle on opposite ends giving both the single subunit and the tetramer a dumbbell-like appearance. Fumarase C has sequence homology to the eukaryotic fumarases, aspartase, arginosuccinate lyase, adenylosuccinate lyase and {delta}-crystallin.

Weaver, T. M.; Levitt, D. G.; Donnelly, M. I.; Wilkins-Stevens, P.; Banaszak, L. J.; Univ. of Minnesota

1995-08-01

285

Phenotypic bistability in Escherichia coli's central carbon metabolism  

PubMed Central

Fluctuations in intracellular molecule abundance can lead to distinct, coexisting phenotypes in isogenic populations. Although metabolism continuously adapts to unpredictable environmental changes, and although bistability was found in certain substrate-uptake pathways, central carbon metabolism is thought to operate deterministically. Here, we combine experiment and theory to demonstrate that a clonal Escherichia coli population splits into two stochastically generated phenotypic subpopulations after glucose-gluconeogenic substrate shifts. Most cells refrain from growth, entering a dormant persister state that manifests as a lag phase in the population growth curve. The subpopulation-generating mechanism resides at the metabolic core, overarches the metabolic and transcriptional networks, and only allows the growth of cells initially achieving sufficiently high gluconeogenic flux. Thus, central metabolism does not ensure the gluconeogenic growth of individual cells, but uses a population-level adaptation resulting in responsive diversification upon nutrient changes. PMID:24987115

Kotte, Oliver; Volkmer, Benjamin; Radzikowski, Jakub L; Heinemann, Matthias

2014-01-01

286

Escherichia coli produces linoleic acid during late stationary phase.  

PubMed Central

Escherichia coli produces linoleic acid in the late stationary phase. This was the case whether the cultures were grown aerobically or anaerobically on a supplemented glucose-salts medium. The linoleic acid was detected by thin-layer chromatography and was measured as the methyl ester by gas chromatography. The linoleic acid methyl ester was identified by its mass spectrum. Lipids extracted from late-stationary-phase cells generated thiobarbituric acid-reactive carbonyl products when incubated with a free radical initiator. In contrast, extracts from log-phase or early-stationary-phase cells failed to do so, in accordance with the presence of polyunsaturated fatty acid only in the stationary-phase cells. PMID:8366020

Rabinowitch, H D; Sklan, D; Chace, D H; Stevens, R D; Fridovich, I

1993-01-01

287

Enteroaggregative Escherichia coli, a heterogenous, underestimated and under-diagnosed E. coli pathotype in Iran  

PubMed Central

The main features of enteroaggregative Escherichia coli (EAEC) pathogenesis include attachment of bacteria to the intestinal mucosa, production of various toxins and cytotoxins, and stimulation of mucosal inflammation. ‘Virulence’ genes encode these features. Comparison of different EAEC isolates has shown that the virulence gene content of these isolates varies considerably. The heterogeneity of EAEC strains was concluded from the results obtained from the volunteer as well as other studies. Although the underlying mechanism behind the apparent increase in O104:H4 virulence is not known, several bacterial factors have been implicated. In this review, the known virulence factors involved in pathogenesis of EAEC pathotype are summarized. PMID:24834248

Jafari, Anis; Aslani, Mohammad Mehdi

2013-01-01

288

Dynamic metabolomic responses of Escherichia coli to nicotine stress.  

PubMed

Previously, we reported the metabolic responses of Pseudomonas sp. strain HF-1, a nicotine-degrading bacterium, to nicotine stress. However, the metabolic effects of nicotine on non-nicotine-degrading bacteria that dominate the environment are still unclear. Here, we have used nuclear magnetic resonance based metabolomics in combination with multivariate data analysis methods to comprehensively analyze the metabolic changes in nicotine-treated Escherichia coli. Our results showed that nicotine caused the changes of energy-related metabolism that we believe are due to enhanced glycolysis and mixed acid fermentation as well as inhibited tricarboxylic acid cycle activity. Furthermore, nicotine resulted in the alteration of choline metabolism with a decreased synthesis of betaine but an increased production of dimethylamine. Moreover, nicotine caused a decrease in amino acid concentration and an alteration of nucleotide synthesis. We hypothesize that these changes caused the decrease in bacterial cell density observed in the experiment. These findings provide a comprehensive insight into the metabolic response of E. coli to nicotine stress. Our study highlights the value of metabolomics in elucidating the metabolic mechanisms of nicotine action. PMID:25093750

Ding, Lijian; Chen, Juanjuan; Zou, Jianding; Zhang, Limin; Ye, Yangfang

2014-08-01

289

Structure of CFA/I fimbriae from enterotoxigenic Escherichia coli  

SciTech Connect

Adhesion pili (fimbriae) play a critical role in initiating the events that lead to intestinal colonization and diarrheal disease by enterotoxigenic Escherichia coli (ETEC), an E. coli pathotype that inflicts an enormous global disease burden. We elucidate atomic structures of an ETEC major pilin subunit, CfaB, from colonization factor antigen I (CFA/I) fimbriae. These data are used to construct models for 2 morphological forms of CFA/I fimbriae that are both observed in vivo: the helical filament into which it is typically assembled, and an extended, unwound conformation. Modeling and corroborative mutational data indicate that proline isomerization is involved in the conversion between these helical and extended forms. Our findings affirm the strong structural similarities seen between class 5 fimbriae (from bacteria primarily causing gastrointestinal disease) and class 1 pili (from bacteria that cause urinary, respiratory, and other infections) in the absence of significant primary sequence similarity. They also suggest that morphological and biochemical differences between fimbrial types, regardless of class, provide structural specialization that facilitates survival of each bacterial pathotype in its preferred host microenvironment. Last, we present structural evidence for bacterial use of antigenic variation to evade host immune responses, in that residues occupying the predicted surface-exposed face of CfaB and related class 5 pilins show much higher genetic sequence variability than the remainder of the pilin protein.

Li, Yong-Fu; Poole, Steven; Nishio, Kazuya; Jang, Ken; Rasulova, Fatima; McVeigh, Annette; Savarino, Stephen J.; Xia, Di; Bullitt, Esther; (BU-M); (NIH); (NMRC)

2009-10-21

290

Molecular response of Escherichia coli adhering onto nanoscale topography  

PubMed Central

Bacterial adhesion onto abiotic surfaces is an important issue in biology and medicine since understanding the bases of such interaction represents a crucial aspect in the design of safe implant devices with intrinsic antibacterial characteristics. In this framework, we investigated the effects of nanostructured metal substrates on Escherichia coli adhesion and adaptation in order to understand the bio-molecular dynamics ruling the interactions at the interface. In particular, we show how highly controlled nanostructured gold substrates impact the bacterial behavior in terms of morphological changes and lead to modifications in the expression profile of several genes, which are crucially involved in the stress response and fimbrial synthesis. These results mainly demonstrate that E. coli cells are able to sense even slight changes in surface nanotopography and to actively respond by activating stress-related pathways. At the same time, our findings highlight the possibility of designing nanoengineered substrates able to trigger specific bio-molecular effects, thus opening the perspective of smartly tuning bacterial behavior by biomaterial design. PMID:23078758

2012-01-01

291

Enhanced Deletion Formation by Aberrant DNA Replication in Escherichia Coli  

PubMed Central

Repeated genes and sequences are prone to genetic rearrangements including deletions. We have investigated deletion formation in Escherichia coli strains mutant for various replication functions. Deletion was selected between 787 base pair tandem repeats carried either on a ColE1-derived plasmid or on the E. coli chromosome. Only mutations in functions associated with DNA Polymerase III elevated deletion rates in our assays. Especially large increases were observed in strains mutant in dnaQ, the ? editing subunit of Pol III, and dnaB, the replication fork helicase. Mutations in several other functions also altered deletion formation: the ? polymerase (dnaE), the ? clamp loader complex (holC, dnaX), and the ? clamp (dnaN) subunits of Pol III and the primosomal proteins, dnaC and priA. Aberrant replication stimulated deletions through several pathways. Whereas the elevation in dnaB strains was mostly recA- and lexA-dependent, that in dnaQ strains was mostly recA- and lexA-independent. Deletion product analysis suggested that slipped mispairing, producing monomeric replicon products, may be preferentially increased in a dnaQ mutant and sister-strand exchange, producing dimeric replicon products, may be elevated in dnaE mutants. We conclude that aberrant Polymerase III replication can stimulate deletion events through several mechanisms of deletion and via both recA-dependent and independent pathways. PMID:9177997

Saveson, C. J.; Lovett, S. T.

1997-01-01

292

Optimization of Taq DNA polymerase enzyme expression in Escherichia coli  

PubMed Central

Background: In the present study, we optimized the experimental conditions using pET15b expression vector to obtain large amounts of Taq DNA polymerase. Materials and Methods: Correct framing of the gene in the expression vector pET15b and its orientation were analyzed by digestion and sequencing. Production of Taq DNA polymerase in Escherichia coli BL21 (DE3) cells was induced by incubation with different concentrations of IPTG. Optimum production occurred with the addition of 1mM IPTG for 2h. The activity of the obtained enzyme was measured by comparing the intensities of the produced DNA bands in PCR reactions. Results: Recombinant plasmid containing taq polymerase gene was confirmed by restriction digestion and DNA sequencing. Purified protein was identified by Western blotting. Optimum condition for the production of the enzyme was induction with 1mM IPTG for 23h. Addition of NP40 increased enzyme stability. Conclusion: We expressed the recombinant Taq DNA polymerase in E. coli using a T7based promoter system and obtained an active and stable enzyme. PMID:23326812

Moazen, Fateme; Rastegari, Ali; Hoseini, Sayed Mehdi; Panjehpour, Mojtaba; Miroliaei, Mehran; Sadeghi, Hamid Mir Mohammad

2012-01-01

293

Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation  

PubMed Central

Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe–S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound cytochromes and an expressed human cystathionine beta-synthase (CBS). The presence of CoPPIX in cytochromes inhibited their electron transport capacity and resulted in a substantially decreased respiration. Bacterial cells adapted to the increased cobalt concentration by inducing a modified mixed acid fermentative pathway under aerobiosis. We capitalized on the ability of E. coli to insert cobalt into PPIX to carry out an expression of CoPPIX-substituted heme proteins. The level of CoPPIX-substitution increased with the number of passages of cells in a cobalt-containing medium. This approach is an inexpensive method to prepare cobalt-substituted heme proteins compared to in vitro enzyme reconstitution or in vivo replacement using metalloporphyrin heme analogs and seems to be especially suitable for complex heme proteins with an additional coenzyme, such as human CBS. PMID:21184140

Majtan, Tomas; Frerman, Frank E.

2011-01-01

294

Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation.  

PubMed

Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe-S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound cytochromes and an expressed human cystathionine beta-synthase (CBS). The presence of CoPPIX in cytochromes inhibited their electron transport capacity and resulted in a substantially decreased respiration. Bacterial cells adapted to the increased cobalt concentration by inducing a modified mixed acid fermentative pathway under aerobiosis. We capitalized on the ability of E. coli to insert cobalt into PPIX to carry out an expression of CoPPIX-substituted heme proteins. The level of CoPPIX-substitution increased with the number of passages of cells in a cobalt-containing medium. This approach is an inexpensive method to prepare cobalt-substituted heme proteins compared to in vitro enzyme reconstitution or in vivo replacement using metalloporphyrin heme analogs and seems to be especially suitable for complex heme proteins with an additional coenzyme, such as human CBS. PMID:21184140

Majtan, Tomas; Frerman, Frank E; Kraus, Jan P

2011-04-01

295

Porin activity in the osmotic shock fluid of Escherichia coli.  

PubMed Central

Osmotic shock fluid of Escherichia coli exhibited pore-forming activity. This activity could be followed by an in vitro assay based on the conductivity increase for ions due to the presence of pores in black lipid membranes. The histogram (the distribution of conductivity increments in a single pore experiment) obtained with osmotic shock fluid from E. coli was identical to the histogram obtained by detergent-solubilized porin isolated from the outer membrane. The osmotic shock fluid from porin-negative mutants also exhibited pore activity, although the histogram and ion specificity were different from those of porin. Antibodies raised against detergent-solubilized porin were able to form precipitin lines by the Ouchterlony immunodiffusion technique when shock fluids, but not detergent-solubilized porin, were used. These antibodies prevented the formation of pores when shock fluids contained porin but not when shock fluids obtained from porin-negative mutants were used. Macroscopic membrane conductivity of shock fluids due to porin exhibited a concentration dependence, in contrast to detergent-solubilized porin. These results indicate that the hydrodynamic properties of periplasmic or "soluble" porin are different from those of the detergent-solubilized porin of the outer membrane. Periplasmic porin comprises about 0.7% of total protein in the osmotic shock fluid. Images PMID:357415

Benz, R; Boehler-Kohler, B A; Dieterle, R; Boos, W

1978-01-01

296

Understanding carbon catabolite repression in Escherichia coli using quantitative models.  

PubMed

Carbon catabolite repression (CCR) controls the order in which different carbon sources are metabolized. Although this system is one of the paradigms of the regulation of gene expression in bacteria, the underlying mechanisms remain controversial. CCR involves the coordination of different subsystems of the cell that are responsible for the uptake of carbon sources, their breakdown for the production of energy and precursors, and the conversion of the latter to biomass. The complexity of this integrated system, with regulatory mechanisms cutting across metabolism, gene expression, and signaling, and that are subject to global physical and physiological constraints, has motivated important modeling efforts over the past four decades, especially in the enterobacterium Escherichia coli. Different hypotheses concerning the dynamic functioning of the system have been explored by a variety of modeling approaches. We review these studies and summarize their contributions to the quantitative understanding of CCR, focusing on diauxic growth in E. coli. Moreover, we propose a highly simplified representation of diauxic growth that makes it possible to bring out the salient features of the models proposed in the literature and confront and compare the explanations they provide. PMID:25475882

Kremling, A; Geiselmann, J; Ropers, D; de Jong, H

2014-12-01

297

Functional analysis of the uropathogenic Escherichia coli R049 gene.  

PubMed

The objective of this study was to determine the function of the novel uropathogenic Escherichia coli (UPEC) gene R049 during host infection. We infected the urinary tracts of mice with E. coli UPEC132 or the R049 deletion mutant UPEC132?R049.The mouse kidneys were harvested at 4 and 8h post-infection and screened for differentially expressed genes by microarray analysis. We identified 379 and 515 differentially expressed genes at 4 and 8h post-infection, respectively. Thirty-four of these genes were associated with inflammatory and immune signaling pathways, including those related to mitogen-activated protein kinase signaling, leukocyte transendothelial migration, cytokine-cytokine receptor interaction, Toll-like receptor signaling, and apoptosis. Protein binding (GO 0005515) was the most prevalent molecular function in the Gene Ontology terms related to differentially expressed genes. In conclusion, R049 expression in UPEC132 is related to the early innate immune and inflammatory responses in UPEC-infected hosts. This work lays the foundation for further research on anti-infective immunity against UPEC. PMID:25644951

Yang, Dongjing; Dong, Jie; Su, Xu; Zhang, Wei; Zhang, Li; Li, Li; Lv, Likun; Guo, Liru

2015-02-01

298

Uncoupler resistance in Escherichia coli: the role of cellular respiration.  

PubMed

Bioenergetic properties of a mutant strain of Escherichia coli K12 designated TUV, which is resistant to the protonophoric uncoupling agent 4,5,6,7-tetrachloro-2-trifluoromethylbenzimidiazole (TTFB) have been compared with those of its non-resistant parent, E. coli K12 Doc-S. Strain TUV grew and respired some 20-30% faster than strain Doc-S, and was cross-resistant to carbonylcyanide p-(trifluoromethoxy)phenylhydrazone and triphenyltin, but not to 2,4-dinitrophenol. Phosphorus nuclear magnetic resonance demonstrated the TTFB-mediated collapse of the transmembrane pH gradient at identical rates in starved cells of both strains, indicating that uncoupler access and function were unimpaired in the mutant under these conditions. Strain TUV displayed enhanced uncoupler resistance and maintained intracellular pH and ATP levels only when respiring. On the other hand, strain TUV also showed increased resistance to novobiocin, implying that its outer wall permeability had been lowered. We suggest that the active resistance of strain TUV results from the exclusion of uncoupler by the interaction of inner and outer membrane components in a manner modulated by the degree of cellular energization. PMID:2698912

Quirk, P G; Jones, M R; Haworth, R S; Beechey, R B; Campbell, I D

1989-10-01

299

The nac (Nitrogen Assimilation Control) Gene from Escherichia coli  

PubMed Central

The nitrogen assimilation control gene, nac, was detected in Escherichia coli but not in Salmonella typhimurium by Southern blotting, using a probe from the Klebsiella aerogenes nac (nacK) gene. The E. coli nac gene (nacE) was isolated from a cosmid clone by complementation of a nac mutation in K. aerogenes. nacE was fully functional in this complementation assay. DNA sequence analysis showed considerable divergence between nacE and nacK, with a predicted amino acid sequence identity of only 79% and most of the divergence in the C-terminal half of the protein sequence. The total predicted size of NACE is 305 amino acids, the same as for NACK. A null mutation, nac-28, was generated by reverse genetics. Mutants bearing nac-28 have a variety of phenotypes related to nitrogen metabolism, including slower growth on cytosine, faster growth on arginine, and suppression of the failure of an Ntr-constitutive mutant to grow with serine as sole nitrogen source. In addition to a loss of nitrogen regulation of histidase formation, nac-28 mutants also showed a loss of a weak repression of glutamate dehydrogenase formation. This repression was unexpected because it is balanced by a NAC-independent activation of glutamate dehydrogenase formation during nitrogen-limited growth. Attempts to purify NACE by using methods established for NACK failed, and NACE appears to be degraded with a half-life at 30°C as short as 15 min during inhibition of protein synthesis. PMID:9495755

Muse, Wilson B.; Bender, Robert A.

1998-01-01

300

Proteomic adaptations to starvation prepare Escherichia coli for disinfection tolerance.  

PubMed

Despite the low nutrient level and constant presence of secondary disinfectants, bacterial re-growth still occurs in drinking water distribution systems. The molecular mechanisms that starved bacteria use to survive low-level chlorine-based disinfectants are not well understood. The objective of this study is to investigate these molecular mechanisms at the protein level that prepare starved cells for disinfection tolerance. Two commonly used secondary disinfectants chlorine and monochloramine, both at 1 mg/L, were used in this study. The proteomes of normal and starved Escherichia coli (K12 MG1655) cells were studied using quantitative proteomics. Over 60-min disinfection, starved cells showed significantly higher disinfection tolerance than normal cells based on the inactivation curves for both chlorine and monochloramine. Proteomic analyses suggest that starvation may prepare cells for the oxidative stress that chlorine-based disinfection will cause by affecting glutathione metabolism. In addition, proteins involved in stress regulation and stress responses were among the ones up-regulated under both starvation and chlorine/monochloramine disinfection. By comparing the fold changes under different conditions, it is suggested that starvation prepares E. coli for disinfection tolerance by increasing the expression of enzymes that can help cells survive chlorine/monochloramine disinfection. Protein co-expression analyses show that proteins in glycolysis and pentose phosphate pathway that were up-regulated under starvation are also involved in disinfection tolerance. Finally, the production and detoxification of methylglyoxal may be involved in the chlorine-based disinfection and cell defense mechanisms. PMID:25463932

Du, Zhe; Nandakumar, Renu; Nickerson, Kenneth W; Li, Xu

2015-02-01

301

Escherichia coli ribonucleotide reductase expression is cell cycle regulated.  

PubMed Central

The expression of the genes encoding ribonucleotide reductase in Escherichia coli was investigated in cultures synchronized by obtaining the smallest cells in a population after sucrose gradient centrifugation. Specific activity of ribonucleotide reductase and DNA initiation were found to increase in parallel, periodically as a function of the cell cycle. The expression of nrd was also determined in cells synchronized by periodic repeated doubling in a phosphate limited medium. Antibodies directed against the B2 subunit of ribonucleotide reductase were raised in a rabbit and purified. Immunoprecipitation of the B2 subunit and RNA-DNA dot blot hybridization assays were developed and employed to determine the expression of ribonucleotide reductase translational and transcriptional products during the cell cycle. Both of nrd-mRNA and B2 subunit expression were found to increase each generation at approximately the same time DNA synthesis was initiated and then to decrease back to the basal level shortly after DNA initiation. These results provided evidence of cell cycle dependent regulation of ribonucleotide reductase in E. coli. When the upstream regulatory region of nrd was fused to a promoterless lacZ gene on a single copy plasmid, lac-mRNA and beta-galactosidase were found to be synthesized in parallel to nrd expression from the chromosomal operon. When nrd sequences surrounding the promoter were removed from this construct, lac-mRNA and beta-galactosidase synthesis were no longer cell cycle regulated. Images PMID:1384814

Sun, L; Fuchs, J A

1992-01-01

302

Purification and properties of carboxylesterase B of Escherichia coli.  

PubMed

Carboxylesterase B produced by Escherichia coli was purified 1,350-fold with a recovery of 12% by successive gel filtrations, DEAE-trisacryl, phenyl-Sepharose chromatography and preparative electrophoresis. The purified enzyme was found to be homogeneous, as judged by a single precipitation line in Ouchterlony double diffusion in an experiment with homologous antiserum. The apparent molecular weight determined by gel filtration and the isoelectric point determined by electrofocusing were 57,000 and 4.6, respectively. Using acetate, propionate and butyrate esters of 1-naphtol, it was observed that elongation of the acyl carbon chain resulted in a progressive increase in velocity of ester hydrolysis. The apparent Km for 1-naphtyl acetate was found to be 0.25 mM. The enzyme was maximally active at pH 7.4 and was found to be unstable below pH 5. Hydrolytic activity was preserved after heat treatment for 30 min at 60 degrees C, but was abolished by heating for 10 min at 70 degrees C. The enzyme was strongly inhibited by low concentrations of di-isopropyl fluorophosphate. This suggested that a serine residue is required for catalytic activity. Esterase was unaffected by tosyl-L-lysin chloromethylketone, iodoacetamide, 4-hydroxy-mercuribenzoate and EDTA. Using antiserum against purified carboxylesterase B of E. coli, significant immunological cross-reactions were observed between this antigen and carboxylesterase B produced by Shigella flexneri, S. boydii and S. sonnei. PMID:6380369

Goullet, P; Picard, B; Laget, P F

1984-01-01

303

In vivo immobilization of D-hydantoinase in Escherichia coli.  

PubMed

D-P-Hydroxyphenylglycine (D-HPG) is a precursor required for the synthesis of semi-synthetic antibiotics. This unnatural amino acid can be produced by a transformation reaction mediated by D-hydantoinase (D-HDT) and d-amidohydrolase. In this study, a method was developed to integrate production and immobilization of recombinant D-HDT in vivo. This was approached by first fusion of the gene encoding D-HDT with phaP (encoding phasin) of Ralstonia eutropha H16. The fusion gene was then expressed in the Escherichia coli strain that carried a heterologous synthetic pathway for polyhydroxyalkanoate (PHA). As a result, d-HDT was found to associate with isolated PHA granules. Further characterization illustrated that D-HDT immobilized on PHA exhibited the maximum activity at pH 9 and 60°C and had a half-life of 95 h at 40°C. Moreover, PHA-bound d-HDT could be reused for 8 times with the conversion yield exceeding 90%. Overall, it illustrates the feasibility of this approach to facilitate in vivo immobilization of enzymes in heterologous E. coli strain, which may open a new avenue of enzyme application in industry. PMID:24508023

Chen, Shan-Yu; Chien, Yi-Wen; Chao, Yun-Peng

2014-07-01

304

Microwave inactivation of Escherichia coli in healthcare waste.  

PubMed

Public healthcare wastes from the city of Ribeirão Preto, SP, Brazil, pre-sterilised in an autoclave, were inoculated with 5 x 10(5) microorganisms of the species Escherichia coli in vegetative form for microwave processing on a laboratory scale. An analysis was made of the influence of radiation exposure time (15, 25, 30 and 40 min) and power per waste mass unit (60, 80 and 100 W/kg) on the percentage of inactivation of the microorganisms at an incoming waste moisture level of 50%. The experimental results were adjusted based on Chick's law. The activation energies and the Arrhenius pre-exponential factors were determined by the least squares method. The kinetic parameters obtained allow one to predict the degree of inactivation achieved with E. coli in typical healthcare waste, based on the radiation exposure time and temperature. For example, the waste disinfection time required for the inactivation level equivalent to 4Log 10 was estimated to range from 48 to 53 min for wastes processed at 100 W/kg and at temperatures of 90-105 degrees C, respectively. Thus, under the operational conditions of the equipment currently used in Ribeirão Preto, the process of inactivation is probably ineffective, since the exposure time to radiation is only 30 min at the average power of approximately 80 W/kg. PMID:17412582

Tonuci, L R S; Paschoalatto, C F P R; Pisani, R

2008-01-01

305

Virulence factors of Escherichia coli isolated from bovine clinical mastitis.  

PubMed

Escherichia coli isolates from bovine mastitis were examined for a selection of virulence factors. The strains originated from Finland and Israel, which have differences in the proportion of mastitis caused by E. coli, clinical pictures of coliform mastitis, environmental conditions and herd management. The genes of nine virulence factors were detected by polymerase chain reaction. Presence of K1 and K5 capsules was assessed by use of specific bacteriophages. Serum resistance was tested by a turbidimetric assay. Out of 160 Finnish isolates, 37% had traT, 14% cnf2, 8% cnf1, 11% aer, 9% f17, 8% sfa, 7% pap, 1% afa8D and 1% afa8E. Out of 113 Israeli isolates, 41% had traT, 4% aer, 3% cnf2, 1% cnf1, 1% sfa and 1% f17. Some of the genes were distributed among two major pathotype groups, with either f17 family or sfa, pap and cnf1 as major determinants. Genes for F17a, CS31A, Afa7D and Afa7E were not detected. Altogether 49% of Finnish and 42% of Israeli isolates had at least one virulence gene, but genes other than traT were present in only 24% of Finnish and 5% of Israeli isolates. Serum resistance was more common among Finnish (94/160) than Israeli isolates (19/113). K1 and K5 capsules were not detected. PMID:11792490

Kaipainen, T; Pohjanvirta, T; Shpigel, N Y; Shwimmer, A; Pyörälä, S; Pelkonen, S

2002-02-26

306

Characterization of intestinal cnf1+ Escherichia coli from weaned pigs.  

PubMed

Escherichia coli isolated from 204 cases of porcine postweaning diarrhoea were tested by PCR for the genes of cytotoxic necrotic factors (CNF) and of cytolethal dystending toxin (CDT). Selected strains were also examined by PCR for the presence of papC-, sfa-, f17-, f18-, and afa-specific sequences encoding P, S, F17, F18 fimbriae and afimbrial adhesins. A 5.9% (12/204) of the strains had cnf1 gene, and two of them had cdt gene as well. Further six cdt+ strains were detected which were cnf-negative. Most of the cnf1+ strains belonged to serogroups O2, O6, O8, O54 characteristic of necrotoxic E. coli (NTEC) of humans. All the cnf1+ strains possessed the genes for P or S fimbriae or both, but were negative for F4, F17, or F18 or afimbrial adhesins. Results suggest that these enteric isolates may have entero- and/or uropathogenic significance in weaned pigs, and may have zoonotic potential for humans. PMID:11100828

Tóth, I; Oswald, E; Mainil, J G; Awad-Masalmeh, M; Nagy, B

2000-10-01

307

Toxigenic Escherichia coli in Spanish piggeries from 1986 to 1991.  

PubMed

Four-hundred and fourteen faecal samples from pigs with diarrhoea, oedema disease or healthy pigs, were collected from 65 piggeries located in different areas of Spain from 1986 to 1991. A total of 1334 Escherichia coli cultures were isolated from the pigs and studied for production of heat-labile (LT) and heat-stable (STa) enterotoxins, verotoxin (VT) and for type 1 (CNF1) and type 2 (CNF2) cytotoxic necrotizing factors. Strains producing enterotoxins (P < 0.001) or verotoxin (P < 0.05) were associated with enteric diseases of pigs. In the majority (82.3%) of piglets with strains, producing verotoxin the strains were also positive for production of STa enterotoxin. The most frequent toxin detected was STa. Although we isolated strains producing CNF1 from 1.5% of sick pigs, they were not statistically associated (P < 0.7) with enteric disease. Pigs may constitute a natural reservoir of CNF1 producing E. coli strains in Spain; their presence in the porcine intestine may be of significance in public health because such strains have been associated with human extraintestinal infections. PMID:8604549

Garabal, J I; Gonzalez, E A; Vazquez, F; Blanco, J; Blanco, M

1995-11-01

308

Production of acetol from glycerol using engineered Escherichia coli.  

PubMed

Escherichia coli Lin43 is a strain which has some mutations in glycerol kinase (GlpK) and the repressor for the glycerol 3-phosphate regulon (GlpR). When exposed to glycerol, it quickly accumulates lethal levels of methylglyoxal, which is a precursor of acetol; acetol is important for the manufacture of polyols, acrolein, dyes, and skin tanning agents. This work reports the engineering of E. coli Lin 43 for the conversion of glycerol into acetol. First, the glyoxalase system was interrupted by deleting the gloA gene, which increased the acetol yield by 32%. In addition, the aldehyde reductase YqhD was overexpressed which led to an increase of acetol production by 11.4-fold. Acetol production was optimized by varying the cell density, glycerol concentration, supplemental carbon source, pH and temperature. Under the optimal conditions (OD600=20, 20 g/L glycerol, 2g/L succinate, pH 7.0, and 28°C), we obtained 5.4 g/L acetol in 21 h. PMID:24113547

Zhu, Hongliang; Yi, Xianyang; Liu, Yi; Hu, Hongbo; Wood, Thomas K; Zhang, Xuehong

2013-12-01

309

A surface accumulator of Escherichia coli in water flow.  

PubMed

The objective of this research is to design and optimise a mini/micro-channel based surface accumulator of Escherichia coli to be detected by acoustic wave biosensors. A computational research has been carried out using the state of the art software, CFD-ACE with water as bacteria bearing fluid. E. coli bacteria have been modelled as random discrete particles tracked by solving the Lagrangian equations. The design challenges are to achieve low shear force (pico-N), high concentration at accumulation and high enough Reynolds number to avoid bacteria swimming. A range of low Reynolds number (Re) from 28.2 to 58.3 has been considered along with the effects of particle-boundary interactions, gravity, Saffman lift and Magnus lift. About four orders of magnitude higher concentration at accumulation than the inlet concentration and lower shear force in the order of less than pico-N have been achieved in the optimised design with particles accumulating at a specific location under random particle-boundary interactions. PMID:18663613

Mayeed, M S; Al-Mekhnaqi, A M; Auner, G W; Newaz, G M

2009-02-01

310

Transcription Factors in Escherichia coli Prefer the Holo Conformation  

PubMed Central

The transcriptional regulatory network of Escherichia coli K-12 is among the best studied gene networks of any living cell. Transcription factors bind to DNA either with their effector bound (holo conformation), or as a free protein (apo conformation) regulating transcription initiation. By using RegulonDB, the functional conformations (holo or apo) of transcription factors, and their mode of regulation (activator, repressor, or dual) were exhaustively analyzed. We report a striking discovery in the architecture of the regulatory network, finding a strong under-representation of the apo conformation (without allosteric metabolite) of transcription factors when binding to their DNA sites to activate transcription. This observation is supported at the level of individual regulatory interactions on promoters, even if we exclude the promoters regulated by global transcription factors, where three-quarters of the known promoters are regulated by a transcription factor in holo conformation. This genome-scale analysis enables us to ask what are the implications of these observations for the physiology and for our understanding of the ecology of E. coli. We discuss these ideas within the framework of the demand theory of gene regulation. PMID:23776535

Balderas-Martínez, Yalbi Itzel; Savageau, Michael; Salgado, Heladia; Pérez-Rueda, Ernesto; Morett, Enrique; Collado-Vides, Julio

2013-01-01

311

Functional reconstitution of cellulose synthase in Escherichia coli.  

PubMed

Cellulose is a high molecular weight polysaccharide of ?1 ? 4-d-glucan widely distributed in nature-from plant cell walls to extracellular polysaccharide in bacteria. Cellulose synthase, together with other auxiliary subunit(s) in the cell membrane, facilitates the fibrillar assembly of cellulose polymer chains into a microfibril. The gene encoding the catalytic subunit of cellulose synthase is cesA and has been identified in many cellulose-producing organisms. Very few studies, however, have shown that recombinant CesA protein synthesizes cellulose polymer, but the mechanism by which CesA protein synthesizes cellulose microfibrils is not known. Here we show that cellulose-synthesizing activity is successfully reconstituted in Escherichia coli by expressing the bacterial cellulose synthase complex of Gluconacetobacter xylinus: CesA and CesB (formerly BcsA and BcsB, respectively). Cellulose synthase activity was, however, only detected when CesA and CesB were coexpressed with diguanyl cyclase (DGC), which synthesizes cyclic-di-GMP (c-di-GMP), which in turn activates cellulose-synthesizing activity in bacteria. Direct observation by electron microscopy revealed extremely thin fibrillar structures outside E. coli cells, which were removed by cellulase treatment. This fiber structure is not likely to be the native crystallographic form of cellulose I, given that it was converted to cellulose II by a chemical treatment milder than ever described. We thus putatively conclude that this fine fiber is an unprecedented structure of cellulose. Despite the inability of the recombinant enzyme to synthesize the native structure of cellulose, the system described in this study, named "CESEC (CEllulose-Synthesizing E. Coli)", represents a useful tool for functional analyses of cellulose synthase and for seeding new nanomaterials. PMID:25285473

Imai, Tomoya; Sun, Shi-Jing; Horikawa, Yoshiki; Wada, Masahisa; Sugiyama, Junji

2014-11-10

312

Cytochrome bd from Escherichia coli catalyzes peroxynitrite decomposition.  

PubMed

Cytochrome bd is a prokaryotic respiratory quinol oxidase phylogenetically unrelated to heme-copper oxidases, that was found to promote virulence in some bacterial pathogens. Cytochrome bd from Escherichia coli was previously reported to contribute not only to proton motive force generation, but also to bacterial resistance to nitric oxide (NO) and hydrogen peroxide (H2O2). Here, we investigated the interaction of the purified enzyme with peroxynitrite (ONOO(-)), another harmful reactive species produced by the host to kill invading microorganisms. We found that addition of ONOO(-) to cytochrome bd in turnover with ascorbate and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) causes the irreversible inhibition of a small (?15%) protein fraction, due to the NO generated from ONOO(-) and not to ONOO(-) itself. Consistently, addition of ONOO(-) to cells of the E. coli strain GO105/pTK1, expressing cytochrome bd as the only terminal oxidase, caused only a minor (?5%) irreversible inhibition of O2 consumption, without measurable release of NO. Furthermore, by directly monitoring the kinetics of ONOO(-) decomposition by stopped-flow absorption spectroscopy, it was found that the purified E. coli cytochrome bd in turnover with O2 is able to metabolize ONOO(-) with an apparent turnover rate as high as ~10mol ONOO(-) (mol enzyme)(-1)s(-1) at 25°C. To the best of our knowledge, this is the first time that the kinetics of ONOO(-) decomposition by a terminal oxidase has been investigated. These results strongly suggest a protective role of cytochrome bd against ONOO(-) damage. PMID:25449967

Borisov, Vitaliy B; Forte, Elena; Siletsky, Sergey A; Sarti, Paolo; Giuffrè, Alessandro

2015-02-01

313

Mechanism for accommodation to cadmium exposure in Escherichia coli B  

SciTech Connect

All organisms possess, to varying degrees, the ability to adapt to changes in their environment. The extent of this capability can be the determining factor in whether or not an organism survives. The adaptation of the enteric microorganism, Escherichia coli, to the heavy metal cadmium is not the result of a beneficial mutation, and has been termed accommodation. A protein was found that binds to, and appears to be induced by cadmium. The work presented in this thesis is directed at (1) determining the mechanism of accommodation of E.coli to cadmium, and (2) determining the potential role of a putative cadmium binding-protein in accomplishing this accommodation. The presence of three chemically related cadmium-binding proteins, possessing molecular weights of 150,000, 67,000, and 38,000, respectively, was demonstrated. The cadmium-protein bond in the 150 and 67 kDa proteins was stable when boiled in sodium dodecyl sulfate, but was lost in the presence of reducing agents. Evidence was obtained which supported the assertion that the lower molecular weight cadmium-binding proteins were proteolytic or oxidative breakdown products of the larger cadmium-binding proteins. The loss of cadmium-binding activity was time dependent, and appeared to be accelerated by the presence of high salt. To determine if the process of accommodation involved the sequestration of cadmium in the outer cell surface, subcellular fractionation experiments were performed under a variety of post-exposure conditions. The possibility that the cell surface was rendered impermeable to cadmium ions during its recovery was also examined. Neither of these processes was found to be involved in the accommodative response. Indeed, the results of these studies support the concept that E.coli circumvents the presence of internal cadmium by converting it to a form that is no longer toxic to the cell.

Kitchen, J.R. Jr.

1989-01-01

314

Effects of ethanol on the Escherichia coli plasma membrane.  

PubMed Central

The effects of ethanol on the fluidity of Escherichia coli plasma membranes were examined by using a variety of fluorescent probes: 1,6-diphenyl-1,3,5-hexatriene, perylene, and a set of n-(9-anthroyloxy) fatty acids. The anthroyloxy fatty acid probes were used to examine the fluidity gradient across the width of the plasma membrane and artificial membranes prepared from lipid extracts of plasma membranes. Ethanol caused a small decrease in the polarization of probes primarily located near the membrane surface. In comparison, hexanol decreased the polarization of probes located more deeply in the membrane. Temperature had a large effect on probes located at all depths. The effects of ethanol on E. coli membranes from cells grown with or without ethanol were also examined. Plasma membranes isolated from cells grown in the presence of ethanol were more rigid than those from control cells. In contrast to plasma membranes, artificial membranes prepared from lipid extracts of ethanol-grown cells were more fluid than those from control cells. These differences are explained by analyses of membrane composition. Membranes from cells grown in the presence of ethanol are more rigid than those from control cells due to a decrease in the lipid-to-protein ratio. This change more than compensates for the fluidizing effect of ethanol and the ethanol-induced increase in membrane C18:1 fatty acid which occurs during growth. Our results suggest that the regulation of the lipid-to-protein ratio of the plasma membrane may be an important adaptive response of E. coli to growth in the presence of ethanol. PMID:6360997

Dombek, K M; Ingram, L O

1984-01-01

315

Role of mismatch repair in the Escherichia coli UVM response.  

PubMed

Mutagenesis at 3,N4-ethenocytosine (epsilonC), a nonpairing mutagenic lesion, is significantly enhanced in Escherichia coli cells pretreated with UV, alkylating agents, or H2O2. This effect, termed UVM (for UV modulation of mutagenesis), is distinct from known DNA damage-inducible responses, such as the SOS response, the adaptive response to alkylating agents, or the oxyR-mediated response to oxidative agents. Here, we have addressed the hypothesis that UVM results from transient depletion of a mismatch repair activity that normally acts to reduce mutagenesis. To test whether the loss of mismatch repair activities results in the predicted constitutive UVM phenotype, E. coli cells defective for methyl-directed mismatch repair, for very-short-patch repair, or for the N-glycosylase activities MutY and MutM were treated with the UVM-inducing agent 1-methyl-3-nitro-1-nitrosoguanidine, with subsequent transfection of M13 viral single-stranded DNA bearing a site-specific epsilonC lesion. Survival of the M13 DNA was measured as transfection efficiency, and mutation fixation at the lesion was characterized by multiplex sequencing technology. The results showed normal UVM induction patterns in all the repair-defective strains tested. In addition, normal UVM induction was observed in cells overexpressing MutH, MutL, or MutS. All strains displayed UVM reactivation, the term used to describe the increased survival of epsilonC-containing DNA in UVM-induced cells. Taken together, these results indicate that the UVM response is independent of known mismatch repair systems in E. coli and may thus represent a previously unrecognized misrepair or misreplication pathway. PMID:8955278

Murphy, H S; Palejwala, V A; Rahman, M S; Dunman, P M; Wang, G; Humayun, M Z

1996-12-01

316

Role of mismatch repair in the Escherichia coli UVM response.  

PubMed Central

Mutagenesis at 3,N4-ethenocytosine (epsilonC), a nonpairing mutagenic lesion, is significantly enhanced in Escherichia coli cells pretreated with UV, alkylating agents, or H2O2. This effect, termed UVM (for UV modulation of mutagenesis), is distinct from known DNA damage-inducible responses, such as the SOS response, the adaptive response to alkylating agents, or the oxyR-mediated response to oxidative agents. Here, we have addressed the hypothesis that UVM results from transient depletion of a mismatch repair activity that normally acts to reduce mutagenesis. To test whether the loss of mismatch repair activities results in the predicted constitutive UVM phenotype, E. coli cells defective for methyl-directed mismatch repair, for very-short-patch repair, or for the N-glycosylase activities MutY and MutM were treated with the UVM-inducing agent 1-methyl-3-nitro-1-nitrosoguanidine, with subsequent transfection of M13 viral single-stranded DNA bearing a site-specific epsilonC lesion. Survival of the M13 DNA was measured as transfection efficiency, and mutation fixation at the lesion was characterized by multiplex sequencing technology. The results showed normal UVM induction patterns in all the repair-defective strains tested. In addition, normal UVM induction was observed in cells overexpressing MutH, MutL, or MutS. All strains displayed UVM reactivation, the term used to describe the increased survival of epsilonC-containing DNA in UVM-induced cells. Taken together, these results indicate that the UVM response is independent of known mismatch repair systems in E. coli and may thus represent a previously unrecognized misrepair or misreplication pathway. PMID:8955278

Murphy, H S; Palejwala, V A; Rahman, M S; Dunman, P M; Wang, G; Humayun, M Z

1996-01-01

317

Engineered biosynthesis of an ansamycin polyketide precursor in Escherichia coli.  

PubMed

Ansamycins such as rifamycin, ansamitocin, and geldanamycin are an important class of polyketide natural products. Their biosynthetic pathways are especially complex because they involve the formation of 3-amino-5-hydroxybenzoic acid (AHBA) followed by backbone assembly by a hybrid nonribosomal peptide synthetase/polyketide synthase. We have reconstituted the ability to synthesize 2,6-dimethyl-3,5,7-trihydroxy-7-(3'-amino-5'-hydroxyphenyl)-2,4-heptadienoic acid (P8/1-OG), an intermediate in rifamycin biosynthesis, in an extensively manipulated strain of Escherichia coli. The parent strain, BAP1, contains the sfp phosphopantetheinyl transferase gene from Bacillus subtilis, which posttranslationally modifies polyketide synthase and nonribosomal peptide synthetase modules. AHBA biosynthesis in this host required introduction of seven genes from Amycolatopsis mediterranei, which produces rifamycin, and Actinosynnema pretiosum, which produces ansamitocin. Because the four-module RifA protein (530 kDa) from the rifamycin synthetase could not be efficiently produced in an intact form in E. coli, it was genetically split into two bimodular proteins separated by matched linker pairs to facilitate efficient inter-polypeptide transfer of a biosynthetic intermediate. A derivative of BAP1 was engineered that harbors the AHBA biosynthetic operon, the bicistronic RifA construct and the pccB and accA1 genes from Streptomyces coelicolor, which enable methylmalonyl-CoA biosynthesis. Fermentation of this strain of E. coli yielded P8/1-OG, an N-acetyl P8/1-OG analog, and AHBA. In addition to providing a fundamentally new route to shikimate and ansamycin-type compounds, this result enables further genetic manipulation of AHBA-derived polyketide natural products with unprecedented power. PMID:12888623

Watanabe, Kenji; Rude, Mathew A; Walsh, Christopher T; Khosla, Chaitan

2003-08-19

318

Production of unmodified human adult hemoglobin in Escherichia coli.  

PubMed Central

We have constructed a plasmid (pHE2) in which the synthetic human alpha- and beta-globin genes and the methionine aminopeptidase (Met-AP) gene from Escherichia coli are coexpressed under the control of separate tac promoters. The Hbs were expressed in E. coli JM109 and purified by fast protein liquid chromatography, producing two major components, a and b. Electrospray mass spectrometry shows that at least 98% and about 90% of the expressed alpha and beta chains of component a, respectively, have the expected masses. The remaining 10% of the beta chain in component a corresponds in mass to the beta chain plus methionine. In component b, both alpha and beta chains have the correct masses without detectable N-terminal methionine (< 2%). These results have been confirmed by Edman degradation studies of the amino-terminal sequences of the alpha and beta chains of these two recombinant Hb (rHb) samples. rHbs from components a and b exhibit visible optical spectra identical to that of human normal adult Hb (Hb A). Component a and Hb A have very similar oxygen-binding properties, but component b shows somewhat altered oxygen binding, especially at low pH values. 1H-NMR spectra of component a and Hb A are essentially identical, whereas those of component b exhibit altered ring current-shifted and hyperfine-shifted proton resonances, indicating altered heme conformation in the beta chain. These altered resonance patterns can be changed to those of Hb A by converting component b to the ferric state and then to the deoxy state and finally back to either the carbonmonoxy or oxy form. Thus, our E. coli expression system produces native, unmodified Hb A in high yield and can be used to produce desired mutant Hbs. PMID:8367471

Shen, T J; Ho, N T; Simplaceanu, V; Zou, M; Green, B N; Tam, M F; Ho, C

1993-01-01

319

Response of Escherichia coli growth rate to osmotic shock  

PubMed Central

It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless “stored” growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan. PMID:24821776

Rojas, Enrique; Theriot, Julie A.; Huang, Kerwyn Casey

2014-01-01

320

Virulence factors in Escherichia coli urinary tract infection.  

PubMed Central

Uropathogenic strains of Escherichia coli are characterized by the expression of distinctive bacterial properties, products, or structures referred to as virulence factors because they help the organism overcome host defenses and colonize or invade the urinary tract. Virulence factors of recognized importance in the pathogenesis of urinary tract infection (UTI) include adhesins (P fimbriae, certain other mannose-resistant adhesins, and type 1 fimbriae), the aerobactin system, hemolysin, K capsule, and resistance to serum killing. This review summarizes the virtual explosion of information regarding the epidemiology, biochemistry, mechanisms of action, and genetic basis of these urovirulence factors that has occurred in the past decade and identifies areas in need of further study. Virulence factor expression is more common among certain genetically related groups of E. coli which constitute virulent clones within the larger E. coli population. In general, the more virulence factors a strain expresses, the more severe an infection it is able to cause. Certain virulence factors specifically favor the development of pyelonephritis, others favor cystitis, and others favor asymptomatic bacteriuria. The currently defined virulence factors clearly contribute to the virulence of wild-type strains but are usually insufficient in themselves to transform an avirulent organism into a pathogen, demonstrating that other as-yet-undefined virulence properties await discovery. Virulence factor testing is a useful epidemiological and research tool but as yet has no defined clinical role. Immunological and biochemical anti-virulence factor interventions are effective in animal models of UTI and hold promise for the prevention of UTI in humans. Images PMID:1672263

Johnson, J R

1991-01-01

321

Binding of collagens to an enterotoxigenic strain of Escherichia coli  

SciTech Connect

An enterotoxigenic strain of Escherichia coli, B34289c, has been shown to bind the N-terminal region of fibronectin with high affinity. We now report that this strain also binds collagen. The binding of 125I-labeled type II collagen to bacteria was time dependent and reversible. Bacteria expressed a limited number of collagen receptors (2.2 x 10(4) per cell) and bound collagen with a Kd of 20 nM. All collagen types tested (I to V) as well as all tested cyanogen bromide-generated peptides (alpha 1(I)CB2, alpha 1(I)CB3, alpha 1(I)CB7, alpha 1(I)CB8, and alpha 2(I)CB4) were recognized by bacterial receptors, as demonstrated by the ability of these proteins to inhibit the binding of 125I-labeled collagen to bacteria. Of several unlabeled proteins tested in competition experiments, fibronectin and its N-terminal region strongly inhibited binding of the radiolabeled collagen to E. coli cells. Conversely, collagen competed with an 125I-labeled 28-kilodalton fibronectin fragment for bacterial binding. Collagen bound to bacteria could be displaced by excess amounts of either unlabeled fibronectin or its N-terminal fragment. Similarly, collagen could displace 125I-labeled N-terminal peptide of fibronectin bound to the bacterial cell surface. Bacteria grown at 41 degrees C or in the presence of glucose did not express collagen or fibronectin receptors. These results indicate the presence of specific binding sites for collagen on the surface of E. coli cells and furthermore that the collagen and fibronectin binding sites are located in close proximity, possibly on the same structure.

Visai, L.; Speziale, P.; Bozzini, S. (Univ. of Pavia (Italy))

1990-02-01

322

Inhibition of Escherichia coli ATP synthase by amphibian antimicrobial peptides.  

PubMed

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

Laughlin, Thomas F; Ahmad, Zulfiqar

2010-04-01

323

Expression of a Streptococcus mutans glucosyltransferase gene in Escherichia coli.  

PubMed Central

Chromosomal DNA from Streptococcus mutans strain UAB90 (serotype c) was cloned into Escherichia coli K-12. The clone bank was screened for any sucrose-hydrolyzing activity by selection for growth on raffinose in the presence of isopropyl-beta-D-thiogalactoside. A clone expressing an S. mutans glucosyltransferase was identified. The S. mutans DNA encoding this enzyme is a 1.73-kilobase fragment cloned into the HindIII site of plasmid pBR322. We designated the gene gtfA. The plasmid-encoded gtfA enzyme, a 55,000-molecular-weight protein, is synthesized at 40% the level of pBR322-encoded beta-lactamase in E. coli minicells. Using sucrose as substrate, the gtfA enzyme catalyzes the formation of fructose and a glucan with an apparent molecular weight of 1,500. We detected the gtfA protein in S. mutans cells with antibody raised against the cloned gtfA enzyme. Immunologically identical gtfA protein appears to be present in S. mutans cells of serotypes c, e, and f, and a cross-reacting protein was made by serotype b cells. Proteins from serotype a, g, and d S. mutans cells did not react with antibody to gtfA enzyme. The gtfA activity was present in the periplasmic space of E. coli clones, since 15% of the total gtfA activity was released by cold osmotic shock and the clones were able to grow on sucrose as sole carbon source. Images PMID:6217191

Robeson, J P; Barletta, R G; Curtiss, R

1983-01-01

324

Modifying thermostability of appA from Escherichia coli.  

PubMed

In order to improve the thermostability of Escherichia coli AppA phytase, Error-prone PCR was used to randomize mutagenesis appA gene, and a gene mutation library was constructed. A mutant I408L was selected from the library by the method of high-throughput screening with 4-methyl-umbelliferylphosphate (4-MUP). The appA gene of the mutant was cloned and expressed in E. coli Origami (DE3). The recombinant protein was purified by Ni-affinity chromatography, and the enzymatic features were analyzed. The results indicated that AppA phytase activities of mutant I408L and wild-type (WT) strain remained at 51.3 and 28%, respectively, after treatment at 85°C for 5 min. It means that the thermostability enhancement of AppA phytase I408L was 23.3% more as compared with WT. The K (m) of both phytase were 0.18 and 0.25 mM, respectively, which indicated that the catalyzing efficiency of I408L was improved. AppA phytase of mutant I408L showed a significant enhancement against trypsin, which was nearly three times compared with WT. In addition, AppA phytase of mutant could be activated by Mg(2+) and Mn(2+); in contrast, it could be inhibited by Ca(2+), Co(2+), Cu(2+), and K(+) in varying degrees, and the enzymatic activity was almost lost the presence of Fe(3+) and Zn(2+). It appears that screening thermotolerant phytase of E. coli by high throughput screening with a fluorescence substrate is a fast, simple, and effective method. The mutant I408L obtained in this study could be used for the large-scale commercial production of phytase. PMID:20213104

Zhu, Weihua; Qiao, Dairong; Huang, Min; Yang, Ge; Xu, Hui; Cao, Yi

2010-10-01

325

Genomic islands of uropathogenic Escherichia coli contribute to virulence.  

PubMed

Uropathogenic Escherichia coli (UPEC) strain CFT073 contains 13 large genomic islands ranging in size from 32 kb to 123 kb. Eleven of these genomic islands were individually deleted from the genome, and nine isogenic mutants were tested for their ability to colonize the CBA/J mouse model of ascending urinary tract infection. Three genomic island mutants (Delta PAI-aspV, Delta PAI-metV, and Delta PAI-asnT) were significantly outcompeted by wild-type CFT073 in the bladders and/or kidneys following transurethral cochallenge (P coli strains but absent from E. coli K-12. We have shown that, in addition to encoding virulence genes, genomic islands contribute to the overall fitness of UPEC strain CFT073 in vivo. PMID:19329634

Lloyd, Amanda L; Henderson, Tiffany A; Vigil, Patrick D; Mobley, Harry L T

2009-06-01

326

From cholera to enterotoxigenic Escherichia coli (ETEC) vaccine development  

PubMed Central

It was shown earlier that immune responses against cholera toxin (CT) as well as Vibrio cholerae lipopolysaccharide (LPS) or whole bacterial cells (WC) were protective and that these different antibody specificities co-operated synergistically for protection against experimental cholera. Similarly, antibodies against the heat-labile toxin (LT) and major colonization factors (CFs) of enterotoxingenic Escherichia coli (ETEC) co-operated synergistically for protection against LT-producing ETEC expressing homologous CFs. Studies in humans revealed that repeated oral antigen administration was optimal in inducing intestinal immune responses. Based on these findings oral inactivated vaccines consisting of toxin antigen and whole cells, i.e. the licensed recombinant cholera B subunit (rCTB)-WC cholera vaccine Dukoral®, and candidate ETEC vaccines have been developed. In different trials the rCTB-WC cholera vaccine has provided very high (85-100%) short term protection, which was significantly higher than that induced by the WC component alone, whereas rCTB-WC and WC alone provided comparable (50-60%), long term protection. An oral ETEC vaccine consisting of rCTB and formalin-inactivated E. coli bacteria expressing major CFs was shown to be safe and immunogenic in adults and children in different countries. The vaccine also induced significant protection against non-mild ETEC diarrhoea, i.e. diarrhoea interfering with daily activity in American travellers but not against ETEC diarrhoea in young children in Egypt. Against this background, a modified ETEC vaccine consisting of recombinant E. coli strains overexpressing the major CFs and a more LT like hybrid toxoid (LCTBA) has been developed. This vaccine will be tested soon alone and together with a mucosal adjuvant, i.e. dmLT, in clinical trials. PMID:21415493

Svennerholm, Ann-Mari

2011-01-01

327

From cholera to enterotoxigenic Escherichia coli (ETEC) vaccine development.  

PubMed

It was shown earlier that immune responses against cholera toxin (CT) as well as Vibrio cholerae lipopolysaccharide (LPS) or whole bacterial cells (WC) were protective and that these different antibody specificities co-operated synergistically for protection against experimental cholera. Similarly, antibodies against the heat-labile toxin (LT) and major colonization factors (CFs) of enterotoxingenic Escherichia coli (ETEC) co-operated synergistically for protection against LT-producing ETEC expressing homologous CFs. Studies in humans revealed that repeated oral antigen administration was optimal in inducing intestinal immune responses. Based on these findings oral inactivated vaccines consisting of toxin antigen and whole cells, i.e. the licensed recombinant cholera B subunit (rCTB)-WC cholera vaccine Dukoral®, and candidate ETEC vaccines have been developed. In different trials the rCTB-WC cholera vaccine has provided very high (85-100%) short term protection, which was significantly higher than that induced by the WC component alone, whereas rCTB-WC and WC alone provided comparable (50-60%), long term protection. An oral ETEC vaccine consisting of rCTB and formalin-inactivated E. coli bacteria expressing major CFs was shown to be safe and immunogenic in adults and children in different countries. The vaccine also induced significant protection against non-mild ETEC diarrhoea, i.e. diarrhoea interfering with daily activity in American travellers but not against ETEC diarrhoea in young children in Egypt. Against this background, a modified ETEC vaccine consisting of recombinant E. coli strains overexpressing the major CFs and a more LT like hybrid toxoid (LCTBA) has been developed. This vaccine will be tested soon alone and together with a mucosal adjuvant, i.e. dmLT, in clinical trials. PMID:21415493

Svennerholm, Ann-Mari

2011-02-01

328

Use of Miniaturized Protein Arrays for Escherichia coli O Serotyping  

PubMed Central

Serological typing of Escherichia coli O antigens is a well-established method used for differentiation and identification of O serotypes commonly associated with disease. In this feasibility study, we have developed a novel somatic antibody-based miniaturized microarray chip, using 17 antisera, which can be used to detect bound whole-cell E. coli antigen with its corresponding immobilized antibody, to assess the feasibility of this approach. The chip was tested using the related 17 control strains, and the O types found by the microarray chip showed 100% correlation with the O types found by conventional typing. A blind trial was performed in which 100 E. coli isolates that had been O serotyped previously by the conventional assay were tested by the array approach. Overall, the O serotypes of 88% of isolates were correctly identified by the microarray method. For several isolates, ambiguity of O-type designation by microarray arose due to increased sensitivity of this method, allowing signal intensities of cross-reactions to be quantified. Investigation of discrepancies between conventional and microarray O serotyping indicated that some isolates upon storage had become untypeable and, therefore, gave poor signal intensity when tested by the microarray or retested by conventional means. For all 20 serotype O26 and O157 isolates, the apparent discrepancy in O serotyping was analyzed further by a third independent test, which confirmed the microarray results. Therefore, the use of miniaturized protein arrays increases the speed and efficiency of O serotyping in a cost-effective manner, and these preliminary findings suggest the microarray approach may have a higher accuracy than those of traditional O-serotyping methods. PMID:16682477

Anjum, Muna F.; Tucker, James D.; Sprigings, Katherine A.; Woodward, Martin J.; Ehricht, Ralf

2006-01-01

329

Genome Sequences of Two Copper-Resistant Escherichia coli Strains Isolated from Copper-Fed Pigs  

PubMed Central

The draft genome sequences of two copper-resistant Escherichia coli strains were determined. These had been isolated from copper-fed pigs and contained additional putative operons conferring copper and other metal and metalloid resistances. PMID:25540351

Lüthje, Freja L.; Hasman, Henrik; Aarestrup, Frank M.; Alwathnani, Hend A.

2014-01-01

330

Chromosome Partitioning in Escherichia coli in the Absence of Dam-Directed Methylation  

PubMed Central

Escherichia coli dam mutants, lacking the GATC DNA methylase, do not produce anucleate cells at high frequencies, suggesting that hemimethylation of the chromosome origin of replication, oriC, is not essential for correct chromosome partitioning. PMID:1551854

Vinella, Daniel; Jaffé, Aline; D'ari, Richard; Kohiyama, Masamichi; Hughes, Patrick

1992-01-01

331

Novel function and regulation of mutagenic DNA polymerases in Escherichia coli  

E-print Network

The observation that mutations in the Escherichia coli genes umuC+ and umuD+ abolish mutagenesis induced by UV-light strongly supported the counterintuitive notion that such mutagenesis is an active rather than passive ...

Jarosz, Daniel F

2007-01-01

332

Advanced Genomic Engineering Strategy based on Recombineering Protocols to “Tailor” Escherichia coli Strains.  

E-print Network

??A systematic approach based on bacteriophage Lambda (Lambda Red) and flippase-flippase recognition targets (FLP-FRT) recombinations was proposed for genomic engineering of Escherichia coli. For demonstration… (more)

Sukhija, Karan

2011-01-01

333

Inhibition of Escherichia coli trimethylamine-N-oxide reductase by food preservatives.  

E-print Network

??Trimethylamine-N-oxide (TMA-0) reductase activity of resting cells of Escherichia coli was inhibited by tetrasodium ethylenediaminetetraacetate (Na?EDTA), benzoic acid (BA), and methylparaben (MP). The 50% inhibitory… (more)

Kruk, Mark W.

1981-01-01

334

Enterococcus and Escherichia coli fecal source apportionment with microbial source tracking genetic markers - is it feasible?  

EPA Science Inventory

Fecal pollution is measured in surface waters using culture-based measurements of enterococci and Escherichia coli bacteria. Source apportionment of these two fecal indicator bacteria is an urgent need for prioritizing remediation efforts and quantifying health risks associated...

335

Importance of the Maintenance Pathway in the Regulation of the Activity of Escherichia coli Ribonucleotide Reductase  

E-print Network

Ribonucleotide reductases (RNRs) catalyze the conversion of nucleotides to deoxynucleotides in all organisms. The Escherichia coli class Ia RNR is composed of ? and ? subunits that form an ?[subscript 2]?[subscript 2] ...

Hristova, Daniela

336

Differential decay of Enterococci and Escherichia coli originating from two fecal pollution sources  

EPA Science Inventory

Using in situ subtropical aquatic mesocosms, fecal source (cattle manure versus sewage) was shown to be the most important contributor to differential loss in viability of fecal indicator bacteria (FIB), specifically enterococci in freshwater and Escherichia coli in marine habita...

337

Draft Genome Sequence of Enterotoxigenic Escherichia coli Strain W25K  

PubMed Central

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease in humans and newly weaned pigs. Here, we report the draft genome sequence of ETEC strain W25K, which causes diarrhea in piglets. PMID:24970825

Ren, Wenkai; Liu, Gang; Yin, Jie; Chen, Shuai; Li, Tiejun; Kong, Xiangfeng; Peng, Yuanyi; Hardwidge, Philip R.

2014-01-01

338

Draft Genome Sequence of Enterotoxigenic Escherichia coli Strain W25K.  

PubMed

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease in humans and newly weaned pigs. Here, we report the draft genome sequence of ETEC strain W25K, which causes diarrhea in piglets. PMID:24970825

Ren, Wenkai; Liu, Gang; Yin, Jie; Chen, Shuai; Li, Tiejun; Kong, Xiangfeng; Peng, Yuanyi; Yin, Yulong; Hardwidge, Philip R

2014-01-01

339

Pathogenesis of Afa/Dr Diffusely Adhering Escherichia coli  

PubMed Central

Over the last few years, dramatic increases in our knowledge about diffusely adhering Escherichia coli (DAEC) pathogenesis have taken place. The typical class of DAEC includes E. coli strains harboring AfaE-I, AfaE-II, AfaE-III, AfaE-V, Dr, Dr-II, F1845, and NFA-I adhesins (Afa/Dr DAEC); these strains (i) have an identical genetic organization and (ii) allow binding to human decay-accelerating factor (DAF) (Afa/DrDAF subclass) or carcinoembryonic antigen (CEA) (Afa/DrCEA subclass). The atypical class of DAEC includes two subclasses of strains; the atypical subclass 1 includes E. coli strains that express AfaE-VII, AfaE-VIII, AAF-I, AAF-II, and AAF-III adhesins, which (i) have an identical genetic organization and (ii) do not bind to human DAF, and the atypical subclass 2 includes E. coli strains that harbor Afa/Dr adhesins or others adhesins promoting diffuse adhesion, together with pathogenicity islands such as the LEE pathogenicity island (DA-EPEC). In this review, the focus is on Afa/Dr DAEC strains that have been found to be associated with urinary tract infections and with enteric infection. The review aims to provide a broad overview and update of the virulence aspects of these intriguing pathogens. Epidemiological studies, diagnostic techniques, characteristic molecular features of Afa/Dr operons, and the respective role of Afa/Dr adhesins and invasins in pathogenesis are described. Following the recognition of membrane-bound receptors, including type IV collagen, DAF, CEACAM1, CEA, and CEACAM6, by Afa/Dr adhesins, activation of signal transduction pathways leads to structural and functional injuries at brush border and junctional domains and to proinflammatory responses in polarized intestinal cells. In addition, uropathogenic Afa/Dr DAEC strains, following recognition of ?1 integrin as a receptor, enter epithelial cells by a zipper-like, raft- and microtubule-dependent mechanism. Finally, the presence of other, unknown virulence factors and the way that an Afa/Dr DAEC strain emerges from the human intestinal microbiota as a “silent pathogen” are discussed. PMID:15831825

Servin, Alain L.

2005-01-01

340

Identification of a Glycoprotein Produced by Enterotoxigenic Escherichia coli  

PubMed Central

Enterotoxigenic Escherichia coli (ETEC) strain H10407 is capable of invading epithelial cell lines derived from the human ileocecum and colon in vitro. Two separate chromosomally encoded invasion loci (tia and tib) have been cloned from this strain. These loci direct nonadherent and noninvasive laboratory strains of E. coli to adhere to and invade cultured human intestinal epithelial cells. The tib locus directs the synthesis of TibA, a 104-kDa outer membrane protein that is directly correlated with the adherence and invasion phenotypes. TibA is synthesized as a 100-kDa precursor (preTibA) that must be modified for biological activity. Outer membranes of recombinant E. coli expressing TibA or preTibA were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and blotted to nitrocellulose. The presence of glycoproteins was detected by oxidization of carbohydrates with periodate and labeling with hydrazide-conjugated digoxigenin. Only TibA could be detected as a glycoprotein. Complementation experiments with tib deletion mutants of ETEC strain H10407 demonstrate that the TibA glycoprotein is expressed in H10407, that the entire tib locus is required for TibA synthesis, and that TibA is the only glycoprotein produced by H10407. Protease treatment of intact H10407 cells removes the carbohydrates on TibA, suggesting that they are surface exposed. TibA shows homology with AIDA-I from diffuse-adhering E. coli and with pertactin precursor from Bordetella pertussis. Both pertactin and AIDA-I are members of the autotransporter family of outer membrane proteins and are afimbrial adhesins that play an important role in the virulence of these organisms. Analysis of the predicted TibA amino acid sequence indicates that TibA is also an autotransporter. Analysis of the tib locus DNA sequence revealed an open reading frame with similarity to RfaQ, a glycosyltransferase. The product of this tib locus open reading frame is proposed to be responsible for TibA modification. These results suggest that TibA glycoprotein acts as an adhesin that may participate in the disease process. PMID:10417177

Lindenthal, Christoph; Elsinghorst, Eric A.

1999-01-01

341

The Genome Sequence of Avian Pathogenic Escherichia coli Strain O1:K1:H7 Shares Strong Similarities with Human Extraintestinal Pathogenic E. coli Genomes  

Microsoft Academic Search

Escherichia coli strains that cause disease outside the intestine are known as extraintestinal pathogenic E. coli (ExPEC) and include human uropathogenic E. coli (UPEC) and avian pathogenic E. coli (APEC). Regard- less of host of origin, ExPEC strains share many traits. It has been suggested that these commonalities may enable APEC to cause disease in humans. Here, we begin to

Timothy J. Johnson; Subhashinie Kariyawasam; Yvonne Wannemuehler; Paul Mangiamele; Sara J. Johnson; Curt Doetkott; Jerod A. Skyberg; Aaron M. Lynne; James R. Johnson; Lisa K. Nolan

2007-01-01

342

Short Communication ELUCIDATING THE GENETIC BASIS FOR ESCHERICHIA COLI DEFENSE AGAINST  

E-print Network

.g., salts, colloidal, nanoparticles), released silver ions (Agþ ) are proposed to be the principalShort Communication ELUCIDATING THE GENETIC BASIS FOR ESCHERICHIA COLI DEFENSE AGAINST SILVER and defense mechanisms against silver are poorly understood at the genetic level. A library of Escherichia

Alvarez, Pedro J.

343

Preliminary Characterization of the Transcriptional Response of the Porcine Intestinal Cell Line IPEC-J2 to Enterotoxigenic Escherichia coli, Escherichia coli, and E. coli Lipopolysaccharide  

PubMed Central

IPEC-J2, a promising in vitro model system, is not well characterized especially on the transcriptional level, in contrast to human counterparts. The aim of this study was to characterize the gene expression in IPEC-J2 cells when coincubated with enterotoxigenic Escherichia coli (ETEC), nonpathogenic E. coli, and E. coli endotoxin. Apical infection of polarized IPEC-J2 monolayers caused a time-dependent decrease in transepithelial electrical resistance (TEER). Microarray analysis showed up-regulation of interleukins when IPEC-J2 were cocultured with E. coli strains this has so far never been measured in this cell line. Highest IL8 expression was found with the ETEC strain possessing the F4 fimbrium, suggesting IPEC-J2 cells to be F4 receptor positive, confirmed in a brush border membrane adhesion assay. It is concluded that the innate immune responses to pathogens and LPS makes the IPEC-J2 cell line a suitable model for research on intestinal host pathogen interaction. PMID:21318186

Geens, Marisa M.; Niewold, Theo A.

2010-01-01

344

Transfer of Carbapenem-Resistant Plasmid from Klebsiella pneumoniae ST258 to Escherichia coli in Patient  

PubMed Central

Klebsiella pneumoniae carbapenemase (KPC) 3–producing Escherichia coli was isolated from a carrier of KPC-3–producing K. pneumoniae. The KPC-3 plasmid was identical in isolates of both species. The patient's gut flora contained a carbapenem-susceptible E. coli strain isogenic with the KPC-3–producing isolate, which suggests horizontal interspecies plasmid transfer. PMID:20507761

Goren, Moran G.; Carmeli, Yehuda; Schwaber, Mitchell J.; Chmelnitsky, Inna; Schechner, Vered

2010-01-01

345

Transfer of carbapenem-resistant plasmid from Klebsiella pneumoniae ST258 to Escherichia coli in patient.  

PubMed

Klebsiella pneumoniae carbapenemase (KPC) 3-producing Escherichia coli was isolated from a carrier of KPC-3-producing K. pneumoniae. The KPC-3 plasmid was identical in isolates of both species. The patient's gut flora contained a carbapenem-susceptible E. coli strain isogenic with the KPC-3-producing isolate, which suggests horizontal interspecies plasmid transfer. PMID:20507761

Goren, Moran G; Carmeli, Yehuda; Schwaber, Mitchell J; Chmelnitsky, Inna; Schechner, Vered; Navon-Venezia, Shiri

2010-06-01

346

B R I E F R E P O R T Escherichia coli Dysbiosis Correlates  

E-print Network

in Children With Cystic Fibrosis Lucas R. Hoffman,1,2,6 Christopher E. Pope,1 Hillary S. Hayden,2 Sonya, suggesting that E. coli could con- tribute to cystic fibrosis gastrointestinal dysfunction. Keywords. cystic fibrosis; microbiota; Escherichia coli; in- flammation; malabsorption. The genetic disease cystic fibrosis

Borenstein, Elhanan

347

Comparison of DNA Hybridization and PCR Assays for Detection of Putative Pathogenic Enteroadherent Escherichia coli  

Microsoft Academic Search

The correlation of the different adherence patterns with DNA probes and PCR primers for the identification of Escherichia coli was analyzed in isolates from children, less than 2 years of age with or without diarrhea, from different regions of Brazil. A total of 1,428 isolates obtained from 338 patients and 322 control children were studied. The enteropathogenic E. coli (EPEC)

Isabel C. A. Scaletsky; Sandra H. Fabbricotti; Katia R. Aranda; Mauro B. Morais; Ulysses Fagundes-Neto

2002-01-01

348

Quantitation by enzyme immunoassay of spirosin from Lactobacillus reuteri and Escherichia coli  

Microsoft Academic Search

Three EIA methods (Direct, Indirect and Sandwich EIA) were studied to quantify spirosin in Lactobacillus reuteri and Escherichia coli cultured under various conditions in an attempt to get some insight into the function of spirosome. Both Direct and Indirect EIA were suited well for the quantitation of L. reuteri spirosin while Direct EIA was appropriate for spirosin of E. coli.

Masayuki Yamato; Mie Hayashi; Yasuhisa Shiomoto; Fusao Ota

1997-01-01

349

Identification of Shiga toxigenic Escherichia coli seropathotypes A and B by multiplex PCR  

Microsoft Academic Search

A multiplex PCR assay was developed to identify the six clinically important enterohemorrhagic Escherichia coli (EHEC) serotypes classified in seropathotypes A and B and to differentiate these from Shiga toxigenic E. coli. The assay simultaneously detects genes for Shiga toxin (stx) and intimin (eae), including allelic variants of both genes, 16S internal amplification control, as well as unique sequences in

S. R. Monday; A. Beisaw; P. C. H. Feng

2007-01-01

350

Biofilm exclusion of uropathogenic bacteria by selected asymptomatic bacteriuria Escherichia coli strains  

Microsoft Academic Search

Many bacterial infections are associated with biofilm formation. In the urinary tract bacterial biofilms develop on both living surfaces and artificial implants, producing chronic and often intractable infections. Escherichia coli is the most common organism associated with urinary tract infections. In contrast to uropathogenic E. coli (UPEC), which cause symptomatic urinary tract infection, asymptomatic bacteriuria (ABU) strains are associated with

Lionel Ferrieres; Viktoria Hancock; Per Klemm

2007-01-01

351

Impact of diversity of colonizing strains on strategies for sampling Escherichia coli from fecal specimens.  

PubMed

Of 49 subjects, 21 were colonized with more than one strain of Escherichia coli and 12 subjects had at least one strain present in fewer than 20% of colonies. The ability to accurately characterize E. coli strain diversity is directly related to the number of colonies sampled and the underlying prevalence of the strain. PMID:18650357

Lautenbach, Ebbing; Bilker, Warren B; Tolomeo, Pam; Maslow, Joel N

2008-09-01

352

Physical Basis of Metal-Binding Specificity in Escherichia coli NikR  

E-print Network

In Escherichia coli and other bacteria, nickel uptake is regulated by the transcription factor NikR. Nickel binding at high-affinity sites in E. coli NikR (EcNikR) facilitates EcNikR binding to the nik operon, where it ...

Phillips, Christine M.

353

Presence of adherent Escherichia coli strains in ileal mucosa of patients with Crohn's disease  

Microsoft Academic Search

Background & Aims: Infectious agents are suspected of being involved in the pathogenesis of Crohn's disease. This study was designed to look for the presence of virulent Escherichia coli strains associated with the ileal mucosa of patients with Crohn's disease. Methods:E. coli strains were recovered from resected chronic ileal lesions (n = 20), neoterminal ileum after surgery from patients with

Arlette Darfeuille-Michaud; Christel Neut; Nicolas Barnich; Emmanuel Lederman; Patrick Di Martino; Pierre Desreumaux; Luc Gambiez; Bernard Joly; Antoine Cortot; Jean-Frédéric Colombel

1998-01-01

354

Emergence and Dissemination of Quinolone-Resistant Escherichia coli in the Community  

Microsoft Academic Search

We studied the evolution of resistance to quinolones in Escherichia coli from 1992 to 1997 in Barcelona, Spain. An increasing proportion of quinolone-resistant E. coli (QREC) infections was observed. QREC strains were more common in patients with nosocomial infections but also increased in patients with community- acquired infections (9% in 1992 to 17% in 1996). Seventy (12%) of 572 episodes

JAVIER GARAU; MARIONA XERCAVINS; MONICA RODRIGUEZ-CARBALLEIRA; JOSEP RAMONG OMEZ-VERA; IGNACIO COLL; DOLORS VIDAL; TERESA LLOVET; ANA RUIZ-BREMON

1999-01-01

355

Growth and survival of Escherichia coli and enterococci populations in the macro-alga Cladophora (Chlorophyta)  

Microsoft Academic Search

The macro-alga Cladophora glomerata is found in streams and lakes worldwide. High concentrations of Escherichia coli and enterococci have been reported in Cladophora along the Lake Michigan shore. The objective of this study was to determine if Cladophora supported growth of these indicator bacteria. Algal leachate readily supported in vitro multiplication of E. coli and enterococci, suggesting that leachates contain

Muruleedhara N Byappanahalli; Dawn A Shively; Meredith B Nevers; Michael J Sadowsky; Richard L Whitman

2003-01-01

356

Draft Genome Sequence of Escherichia coli W26, an Enteric Strain Isolated from Cow Feces  

PubMed Central

An enteric bacterium, Escherichia coli W26 (KACC 16630), was isolated from feces from a healthy cow in South Korea. Here, we report the draft genome sequence of the isolate, which is closely affiliated with commensal strains belonging to E. coli phylogroup B1. PMID:22933771

Kim, Mincheol; Yi, Hana; Cho, Yong-Joon; Jang, Jeonghwan; Hur, Hor-Gil

2012-01-01

357

Complete Genome Sequence of Enterotoxigenic Escherichia coli N4-Like Podophage Pollock  

PubMed Central

Enterotoxigenic Escherichia coli is a multidrug-resistant bacterium that is well known for its ability to cause diarrhea in humans. Bacteriophages may be used to treat clinical cases involving bacterial dysentery. Here, we present the complete genome sequence of an enterotoxigenic E. coli phage, Pollock, an N4-like podophage. PMID:25635029

Patel, Roosheel S.; Lessor, Lauren E.; Hernandez, Adriana C.

2015-01-01

358

ESCHERICHIA COLI O157:H7 AND SALMONELLA IN WHITE-TAILED DEER AND LIVESTOCK  

Technology Transfer Automated Retrieval System (TEKTRAN)

Escherichia coli O157 and Salmonella spp. are among the leading causes of food-borne illness in the United States and these bacteria have been isolated from numerous ruminant animal sources. The objective of this study was to assess the incidence of E. coli O157 and Salmonella spp. in white-tailed ...

359

Characterization and Genome Sequencing of a Novel Coliphage Isolated from Engineered Escherichia coli  

Microsoft Academic Search

Objectives: To characterize morphological, physicochemical and genomic features of a novel virulent coliphage which was isolated from an engineered Escherichia coli culture and termed engineered E. coli phage (EEP). Methods and Results: Electron microscopy revealed that EEP has an icosahedral head (62 nm in diameter) and a long, flexible tail (138 nm in length). EEP was able to infect all

Shu Li; Lina Liu; Junmin Zhu; Lingyun Zou; Ming Li; Yanguang Cong; Xiancai Rao; Xiaomei Hu; Yingbing Zhou; Zhijin Chen; Fuquan Hu

2010-01-01

360

Detection and Recovery of Shiga Toxins and Escherichia Coli O157  

Technology Transfer Automated Retrieval System (TEKTRAN)

Shiga toxin-producing Escherichia coli (STEC) are among the most costly foodborne pathogens. In the United States, recent annual cost estimates for acute care ranged from $1 to $2 billion. These were based on the assumption that E. coli O157:H7 led to 73,000 illnesses and 61 deaths each year. The pa...

361

Flow-cytometric study of vital cellular functions in Escherichia coli during solar disinfection (SODIS)  

Microsoft Academic Search

The effectiveness of solar disinfection (SODIS), a low-cost household water treatment method for developing countries, was investigated with flow cytometry and viability stains for the enteric bacterium Escherichia coli. A better understanding of the process of injury or death of E. coli during SODIS could be gained by investigating six different cellular functions, namely: efflux pump activity (Syto 9 plus

Michael Berney; Hans-Ulrich Weilenmann; Thomas Egli

2006-01-01

362

Complete Genome Sequences of Two Escherichia coli O145:H28 Outbreak Strains of Food Origin.  

PubMed

Escherichia coli O145:H28 strain RM12581 was isolated from bagged romaine lettuce during a 2010 U.S. lettuce-associated outbreak. E. coli O145:H28 strain RM12761 was isolated from ice cream during a 2007 ice cream-associated outbreak in Belgium. Here we report the complete genome sequences and annotation of both strains. PMID:24855308

Cooper, Kerry K; Mandrell, Robert E; Louie, Jacqueline W; Korlach, Jonas; Clark, Tyson A; Parker, Craig T; Huynh, Steven; Chain, Patrick S G; Ahmed, Sanaa; Carter, Michelle Qiu

2014-01-01

363

Complete Genome Sequence of Enterotoxigenic Escherichia coli N4-Like Podophage Pollock.  

PubMed

Enterotoxigenic Escherichia coli is a multidrug-resistant bacterium that is well known for its ability to cause diarrhea in humans. Bacteriophages may be used to treat clinical cases involving bacterial dysentery. Here, we present the complete genome sequence of an enterotoxigenic E. coli phage, Pollock, an N4-like podophage. PMID:25635029

Patel, Roosheel S; Lessor, Lauren E; Hernandez, Adriana C; Kuty Everett, Gabriel F

2015-01-01

364

Characterization of a Hemoglobin Protease Secreted by the Pathogenic Escherichia coli Strain EB1  

Microsoft Academic Search

Summary Many pathogenic bacteria can use heme compounds as a source of iron. Pathogenic Escherichia coli strains are capable of using hemoglobin as an iron source. However, the mechanism of heme acquisition from hemoglobin is not understood for this microorganism. We present the first molecular characterization of a hemoglobin protease (Hbp) from a human pathogenic E. coli strain. The enzyme

Ben R. Otto; Silvy J. M. van Dooren; Jan H. Nuijens; Joen Luirink; Bauke Oudega

365

Enhancement of the Antibiotic Activity against a Multiresistant Escherichia coli by Mentha arvensis L. and Chlorpromazine  

Microsoft Academic Search

Background: This is the first report testing the antibiotic resistance-modifying activity of Mentha arvensis. Methods: In this study an ethanol extract of M. arvensis L. and chlorpromazine were tested for their antimicrobial activity alone or in combination with conventional antibiotics against strains of Escherichia coli. Results: The growth of two E. coli strains tested was not inhibited by the extract.

Henrique D. M. Coutinho; José G. M. Costa; Edeltrudes O. Lima; Vivyanne S. Falcão-Silva; José P. Siqueira-Júnior

2008-01-01

366

DETECTION OF ESCHERICHIA COLI IN WATER USING A COLORIMETRIC GENE PROBE ASSAY  

EPA Science Inventory

A commercially available DNA hydribization assay (Gene-trak , Framingham, MA. USA) was compared with the EC-MUG procedure for the detection of Escherichia coli in water. The gene probe gave positive responses for pure cultures of E. coli 0157:H7, E. fergusonii, Shigella sonnei, S...

367

Complete Genome Sequences of Two Escherichia coli O145:H28 Outbreak Strains of Food Origin  

PubMed Central

Escherichia coli O145:H28 strain RM12581 was isolated from bagged romaine lettuce during a 2010 U.S. lettuce-associated outbreak. E. coli O145:H28 strain RM12761 was isolated from ice cream during a 2007 ice cream-associated outbreak in Belgium. Here we report the complete genome sequences and annotation of both strains. PMID:24855308

Cooper, Kerry K.; Mandrell, Robert E.; Louie, Jacqueline W.; Korlach, Jonas; Clark, Tyson A.; Parker, Craig T.; Huynh, Steven; Chain, Patrick S. G.; Ahmed, Sanaa

2014-01-01

368

Synergistic induction of the heat shock response in Escherichia coli by simultaneous treatment with chemical inducers.  

PubMed

Escherichia coli strains carrying transcriptional fusions of four sigma 32-controlled E. coli heat shock promoters to luxCDABE or lacZ reporter genes were stressed by chemicals added singly or in pairs. Much more than additive induction resulted from combinations of cadmium chloride, copper sulfate, ethanol, formamide, 4-nitrophenol, and pentachlorophenol. PMID:7592357

Van Dyk, T K; Reed, T R; Vollmer, A C; LaRossa, R A

1995-10-01

369

Survival of Escherichia coli in the environment: fundamental and public health aspects  

Microsoft Academic Search

In this review, our current understanding of the species Escherichia coli and its persistence in the open environment is examined. E. coli consists of six different subgroups, which are separable by genomic analyses. Strains within each subgroup occupy various ecological niches, and can be broadly characterized by either commensalistic or different pathogenic behaviour. In relevant cases, genomic islands can be

Jan Dirk van Elsas; Alexander V Semenov; Rodrigo Costa; Jack T Trevors; JD van Elsas

2011-01-01

370

Translocation of Shiga-toxin producting cells of Escherichia coli in chemically-injected beef subprimals  

Technology Transfer Automated Retrieval System (TEKTRAN)

Introduction: Relatively little information is available regarding the translocation of Escherichia coli O157:H7 (ECOH) and non-O157:H7 verocytotoxigenic E. coli (STEC) into beef subprimals following chemical tenderization. Purpose: Quantify translocation of ECOH or STEC from the surface into the i...

371

Enhanced Display of Lipase on the Escherichia coli Cell Surface, Based on Transcriptome Analysis? †  

PubMed Central

A cell surface display system was developed using Escherichia coli OmpC as an anchoring motif. The fused Pseudomonas fluorescens SIK W1 lipase was successfully displayed on the surface of E. coli cells, and the lipase activity could be enhanced by the coexpression of the gadBC genes identified by transcriptome analysis. PMID:19948866

Baek, Jong Hwan; Han, Mee-Jung; Lee, Seung Hwan; Lee, Sang Yup

2010-01-01

372

Metabolite profiling of foodborne disease significance – case study Escherichia coli O157  

Technology Transfer Automated Retrieval System (TEKTRAN)

In the United States, Escherichia coli (E. coli) O157 infection, associated with the consumption of contaminated ground beef, has resulted in an unnecessary burden for both the meat industry and the health care system, with meat recalls and often fatal human disease. Cattle, the primary reservoirs f...

373

Antibiotic resistant Escherichia coli and Salmonella enterica in the beef production and processing chain  

Technology Transfer Automated Retrieval System (TEKTRAN)

Background: Concerns have been raised that extended-spectrum cephalosporin-resistant Escherichia coli (CefR EC), trimethoprim-sulfamethoxazole-resistant E. coli (TxsR EC), extended-spectrum cephalosporin-resistant Salmonella enterica (CefR SE), and nalidixic acid-resistant S. enterica (NalR SE) in c...

374

ESCHERICHIA COLI AND TOTAL COLIFORMS IN WATER AND SEDIMENTS AT LAKE MARINAS  

EPA Science Inventory

Escherichia coli, a fecal coliform, and total coliforms were monitored between September 1999 to October 2001 in five marinas on Lake Texoma, located on the Oklahoma and Texas border. General trend was that densities of E. coli were lower in the summer season due to the lower ...

375

Evaluation of Select Sensors for Real-Time Monitoring of Escherichia coli in Water Distribution Systems?  

PubMed Central

This study evaluated real-time sensing of Escherichia coli as a microbial contaminant in water distribution systems. Most sensors responded to increased E. coli concentrations, showing that select sensors can detect microbial water quality changes and be utilized as part of a contaminant warning system. PMID:21357435

Miles, Syreeta L.; Sinclair, Ryan G.; Riley, Mark R.; Pepper, Ian L.

2011-01-01

376

Hamster (Mesocricetus auratus) enteritis caused by epithelial cell-invasive Escherichia coli.  

PubMed Central

When inoculated orally, Escherichia coli strain 1056 caused acute enteritis in 7 of 22 weanling hamsters. E. coli strain 1056 was isolated from the ileum of a hamster with proliferative ileitis. It was lactose negative, nonmotile, and anaerogenic. By electron microscopy and indirect fluorescent-antibody techniques, E. coli strain 1056 was detected in absorptive epithelial cells, resembling invasive E. coli and shigella infections of other species. Ileitis did not progress to epithelial cell hyperplasia, which is characteristic of proliferative ileitis of hamsters. A control group of 10 hamsters, inoculated with nonenteropathogenic E. coli isolated from a normal hamster, did not develop signs or lesions. Images PMID:7014460

Frisk, C S; Wagner, J E; Owens, D R

1981-01-01

377

Structure of Escherichia coli Hfq bound to polyriboadenylate RNA  

PubMed Central

Hfq is a small, highly abundant hexameric protein that is found in many bacteria and plays a critical role in mRNA expression and RNA stability. As an “RNA chaperone,” Hfq binds AU-rich sequences and facilitates the trans annealing of small RNAs (sRNAs) to their target mRNAs, typically resulting in the down-regulation of gene expression. Hfq also plays a key role in bacterial RNA decay by binding tightly to polyadenylate [poly(A)] tracts. The structural mechanism by which Hfq recognizes and binds poly(A) is unknown. Here, we report the crystal structure of Escherichia coli Hfq bound to the poly(A) RNA, A15. The structure reveals a unique RNA binding mechanism. Unlike uridine-containing sequences, which bind to the “proximal” face, the poly(A) tract binds to the “distal” face of Hfq using 6 tripartite binding motifs. Each motif consists of an adenosine specificity site (A site), which is effected by peptide backbone hydrogen bonds, a purine nucleotide selectivity site (R site), and a sequence-nondiscriminating RNA entrance/exit site (E site). The resulting implication that Hfq can bind poly(A-R-N) triplets, where R is a purine nucleotide and N is any nucleotide, was confirmed by binding studies. Indeed, Hfq bound to the oligoribonucleotides (AGG)8, (AGC)8, and the shorter (A-R-N)4 sequence, AACAACAAGAAG, with nanomolar affinities. The abundance of (A-R-N)4 and (A-R-N)5 triplet repeats in the E. coli genome suggests additional RNA targets for Hfq. Further, the structure provides insight into Hfq-mediated sRNA-mRNA annealing and the role of Hfq in RNA decay. PMID:19889981

Link, Todd M.; Valentin-Hansen, Poul; Brennan, Richard G.

2009-01-01

378

Purification of the membrane-bound hydrogenase of Escherichia coli.  

PubMed Central

The membrane-bound hydrogenase (EC class 1.12) of aerobically grown Escherichia coli cells was solubilized by treatment with deoxycholate and pancreatin. The enzyme was further purified to electrophoretic homogeneity by chromoatographic methods, including hydrophobic-interaction chromatography, with a yield of 10% as judged by activity and an overall purification of 2140-fold. The hydrogenase was a dimer of identical subunits with a mol.wt. of 113,000 and contained 12 iron and 12 acid-labile sulphur atoms per molecule. The epsilon 400 was 49,000M-1 . cm-1. The hydrogenase catalysed both H2 evolution and H2 uptake with a variety of artificial electron carriers, but would not interact with flavodoxin, ferredoxin or nicotinamide and flavin nucleotides. We were unable to identify any physiological electron carrier for the hydrogenase. With Methyl Viologen as the electron carrier, the pH optimum for H2 evolution and H2 uptake was 6.5 and 8.5 respectively. The enzyme was stable for long periods at neutral pH, low temperatures and under anaerobic conditions. The half-life of the hydrogenase under air at room temperature was about 12 h, but it could be stabilized by Methyl Viologen and Benzyl Viologen, both of which are electron carriers for the enzyme, and by bovine serum albumin. The hydrogenase was strongly inhibited by carbon monoxide (Ki = 1870Pa), heavy-metal salts and high concentrations of buffers, but was resistant to inhibition by thiol-blocking and metal-complexing reagents. These aerobically grown E. coli cells lacked formate hydrogenlyase activity and cytochrome c552. PMID:393247

Adams, M W; Hall, D O

1979-01-01

379

The nac (nitrogen assimilation control) gene from Escherichia coli.  

PubMed

The nitrogen assimilation control gene, nac, was detected in Escherichia coli but not in Salmonella typhimurium by Southern blotting, using a probe from the Klebsiella aerogenes nac (nacK) gene. The E. coli nac gene (nacE) was isolated from a cosmid clone by complementation of a nac mutation in K. aerogenes. nacE was fully functional in this complementation assay. DNA sequence analysis showed considerable divergence between nacE and nacK, with a predicted amino acid sequence identity of only 79% and most of the divergence in the C-terminal half of the protein sequence. The total predicted size of NAC(E) is 305 amino acids, the same as for NAC(K). A null mutation, nac-28, was generated by reverse genetics. Mutants bearing nac-28 have a variety of phenotypes related to nitrogen metabolism, including slower growth on cytosine, faster growth on arginine, and suppression of the failure of an Ntr-constitutive mutant to grow with serine as sole nitrogen source. In addition to a loss of nitrogen regulation of histidase formation, nac-28 mutants also showed a loss of a weak repression of glutamate dehydrogenase formation. This repression was unexpected because it is balanced by a NAC-independent activation of glutamate dehydrogenase formation during nitrogen-limited growth. Attempts to purify NAC(E) by using methods established for NAC(K) failed, and NAC(E) appears to be degraded with a half-life at 30 degrees C as short as 15 min during inhibition of protein synthesis. PMID:9495755

Muse, W B; Bender, R A

1998-03-01

380

Cadmium Toxicity in Glutathione Mutants of Escherichia coli? †  

PubMed Central

The higher affinity of Cd2+ for sulfur compounds than for nitrogen and oxygen led to the theoretical consideration that cadmium toxicity should result mainly from the binding of Cd2+ to sulfide, thiol groups, and sulfur-rich complex compounds rather than from Cd2+ replacement of transition-metal cations from nitrogen- or oxygen-rich biological compounds. This hypothesis was tested by using Escherichia coli for a global transcriptome analysis of cells synthesizing glutathione (GSH; wild type), ?-glutamylcysteine (?gshB mutant), or neither of the two cellular thiols (?gshA mutant). The resulting data, some of which were validated by quantitative reverse transcription-PCR, were sorted using the KEGG (Kyoto Encyclopedia of Genes and Genomes) orthology system, which groups genes hierarchically with respect to the cellular functions of their respective products. The main difference among the three strains concerned tryptophan biosynthesis, which was up-regulated in wild-type cells upon cadmium shock and strongly up-regulated in ?gshA cells but repressed in ?gshB cells containing ?-glutamylcysteine instead of GSH. Overall, however, all three E. coli strains responded to cadmium shock similarly, with the up-regulation of genes involved in protein, disulfide bond, and oxidative damage repair; cysteine and iron-sulfur cluster biosynthesis; the production of proteins containing sensitive iron-sulfur clusters; the storage of iron; and the detoxification of Cd2+ by efflux. General energy conservation pathways and iron uptake were down-regulated. These findings indicated that the toxic action of Cd2+ indeed results from the binding of the metal cation to sulfur, lending support to the hypothesis tested. PMID:18539742

Helbig, Kerstin; Grosse, Cornelia; Nies, Dietrich H.

2008-01-01

381

Characterization of Plant ?-Ureidopropionase and Functional Overexpression in Escherichia coli  

PubMed Central

Pyrimidine bases are rapidly catabolized in growing plant tissues. The final enzyme of the catabolic pathway, ?-ureidopropionase (?-UP; EC 3.5.1.6), was partially purified from the shoots of etiolated maize (Zea mays) seedlings. The enzyme had a Km for ?-ureidopropionate (the substrate derived from uracil) of 11 ?m. Only one enantiomer of racemic ?-ureidoisobutyrate (derived from thymine) was processed with a Km of 6 ?m. The enzyme was inactivated by dialysis against 1,10-phenanthroline and activity could be partially restored by addition of Zn2+. Maize ?-UP was very sensitive to inactivation by iodoacetamide. This could be prevented by addition of substrate, indicating the presence of an active site Cys. The enzyme was strongly inhibited by short chain aliphatic acids and aryl propionates, the most potent inhibitor of which was 2-(2, 6-dinitrophenoxy)-propionate (I50 = 0.5 ?m). A gene for Arabidopsis ?-UP encodes a polypeptide of 405 amino acids and has about 55% homology with the enzymes from other eukaryotic organisms. Several highly conserved residues link the plant ?-UP with a larger class of prokaryotic and eukaryotic amidohydrolases. An Arabidopsis cDNA truncated at the N terminus by 14 residues was cloned and overexpressed in Escherichia coli. The recombinant enzyme (43.7 kD) was soluble, functional, and purified to homogeneity with yields of 15 to 20 mg per 30 g fresh weight of E. coli cells. The recombinant enzyme from Arabidopsis and the native enzyme from maize had molecular masses of approximately 440 kD, indicating the enzyme is a decamer at pH 7. PMID:11161056

Walsh, Terence A.; Green, Susan B.; Larrinua, Ignacio M.; Schmitzer, Paul R.

2001-01-01

382

Control of rRNA transcription in Escherichia coli.  

PubMed Central

The control of rRNA synthesis in response to both extra- and intracellular signals has been a subject of interest to microbial physiologists for nearly four decades, beginning with the observations that Salmonella typhimurium cells grown on rich medium are larger and contain more RNA than those grown on poor medium. This was followed shortly by the discovery of the stringent response in Escherichia coli, which has continued to be the organism of choice for the study of rRNA synthesis. In this review, we summarize four general areas of E. coli rRNA transcription control: stringent control, growth rate regulation, upstream activation, and anti-termination. We also cite similar mechanisms in other bacteria and eukaryotes. The separation of growth rate-dependent control of rRNA synthesis from stringent control continues to be a subject of controversy. One model holds that the nucleotide ppGpp is the key effector for both mechanisms, while another school holds that it is unlikely that ppGpp or any other single effector is solely responsible for growth rate-dependent control. Recent studies on activation of rRNA synthesis by cis-acting upstream sequences has led to the discovery of a new class of promoters that make contact with RNA polymerase at a third position, called the UP element, in addition to the well-known -10 and -35 regions. Lastly, clues as to the role of antitermination in rRNA operons have begun to appear. Transcription complexes modified at the antiterminator site appear to elongate faster and are resistant to the inhibitory effects of ppGpp during the stringent response. PMID:8531889

Condon, C; Squires, C; Squires, C L

1995-01-01

383

Pyrosequencing of the Vir plasmid of necrotoxigenic Escherichia coli.  

PubMed

Necrotoxigenic Escherichia coli, or NTEC, are defined as E. coli producing the toxin known as cytotoxic necrotizing factor, or CNF. NTEC are responsible for various diseases of humans and animals, including urinary tract infection, septicemia, and diarrhea. A subgroup of NTEC known as NTEC-2 produce a variant of CNF (CNF-2) whose gene is located on a plasmid known as Vir. Because of its involvement in NTEC-2 pathogenesis and its broad distribution among production animals, a Vir plasmid from a bovine NTEC-2 strain was sequenced and analyzed. This plasmid was found to belong to the RepFIB and RepFIIA replicon types, and it totaled 138,682 base pairs in size. Within this plasmid was an approximately 60-kb pathogenicity island, defined by its possession of multiple virulence factors within distinct genetic regions of lower G+C content bounded by inverted repeats. Within this PAI were a variety of putative virulence factors, including F17b fimbrial genes, genes of a novel fimbrial operon, tibAC, hemolysins, and the cnf2 and cdt toxin-encoding genes. The occurrence of this plasmid's virulence- and replication-associated genes was sought among a collection of 96 CNF-2-positive isolates. The most prevalent genes among this collection included repA (RepFIB), cnf2, an ompP homolog, and the tib-AC genes encoding for aggregation and biofilm formation. The Vir plasmid has evolved from an IncFIB ancestral backbone, with the RepFIB locus apparently driving the acquisition of its accessory virulence-associated elements via site-specific recombination. Overall, the completed sequence of a Vir plasmid increases our understanding of NTEC-2 pathogenomics and IncFIB plasmid evolution. PMID:20060660

Johnson, Timothy J; DebRoy, Chitrita; Belton, Shayla; Williams, Michele L; Lawrence, Mark; Nolan, Lisa K; Thorsness, Jessica L

2010-07-29

384

Structure and function of Escherichia coli endonuclease III  

SciTech Connect

One of the most exciting areas of atomic structural studies on protein-DNA interactions has been the studies on on DNA repair enzymes. The atomic structures of endonuclease III and endonuclease V, a phage T4 enzyme that repairs pyrimidine dimers, are a significant advance, as they provide the first structural information concerning the mechanism by which enzymes can recognize altered bases in DNA. Endonuclease III from Escherichia coli is a DNA repair enzyme with two distinct activities: it is a DNA N-glycosylase that acts upon ring-saturated, ring-rearranged, and ring-contracted pyrimidines and is an AP lyase. The name endonuclease III was originally applied to an activity that nicked heavily UV-irradiated DNA. The enzyme was found to be identical with E. coli x-ray endonuclease, with an endonuclease that cleaves DNA damaged by UV irradiation, osmium tetroxide, x-rays, or acid, and with urea-DNA glycosylase. The identification of endonuclease III with these various other activities is due to the broad substrate specificity of the enzyme. It has been shown to release dihydrothymine, cis- and trans-thymine glycol, urea, methyltartronylurea and 5-hydroxy-5-methylhydantoin, 6-hydroxy-5,6-dihydrothymine, uracil hydrate, and cytosine hydrate from DNA. Endonuclease III has been shown to be an AP lyase rather than a true AP endonuclease; it cleaves the phosphodiester bond adjacent to an AP site by a {beta}-elimination reaction rather than a hydrolytic reaction. The syn stereochemical course of the {beta}-elimination reaction has been defined: the 2{prime}-pro-S hydrogen is abstracted, and a trans {alpha}{beta}-unsaturated aldose is produced.

Cunningham, R.P.; Ahern, H.; Xing, D. [State Univ. of New York, Albany, NY (United States)] [and others

1994-12-31

385

Conditional lethal amber mutations in essential Escherichia coli genes.  

PubMed

The essential genes of microorganisms encode biological functions important for survival and thus tend to be of high scientific interest. Drugs that interfere with essential functions are likely to be interesting candidates for antimicrobials. However, these genes are hard to study genetically because knockout mutations in them are by definition inviable. We recently described a conditional mutation system in Escherichia coli that uses a plasmid to produce an amber suppressor tRNA regulated by the arabinose promoter. This suppressor was used here in the construction of amber mutations in seven essential E. coli genes. Amber stop codons were introduced as "tagalong" mutations in the flanking DNA of a downstream antibiotic resistance marker by lambda red recombination. The drug marker was removed by expression of I-SceI meganuclease, leaving a markerless mutation. We demonstrate the method with the genes frr, gcpE, lpxC, map, murA, ppa, and rpsA. We were unable to isolate an amber mutation in ftsZ. Kinetics of cell death and morphological changes were measured following removal of arabinose. As expected given the wide range of cellular mechanisms represented, different mutants showed widely different death curves. All of the mutations were bactericidal except the mutation in gcpE, which was bacteriostatic. The strain carrying an amber mutation in murA was by far the most sensitive, showing rapid killing in nonpermissive medium. The MurA protein is critical for peptidoglycan synthesis and is the target for the antibiotic fosfomycin. Such experiments may inexpensively provide valuable information for the identification and prioritization of targets for antibiotic development. PMID:15090508

Herring, Christopher D; Blattner, Frederick R

2004-05-01

386

A domain sequence approach to pangenomics: applications to Escherichia coli  

PubMed Central

The study of microbial pangenomes relies on the computation of gene families, i.e. the clustering of coding sequences into groups of essentially similar genes. There is no standard approach to obtain such gene families. Ideally, the gene family computations should be robust against errors in the annotation of genes in various genomes. In an attempt to achieve this robustness, we propose to cluster sequences by their domain sequence, i.e. the ordered sequence of domains in their protein sequence. In a study of 347 genomes from Escherichia coli we find on average around 4500 proteins having hits in Pfam-A in every genome, clustering into around 2500 distinct domain sequence families in each genome. Across all genomes we find a total of 5724 such families. A binomial mixture model approach indicates this is around 95% of all domain sequences we would expect to see in E. coli in the future. A Heaps law analysis indicates the population of domain sequences is larger, but this analysis is also very sensitive to smaller changes in the computation procedure. The resolution between strains is good despite the coarse grouping obtained by domain sequence families. Clustering sequences by their ordered domain content give us domain sequence families, who are robust to errors in the gene prediction step. The computational load of the procedure scales linearly with the number of genomes, which is needed for the future explosion in the number of re-sequenced strains. The use of domain sequence families for a functional classification of strains clearly has some potential to be explored. PMID:24555018

Snipen, Lars-Gustav

2013-01-01

387

Chimeras of Escherichia coli and Mycobacterium tuberculosis Single-Stranded DNA Binding Proteins: Characterization and Function in Escherichia coli  

PubMed Central

Single stranded DNA binding proteins (SSBs) are vital for the survival of organisms. Studies on SSBs from the prototype, Escherichia coli (EcoSSB) and, an important human pathogen, Mycobacterium tuberculosis (MtuSSB) had shown that despite significant variations in their quaternary structures, the DNA binding and oligomerization properties of the two are similar. Here, we used the X-ray crystal structure data of the two SSBs to design a series of chimeric proteins (m?1, m?1??2, m?1–?5, m?1–?6 and m?4–?5) by transplanting ?1, ?1??2, ?1–?5, ?1–?6 and ?4–?5 regions, respectively of the N-terminal (DNA binding) domain of MtuSSB for the corresponding sequences in EcoSSB. In addition, m?1??2ESWR SSB was generated by mutating the MtuSSB specific ‘PRIY’ sequence in the ?2 strand of m?1??2 SSB to EcoSSB specific ‘ESWR’ sequence. Biochemical characterization revealed that except for m?1 SSB, all chimeras and a control construct lacking the C-terminal domain (?C SSB) bound DNA in modes corresponding to limited and unlimited modes of binding. However, the DNA on MtuSSB may follow a different path than the EcoSSB. Structural probing by protease digestion revealed that unlike other SSBs used, m?1 SSB was also hypersensitive to chymotrypsin treatment. Further, to check for their biological activities, we developed a sensitive assay, and observed that m?1–?6, MtuSSB, m?1??2 and m?1–?5 SSBs complemented E. coli ?ssb in a dose dependent manner. Complementation by the m?1–?5 SSB was poor. In contrast, m?1??2ESWR SSB complemented E. coli as well as EcoSSB. The inefficiently functioning SSBs resulted in an elongated cell/filamentation phenotype of E. coli. Taken together, our observations suggest that specific interactions within the DNA binding domain of the homotetrameric SSBs are crucial for their biological function. PMID:22174737

Bharti, Sanjay Kumar; Rex, Kervin; Sreedhar, Pujari; Krishnan, Neeraja; Varshney, Umesh

2011-01-01

388

Inhibition of Attaching and Effacing Lesion Formation following Enteropathogenic Escherichia coli and Shiga Toxin-Producing E. coli Infection  

Microsoft Academic Search

Enteropathogenic Escherichia coli (EPEC) and Shiga toxin-producing E. coli (STEC) induce cytoskeletal changes in infected epithelial cells. To further characterize host cytosolic responses to infection, a series of specific cell-signaling inhibitors were employed. Initial bacterial adhesion to HEp-2 epithelial cells was not reduced, whereas -actinin accumulation in infected cells was blocked by a phosphoinositide-specific phos- pholipase C inhibitor (ET-18-OCH3), phosphoinositide

KATHENE JOHNSON-HENRY; JOHN L. WALLACE; NAVEEN S. BASAPPA; ROHINI SONI; GILBERT K. P. WU; PHILIP M. SHERMAN

2001-01-01

389

Non-O157 Shiga toxin-producing Escherichia coli associated with venison.  

PubMed

We investigated an outbreak of non-O157 Shiga toxin-producing Escherichia coli at a high school in Minnesota, USA, in November 2010. Consuming undercooked venison and not washing hands after handling raw venison were associated with illness. E. coli O103:H2 and non-Shiga toxin-producing E. coli O145:NM were isolated from ill students and venison. PMID:22305114

Rounds, Joshua M; Rigdon, Carrie E; Muhl, Levi J; Forstner, Matthew; Danzeisen, Gregory T; Koziol, Bonnie S; Taylor, Charlott; Shaw, Bryanne T; Short, Ginette L; Smith, Kirk E

2012-02-01

390

Virulence Patterns of Escherichia coli K1 Strains Associated with Neonatal Meningitis  

Microsoft Academic Search

The prevalence of the ibe10 gene, of the pap, afa, and sfa adhesin-encoding operons, and of a 14.9-kb rrn-containing HindIII fragment was studied for 67 Escherichia coli neonatal meningitis strains, 58 E. coli K1 commensal strains, and 47 E. coli blood isolates from neonates without meningitis. ibe10, sfa, and the 14.9-kb HindIII fragment were observed significantly more often in the

EDOUARD BINGEN; STEPHANE BONACORSI; NAIMA BRAHIMI; ERICK DENAMUR; JACQUES ELION

1997-01-01

391

Colonization with extraintestinal pathogenic Escherichia coli among nursing home residents and its relationship to fluoroquinolone resistance.  

PubMed

In a cross-sectional fecal prevalence survey involving 49 residents of a Veterans Affairs nursing home, 59% of subjects were colonized with extraintestinal pathogenic Escherichia coli (ExPEC), 22% were colonized with adhesin-positive E. coli, and 51% were colonized with fluoroquinolone-resistant E. coli. Among 80 unique isolates, adhesins correlated negatively and aerobactin correlated positively with fluoroquinolone resistance. PMID:15328142

Maslow, Joel N; Lautenbach, Ebbing; Glaze, Thomas; Bilker, Warren; Johnson, James R

2004-09-01

392

Prevalence of Virulence Genes and Clonality in Escherichia coli Strains That Cause Bacteremia in Cancer Patients  

Microsoft Academic Search

Phenotypic analysis of Escherichia coli strains causing bacteremia in cancer patients suggests that they possess specific virulence properties. To investigate this hypothesis, we compared the frequency of the viru- lence-related genes cnf1, cnf2, papC, hlyC, and iut in 155 E. coli strains isolated from hospitalized cancer patients with epidemiologically unrelated cases of bacteremia to their frequency in 70 E. coli

FARIDA HILALI; RAYMOND RUIMY; PATRICK SAULNIER; CHRISTIAN BARNABE; CHANTAL LEBOUGUENEC; MICHEL TIBAYRENC; ANTOINE ANDREMONT

2000-01-01

393

Molecular epidemiology unravels the complexity of neonatal Escherichia coli acquisition in twins.  

PubMed

Combined analysis of restriction fragment length polymorphism of regions of genes coding for rRNA (ribotyping) and esterase electrophoretic typing was used to document neonatal acquisition of Escherichia coli in twins. Our study shows vertical mother-to-infant transmission of one strain of E. coli to one twin and the development of neonatal septicemia with a distinct nonvirulent carboxylesterase type B1 E. coli strain for the other twin. PMID:1629351

Bingen, E H; Denamur, E; Picard, B; Goullet, P; Lambert-Zechovsky, N Y; Brahimi, N; Mercier, J C; Beaufils, F; Elion, J

1992-07-01

394

Molecular epidemiology unravels the complexity of neonatal Escherichia coli acquisition in twins.  

PubMed Central

Combined analysis of restriction fragment length polymorphism of regions of genes coding for rRNA (ribotyping) and esterase electrophoretic typing was used to document neonatal acquisition of Escherichia coli in twins. Our study shows vertical mother-to-infant transmission of one strain of E. coli to one twin and the development of neonatal septicemia with a distinct nonvirulent carboxylesterase type B1 E. coli strain for the other twin. Images PMID:1629351

Bingen, E H; Denamur, E; Picard, B; Goullet, P; Lambert-Zechovsky, N Y; Brahimi, N; Mercier, J C; Beaufils, F; Elion, J

1992-01-01

395

Isolation and characterization of shiga toxin-producing Escherichia coli from meat and dairy products  

Microsoft Academic Search

Shiga toxin-producing Escherichia coli (STEC) strains were detected among 250 E. coli strains isolated from 204 food samples (meat and dairy products) obtained from butcher shops and retail stores in BEN AROUS (a Tunisian State\\/south east of the Tunisian capital). These 250 E. coli strains were isolated by applying culture techniques using sorbitol MacConkey (SMAC) agar after preenrichment of the

N Al-Gallas; R Ben Aissa R; Th Attia Annabi; O Bahri; A Boudabous

2002-01-01

396

Virulence genes of Shiga toxin-producing Escherichia coli isolated from food, animals and humans  

Microsoft Academic Search

The presence of virulence genes, encoding enterohemorrhagic Escherichia coli (EHEC)-hemolysin (EHEC-hlyA), intimin (eae), and Shiga toxins 1 (stx1) and 2 (stx2), in 178 isolates of pathogenic E. coli, was determined using the polymerase chain reaction with primers specific for each virulence gene. The tested organisms were 120 isolates of E. coli O157:H7 from human patients, cattle, sheep and foods, 16

Jianghong Meng; Shaohua Zhao; Michael P Doyle

1998-01-01

397

First Detection of Shiga Toxin-Producing Escherichia coli in Shellfish and Coastal Environments of Morocco  

Microsoft Academic Search

Shiga toxin Escherichia coli (STEC), also called verotoxin-producing E. coli, is a major cause of food-borne illness, capable of causing hemorrhagic colitis and hemolytic–uremic syndrome (HUS). This\\u000a study was carried out to evaluate the presence of (STEC) and E. coli O157:H7 in shellfish and Mediterranean coastal environments of Morocco. The contamination of shellfish and marine environment\\u000a with Shiga toxin-producing E.

Mohamed Bennani; Samira Badri; Tarik Baibai; Nadia Oubrim; Mohammed Hassar; Nozha Cohen; Hamid Amarouch

398

Murine Monoclonal Antibodies against Escherichia coli O4 Lipopolysaccharide and H5 Flagellin  

PubMed Central

Two murine monoclonal antibodies (MAb), 2C5-F10 and 8D1-H10, reactive with Escherichia coli O4 and H5 antigens, respectively, were generated and characterized. Enzyme immunoassays and immunoblots demonstrated that MAb 2C5-F10 reacted specifically with lipopolysaccharide O antigen of E. coli O4 isolates, while MAb 8D1-H10 reacted with E. coli strains expressing H5 flagella. PMID:11526192

Rivera-Betancourt, Mildred; Keen, James E.

2001-01-01

399

Proteomic Study of Recombinant Escherichia coli Expressing Beauveria bassiana Chitinase Gene  

Microsoft Academic Search

This research aims to investigate the effect of Beauveria bassiana chitinase gene on the protein profile of recombinant Escherichia coli by using a proteomic approach. Total protein expressed in non-recombinant E. coli (pSE420) and recombinant E. coli (pDSM1) was analyzed by two-dimensional polyacrylamide gel electrophoresis. The expression profiles of recombinants were then compared with those of non-recombinants. Three protein spots

Khemika Lomthaisong

2008-01-01

400

Production of hydroxycinnamoyl anthranilates from glucose in Escherichia coli  

PubMed Central

Background Oats contain hydroxycinnamoyl anthranilates, also named avenanthramides (Avn), which have beneficial health properties because of their antioxidant, anti-inflammatory, and antiproliferative effects. The microbial production of hydroxycinnamoyl anthranilates is an eco-friendly alternative to chemical synthesis or purification from plant sources. We recently demonstrated in yeast (Saccharomyces cerevisiae) that coexpression of 4-coumarate: CoA ligase (4CL) from Arabidopsis thaliana and hydroxycinnamoyl/benzoyl-CoA/anthranilate N-hydroxycinnamoyl/benzoyltransferase (HCBT) from Dianthus caryophyllusenabled the biological production of several cinnamoyl anthranilates upon feeding with anthranilate and various cinnamates. Using engineering strategies to overproduce anthranilate and hydroxycinnamates, we describe here an entire pathway for the microbial synthesis of two Avns from glucose in Escherichia coli. Results We first showed that coexpression of HCBT and Nt4CL1 from tobacco in the E. coli anthranilate-accumulating strain W3110 trpD9923 allowed the production of Avn D [N-(4?-hydroxycinnamoyl)-anthranilic acid] and Avn F [N-(3?,4?-dihydroxycinnamoyl)-anthranilic acid] upon feeding with p-coumarate and caffeate, respectively. Moreover, additional expression in this strain of a tyrosine ammonia-lyase from Rhodotorula glutinis (RgTAL) led to the conversion of endogenous tyrosine into p-coumarate and resulted in the production of Avn D from glucose. Second, a 135-fold improvement in Avn D titer was achieved by boosting tyrosine production using two plasmids that express the eleven genes necessary for tyrosine synthesis from erythrose 4-phosphate and phosphoenolpyruvate. Finally, expression of either the p-coumarate 3-hydroxylase Sam5 from Saccharothrix espanensis or the hydroxylase complex HpaBC from E. coli resulted in the endogenous production of caffeate and biosynthesis of Avn F. Conclusion We established a biosynthetic pathway for the microbial production of valuable hydroxycinnamoyl anthranilates from an inexpensive carbon source. The proposed pathway will serve as a platform for further engineering toward economical and sustainable bioproduction of these pharmaceuticals and other related aromatic compounds. PMID:23806124

2013-01-01

401

Clonal relationships among bloodstream isolates of Escherichia coli.  

PubMed

The clonal relationships among 187 bloodstream isolates of Escherichia coli from 179 patients at Boston, Mass., Long Beach, Calif., and Nairobi, Kenya, were determined by multilocus enzyme electrophoresis (MLEE), analysis of polymorphisms associated with the ribosomal operon (ribotyping), and serotyping. MLEE based on 20 enzymes resolved 101 electrophoretic types (ETs), forming five clusters; ribotyping resolved 56 distinct patterns concordant with the analysis by MLEE. The isolates at each study site formed a genetically diverse group and demonstrated similar clonal structures, with the same small subset of lineages accounting for the majority of isolates at each site. Moreover, two ribotypes accounted for approximately 30% of the isolates at each study site. One cluster contained the majority (65%) of isolates and, by direct comparison of the ETs and ribotypes of individual isolates, was genetically indistinguishable from the largest cluster for each of two other collections of E. coli causing pyelonephritis and neonatal meningitis (R. K. Selander, T. K. Korhonen, V. Väisänen-Rhen, P. H. Williams, P. E. Pattison, and D. A. Caugent, Infect. Immun. 52:213-222, 1986; M. Arthur, C. E. Johnson, R. H. Rubin, R. D. Arbeit, C. Campanelli, C. Kim, S. Steinbach, M. Agarwal, R. Wilkinson, and R. Goldstein, Infect. Immun. 57:303-313, 1989), thus defining a virulent set of lineages. The isolates within these virulent lineages typically carried DNA homologous to the adhesin operon pap or sfa and the hemolysin operon hly and expressed O1, O2, O4, O6, O18, O25, or O75 antigens. DNA homologous to pap was distributed among isolates of each major cluster, whereas hly was restricted to isolates of two clusters, typically detected in pap-positive strains, and sfa was restricted to isolates of one cluster, typically detected in pap- and hly-positive strains. The occurrence of pap-positive isolates in the same geographically and genetically divergent lineages suggests that this operon was acquired early in the radiation of E. coli, while hly and sfa were acquired subsequently, most likely by pap-positive and pap- and hly-positive precursors, respectively. PMID:7790051

Maslow, J N; Whittam, T S; Gilks, C F; Wilson, R A; Mulligan, M E; Adams, K S; Arbeit, R D

1995-07-01

402

Overexpression of peanut diacylglycerol acyltransferase 2 in Escherichia coli.  

PubMed

Diacylglycerol acyltransferase (DGAT) is the rate-limiting enzyme in triacylglycerol biosynthesis in eukaryotic organisms. Triacylglycerols are important energy-storage oils in plants such as peanuts, soybeans and rape. In this study, Arachis hypogaea type 2 DGAT (AhDGAT2) genes were cloned from the peanut cultivar 'Luhua 14' using a homologous gene sequence method and rapid amplification of cDNA ends. To understand the role of AhDGAT2 in triacylglycerol biosynthesis, two AhDGAT2 nucleotide sequences that differed by three amino acids were expressed as glutathione S-transferase (GST) fusion proteins in Escherichia coli Rosetta (DE3). Following IPTG induction, the isozymes (AhDGAT2a and AhDGAT2b) were expressed as 64.5 kDa GST fusion proteins. Both AhDGAT2a and AhDGAT2b occurred in the host cell cytoplasm and inclusion bodies, with larger amounts in the inclusion bodies. Overexpression of AhDGATs depressed the host cell growth rates relative to non-transformed cells, but cells harboring empty-vector, AhDGAT2a-GST, or AhDGAT2b-GST exhibited no obvious growth rate differences. Interestingly, induction of AhDGAT2a-GST and AhDGAT2b-GST proteins increased the sizes of the host cells by 2.4-2.5 times that of the controls (post-IPTG induction). The total fatty acid (FA) levels of the AhDGAT2a-GST and AhDGAT2a-GST transformants, as well as levels of C12:0, C14:0, C16:0, C16:1, C18:1n9c and C18:3n3 FAs, increased markedly, whereas C15:0 and C21:0 levels were lower than in non-transformed cells or those containing empty-vectors. In addition, the levels of some FAs differed between the two transformant strains, indicating that the two isozymes might have different functions in peanuts. This is the first time that a full-length recombinant peanut DGAT2 has been produced in a bacterial expression system and the first analysis of its effects on the content and composition of fatty acids in E. coli. Our results indicate that AhDGAT2 is a strong candidate gene for efficient FA production in E. coli. PMID:23593473

Peng, Zhenying; Li, Lan; Yang, Lianqun; Zhang, Bin; Chen, Gao; Bi, Yuping

2013-01-01

403

Clonal relationships among bloodstream isolates of Escherichia coli.  

PubMed Central

The clonal relationships among 187 bloodstream isolates of Escherichia coli from 179 patients at Boston, Mass., Long Beach, Calif., and Nairobi, Kenya, were determined by multilocus enzyme electrophoresis (MLEE), analysis of polymorphisms associated with the ribosomal operon (ribotyping), and serotyping. MLEE based on 20 enzymes resolved 101 electrophoretic types (ETs), forming five clusters; ribotyping resolved 56 distinct patterns concordant with the analysis by MLEE. The isolates at each study site formed a genetically diverse group and demonstrated similar clonal structures, with the same small subset of lineages accounting for the majority of isolates at each site. Moreover, two ribotypes accounted for approximately 30% of the isolates at each study site. One cluster contained the majority (65%) of isolates and, by direct comparison of the ETs and ribotypes of individual isolates, was genetically indistinguishable from the largest cluster for each of two other collections of E. coli causing pyelonephritis and neonatal meningitis (R. K. Selander, T. K. Korhonen, V. Väisänen-Rhen, P. H. Williams, P. E. Pattison, and D. A. Caugent, Infect. Immun. 52:213-222, 1986; M. Arthur, C. E. Johnson, R. H. Rubin, R. D. Arbeit, C. Campanelli, C. Kim, S. Steinbach, M. Agarwal, R. Wilkinson, and R. Goldstein, Infect. Immun. 57:303-313, 1989), thus defining a virulent set of lineages. The isolates within these virulent lineages typically carried DNA homologous to the adhesin operon pap or sfa and the hemolysin operon hly and expressed O1, O2, O4, O6, O18, O25, or O75 antigens. DNA homologous to pap was distributed among isolates of each major cluster, whereas hly was restricted to isolates of two clusters, typically detected in pap-positive strains, and sfa was restricted to isolates of one cluster, typically detected in pap- and hly-positive strains. The occurrence of pap-positive isolates in the same geographically and genetically divergent lineages suggests that this operon was acquired early in the radiation of E. coli, while hly and sfa were acquired subsequently, most likely by pap-positive and pap- and hly-positive precursors, respectively. PMID:7790051

Maslow, J N; Whittam, T S; Gilks, C F; Wilson, R A; Mulligan, M E; Adams, K S; Arbeit, R D

1995-01-01

404

Novel phage-based bio-processing of pathogenic Escherichia coli and its biofilms.  

PubMed

To explore new approaches of phage-based bio-process of specifically pathogenic Escherichia coli bacteria in food products within a short period. One hundred and forty highly lytic designed coliphages were used. Escherichia coli naturally contaminated and Enterohemorrhagic Escherichia coli experimentally inoculated samples of lettuce, cabbage, meat, and egg were used. In addition, experimentally produced biofilms of E. coli were tested. A phage concentration of 10(3) PFU/ml was used for food products immersion, and for spraying of food products, 10(5) PFU/ml of a phage cocktail was used by applying a 20-s optimal dipping time in a phage cocktail. Food samples were cut into pieces and were either sprayed with or held in a bag immersed in lambda buffer containing a cocktail of 140 phages. Phage bio-processing was successful in eliminating completely E. coli in all processed samples after 48 h storage at 4°C. Partial elimination of E. coli was observed in earlier storage periods (7 and 18 h) at 24° and 37°C. Moreover, E. coli biofilms were reduced >3 log cycles upon using the current phage bio-processing. The use of a phage cocktail of 140 highly lytic designed phages proved highly effective in suppressing E. coli contaminating food products. Proper decontamination/prevention methods of pathogenic E. coli achieved in this study can replace the current chemically less effective decontamination methods. PMID:22806779

Jassim, S A A; Abdulamir, A S; Abu Bakar, F

2012-01-01

405

Differentiation of escherichia coli serotypes using dc gradient insulator dielectrophoresis  

PubMed Central

Bacteria play a significant role in both human health and disease. An estimated 9.4 million cases of foodborne illness occur in the United States each year. As a result, rapid identification and characterization of microorganisms remains an important research objective. Despite limitations, selective culturing retains a central role amongst a cadre of identification strategies. For the past decade, separations-based approaches to rapid bacterial identification have been under investigation. Gradient insulator dielectrophoresis (g-iDEP) promises benefits in the form of rapid and specific separation of very similar bacteria, including serotypes of a single species. Furthermore, this approach allows simultaneous concentration of analyte, facilitating detection and downstream analysis. Differentiation of three serotypes or strains of Escherichia coli bacteria is demonstrated within a single g-iDEP microchannel, based on their characteristic electrokinetic properties. Whole cells were captured and concentrated using a range of applied potentials, which generated average electric fields between 160 and 470 V/cm. Bacteria remained viable after exposure to these fields, as determined by cellular motility. These results indicate the potential g-iDEP holds in terms of both separatory power and the possibility for diagnostic applications. PMID:24202194

Jones, Paul V.; DeMichele, Alexa F.; Kemp, LaKeta; Hayes, Mark A.

2014-01-01

406

Production of salidroside in metabolically engineered Escherichia coli  

PubMed Central

Salidroside (1) is the most important bioactive component of Rhodiola (also called as “Tibetan Ginseng”), which is a valuable medicinal herb exhibiting several adaptogenic properties. Due to the inefficiency of plant extraction and chemical synthesis, the supply of salidroside (1) is currently limited. Herein, we achieved unprecedented biosynthesis of salidroside (1) from glucose in a microorganism. First, the pyruvate decarboxylase ARO10 and endogenous alcohol dehydrogenases were recruited to convert 4-hydroxyphenylpyruvate (2), an intermediate of L-tyrosine pathway, to tyrosol (3) in Escherichia coli. Subsequently, tyrosol production was improved by overexpressing the pathway genes, and by eliminating competing pathways and feedback inhibition. Finally, by introducing Rhodiola-derived glycosyltransferase UGT73B6 into the above-mentioned recombinant strain, salidroside (1) was produced with a titer of 56.9?mg/L. Interestingly, the Rhodiola-derived glycosyltransferase, UGT73B6, also catalyzed the attachment of glucose to the phenol position of tyrosol (3) to form icariside D2 (4), which was not reported in any previous literatures. PMID:25323006

Bai, Yanfen; Bi, Huiping; Zhuang, Yibin; Liu, Chang; Cai, Tao; Liu, Xiaonan; Zhang, Xueli; Liu, Tao; Ma, Yanhe

2014-01-01

407

Regulation of Acetyl Coenzyme A Synthetase in Escherichia coli  

PubMed Central

Cells of Escherichia coli growing on sugars that result in catabolite repression or amino acids that feed into glycolysis undergo a metabolic switch associated with the production and utilization of acetate. As they divide exponentially, these cells excrete acetate via the phosphotransacetylase-acetate kinase pathway. As they begin the transition to stationary phase, they instead resorb acetate, activate it to acetyl coenzyme A (acetyl-CoA) by means of the enzyme acetyl-CoA synthetase (Acs) and utilize it to generate energy and biosynthetic components via the tricarboxylic acid cycle and the glyoxylate shunt, respectively. Here, we present evidence that this switch occurs primarily through the induction of acs and that the timing and magnitude of this induction depend, in part, on the direct action of the carbon regulator cyclic AMP receptor protein (CRP) and the oxygen regulator FNR. It also depends, probably indirectly, upon the glyoxylate shunt repressor IclR, its activator FadR, and many enzymes involved in acetate metabolism. On the basis of these results, we propose that cells induce acs, and thus their ability to assimilate acetate, in response to rising cyclic AMP levels, falling oxygen partial pressure, and the flux of carbon through acetate-associated pathways. PMID:10894724

Kumari, Suman; Beatty, Christine M.; Browning, Douglas F.; Busby, Stephen J. W.; Simel, Erica J.; Hovel-Miner, Galadriel; Wolfe, Alan J.

2000-01-01

408

Indole-3-acetic acid improves Escherichia coli's defences to stress.  

PubMed

Indole-3-acetic acid (IAA) is a ubiquitous molecule playing regulatory roles in many living organisms. To elucidate the physiological changes induced by IAA treatment, we used Escherichia coli K-12 as a model system. By microarray analysis we found that 16 genes showed an altered expression level in IAA-treated cells. One-third of these genes encode cell envelope components, or proteins involved in bacterial adaptation to unfavourable environmental conditions. We thus investigated the effect of IAA treatment on some of the structural components of the envelope that may be involved in cellular response to stresses. This showed that IAA-treated cells had increased the production of trehalose, lipopolysaccharide (LPS), exopolysaccharide (EPS) and biofilm. We demonstrated further that IAA triggers an increased tolerance to several stress conditions (heat and cold shock, UV-irradiation, osmotic and acid shock and oxidative stress) and different toxic compounds (antibiotics, detergents and dyes) and this correlates with higher levels of the heat shock protein DnaK. We suggest that IAA triggers an increased level of alert and protection against external adverse conditions by coordinately enhancing different cellular defence systems. PMID:16555073

Bianco, C; Imperlini, E; Calogero, R; Senatore, B; Amoresano, A; Carpentieri, A; Pucci, P; Defez, R

2006-06-01

409

Engineering modular ester fermentative pathways in Escherichia coli.  

PubMed

Sensation profiles are observed all around us and are made up of many different molecules, such as esters. These profiles can be mimicked in everyday items for their uses in foods, beverages, cosmetics, perfumes, solvents, and biofuels. Here, we developed a systematic 'natural' way to derive these products via fermentative biosynthesis. Each ester fermentative pathway was designed as an exchangeable ester production module for generating two precursors- alcohols and acyl-CoAs that were condensed by an alcohol acyltransferase to produce a combinatorial library of unique esters. As a proof-of-principle, we coupled these ester modules with an engineered, modular, Escherichia coli chassis in a plug-and-play fashion to create microbial cell factories for enhanced anaerobic production of a butyrate ester library. We demonstrated tight coupling between the modular chassis and ester modules for enhanced product biosynthesis, an engineered phenotype useful for directed metabolic pathway evolution. Compared to the wildtype, the engineered cell factories yielded up to 48 fold increase in butyrate ester production from glucose. PMID:25281839

Layton, Donovan S; Trinh, Cong T

2014-10-01

410

relA Enhances the Adherence of Enteropathogenic Escherichia coli  

PubMed Central

Enteropathogenic Escherichia coli (EPEC) is a known causative agent of diarrhea in children. In the process of colonization of the small intestine, EPEC synthesizes two types of adhesins, the bundle-forming pilus (BFP) and intimin. The BFP pilus is an adhesin associated with the initial stages of adherence of EPEC to epithelial cells, while the outer membrane protein intimin carries out the intimate adherence that takes place at the third stage of infection. BFP is encoded by the bfp operon located in plasmid EAF, present only in typical EPEC isolates, while eae, the gene that encodes intimin is situated in the LEE, a chromosomal pathogenicity island. Transcription of bfp and eae is regulated by the products of the perABC operon, also present in plasmid EAF. Here we show that deletion of relA, that encodes a guanosine penta and tetraphosphate synthetase impairs EPEC adherence to epithelial cells in vitro. In the absence of relA, the transcription of the regulatory operon perABC is reduced, resulting in lower levels of BFP and intimin. Bacterial adherence, BFP and intimin synthesis and perABC expression are restored upon complementation with the wild-type relA allele. PMID:24643076

Spira, Beny; Ferreira, Gerson Moura; de Almeida, Luiz Gustavo

2014-01-01

411

Penicillin-binding site on the Escherichia coli cell envelope  

SciTech Connect

The binding of /sup 35/S-labeled penicillin to distinct penicillin-binding proteins (PBPs) of the cell envelope obtained from the sonication of Escherichia coli was studied at different pHs ranging from 4 to 11. Experiments distinguishing the effect of pH on penicillin binding by PBP 5/6 from its effect on beta-lactamase activity indicated that although substantial binding occurred at the lowest pH, the amount of binding increased with pH, reaching a maximum at pH 10. Based on earlier studies, it is proposed that the binding at high pH involves the formation of a covalent bond between the C-7 of penicillin and free epsilon amino groups of the PBPs. At pHs ranging from 4 to 8, position 1 of penicillin, occupied by sulfur, is considered to be the site that establishes a covalent bond with the sulfhydryl groups of PBP 5. The use of specific blockers of free epsilon amino groups or sulfhydryl groups indicated that wherever the presence of each had little or no effect on the binding of penicillin by PBP 5, the presence of both completely prevented binding. The specific blocker of the hydroxyl group of serine did not affect the binding of penicillin.

Amaral, L.; Lee, Y.; Schwarz, U.; Lorian, V.

1986-08-01

412

Isoprenoid pathway optimization for Taxol precursor overproduction in Escherichia coli.  

PubMed

Taxol (paclitaxel) is a potent anticancer drug first isolated from the Taxus brevifolia Pacific yew tree. Currently, cost-efficient production of Taxol and its analogs remains limited. Here, we report a multivariate-modular approach to metabolic-pathway engineering that succeeded in increasing titers of taxadiene--the first committed Taxol intermediate--approximately 1 gram per liter (~15,000-fold) in an engineered Escherichia coli strain. Our approach partitioned the taxadiene metabolic pathway into two modules: a native upstream methylerythritol-phosphate (MEP) pathway forming isopentenyl pyrophosphate and a heterologous downstream terpenoid-forming pathway. Systematic multivariate search identified conditions that optimally balance the two pathway modules so as to maximize the taxadiene production with minimal accumulation of indole, which is an inhibitory compound found here. We also engineered the next step in Taxol biosynthesis, a P450-mediated 5?-oxidation of taxadiene to taxadien-5?-ol. More broadly, the modular pathway engineering approach helped to unlock the potential of the MEP pathway for the engineered production of terpenoid natural products. PMID:20929806

Ajikumar, Parayil Kumaran; Xiao, Wen-Hai; Tyo, Keith E J; Wang, Yong; Simeon, Fritz; Leonard, Effendi; Mucha, Oliver; Phon, Too Heng; Pfeifer, Blaine; Stephanopoulos, Gregory

2010-10-01

413

Hydroxylated naphthoquinones as substrates for Escherichia coli anaerobic reductases.  

PubMed Central

We have used two hydroxylated naphthoquinol menaquinol analogues, reduced plumbagin (PBH2, 5-hydroxy-2-methyl-1,4-naphthoquinol) and reduced lapachol [LPCH2, 2-hydroxy-3-(3-methyl-2-butenyl)-1, 4-naphthoquinol], as substrates for Escherichia coli anaerobic reductases. These compounds have optical, solubility and redox properties that make them suitable for use in studies of the enzymology of menaquinol oxidation. Oxidized plumbagin and oxidized lapachol have well resolved absorbances at 419 nm (epsilon=3.95 mM-1. cm-1) and 481 nm (epsilon=2.66 mM-1.cm-1) respectively (in Mops/KOH buffer, pH 7.0). PBH2 is a good substrate for nitrate reductase A (Km=282+/-28 microM, kcat=120+/-6 s-1) and fumarate reductase (Km=155+/-24 microM, kcat=30+/-2 s-1), but not for DMSO reductase. LPCH2 is a good substrate for nitrate reductase A (Km=57+/-35 microM, kcat=68+/-13 s-1), fumarate reductase (Km=85+/-27 microM, kcat=74+/-6 s-1) and DMSO reductase (Km=238+/-30 microM, kcat=191+/-21 s-1). The sensitivity of enzymic LPCH2 and PBH2 oxidation to 2-n-heptyl-4-hydroxyquinoline N-oxide inhibition is consistent with their oxidation occurring at sites of physiological quinol binding. PMID:9576848

Rothery, R A; Chatterjee, I; Kiema, G; McDermott, M T; Weiner, J H

1998-01-01

414

Iron induces bimodal population development by Escherichia coli.  

PubMed

Bacterial biofilm formation is a complex developmental process involving cellular differentiation and the formation of intricate 3D structures. Here we demonstrate that exposure to ferric chloride triggers rugose biofilm formation by the uropathogenic Escherichia coli strain UTI89 and by enteric bacteria Citrobacter koseri and Salmonella enterica serovar typhimurium. Two unique and separable cellular populations emerge in iron-triggered, rugose biofilms. Bacteria at the air-biofilm interface express high levels of the biofilm regulator csgD, the cellulose activator adrA, and the curli subunit operon csgBAC. Bacteria in the interior of rugose biofilms express low levels of csgD and undetectable levels of matrix components curli and cellulose. Iron activation of rugose biofilms is linked to oxidative stress. Superoxide generation, either through addition of phenazine methosulfate or by deletion of sodA and sodB, stimulates rugose biofilm formation in the absence of high iron. Additionally, overexpression of Mn-superoxide dismutase, which can mitigate iron-derived reactive oxygen stress, decreases biofilm formation in a WT strain upon iron exposure. Not only does reactive oxygen stress promote rugose biofilm formation, but bacteria in the rugose biofilms display increased resistance to H(2)O(2) toxicity. Altogether, we demonstrate that iron and superoxide stress trigger rugose biofilm formation in UTI89. Rugose biofilm development involves the elaboration of two distinct bacterial populations and increased resistance to oxidative stress. PMID:23359678

DePas, William H; Hufnagel, David A; Lee, John S; Blanco, Luz P; Bernstein, Hans C; Fisher, Steve T; James, Garth A; Stewart, Philip S; Chapman, Matthew R

2013-02-12

415

Transposon Mutagenesis Identifies Uropathogenic Escherichia coli Biofilm Factors  

PubMed Central

Uropathogenic Escherichia coli (UPEC), which accounts for 85% of urinary tract infections (UTI), assembles biofilms in diverse environments, including the host. Besides forming biofilms on biotic surfaces and catheters, UPEC has evolved an intracellular pathogenic cascade that culminates in the formation of biofilm-like intracellular bacterial communities (IBCs) within bladder epithelial cells. Rapid bacterial replication during IBC formation augments a build-up in bacterial numbers and persistence within the host. Relatively little is known about factors mediating UPEC biofilm formation and how these overlap with IBC formation. To address this gap, we screened a UPEC transposon mutant library in three in vitro biofilm conditions: Luria broth (LB)-polyvinyl chloride (PVC), YESCA (yeast extract-Casamino Acids)-PVC, and YESCA-pellicle that are dependent on type 1 pili (LB) and curli (YESCA), respectively. Flagella are important in all three conditions. Mutants were identified that had biofilm defects in all three conditions but had no significant effects on the expression of type 1 pili, curli, or flagella. Thus, this approach uncovered a comprehensive inventory of novel effectors and regulators that are involved in UPEC biofilm formation under multiple conditions. A subset of these mutants was found to be dramatically attenuated and unable to form IBCs in a murine model of UTI. Collectively, this study expands our insights into UPEC multicellular behavior that may provide insights into IBC formation and virulence. PMID:22984258

Hadjifrangiskou, Maria; Gu, Alice P.; Pinkner, Jerome S.; Kostakioti, Maria; Zhang, Ellisa W.; Greene, Sarah E.

2012-01-01

416

Thermolabile antifreeze protein produced in Escherichia coli for structural analysis.  

PubMed

The only hyperactive antifreeze protein (AFP) found to date in fishes is an extreme variant of the 3-kDa, alpha-helical, alanine-rich type I AFP, which is referred to here as type Ih. Purification of the 33-kDa homodimeric AFP Ih from a natural source was hampered by its low levels in fish plasma; by the need to remove the more abundant smaller isoforms; and by its extreme thermolability. Moreover, ice affinity as a purification tool was spoiled by the tendency of fish IgM antibodies to bind to ice in the presence of AFPs. In order to produce enough protein for crystallography we expressed AFP Ih as a recombinant protein in the Arctic Express® strain of Escherichia coli at 12 °C, just below the thermal denaturation temperature of 16-18 °C. His-tags were not useful because they compromised the activity and yield of AFP Ih. But in the absence of fish antibodies we were able to recover 10-mg quantities of the antifreeze protein using two cycles of ice affinity purification followed by anion-exchange chromatography to remove contaminating chaperones. The purified recombinant AFP Ih yielded diffraction-quality crystals with an extremely asymmetrical unit cell. By transferring the genes of the chaperones into a methionine auxotroph we were able to grow this host at low temperatures and produce sufficient selenomethionine-labeled AFP Ih for crystallography. PMID:22155222

Lin, Feng-Hsu; Sun, Tianjun; Fletcher, Garth L; Davies, Peter L

2012-03-01

417

Glutathione and Transition-Metal Homeostasis in Escherichia coli?  

PubMed Central

Glutathione (GSH) and its derivative phytochelatin are important binding factors in transition-metal homeostasis in many eukaryotes. Here, we demonstrate that GSH is also involved in chromate, Zn(II), Cd(II), and Cu(II) homeostasis and resistance in Escherichia coli. While the loss of the ability to synthesize GSH influenced metal tolerance in wild-type cells only slightly, GSH was important for residual metal resistance in cells without metal efflux systems. In mutant cells without the P-type ATPase ZntA, the additional deletion of the GSH biosynthesis system led to a strong decrease in resistance to Cd(II) and Zn(II). Likewise, in mutant cells without the P-type ATPase CopA, the removal of GSH led to a strong decrease of Cu(II) resistance. The precursor of GSH, ?-glutamylcysteine (?EC), was not able to compensate for a lack of GSH. On the contrary, ?EC-containing cells were less copper and cadmium tolerant than cells that contained neither ?EC nor GSH. Thus, GSH may play an important role in trace-element metabolism not only in higher organisms but also in bacteria. PMID:18539744

Helbig, Kerstin; Bleuel, Corinna; Krauss, Gerd J.; Nies, Dietrich H.

2008-01-01

418

Stochastic switching induced adaptation in a starved Escherichia coli population.  

PubMed

Population adaptation can be determined by stochastic switching in living cells. To examine how stochastic switching contributes to the fate decision for a population under severe stress, we constructed an Escherichia coli strain crucially dependent on the expression of a rewired gene. The gene essential for tryptophan biosynthesis, trpC, was removed from the native regulatory unit, the Trp operon, and placed under the extraneous control of the lactose utilisation network. Bistability of the network provided the cells two discrete phenotypes: the induced and suppressed level of trpC. The two phenotypes permitted the cells to grow or not, respectively, under conditions of tryptophan depletion. We found that stochastic switching between the two states allowed the initially suppressed cells to form a new population with induced trpC in response to tryptophan starvation. However, the frequency of the transition from suppressed to induced state dropped off dramatically in the starved population, in comparison to that in the nourished population. This reduced switching rate was compensated by increasing the initial population size, which probably provided the cell population more chances to wait for the rarely appearing fit cells from the unfit cells. Taken together, adaptation of a starved bacterial population because of stochasticity in the gene rewired from the ancient regulon was experimentally confirmed, and the nutritional status and the population size played a great role in stochastic adaptation. PMID:21931628

Shimizu, Yoshihiro; Tsuru, Saburo; Ito, Yoichiro; Ying, Bei-Wen; Yomo, Tetsuya

2011-01-01

419

Chromosomal replication incompatibility in Dam methyltransferase deficient Escherichia coli cells.  

PubMed Central

Dam methyltransferase deficient Escherichia coli cells containing minichromosomes were constructed. Free plasmid DNA could not be detected in these cells and the minichromosomes were found to be integrated in multiple copies in the origin of replication (oriC) region of the host chromosome. The absence of the initiation cascade in Dam- cells is proposed to account for this observation of apparent incompatibility between plasmid and chromosomal copies of oriC. Studies using oriC-pBR322 chimeric plasmids and their deletion derivatives indicated that the incompatibility determinant is an intact and functional oriC sequence. The seqA2 mutation was found to overcome the incompatability phenotype by increasing the cellular oriC copy number 3-fold thereby allowing minichromosomes to coexist with the chromosome. The replication pattern of a wild-type strain with multiple integrated minichromosomes in the oriC region of the chromosome, led to the conclusion that initiation of DNA replication commences at a fixed cell mass, irrespective of the number of origins contained on the chromosome. Images PMID:8918477

Løbner-Olesen, A; von Freiesleben, U

1996-01-01

420

Topological domain structure of the Escherichia coli chromosome  

PubMed Central

The circular chromosome of Escherichia coli is organized into independently supercoiled loops, or topological domains. We investigated the organization and size of these domains in vivo and in vitro. Using the expression of >300 supercoiling-sensitive genes to gauge local chromosomal supercoiling, we quantitatively measured the spread of relaxation from double-strand breaks generated in vivo and thereby calculated the distance to the nearest domain boundary. In a complementary approach, we gently isolated chromosomes and examined the lengths of individual supercoiled loops by electron microscopy. The results from these two very different methods agree remarkably well. By comparing our results to Monte Carlo simulations of domain organization models, we conclude that domain barriers are not placed stably at fixed sites on the chromosome but instead are effectively randomly distributed. We find that domains are much smaller than previously reported, ?10 kb on average. We discuss the implications of these findings and present models for how domain barriers may be generated and displaced during the cell cycle in a stochastic fashion. PMID:15256503

Postow, Lisa; Hardy, Christine D.; Arsuaga, Javier; Cozzarelli, Nicholas R.

2004-01-01

421

Endonuclease IV of Escherichia coli is induced by paraquat  

SciTech Connect

The addition of paraquat (methyl viologen) to a growing culture of Escherichia coli K-12 led within 1 hr to a 10- to 20-fold increase in the level of endonuclease IV, a DNase for apurinic/apyrimidinic sites. The induction was blocked by chloramphenicol. Increases of 3-fold or more were also seen with plumbagin, menadione, and phenazine methosulfate. H/sub 2/O/sub 2/ produced no more than a 2-fold increase in endonuclease IV activity. The following agents had no significant effect: streptonigrin, nitrofurantoin, tert-butyl hydroperoxide, ..gamma.. rays, 260-nm UV radiation, methyl methanesulfonate, mitomycin C, and ascorbate. Paraquat, plumbagin, menadione, and phenazine methosulfate are known to generate superoxide radical anions via redox cycling in vivo. A mutant lacking superoxide dismutase was unusually sensitive to induction by paraquat. In addition, endonuclease IV could be induced by merely growing the mutant in pure O/sub 2/. The levels of endonuclease IV in uninduced or paraquat-treated cells were unaffected by mutations of oxyR, a H/sub 2/O/sub 2/-inducible gene that governs an oxidative-stress regulon. The results indicate that endonuclease IV is an inducible DNA-repair enzyme and that its induction can be mediated via the production of superoxide radicals.

Chan, E.; Weiss, B.

1987-05-01

422

Regulation of methionine transport activity in Escherichia coli.  

PubMed Central

Methionine transport activity in cells of Escherichia coli K-12 is regulated by the level of the internal methionine pool. Transport activity is depressed either in cells grown in the presence of methionine or in cells exposed to methionine immediately prior to harvest. Alpha-Keto-gamma-methiol-butyrate, D-methionine, or methionine sulfoxide have little effect on the initial rate of uptake of L-methionine when they are added simultaneously with the substrate. However, methionine transport is markedly reduced in cells exposed to these sources of L-methionine before the addition of substrate. This reduction is prevented if the cells are treated with amino oxyacetic acid. The initial rate of uptake into L-methionine-loaded cells was lower than that into unloaded cells. This inhibition affected both methionine transport systems and the inhibition by the internal pool appeared to be non-competitive with the external methionine concentration. Two classes of mutants with increased methionine pools have decreased rates of uptake. Conversely, starvation for methionine in a methionine auxotroph with high rates of methionine degradation resulted in a substantial increase in the rate of methionine transport. Thus, these transport systems are subject to regulation by the internal pool size and possibly by repression. PMID:1091617

Kadner, R J

1975-01-01

423

Effects of Phenethyl Alcohol on Phospholipid Metabolism in Escherichia coli  

PubMed Central

The incorporation of labeled precursors into the deoxyribonucleic acid, ribonucleic acid (RNA), proteins, and phospholipids of Escherichia coli cultured in the presence of phenethyl alcohol (PEA) was determined. PEA inhibited the uptake of labeled uracil to the same extent in cells exhibiting relaxed and stringent control of RNA synthesis. This indicates that PEA does not primarily affect amino acid synthesis or activation. Uptake of labeled acetate into the phospholipid fraction was more sensitive to inhibition by low concentrations of PEA than was the uptake of labeled precursors into the macromolecules. Thymine starvation or the addition of nalidixic acid (10 ?g/ml) had no effect on acetate incorporation. Chloramphenicol (25 ?g/ml) was a much less effective inhibitor of acetate incorporation than was PEA. The distribution of labeled acetate incorporated into phospholipids was markedly affected by the presence of PEA. The uptake of acetate into phosphatidylethanolamine and phosphatidylglycerol was inhibited, whereas the uptake of acetate into the cardiolipin fraction was unaffected. Since acetate incorporation into phospholipid was quite sensitive to PEA, we suggest that the PEA-sensitive component required for the initiation of replication may be a phospholipid(s). PMID:4550658

Nunn, William D.; Tropp, Burton E.

1972-01-01

424

Effect of antioxidants in experimental Escherichia coli septicemia.  

PubMed

Free radicals have been implicated in the pathogenesis of gram-negative bacterial sepsis. We assessed the effectiveness of antioxidants and chelators to alter oxidative injury in established severe experimental Escherichia coli septicemia. One hour after challenge by intraperitoneal injection of bacteria, 36 rabbits were treated with moxalactam and randomized in sets of three to receive either placebo, superoxide dismutase (SOD), or a combination of antioxidants and chelators consisting of SOD, sodium thiosulfate, alpha-tocopherol, deferoxamine, and diethyldithiocarbamate. Throughout the course of treatment, levels of bacteremia and endotoxemia were similar among the three experimental groups. Neither antioxidant-treated group was significantly different from the control group in mean arterial blood pressure, leukocyte count, platelet count, core temperature, blood lactate, oxygenation or survival. Arterial pH and [HCO3-] were significantly lower in the antioxidant combination group compared to the control and SOD groups (P less than .01). In this model, antioxidant and chelator therapy does not substantially ameliorate established septicemia. PMID:2684447

Broner, C W; Shenep, J L; Stidham, G L; Stokes, D C; Fairclough, D; Schonbaum, G R; Rehg, J E; Hildner, W K

1989-10-01

425

Genomic Characterization of Enteroaggregative Escherichia coli From Children in Mali  

PubMed Central

Background.?Enteroaggregative Escherichia coli (EAEC) is a cause of epidemic and sporadic diarrhea, yet its role as an enteric pathogen is not fully understood. Methods.?We characterized 121 EAEC strains isolated in 2008 as part of a case-control study of moderate to severe acute diarrhea among children 0–59 months of age in Bamako, Mali. We applied multiplex polymerase chain reaction and comparative genome hybridization to identify potential virulence factors among the EAEC strains, coupled with classification and regression tree modeling to reveal combinations of factors most strongly associated with illness. Results.?The gene encoding the autotransporter protease SepA, originally described in Shigella species, was most strongly associated with diarrhea among the EAEC strains tested (odds ratio, 5.6 [95% confidence interval, 1.92–16.17]; P = .0006). In addition, we identified 3 gene combinations correlated with diarrhea: (1) a clonal group positive for sepA and a putative hemolysin; (2) a group harboring the EAST-1 enterotoxin and the flagellar type H33 but no other previously identified EAEC virulence factor; and (3) a group carrying several of the typical EAEC virulence genes. Conclusion.?Our data suggest that only a subset of EAEC strains are pathogenic in Mali and suggest that sepA may serve as a valuable marker for the most virulent isolates. PMID:22184729

Boisen, Nadia; Scheutz, Flemming; Rasko, David A.; Redman, Julia C.; Persson, Søren; Simon, Jakub; Kotloff, Karen L.; Levine, Myron M.; Sow, Samba; Tamboura, Boubou; Toure, Aliou; Malle, Dramane; Panchalingam, Sandra; Krogfelt, Karen A.

2012-01-01

426

[Electrophoretic typing of Escherichia coli esterases in septicemia].  

PubMed

Esterases produced by 175 strains of Escherichia coli isolated from 34 patients with septicaemia were subjected to electrophoresis in acrylamide-agarose gel. Forty-four electrophoretic types were identified, and the septicaemias were divided into two groups according to whether or not all the strains isolated in a given patient were of the same electrophoretic type. In the first group (21 patients) the presence of one single electrophoretic type demonstrated that the strains isolated from haemocultures and those isolated from focal specimens were identical and could be held responsible for infection in different foci. In the second group (13 patients) the presence of different electrophoretic types in the same patient either discard an relationship between strain from haemoculture and strain from focal specimen, or demonstrated that different strains could coexist in a focus of infection, or revealed successive and overlapping infections. These results not only provide precise information on the nature of bacteria responsible for infections, but also have interesting pathophysiological and epidemiological implications. PMID:6232532

Goullet, P; Picard, B

1984-04-21

427

Response surface methodology of nitrilase production by recombinant Escherichia coli  

PubMed Central

Growth and nitrilase production by recombinant Escherichia coli cells harbouring pET 21 (b) plasmid, for the expression of Pseudomonas putida nitrilase were improved using response surface methodology. Central composite design was used for obtaining ideal concentration of critical medium components which include fructose, tryptone, yeast extract and lactose. The optimal values for the concentration of fructose, tryptone, yeast extract and lactose were found to be 1.13, 2.26, 3.25 and 0.9 % (w/v), respectively. Here, fructose served as carbon source for the growth while lactose was preferably used as inducer for the expression of foreign protein. Yeast extract in the medium was used as a growth promoter while tryptone was added as a major nitrogen source. Using this optimized medium, an experimental growth of 6.67 (OD at 600 nm) and nitrilase activity of 27.13 U/ml was achieved. This approach for medium development led to an enhancement of the growth and enzyme activity by 1.4 and 2.2 times, respectively, as compared to the un-optimized medium. PMID:24031726

Dubey, Sachin; Singh, Amit; Banerjee, Uttam C.

2011-01-01

428

Evolution of diversity in spatially structured Escherichia coli populations.  

PubMed

The stochastic Ricker population model was used to investigate the generation and maintenance of genetic diversity in a bacterial population grown in a spatially structured environment. In particular, we showed that Escherichia coli undergoes dramatic genetic diversification when grown as a biofilm. Using a novel biofilm entrapment method, we retrieved 64 clones from each of six different depths of a mature biofilm, and after subculturing for approximately 30 generations, we measured their growth kinetics in three different media. We fit a stochastic Ricker population growth model to the recorded growth curves. The growth kinetics of clonal lineages descendant from cells sampled at different biofilm depths varied as a function of both the depth in the biofilm and the growth medium used. We concluded that differences in the growth dynamics of clones were heritable and arose during adaptive evolution under local conditions in a spatially heterogeneous environment. We postulate that under nutrient-limited conditions, selective sweeps would be protracted and would be insufficient to purge less-fit variants, a phenomenon that would allow the coexistence of genetically distinct clones. These findings contribute to the current understanding of biofilm ecology and complement current hypotheses for the maintenance and generation of microbial diversity in spatially structured environments. PMID:19648364

Ponciano, José Miguel; La, Hyun-Joon; Joyce, Paul; Forney, Larry J

2009-10-01

429

The Transcription Unit Architecture of the Escherichia Coli Genome  

SciTech Connect

Under EMSL User Proposal 25660, the authors reported that bacterial genomes are organized by structural and functional elements, including promoters, transcription start and termination sites, open reading frames, regulatory noncoding regions, untranslated regions and transcription units. Here, we iteratively integrate high-throughput, genome-wide measurements of RNA polymerase binding locations and mRNA transcript abundance, 5? sequences and translation into proteins to determine the organizational structure of the Escherichia coli K-12 MG1655 genome. Integration of the organizational elements provides an experimentally annotated transcription unit architecture, including alternative transcription start sites, 5? untranslated region, boundaries and open reading frames of each transcription unit. A total of 4,661 transcription units were identified, representing an increase of >530% over current knowledge. This comprehensive transcription unit architecture allows for the elucidation of condition-specific uses of alternative sigma factors at the genome scale. Furthermore, the transcription unit architecture provides a foundation on which to construct genome-scale transcriptional and translational regulatory networks.

Cho, Byung-Kwan; Zengler, Karsten; Qiu, Yu; Park, Young S.; Knight, Eric M.; Barrett, Christian; Gao, Yuan; Palsson, Bernhard O.

2009-11-30

430

High-Yield Resveratrol Production in Engineered Escherichia coli ? †  

PubMed Central

Plant polyphenols have been the subject of several recent scientific investigations since many of the molecules in this class have been found to be highly active in the human body, with a plethora of health-promoting activities against a variety of diseases, including heart disease, diabetes, and cancer, and with even the potential to slow aging. Further development of these potent natural therapeutics hinges on the formation of robust industrial production platforms designed using specifically selected as well as engineered protein sources along with the construction of optimal expression platforms. In this work, we first report the investigation of various stilbene synthases from an array of plant species considering structure-activity relationships, their expression efficiency in microorganisms, and their ability to synthesize resveratrol. Second, we looked into the construct environment of recombinantly expressed stilbene synthases, including different promoters, construct designs, and host strains, to create an Escherichia coli strain capable of producing superior resveratrol titers sufficient for commercial usage. Further improvement of metabolic capabilities of the recombinant strain aimed at improving the intracellular malonyl-coenzyme A pool, a resveratrol precursor, resulted in a final improved titer of 2.3 g/liter resveratrol. PMID:21441338

Lim, Chin Giaw; Fowler, Zachary L.; Hueller, Thomas; Schaffer, Steffen; Koffas, Mattheos A. G.

2011-01-01

431

The unstructured domain of colicin N kills Escherichia coli  

PubMed Central

Bacteria often produce toxins which kill competing bacteria. Colicins, produced by and toxic to Escherichia coli bacteria are three-domain proteins so efficient that one molecule can kill a cell. The C-terminal domain carries the lethal activity and the central domain is required for surface receptor binding. The N-terminal domain, required for translocation across the outer membrane, is always intrinsically unstructured. It has always been assumed therefore that the C-terminal cytotoxic domain is required for the bactericidal activity. Here we report the unexpected finding that in isolation, the 90-residue unstructured N-terminal domain of colicin N is cytotoxic. Furthermore it causes ion leakage from cells but, unlike known antimicrobial peptides (AMPs) with this property, shows no membrane binding behaviour. Finally, its activity remains strictly dependent upon the same receptor proteins (OmpF and TolA) used by full-length colicin N. This mechanism of rapid membrane disruption, via receptor mediated binding of a soluble peptide, may reveal a new target for the development of highly specific antibacterials. PMID:23672584

Johnson, Christopher L; Ridley, Helen; Pengelly, Robert J; Salleh, Mohd Zulkifli; Lakey, Jeremy H

2013-01-01

432

Response surface methodology of nitrilase production by recombinant Escherichia coli.  

PubMed

Growth and nitrilase production by recombinant Escherichia coli cells harbouring pET 21 (b) plasmid, for the expression of Pseudomonas putida nitrilase were improved using response surface methodology. Central composite design was used for obtaining ideal concentration of critical medium components which include fructose, tryptone, yeast extract and lactose. The optimal values for the concentration of fructose, tryptone, yeast extract and lactose were found to be 1.13, 2.26, 3.25 and 0.9 % (w/v), respectively. Here, fructose served as carbon source for the growth while lactose was preferably used as inducer for the expression of foreign protein. Yeast extract in the medium was used as a growth promoter while tryptone was added as a major nitrogen source. Using this optimized medium, an experimental growth of 6.67 (OD at 600 nm) and nitrilase activity of 27.13 U/ml was achieved. This approach for medium development led to an enhancement of the growth and enzyme activity by 1.4 and 2.2 times, respectively, as compared to the un-optimized medium. PMID:24031726

Dubey, Sachin; Singh, Amit; Banerjee, Uttam C

2011-07-01

433

Chromosome Replication in Escherichia coli: Life on the Scales  

PubMed Central

At all levels of Life, systems evolve on the 'scales of equilibria'. At the level of bacteria, the individual cell must favor one of two opposing strategies and either take risks to grow or avoid risks to survive. It has been proposed in the Dualism hypothesis that the growth and survival strategies depend on non-equilibrium and equilibrium hyperstructures, respectively. It has been further proposed that the cell cycle itself is the way cells manage to balance the ratios of these types of hyperstructure so as to achieve the compromise solution of living on the two scales. Here, we attempt to re-interpret a major event, the initiation of chromosome replication in Escherichia coli, in the light of scales of equilibria. This entails thinking in terms of hyperstructures as responsible for intensity sensing and quantity sensing and how this sensing might help explain the role of the DnaA protein in initiation of replication. We outline experiments and an automaton approach to the cell cycle that should test and refine the scales concept. PMID:25371267

Norris, Vic; Amar, Patrick

2012-01-01

434

Specific Ion effects on macromolecular interactions in escherichia coli extracts.  

PubMed

Protein characterization in situ remains a major challenge for protein science. Here, the interactions of ?Tat-GB1 in Escherichia coli cell extracts were investigated by NMR spectroscopy and size exclusion chromatography (SEC). ?Tat-GB1 was found to participate in high molecular weight complexes that remain intact at physiologically-relevant ionic strength. This observation helps to explain why ?Tat-GB1 was not detected by in-cell NMR spectroscopy. Extracts pre-treated with RNase A had a different SEC elution profile indicating that ?Tat-GB1 predominantly interacted with RNA. The roles of biological and laboratory ions in mediating macromolecular interactions were studied. Interestingly, the interactions of ?Tat-GB1 could be disrupted by biologically-relevant multivalent ions. The most effective shielding of interactions occurred in Mg(2+) -containing buffers. Moreover, a combination of RNA digestion and Mg(2+) greatly enhanced the NMR detection of ?Tat-GB1 in cell extracts. This article is protected by copyright. All rights reserved. PMID:25492389

Kyne, Ciara; Ruhle, Brian; Gautier, Virginie W; Crowley, Peter B

2014-12-01

435

Three-dimensional reconstruction of the ribosome from Escherichia coli.  

PubMed

Three-dimensional image reconstruction has been applied to electron micrographs of noncrystalline, negatively stained ribosomes obtained from Escherichia coli. Several independent reconstructions all show an overall appearance resembling models that had been derived earlier by direct visual interpretation of electron micrographs. The reconstructed ribosomes show numerous structural details not recognized previously, some of which may be functionally significant. A large elongate cavity (approximately 8-nm long x 5-nm wide x 6-nm [maximal] deep) is present on the surface of the ribosome near the base of its stalk and is identifiable as a portion of a feature termed the interface canyon, which was detected in prior reconstructions of the large ribosomal subunit (Radermacher, M., T. Wagenknecht, A. Verschoor, and J. Frank. 1987. EMBO (Eur. Mol. Biol. Organ.) J. 6:1107-1114). On the back of the ribosome, near the base of the central protuberance, is a hole leading to the interface canyon, which likely represents an exit site for the elongating polypeptide produced during protein biosynthesis. The exposed portion of the interface canyon appears well suited to bind two tRNA molecules in a configuration that is consistent with biochemical and structural data on the mechanism of peptide bond biosynthesis. PMID:2649163

Wagenknecht, T; Carazo, J M; Radermacher, M; Frank, J

1989-03-01

436

Escherichia coli expression, refolding and characterization of human laforin.  

PubMed

Laforin is a unique human dual-specificity phosphatase as it contains an amino terminal carbohydrate binding module (CBM). Laforin gene mutations lead to Lafora disease, a progressive myoclonus epilepsy with an early fatal issue. Previous attempts to produce recombinant laforin faced various difficulties, namely the appearance of protein inclusion bodies, the contamination with bacterial proteins and a high tendency of the protein to aggregate, despite the use of fusion tags to improve solubility and ease the purification process. In this work, we have expressed human laforin in Escherichia coli in the form of inclusion bodies devoid of any fusion tags. After a rapid dilution refolding step, the protein was purified by two chromatographic steps, yielding 5-7mg of purified protein per liter of bacterial culture. The purified protein was shown to have the kinetic characteristics of a dual-specificity phosphatase, and a functional carbohydrate binding module. With this protocol, we were able for the first time, to produce and purify laforin without fusion tags in the amounts traditionally needed for the crystallographic structural studies paving the way to the understanding of the molecular mechanisms of laforin activity and to the development of novel therapies for Lafora disease. PMID:20152902

Castanheira, Pedro; Moreira, Susana; Gama, Miguel; Faro, Carlos

2010-06-01

437

Torque generated by the flagellar motor of Escherichia coli.  

PubMed Central

Cells of the bacterium Escherichia coli were tethered and spun in a high-frequency rotating electric field at a series of discrete field strengths. This was done first at low field strengths, then at field strengths generating speeds high enough to disrupt motor function, and finally at low field strengths. Comparison of the initial and final speed versus applied-torque plots yielded relative motor torque. For backward rotation, motor torque rose steeply at speeds close to zero, peaking, on average, at about 2.2 times the stall torque. For forward rotation, motor torque remained approximately constant up to speeds of about 60% of the zero-torque speed. Then the torque dropped linearly with speed, crossed zero, and reached a minimum, on average, at about -1.7 times the stall torque. The zero-torque speed increased with temperature (about 90 Hz at 11 degrees C, 140 Hz at 16 degrees C, and 290 Hz at 23 degrees C), while other parameters remained approximately constant. Sometimes the motor slipped at either extreme (delivered constant torque over a range of speeds), but eventually it broke. Similar results were obtained whether motors broke catastrophically (suddenly and completely) or progressively or were de-energized by brief treatment with an uncoupler. These results are consistent with a tightly coupled ratchet mechanism, provided that elastic deformation of force-generating elements is limited by a stop and that mechanical components yield at high applied torques. PMID:8298044

Berg, H C; Turner, L

1993-01-01

438

Escherichia coli inactivation mechanism by pressurized CO2.  

PubMed

The effects of pressurized CO2 on the survival of Escherichia coli and the mechanism of cell inactivation were studied. Bacterial cultures were inoculated in nutrient broth and incubated at 30 degrees C for 18 h. Exposure of the cells to CO2 under pressures ranging from 2.5 to 25 MPa and at temperatures between 8 and 40 degrees C was performed in a double-walled reactor with a 1 L capacity. The effect of the treatment on the cells was evaluated by plating and by transmission and scanning electron microscopy observation. Vapour CO2 generated a bacteriostatic effect. In liquid or supercritical state, CO2 provided a bactericidal effect. The bactericidal effect increased with pressure and temperature. The mechanism of cell inactivation by liquid CO2 involved two stages. First, cell stress caused by the CO2 penetration provoked cell wall collapse and cellular content precipitation. Second, the cell death caused by supercritical extraction of intracellular substances and cell envelope perforation resulted in leaking of intracellular constituents. In supercritical conditions, the cell inactivation process had one single phase: cellular death. PMID:17473890

Oulé, Mathias K; Tano, Kablan; Bernier, Anne-Marie; Arul, Joseph

2006-12-01

439

Oxidative stress responses in Escherichia coli and Salmonella typhimurium.  

PubMed Central

Oxidative stress is strongly implicated in a number of diseases, such as rheumatoid arthritis, inflammatory bowel disorders, and atherosclerosis, and its emerging as one of the most important causative agents of mutagenesis, tumorigenesis, and aging. Recent progress on the genetics and molecular biology of the cellular responses to oxidative stress, primarily in Escherichia coli and Salmonella typhimurium, is summarized. Bacteria respond to oxidative stress by invoking two distinct stress responses, the peroxide stimulon and the superoxide stimulon, depending on whether the stress is mediated by peroxides or the superoxide anion. The two stimulons each contain a set of more than 30 genes. The expression of a subset of genes in each stimulon is under the control of a positive regulatory element; these genes constitute the OxyR and SoxRS regulons. The schemes of regulation of the two regulons by their respective regulators are reviewed in detail, and the overlaps of these regulons with other stress responses such as the heat shock and SOS responses are discussed. The products of Oxy-R- and SoxRS-regulated genes, such as catalases and superoxide dismutases, are involved in the prevention of oxidative damage, whereas others, such as endonuclease IV, play a role in the repair of oxidative damage. The potential roles of these and other gene products in the defense against oxidative damage in DNA, proteins, and membranes are discussed in detail. A brief discussion of the similarities and differences between oxidative stress responses in bacteria and eukaryotic organisms concludes this review. PMID:1779927

Farr, S B; Kogoma, T

1991-01-01

440

Hsp31 of Escherichia coli K-12 is glyoxalase III.  

PubMed

Hsp31 encoded by hchA is known as a heat-inducible molecular chaperone. Although structure studies revealed that Hsp31 has a putative catalytic triad consisting of Asp-214, His-186 and Cys-185, its enzymatic function, besides weak amino-peptidase activity, is still unknown. We found that Hsp31 displays glyoxalase activity that catalyses the conversion of methylglyoxal (MG) to d-lactate without an additional cofactor. The glyoxalase activity was completely abolished in the hchA-deficient strain, confirming the relationship between the hchA gene and its enzymatic activity in vivo. Hsp31 exhibits Michaelis-Menten kinetics for substrates MG with K(m) and k(cat) of 1.43±0.12 mM and 156.9±5.5 min?¹ respectively. The highest glyoxalase activity was found at 35-40 °C and pH of 6.0-8.0, and the activity was significantly inhibited by Cu²?, Fe³? and Zn²?. Mutagenesis studies based on our evaluation of conserved catalytic residues revealed that the Cys-185 and Glu-77 were essential for catalysis, whereas His-186 was less crucial for enzymatic function, although it participates in the catalytic process. The stationary-phase Escherichia coli cells became more susceptible to MG when hchA was deleted, which was complemented by an expression of plasmid-encoded hchA. Furthermore, an accumulation of intracellular MG was observed in hchA-deficient strains. PMID:21696459

Subedi, Krishna P; Choi, Dongwook; Kim, Insook; Min, Bumchan; Park, Chankyu

2011-08-01