A dominant mutation in Escherichia coli OmpR lies within a domain which is highly conserved in a large family of bacterial regulatory proteins

1988 ◽  
Vol 211 (3) ◽  
pp. 538-540 ◽  
Author(s):  
Kazuhiro Ikenaka ◽  
Kangla Tsung ◽  
Dorothy E. Comeau ◽  
Masayori Inouye
Keyword(s):  
Escherichia Coli ◽  
Large Family ◽  
Regulatory Proteins ◽  
Dominant Mutation

Escherichia coli tol and rcs genes participate in the complex network affecting curli synthesis

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2487-2497 ◽  
Author(s):  
Anne Vianney ◽  
Grégory Jubelin ◽  
Sophie Renault ◽  
Corine Dorel ◽  
Philippe Lejeune ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Membrane Integrity ◽  
Regulatory Proteins ◽  
Gram Negative Bacteria ◽  
Dependent Manner ◽  
Dominant Effect ◽  
Gram Negative ◽  
E Coli

Curli are necessary for the adherence of Escherichia coli to surfaces, and to each other, during biofilm formation, and the csgBA and csgDEFG operons are both required for their synthesis. A recent survey of gene expression in Pseudomonas aeruginosa biofilms has identified tolA as a gene activated in biofilms. The tol genes play a fundamental role in maintaining the outer-membrane integrity of Gram-negative bacteria. RcsC, the sensor of the RcsBCD phosphorelay, is involved, together with RcsA, in colanic acid capsule synthesis, and also modulates the expression of tolQRA and csgDEFG. In addition, the RcsBCD phosphorelay is activated in tol mutants or when Tol proteins are overexpressed. These results led the authors to investigate the role of the tol genes in biofilm formation in laboratory and clinical isolates of E. coli. It was shown that the adherence of cells was lowered in the tol mutants. This could be the result of a drastic decrease in the expression of the csgBA operon, even though the expression of csgDEFG was slightly increased under such conditions. It was also shown that the Rcs system negatively controls the expression of the two csg operons in an RcsA-dependent manner. In the tol mutants, activation of csgDEFG occurred via OmpR and was dominant upon repression by RcsB and RcsA, while these two regulatory proteins repressed csgBA through a dominant effect on the activator protein CsgD, thus affecting curli synthesis. The results demonstrate that the Rcs system, previously known to control the synthesis of the capsule and the flagella, is an additional component involved in the regulation of curli. Furthermore, it is shown that the defect in cell motility observed in the tol mutants depends on RcsB and RcsA.

Functional and structural analysis of members of the TorD family, a large chaperone family dedicated to molybdoproteins

Microbiology ◽  
2004 ◽  
Vol 150 (4) ◽  
pp. 935-943 ◽  
Author(s):  
Marianne Ilbert ◽  
Vincent Méjean ◽  
Chantal Iobbi-Nivol
Keyword(s):  
Escherichia Coli ◽  
Structural Analysis ◽  
Family Member ◽  
Signal Sequence ◽  
Large Family ◽  
Inhibitory Effect ◽  
Cytoplasmic Protein ◽  
Dmso Reductase ◽  
Tmao Reductase ◽  
Positive Effect

The trimethylamine N-oxide (TMAO) reductase TorA, a DMSO reductase family member, is a periplasmic molybdoenzyme of Escherichia coli. The cytoplasmic protein TorD acts as a chaperone for TorA, allowing the efficient insertion of the molybdenum cofactor into the apoform of the enzyme prior to its secretion. This paper demonstrates that TorD is a member of a large family of prokaryotic proteins that are structurally related. Moreover, their genes generally belong to operons also encoding molybdoenzymes of the DMSO reductase family. Both the TorD and the DMSO reductase families present a similar phylogenetic organization, suggesting a co-evolution of these two families of proteins. This hypothesis is also supported by the fact that the TorD and DmsD chaperones cannot replace each other and thus appear dedicated to specific molybdopartners. Interestingly, it was found that the positive effect of TorD on TorA maturation, and the partial inhibitory effect of DmsD and homologues, are independent of the TorA signal sequence.

scholarly journals Characterization and Functional Analysis of AatB, a Novel Autotransporter Adhesin and Virulence Factor of Avian Pathogenic Escherichia coli

2013 ◽  
Vol 81 (7) ◽  
pp. 2437-2447 ◽  
Author(s):  
Xiangkai ZhuGe ◽  
Shaohui Wang ◽  
Hongjie Fan ◽  
Zihao Pan ◽  
Jianluan Ren ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Large Family ◽  
Extracellular Proteins ◽  
Dimensional Structure ◽  
Phylogenetic Groups ◽  
Passenger Domain ◽  
Content Type

ABSTRACTAutotransporter (AT) proteins constitute a large family of extracellular proteins that contribute to bacterial virulence. A novel AT adhesin gene,aatB, was identified in avian pathogenicEscherichia coli(APEC) DE205B via genomic analyses. The open reading frame ofaatBwas 1,017 bp, encoding a putative 36.3-kDa protein which contained structural motifs characteristic for AT proteins: a signal peptide, a passenger domain, and a translocator domain. The predicted three-dimensional structure of AatB consisted of two distinct domains, the C-terminal β-barrel translocator domain and an N-terminal passenger domain. The prevalence analyses ofaatBin APEC indicated thataatBwas detected in 26.4% (72/273) of APEC strains and was strongly associated with phylogenetic groups D and B2. Quantitative real-time reverse transcription-PCR analyses revealed that AatB expression was increased during infectionin vitroandin vivo. Moreover, AatB could elicit antibodies in infected ducks, suggesting that AatB is involved in APEC pathogenicity. Thus, APEC DE205B strains with a mutatedaatBgene and mutated strains complemented with theaatBgene were constructed. Inactivation ofaatBresulted in a reduced capacity to adhere to DF-1 cells, defective virulence capacityin vivo, and decreased colonization capacity in lung during systemic infection compared with the capacities of the wild-type strain. Furthermore, these capacities were restored in the complementation strains. These results indicated that AatB makes a significant contribution to APEC virulence through bacterial adherence to host tissuesin vivoandin vitro. In addition, biofilm formation assays with strain AAEC189 expressing AatB indicated that AatB mediates biofilm formation.

scholarly journals Mechanical slowing-down of cytoplasmic diffusion allows in vivo counting of proteins in individual cells

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Burak Okumus ◽  
Dirk Landgraf ◽  
Ghee Chuan Lai ◽  
Somenath Bakshi ◽  
Juan Carlos Arias-Castro ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Single Molecule ◽  
Exponential Phase ◽  
Regulatory Proteins ◽  
Adapter Protein ◽  
Average Cell ◽  
E Coli ◽  
Slowing Down ◽  
Automated Microscopy

AbstractMany key regulatory proteins in bacteria are present in too low numbers to be detected with conventional methods, which poses a particular challenge for single-cell analyses because such proteins can contribute greatly to phenotypic heterogeneity. Here we develop a microfluidics-based platform that enables single-molecule counting of low-abundance proteins by mechanically slowing-down their diffusion within the cytoplasm of liveEscherichia coli(E. coli) cells. Our technique also allows for automated microscopy at high throughput with minimal perturbation to native physiology, as well as viable enrichment/retrieval. We illustrate the method by analysing the control of the master regulator of theE. colistress response, RpoS, by its adapter protein, SprE (RssB). Quantification of SprE numbers shows that though SprE is necessary for RpoS degradation, it is expressed at levels as low as 3–4 molecules per average cell cycle, and fluctuations in SprE are approximately Poisson distributed during exponential phase with no sign of bursting.

scholarly journals Binding of CFA/I Pili of Enterotoxigenic Escherichia coli to Asialo-GM1 Is Mediated by the Minor Pilin CfaE

2016 ◽  
Vol 84 (5) ◽  
pp. 1642-1649 ◽  
Author(s):  
T. P. Vipin Madhavan ◽  
James D. Riches ◽  
Martin J. Scanlon ◽  
Glen C. Ulett ◽  
Harry Sakellaris
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Current Model ◽  
Large Family ◽  
Binding Activity ◽  
Enterotoxigenic Escherichia Coli ◽  
Intestinal Epithelial ◽  
Content Type ◽  
Asialo Gm1

CFA/I pili are representatives of a large family of related pili that mediate the adherence of enterotoxigenicEscherichia colito intestinal epithelial cells. They are assembled via the alternate chaperone-usher pathway and consist of two subunits, CfaB, which makes up the pilus shaft and a single pilus tip-associated subunit, CfaE. The current model of pilus-mediated adherence proposes that CFA/I has two distinct binding activities; the CfaE subunit is responsible for binding to receptors of unknown structure on erythrocyte and intestinal epithelial cell surfaces, while CfaB binds to various glycosphingolipids, including asialo-GM1. In this report, we present two independent lines of evidence that, contrary to the existing model, CfaB does not bind to asialo-GM1 independently of CfaE. Neither purified CfaB subunits nor CfaB assembled into pili bind to asialo-GM1. Instead, we demonstrate that binding activity toward asialo-GM1 resides in CfaE and this is essential for pilus binding to Caco-2 intestinal epithelial cells. We conclude that the binding activities of CFA/I pili for asialo-GM1, erythrocytes, and intestinal cells are inseparable, require the same amino acid residues in CfaE, and therefore depend on the same or very similar binding mechanisms.

Effects of global regulatory proteins and environmental conditionson fimbrial gene expression of F1651 and F1652 producedby Escherichia coli causing septicaemia in pigs

2000 ◽  
Vol 151 (7) ◽  
pp. 563-574 ◽  
Author(s):  
France Daigle ◽  
Céline Forget ◽  
Christine Martin ◽  
Marc Drolet ◽  
Marie-Catherine Tessier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Regulatory Proteins

scholarly journals Susceptibility of Tigecycline against Carbapenem Resistant Enterobacteriaceae

2021 ◽  
Keyword(s):  
Escherichia Coli ◽  
Respiratory Tract ◽  
Antimicrobial Susceptibility ◽  
Bacterial Infections ◽  
Large Family ◽  
Klebsiella Species ◽  
Cross Sectional ◽  
E Coli ◽  
Carbapenem Resistant ◽  
Carbapenem Resistant Enterobacteriaceae

Background: Enterobacteriaceae, a large family of Gram-negative bacteria, are one of the commonest etiological agents causing serious bacterial infections to humans. Carbapenems are the group of antibiotics with a broad spectrum of antimicrobial action. Infections caused due to Carbapenem resistant Enterobacteriaceae (CRE) are a huge challenge for existing medical practice. Therefore, this project aimed to find out the antimicrobial susceptibility pattern of Tigecycline against CRE. Methods: This cross-sectional study with non-probability consecutive sampling was done at Ziauddin Hospital Microbiology Laboratory from 15th August 2017 to 15th April 2018. Accordingly, 151 isolates of CRE were collected from cultures of blood, respiratory tract, wound pus and other body fluids. The growth inhibition zones were measured following the Food and Drug Administration (FDA) disk diffusion breakpoint criteria. Frequencies and percentages were computed for gender, microorganism, and antimicrobial susceptibility. Chi-squared test was applied and p≤ 0.05 was considered as statistically significant. Results: Klebsiella species were most commonly isolated pathogen, 67.5% (n=102) followed by Escherichia coli (E. coli) 23.2% (n=35), Enterobacter 7.3% (n=11) and Serratia species 2% (n=3). Tigecycline was 97% (34 /35) sensitive for E. coli, 86.3% (88/102) for Klebsiella species), 91% (10/11) for Enterobacter species, and 100% for Serratia species. Klebsiella species showed the highest rate of resistance to tigecycline i.e., 13.7% of the total Klebsiella isolates. Conclusion: Among the Enterobacteriaceae family, Klebsiella species have the greatest ability to acquire resistance. Tigecycline showed good activity against isolates of CRE recovered from infections of skin, soft tissue, intra-abdomen, lower respiratory tract and blood stream. Keywords: Carbapenems; beta-Lactamases; Anti-Bacterial Agents; Tigecycline; Klebsiella; Escherichia coli.

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