scholarly journals Modulation of Enteropathogenic Escherichia coli Virulence by Quorum Sensing

2004 ◽  
Vol 72 (4) ◽  
pp. 2329-2337 ◽  
Author(s):  
Marcelo P. Sircili ◽  
Matthew Walters ◽  
Luis R. Trabulsi ◽  
Vanessa Sperandio
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Quorum Sensing ◽  
Type Iii Secretion ◽  
Virulence Genes ◽  
Integration Host Factor ◽  
Exponential Phase ◽  
Abnormal Behavior ◽  
Type Iii ◽  
Enterocyte Effacement

ABSTRACT Enteropathogenic Escherichia coli (EPEC) produces a lesion on epithelial cells called the attaching and effacing (AE) lesion. All genes necessary for AE are encoded within the locus of enterocyte effacement (LEE). EPEC also adheres in a characteristic pattern to epithelial cells by forming microcolonies, usually referred to as localized adherence (LA). LA is mediated by the bundle-forming pilus and flagella. The LEE genes are directly activated by the LEE-encoded regulator (Ler). Transcription of Ler is under the control of Per, integration host factor, Fis, BipA, and quorum sensing (QS), specifically through the luxS system. QS activates expression of the LEE genes in EPEC, with QseA activating transcription of ler. Here we report that transcription of the LEE genes and type III secretion are diminished in both luxS and qseA mutants. Transcription of the LEE genes is affected in both mutants mostly during the mid-exponential phase of growth. Transcription of qseA itself is diminished throughout growth in a luxS mutant and is under autorepression. Furthermore, QS activation of type III secretion is independent of per, given that QseA still activates type III secretion in a per mutant strain. Both mutants are deficient in adherence to epithelial cells and form smaller microcolonies. Several factors may contribute to this abnormal behavior: transcription of LEE genes and type III secretion are diminished, and expression of flagella and Per is altered in both mutants. These results suggest that QS is involved in modulating the regulation of the EPEC virulence genes.

scholarly journals Quorum-Sensing Escherichia coli Regulator A: a Regulator of the LysR Family Involved in the Regulation of the Locus of Enterocyte Effacement Pathogenicity Island in Enterohemorrhagic E. coli

2002 ◽  
Vol 70 (6) ◽  
pp. 3085-3093 ◽  
Author(s):  
Vanessa Sperandio ◽  
Caiyi C. Li ◽  
James B. Kaper
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Type Iii Secretion ◽  
Pathogenicity Island ◽  
The Other ◽  
E Coli ◽  
Type Iii ◽  
Enterocyte Effacement ◽  
K 12 ◽  
Lysr Family

ABSTRACT The locus of enterocyte effacement (LEE) is a chromosomal pathogenicity island that encodes the proteins involved in the formation of the attaching and effacing lesions by enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC). The LEE comprises 41 open reading frames organized in five major operons, LEE1, LEE2, LEE3, tir (LEE5), and LEE4, which encode a type III secretion system, the intimin adhesin, the translocated intimin receptor (Tir), and other effector proteins. The first gene of LEE1 encodes the Ler regulator, which activates all the other genes within the LEE. We previously reported that the LEE genes were activated by quorum sensing through Ler (V. Sperandio, J. L. Mellies, W. Nguyen, S. Shin, and J. B. Kaper, Proc. Natl. Acad. Sci. USA 96:15196-15201, 1999). In this study we report that a putative regulator in the E. coli genome is itself activated by quorum sensing. This regulator is encoded by open reading frame b3243; belongs to the LysR family of regulators; is present in EHEC, EPEC, and E. coli K-12; and shares homology with the AphB and PtxR regulators of Vibrio cholerae and Pseudomonas aeruginosa, respectively. We confirmed the activation of b3243 by quorum sensing by using transcriptional fusions and renamed this regulator quorum-sensing E. coli regulator A (QseA). We observed that QseA activated transcription of ler and therefore of the other LEE genes. An EHEC qseA mutant had a striking reduction of type III secretion activity, which was complemented when qseA was provided in trans. Similar results were also observed with a qseA mutant of EPEC. The QseA regulator is part of the regulatory cascade that regulates EHEC and EPEC virulence genes by quorum sensing.

scholarly journals Characterization of the Effects of Salicylidene Acylhydrazide Compounds on Type III Secretion in Escherichia coli O157:H7

2009 ◽  
Vol 77 (10) ◽  
pp. 4209-4220 ◽  
Author(s):  
Jai J. Tree ◽  
Dai Wang ◽  
Carol McInally ◽  
Arvind Mahajan ◽  
Abigail Layton ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Virulence Genes ◽  
Escherichia Coli O157 ◽  
Transcriptional Responses ◽  
Type Iii ◽  
Dna Elements ◽  
Antivirulence Agents ◽  
Related Compounds

ABSTRACTRecent work has highlighted a number of compounds that target bacterial virulence by affecting gene regulation. In this work, we show that small-molecule inhibitors affect the expression of the type III secretion system (T3SS) ofEscherichia coliO157:H7 in liquid culture and when this bacterium is attached to bovine epithelial cells. Inhibition of T3SS expression resulted in a reduction in the capacity of the bacteria to form attaching and effacing lesions. Our results show that there is marked variation in the abilities of four structurally related compounds to inhibit the T3SS of a panel of isolates. Using transcriptomics, we performed a comprehensive analysis of the conserved and inhibitor-specific transcriptional responses to these four compounds. These analyses of gene expression show that numerous virulence genes, located on horizontally acquired DNA elements, are affected by the compounds, but the number of genes significantly affected varied markedly for the different compounds. Overall, we highlight the importance of assessing the effect of such “antivirulence” agents on a range of isolates and discuss the possible mechanisms which may lead to the coordinate downregulation of horizontally acquired virulence genes.

scholarly journals Type III Secretion-Dependent Sensitivity of Escherichia coli O157 to Specific Ketolides

2015 ◽  
Vol 60 (1) ◽  
pp. 459-470 ◽  
Author(s):  
Romina J. Fernandez-Brando ◽  
Nao Yamaguchi ◽  
Amin Tahoun ◽  
Sean P. McAteer ◽  
Trudi Gillespie ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Bacterial Colonization ◽  
Effector Proteins ◽  
Content Type ◽  
E Coli ◽  
Type Iii ◽  
Bacterial Binding

ABSTRACTA subset of Gram-negative bacterial pathogens uses a type III secretion system (T3SS) to open up a conduit into eukaryotic cells in order to inject effector proteins. These modulate pathways to enhance bacterial colonization. In this study, we screened established bioactive compounds for any that could repress T3SS expression in enterohemorrhagicEscherichia coli(EHEC) O157. The ketolides telithromycin and, subsequently, solithromycin both demonstrated repressive effects on expression of the bacterial T3SS at sub-MICs, leading to significant reductions in bacterial binding and actin-rich pedestal formation on epithelial cells. Preincubation of epithelial cells with solithromycin resulted in significantly less attachment ofE. coliO157. Moreover, bacteria expressing the T3SS were more susceptible to solithromycin, and there was significant preferential killing ofE. coliO157 bacteria when they were added to epithelial cells that had been preexposed to the ketolide. This killing was dependent on expression of the T3SS. Taken together, this research indicates that the ketolide that has accumulated in epithelial cells may traffic back into the bacteria via the T3SS. Considering that neither ketolide induces the SOS response, nontoxic members of this class of antibiotics, such as solithromycin, should be considered for future testing and trials evaluating their use for treatment of EHEC infections. These antibiotics may also have broader significance for treating infections caused by other pathogenic bacteria, including intracellular bacteria, that express a T3SS.

scholarly journals A Gene from the Locus of Enterocyte Effacement That Is Required for Enteropathogenic Escherichia coli To Increase Tight-Junction Permeability Encodes a Chaperone for EspF

2002 ◽  
Vol 70 (5) ◽  
pp. 2271-2277 ◽  
Author(s):  
Simon J. Elliott ◽  
Colin B. O'Connell ◽  
Athanasia Koutsouris ◽  
Carl Brinkley ◽  
Michael S. Donnenberg ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Tight Junction ◽  
Type Iii Secretion ◽  
Barrier Properties ◽  
Type Iii ◽  
Tight Junction Permeability ◽  
Secretion Chaperone ◽  
Enterocyte Effacement ◽  
Protein Rich

ABSTRACT Disruption of the barrier properties of the enterocyte tight junction is believed to be important in the pathogenesis of diarrhea caused by enteropathogenic Escherichia coli (EPEC). This phenotype can be measured in vitro as the ability of EPEC to reduce transepithelial resistance (TER) across enterocyte monolayers and requires the products of the locus of enterocyte effacement (LEE) and, in particular, the type III secreted effector protein EspF. We report a second LEE-encoded gene that is also necessary for EPEC to fully reduce TER. rorf10 is not necessary for EPEC adherence, EspADB secretion, or formation of attaching and effacing lesions. However, rorf10 mutants have a diminished TER phenotype, reduced intracellular levels of EspF, and a reduced ability to translocate EspF into epithelial cells. The product of rorf10 is a 14-kDa intracellular protein rich in α-helices that specifically interacts with EspF but not with Tir or other EPEC secreted proteins. These properties are consistent with the hypothesis that rorf10 encodes a type III secretion chaperone for EspF, and we rename this protein CesF, the chaperone for EPEC secreted protein F.

scholarly journals Characterization of Two Non-Locus of Enterocyte Effacement-Encoded Type III-Translocated Effectors, NleC and NleD, in Attaching and Effacing Pathogens

2005 ◽  
Vol 73 (12) ◽  
pp. 8411-8417 ◽  
Author(s):  
Olivier Marchés ◽  
Siouxsie Wiles ◽  
Francis Dziva ◽  
Roberto M. La Ragione ◽  
Stephanie Schüller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Secretion System ◽  
Host Cells ◽  
Deletion Mutants ◽  
Intestinal Colonization ◽  
Type Iii ◽  
Enterocyte Effacement

ABSTRACT Intestinal colonization by enteropathogenic and enterohemorrhagic Escherichia coli requires the locus of enterocyte effacement-encoded type III secretion system. We report that NleC and NleD are translocated into host cells via this system. Deletion mutants induced attaching and effacing lesions in vitro, while infection of calves or lambs showed that neither gene was required for colonization.

scholarly journals Regulators Encoded in the Escherichia coli Type III Secretion System 2 Gene Cluster Influence Expression of Genes within the Locus for Enterocyte Effacement in Enterohemorrhagic E. coli O157:H7

2004 ◽  
Vol 72 (12) ◽  
pp. 7282-7293 ◽  
Author(s):  
Lihong Zhang ◽  
Roy R. Chaudhuri ◽  
Chrystala Constantinidou ◽  
Jon L. Hobman ◽  
Mala D. Patel ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Regulatory Genes ◽  
E Coli ◽  
Type Iii ◽  
System 2 ◽  
Enterocyte Effacement

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 subverts host cells through a type III secretion system encoded by the locus for enterocyte effacement (LEE). Genome sequencing of this pathotype revealed the existence of a gene cluster encoding components of a second cryptic type III secretion system, E. coli type III secretion system 2 (ETT2). Recently, we showed that the ETT2 gene cluster is present in whole or in part in the majority of E. coli strains but is unable to encode a functional secretion system in most strains, including EHEC O157:H7. However, here we show that mutational inhibition of two regulatory genes (ECs3720 or etrA and ECs3734 or eivF) from the ETT2 cluster in EHEC O157:H7 leads to greatly increased secretion of proteins encoded by the LEE and to increased adhesion to human intestinal cells. Studies in which transcriptional fusions and microarrays were used indicated that EtrA and EivF exert profound negative effects on gene transcription within the LEE. Consistent with these observations, expression of these regulators in an EHEC O26:H- strain led to suppression of protein secretion under LEE-inducing conditions. These findings provide fresh examples of the influence of mobile genetic elements on regulation of the LEE and of cross talk between type III secretion system gene clusters. In addition, they provide a cautionary tale because they show that the effects of regulatory genes can outlive widespread decay of other genes in a functionally coherent gene cluster, a phenomenon that we have named the “Cheshire cat effect.” It also seems likely that variations in the ETT2 regulator repertoire might account for strain-to-strain variation in secretion of LEE-encoded proteins.

CesAB is an enteropathogenic Escherichia coli chaperone for the type-III translocator proteins EspA and EspB

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3639-3647 ◽  
Author(s):  
Elizabeth A. Creasey ◽  
Devorah Friedberg ◽  
Robert K. Shaw ◽  
Tatiana Umanski ◽  
Stuart Knutton ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Interactions ◽  
Type Iii Secretion ◽  
Secretion System ◽  
Effector Proteins ◽  
Enteropathogenic Escherichia Coli ◽  
Type Iii ◽  
Mucosal Surfaces ◽  
Enterocyte Effacement ◽  
Bacterial Cytoplasm

Enteropathogenic Escherichia coli (EPEC) are extracellular pathogens that colonize mucosal surfaces of the intestine via formation of attaching and effacing (A/E) lesions. The genes responsible for induction of the A/E lesions are located on a pathogenicity island, termed the locus of enterocyte effacement (LEE), which encodes the adhesin intimin and the type III secretion system needle complex, translocator and effector proteins. One of the major EPEC translocator proteins, EspA, forms a filamentous conduit along which secreted proteins travel before they arrive at the translocation pore in the plasma membrane of the host cell, which is composed of EspB and EspD. Prior to secretion, many type III proteins, including translocators, are maintained in the bacterial cytoplasm by association with a specific chaperone. In EPEC, chaperones have been identified for the effector proteins Tir, Map and EspF, and the translocator proteins EspD and EspB. In this study, CesAB (Orf3 of the LEE) was identified as a chaperone for EspA and EspB. Specific CesAB–EspA and CesAB–EspB protein interactions are demonstrated. CesAB was essential for stability of EspA within the bacterial cell prior to secretion. Furthermore, a cesAB mutant failed to secrete EspA, as well as EspB, to assemble EspA filaments, to induce A/E lesion following infection of HEp-2 cells and to adhere to, or cause haemolysis of, erythrocytes.

scholarly journals Secreted indole serves as a signal for expression of type III secretion system translocators in enterohaemorrhagic Escherichia coli O157 : H7

Microbiology ◽  
2009 ◽  
Vol 155 (2) ◽  
pp. 541-550 ◽  
Author(s):  
Hidetada Hirakawa ◽  
Toshio Kodama ◽  
Asuka Takumi-Kobayashi ◽  
Takeshi Honda ◽  
Akihito Yamaguchi
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Physiological Role ◽  
Type Iii Secretion System ◽  
Enteric Bacteria ◽  
Secretion System ◽  
Type Iii ◽  
Enterohaemorrhagic Escherichia Coli ◽  
Enhanced Secretion ◽  
Enterocyte Effacement

Indole is produced by tryptophanase during growth of enteric bacteria and accumulates in the culture medium. The physiological role of indole production is poorly understood. We discovered that enterohaemorrhagic Escherichia coli (EHEC) O157 : H7 with a tnaA deletion has decreased secretion of EspA and EspB via the type III secretion system and as a result there is reduced formation of attaching and effacing (A/E) lesions in HeLa cells. Addition of indole restored and enhanced secretion of EspA and EspB and formation of A/E lesions by the tnaA deletion mutant EHEC. Indole addition moderately increased the promoter activity of LEE4 genes, including espA and espB, in the locus of enterocyte effacement. Thus in EHEC indole can serve to signal EspA and EspB expression and secretion and stimulate the ability of EHEC to form A/E lesions on human cells.

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