Glucose Decreases Virulence Gene Expression of Escherichia coli O157:H7

2012 ◽  
Vol 75 (4) ◽  
pp. 748-752 ◽  
Author(s):  
V. DELCENSERIE ◽  
G. LaPOINTE ◽  
T. CHARASLERTRANGSI ◽  
A. RABALSKI ◽  
M. W. GRIFFITHS
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Quorum Sensing ◽  
Shiga Toxin ◽  
Virulence Gene ◽  
Escherichia Coli O157 ◽  
Virulence Gene Expression ◽  
E Coli ◽  
Reverse Transcription Pcr ◽  
Enterocyte Effacement

Escherichia coli O157:H7 is responsible for a human toxico-infection that can lead to severe complications such as hemolytic uremic syndrome. Inside the intestine, E. coli O157:H7 forms typical attaching-effacing lesions and produces Shiga toxins. The genes that are responsible for these lesions are located in a pathogenicity island called the locus of enterocyte effacement (LEE). LEE gene expression is influenced by quorum sensing through the luxS system. In this study, the effect of glucose on the expression of several genes from LEE, on the expression of Shiga toxin genes, and on the expression of luxS was assessed with real-time, reverse transcription PCR. All concentrations of glucose (from 0.1 to 1%) were able to down-regulate genes from the LEE operon. A slight down-regulation of genes implicated in Shiga toxin expression was also observed but was significant for low doses of glucose (0.1 to 0.5%) only. A slight but significant increase in luxS expression was observed with 1% glucose. This confirms that in addition to quorum sensing, the presence or absence of nutrients such as glucose has an impact on the down- or upregulation of LEE-encoded virulence genes by the bacterium. The influence of glucose on the virulence of E. coli O157:H7 has received little attention, and these results suggest that glucose can have an important effect on the virulence of E. coli O157:H7.

scholarly journals Reconstitution of Acetosyringone-Mediated Agrobacterium tumefaciens Virulence Gene Expression in the Heterologous Host Escherichia coli

2001 ◽  
Vol 183 (12) ◽  
pp. 3704-3711 ◽  
Author(s):  
Scott M. Lohrke ◽  
Hongjiang Yang ◽  
Shouguang Jin
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Agrobacterium Tumefaciens ◽  
Virulence Genes ◽  
Virulence Gene ◽  
Dependent Manner ◽  
Gene Encoding ◽  
Virulence Gene Expression ◽  
E Coli ◽  
Glucose Binding

ABSTRACT The ability to utilize Escherichia coli as a heterologous system in which to study the regulation ofAgrobacterium tumefaciens virulence genes and the mechanism of transfer DNA (T-DNA) transfer would provide an important tool to our understanding and manipulation of these processes. We have previously reported that the rpoA gene encoding the alpha subunit of RNA polymerase is required for the expression of lacZ gene under the control of virB promoter (virBp::lacZ) in E. colicontaining a constitutively active virG gene [virG(Con)]. Here we show that an RpoA hybrid containing the N-terminal 247 residues from E. coli and the C-terminal 89 residues from A. tumefaciens was able to significantly express virBp::lacZ in E. coli in a VirG(Con)-dependent manner. Utilization oflac promoter-driven virA and virGin combination with the A. tumefaciens rpoA construct resulted in significant inducer-mediated expression of thevirBp::lacZ fusion, and the level ofvirBp::lacZ expression was positively correlated to the copy number of the rpoA construct. This expression was dependent on VirA, VirG, temperature, and, to a lesser extent, pH, which is similar to what is observed in A. tumefaciens. Furthermore, the effect of sugars on virgene expression was observed only in the presence of thechvE gene, suggesting that the glucose-binding protein ofE. coli, a homologue of ChvE, does not interact with the VirA molecule. We also evaluated other phenolic compounds in induction assays and observed significant expression with syringealdehyde, a low level of expression with acetovanillone, and no expression with hydroxyacetophenone, similar to what occurs in A. tumefaciens strain A348 from which the virA clone was derived. These data support the notion that VirA directly senses the phenolic inducer. However, the overall level of expression of thevir genes in E. coli is less than what is observed in A. tumefaciens, suggesting that additional gene(s) from A. tumefaciens may be required for the full expression of virulence genes in E. coli.

scholarly journals The Locus of Enterocyte Effacement (LEE)-Encoded Regulator Controls Expression of Both LEE- and Non-LEE-Encoded Virulence Factors in Enteropathogenic and EnterohemorrhagicEscherichia coli

2000 ◽  
Vol 68 (11) ◽  
pp. 6115-6126 ◽  
Author(s):  
Simon J. Elliott ◽  
Vanessa Sperandio ◽  
Jorge A. Girón ◽  
Sooan Shin ◽  
Jay L. Mellies ◽  
...  
Keyword(s):  
Gene Expression ◽  
Virulence Gene ◽  
Global Regulator ◽  
Lesion Formation ◽  
Virulence Gene Expression ◽  
E Coli ◽  
Secretion Pathway ◽  
Regulatory Cascade ◽  
Enterocyte Effacement ◽  
Maximal Expression

ABSTRACT Regulation of virulence gene expression in enteropathogenicEscherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) is incompletely understood. In EPEC, the plasmid-encoded regulator Per is required for maximal expression of proteins encoded on the locus of enterocyte effacement (LEE), and a LEE-encoded regulator (Ler) is part of the Per-mediated regulatory cascade upregulating the LEE2, LEE3, andLEE4 promoters. We now report that Ler is essential for the expression of multiple LEE-located genes in both EPEC and EHEC, including those encoding the type III secretion pathway, the secreted Esp proteins, Tir, and intimin. Ler is therefore central to the process of attaching and effacing (AE) lesion formation. Ler also regulates the expression of LEE-located genes not required for AE-lesion formation, including rorf2, orf10,rorf10, orf19, and espF, indicating that Ler regulates additional virulence properties. In addition, Ler regulates the expression of proteins encoded outside the LEE that are not essential for AE lesion formation, including TagA in EHEC and EspC in EPEC. Δler mutants of both EPEC and EHEC show altered adherence to epithelial cells and express novel fimbriae. Ler is therefore a global regulator of virulence gene expression in EPEC and EHEC.

scholarly journals Adherence and associated virulence gene expression in acid-treated Escherichia coli O157 : H7 in vitro and in ligated pig intestine

Microbiology ◽  
2012 ◽  
Vol 158 (4) ◽  
pp. 1084-1093 ◽  
Author(s):  
Xianhua Yin ◽  
Yanni Feng ◽  
Yang Lu ◽  
James R. Chambers ◽  
Joshua Gong ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Virulence Gene ◽  
Escherichia Coli O157 ◽  
Virulence Gene Expression

Transcriptional Activator OvrA Encoded in O Island 19 Modulates Virulence Gene Expression in Enterohemorrhagic Escherichia coli O157:H7

2019 ◽  
Author(s):  
Bin Liu ◽  
Junyue Wang ◽  
Lu Wang ◽  
Peng Ding ◽  
Pan Yang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Gene Promoter ◽  
Virulence Gene ◽  
Coli Strain ◽  
Enterohemorrhagic Escherichia Coli ◽  
Bacterial Adherence ◽  
Host Cells ◽  
Virulence Gene Expression ◽  
E Coli

AbstractThe human intestinal pathogen enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes bloody diarrhea, hemorrhagic colitis, and fatal hemolytic uremic syndrome. Its genome contains 177 unique O islands (OIs), which contribute largely to the high virulence and pathogenicity although most OI genes remain uncharacterized. In the current study, we demonstrated that OI-19 is required for EHEC O157:H7 adherence to host cells. Z0442 (OI-encoded virulence regulator A [OvrA]) encoded in OI-19 positively regulated bacterial adherence by activating locus of enterocyte effacement (LEE) gene expression through direct OvrA binding to the gene promoter region of the LEE gene master regulator Ler. Mouse colonization experiments revealed that OvrA promotes EHEC O157:H7 adherence in mouse intestine, preferentially the colon. Finally, OvrA also regulated virulence in other non-O157 pathogenic E. coli, including EHEC strains O145:H28 and O157:H16 and enteropathogenic E. coli strain O55:H7. Our work markedly enriches the understanding of bacterial adherence control and provides another example of laterally acquired regulators that mediate LEE gene expression.

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