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Transcriptomic analysis for Pch/ Ler regulon in enterohaemorrhagic Escherichia coli O157:H7

ABSTRACT: Enterohaemorrhagic Escherichia coli (EHEC) is an emerging pathogen that causes diarrhea and heamolytic uremic syndrome. Much of the genomic information that affects virulence is acquired via horizontal transfer. Genes necessary for attaching and effacing lesions are located in the LEE pathogenicity island. LEE gene transcription is positively regulated by Ler, which is also encoded by the LEE, and by Pch regulators, which are encoded at other loci. We identified genes whose transcription profiles were similar to those of the LEE genes, by comparing the effects of altering ler and pch transcript levels. We assigned these genes into two classes, according to their transcription profiles. Keywords: Genetic modification

ORGANISM(S): Escherichia coli Escherichia coli O157:H7 str. Sakai

PROVIDER: GSE9752 | GEO | 2008/02/01

SECONDARY ACCESSION(S): PRJNA103679

REPOSITORIES: GEO

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Transcriptomic analysis for Pch/ Ler regulon in enterohaemorrhagic Escherichia coli O157:H7

Project description:Enterohaemorrhagic Escherichia coli (EHEC) is an emerging pathogen that causes diarrhea and heamolytic uremic syndrome. Much of the genomic information that affects virulence is acquired via horizontal transfer. Genes necessary for attaching and effacing lesions are located in the LEE pathogenicity island. LEE gene transcription is positively regulated by Ler, which is also encoded by the LEE, and by Pch regulators, which are encoded at other loci. We identified genes whose transcription profiles were similar to those of the LEE genes, by comparing the effects of altering ler and pch transcript levels. We assigned these genes into two classes, according to their transcription profiles. 13 sets of comparison between transcription profiles in strains with different pch or ler genotypes. Labelling of cDNA and hybridization were performed twice with independently prepared RNAs.

2010-05-26 | E-GEOD-9752 | biostudies-arrayexpress

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Project description:Escherichia coli O157:H7 is a food-borne pathogen that causes bloody diarrhea and hemolytic uremic syndrome. Hfq is an sRNA chaperone protein that is involved in post-transcriptional regulation of virulence genes in pathogenic bacteria. In EHEC strain EDL933, Hfq acts a negative regulator of the locus of enterocyte effacement (LEE) that encodes most of the proteins involved in type three secretion and attaching and effacing lesions. We deleted hfq in E. coli O157:H7 strain 86-24 and compared global transcription profiles of the hfq mutant to the wild type strain in exponential growth phase. Deletion of hfq affected transcription of genes common to nonpathogenic and pathogenic strains of E. coli as well as pathogen-specific genes. Downregulated genes in the hfq mutant included ler as well as genes encoded in LEE2-5 that encode for type three secretion and AE lesion formation. Decreased expression of the LEE genes in the hfq mutant occurred at mid-, late, and stationary growth phases in both LB and DMEM media as detected by qRT-PCR. We also confirmed decreased regulation of the LEE genes by examining secreted proteins and AE lesion formation by the hfq mutant and WT strains. Deletion of hfq also caused decreased expression of the two-component system qseBC involved in inter-kingdom signaling and virulence gene regulation in EHEC as well as an increase in stx2AB expression that encodes for the deadly Shiga toxin. Altogether, these data indicate that Hfq plays a different regulatory role in EHEC 86-24 from what has been reported for EHEC strain EDL933 and that the role of Hfq in EHEC virulence regulation extends beyond the LEE. Comparison of transcriptional regulation of the WT 86-24 isolate and the hfq mutant for the identification of regulated targets that were followed up by functional analysis.

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