title: Hfq affects the expression of the LEE pathogenicity island in enterohaemorrhagic Escherichia coli.
abstract: Colonization of the intestinal epithelium by enterohaemorrhagic Escherichia coli (EHEC) is characterized by an attaching and effacing (A/E) histopathology. The locus of enterocyte effacement (LEE) pathogenicity island encodes many genes required for the A/E phenotype including the global regulator of EHEC virulence gene expression, Ler. The LEE is subject to a complex regulatory network primarily targeting ler transcription. The RNA chaperone Hfq, implicated in post-transcriptional regulation, is an important virulence factor in many bacterial pathogens. Although post-transcriptional regulation of EHEC virulence genes is known to occur, a regulatory role of Hfq in EHEC virulence gene expression has yet to be defined. Here, we show that an hfq mutant expresses increased levels of LEE-encoded proteins prematurely, leading to earlier A/E lesion formation relative to wild type. Hfq indirectly affects LEE expression in exponential phase independent of Ler by negatively controlling levels of the regulators GrlA and GrlR through post-transcriptional regulation of the grlRA messenger. Moreover, Hfq negatively affects LEE expression in stationary phase independent of GrlA and GrlR. Altogether, Hfq plays an important role in co-ordinating the temporal expression of the LEE by controlling grlRA expression at the post-transcriptional level.
authors: Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore St., Baltimore, MD 21201, USA.
authors: Anne-Marie
authors: AM
authors: Hansen
authors: James B
authors: JB
authors: Kaper
mesh_terms: D054324:Enterohemorrhagic Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D044404:Genomic Islands; D035001:Host Factor 1 Protein / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; C513430:GrlA protein, E coli; C513429:GrlR protein, E coli; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein; C457340:LEE protein, E coli; D010750:Phosphoproteins; D012329:RNA, Bacterial; D012097:Repressor Proteins; D015534:Trans-Activators