title: DegP is involved in Cpx-mediated posttranscriptional regulation of the type III secretion apparatus in enteropathogenic Escherichia coli.
abstract: The Cpx envelope stress response facilitates adaptation to envelope stresses that lead to the misfolding of periplasmic proteins. Cpx-mediated adaptation involves elevated expression of periplasmic proteases and chaperones. Previously, we demonstrated that induction of the Cpx envelope stress response in enteropathogenic Escherichia coli (EPEC) also results in inhibition of type III secretion (T3S) and that this is correlated with downregulated transcription of the relevant genes. Here, we investigated whether the Cpx stress response might also exert posttranscriptional effects on the T3S apparatus. We show that DsbA is required for T3S, while removal of transcription factor CpxR or the Cpx-regulated folding factor CpxP or PpiA has minimal effects. Conversely, the entire T3S complex is removed from the envelope when the Cpx response is activated. Overexpression of the chaperone/protease DegP mimics the Cpx-dependent inhibition of the T3S complex at a posttranscriptional level, and mutation of degP partly abrogates the ability of the Cpx response to inhibit the T3S complex and motility. We present data that suggest that both the protease and chaperone activities of DegP are likely important for the impact on T3S. Altogether, our data indicate that DegP is normally a part of the Cpx-mediated inhibition of virulence determinant expression in EPEC and that additional factors are involved.
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: MacRitchie
authors.forename: Nicole
authors.initials: N
authors.lastname: Acosta
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Raivio
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D054308:Enteropathogenic Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D049449:Luminescence; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009068:Movement; D009154:Mutation; D033903:Periplasmic Proteins / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D059748:Proteolysis; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; C491730:CpxP protein, E coli; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D033903:Periplasmic Proteins; C085504:CpxR protein, Bacteria; C061682:DegP protease; D012697:Serine Endopeptidases