Hfq reduces envelope stress by controlling expression of envelope‐localized proteins and protein complexes in enteropathogenic Escherichia coli. Issue 4 (15th April 2014)

• Record Type: Journal Article
• Authors: Vogt, Stefanie L.; Raivio, Tracy L.
• Is Part Of: Molecular microbiology. Volume 92:Issue 4(2014)
• Page Start: 681
• Page End: 697
• Publication Date: 2014-04-15
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12581
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Gram‐negative bacteria possess several envelope stress responses that detect and respond to damage to this critical cellular compartment. The σ<sup>E</sup> envelope stress response senses the misfolding of outer membrane proteins (OMPs), while the Cpx two‐component system is believed to detect the misfolding of periplasmic and inner membrane proteins. Recent studies in several Gram‐negative organisms found that deletion of <italic>hfq</italic>, encoding a small RNA chaperone protein, activates the σ<sup>E</sup> envelope stress response. In this study, we assessed the effects of deleting <italic>hfq</italic> upon activity of the σ<sup>E</sup> and Cpx responses in non‐pathogenic and enteropathogenic (EPEC) strains of <italic>E</italic><italic>scherichia coli</italic>. We found that the σ<sup>E</sup> response was activated in Δ<italic>hfq</italic> mutants of all <italic>E</italic><italic>. coli</italic> strains tested, resulting from the misregulation of OMPs. The Cpx response was activated by loss of <italic>hfq</italic> in EPEC, but not in <italic>E</italic><italic>. coli</italic> K‐12. Cpx pathway activation resulted in part from overexpression of the bundle‐forming pilus (BFP) in EPEC Δ<italic>hfq</italic>. We found that Hfq repressed expression of the BFP via PerA, a master regulator of virulence in EPEC. This study shows that Hfq has a more extensive role in regulating the expression of envelope proteins and horizontally acquired virulence genes in <italic>E</italic><italic>. coli</italic> than previously recognized.</p> </abstract>