Hfq reduces envelope stress by controlling expression of envelope-localized proteins and protein complexes in enteropathogenic Escherichia coli

作者：Vogt Stefanie L; Raivio Tracy L^*

来源：Molecular Microbiology, 2014, 92(4): 681-697.

DOI：10.1111/mmi.12581

Gram-negative bacteria possess several envelope stress responses that detect and respond to damage to this critical cellular compartment. The sigma(E) 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 hfq, encoding a small RNA chaperone protein, activates the sigma(E) envelope stress response. In this study, we assessed the effects of deleting hfq upon activity of the sigma(E) and Cpx responses in non-pathogenic and enteropathogenic (EPEC) strains of Escherichia coli. We found that the sigma(E) response was activated in hfq mutants of all E.coli strains tested, resulting from the misregulation of OMPs. The Cpx response was activated by loss of hfq in EPEC, but not in E.coliK-12. Cpx pathway activation resulted in part from overexpression of the bundle-forming pilus (BFP) in EPEC hfq. 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 E.coli than previously recognized.

• 出版日期2014-5