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Hfq reduces envelope stress by controlling expression of envelope‐localized proteins and protein complexes in enteropathogenic E scherichia coli
Author(s) -
Vogt Stefanie L.,
Raivio Tracy L.
Publication year - 2014
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12581
Subject(s) - biology , enteropathogenic escherichia coli , periplasmic space , cell envelope , virulence , bacterial outer membrane , microbiology and biotechnology , escherichia coli , inner membrane , pilus , gene , genetics , mitochondrion
Summary G ram‐negative bacteria possess several envelope stress responses that detect and respond to damage to this critical cellular compartment. The σ 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 G ram‐negative organisms found that deletion of hfq , encoding a small RNA chaperone protein, activates the σ E envelope stress response. In this study, we assessed the effects of deleting hfq upon activity of the σ E and Cpx responses in non‐pathogenic and enteropathogenic ( EPEC ) strains of E scherichia coli . We found that the σ E response was activated in Δ 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 . coli K ‐12. Cpx pathway activation resulted in part from overexpression of the bundle‐forming pilus ( BFP ) in EPEC Δ 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.