Multiple pathways for regulation of sigmaS (RpoS) stability in Escherichia coli via the action of multiple anti-adaptors

Mol Microbiol. 2008 Apr;68(2):298-313. doi: 10.1111/j.1365-2958.2008.06146.x.


SigmaS, the stationary phase sigma factor of Escherichia coli and Salmonella, is regulated at multiple levels. The sigmaS protein is unstable during exponential growth and is stabilized during stationary phase and after various stress treatments. Degradation requires both the ClpXP protease and the adaptor RssB. The small antiadaptor protein IraP is made in response to phosphate starvation and interacts with RssB, causing sigmaS stabilization under this stress condition. IraP is essential for sigmaS stabilization in some but not all starvation conditions, suggesting the existence of other anti-adaptor proteins. We report here the identification of new regulators of sigmaS stability, important under other stress conditions. IraM (inhibitor of RssB activity during Magnesium starvation) and IraD (inhibitor of RssB activity after DNA damage) inhibit sigmaS proteolysis both in vivo and in vitro. Our results reveal that multiple anti-adaptor proteins allow the regulation of sigmaS stability through the regulation of RssB activity under a variety of stress conditions.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Artificial Gene Fusion
  • Bacterial Proteins / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Endopeptidase Clp / metabolism
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Escherichia coli / physiology*
  • Escherichia coli Proteins / biosynthesis
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Gene Deletion
  • Genes, Reporter
  • Hydrogen Peroxide / pharmacology
  • Models, Biological
  • Sigma Factor / metabolism*
  • Trans-Activators / biosynthesis
  • Transcription Factors / metabolism*
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism


  • Anti-Bacterial Agents
  • AppY protein, E coli
  • Bacterial Proteins
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • IraM protein, E coli
  • IraP protein, E coli
  • Sigma Factor
  • Trans-Activators
  • Transcription Factors
  • rssB protein, E coli
  • sigma factor KatF protein, Bacteria
  • Hydrogen Peroxide
  • beta-Galactosidase
  • ClpXP protease, E coli
  • Endopeptidase Clp