RsrA, an anti-sigma factor regulated by redox change

EMBO J. 1999 Aug 2;18(15):4292-8. doi: 10.1093/emboj/18.15.4292.


SigR (sigma(R)) is a sigma factor responsible for inducing the thioredoxin system in response to oxidative stress in the antibiotic-producing, Gram-positive bacterium Streptomyces coelicolor A3(2). Here we identify a redox-sensitive, sigma(R)-specific anti-sigma factor, RsrA, which binds sigma(R) and inhibits sigma(R)-directed transcription in vitro only under reducing conditions. Exposure to H(2)O(2) or to the thiol-specific oxidant diamide caused the dissociation of the sigma(R)-RsrA complex, thereby allowing sigma(R)-dependent transcription. This correlated with intramolecular disulfide bond formation in RsrA. Thioredoxin was able to reduce oxidized RsrA, suggesting that sigma(R), RsrA and the thioredoxin system comprise a novel feedback homeostasis loop that senses and responds to changes in the intracellular thiol-disulfide redox balance.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins*
  • Disulfides / chemistry
  • Mass Spectrometry
  • Molecular Sequence Data
  • Oxidation-Reduction
  • Sequence Homology, Amino Acid
  • Sigma Factor / antagonists & inhibitors*
  • Substrate Specificity
  • Surface Plasmon Resonance
  • Thioredoxins / metabolism
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Transcription, Genetic


  • Bacterial Proteins
  • Disulfides
  • RsrA protein, Streptomyces coelicolor
  • Sigma Factor
  • Transcription Factors
  • Thioredoxins

Associated data

  • GENBANK/AJ010320