RsrA, an anti-sigma factor regulated by redox change.
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.
Kang
J G
JG
Department of Microbiology, College of Natural Sciences, and Research Center for Molecular Microbiology, Seoul National University, Seoul 151-742, Korea.
Paget
M S
MS
Seok
Y J
YJ
Hahn
M Y
MY
Bae
J B
JB
Hahn
J S
JS
Kleanthous
C
C
Buttner
M J
MJ
Roe
J H
JH
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D004220:Disulfides / Q000737:chemistry; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor / Q000037:antagonists & inhibitors*; D013379:Substrate Specificity; D020349:Surface Plasmon Resonance; D013879:Thioredoxins / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004220:Disulfides; C121147:RsrA protein, Streptomyces coelicolor; D012808:Sigma Factor; D014157:Transcription Factors; D013879:Thioredoxins