H2O2-sensitive fur-like repressor CatR regulating the major catalase gene in Streptomyces coelicolor.
Streptomyces coelicolor produces three distinct catalases to cope with oxidative and osmotic stresses and allow proper growth and differentiation. The major vegetative catalase A (CatA) is induced by H(2)O(2) and is required for efficient aerobic growth. In order to investigate the H(2)O(2)-dependent regulatory mechanism, an H(2)O(2)-resistant mutant (HR40) overproducing CatA was isolated from S. coelicolor A3(2). Based on the genetic map location of the mutated locus in HR40, the wild type catR gene was isolated from the ordered cosmid library of S. coelicolor by screening for its ability to suppress the HR40 phenotype. catR encodes a protein of 138 amino acids (15319 Da), with sequence homology to ferric uptake regulator (Fur)-like proteins. Disruption of catR caused CatA overproduction as observed in the HR40 mutant, confirming the role of CatR as a negative regulator of catA expression. The levels of catA and catR transcripts were higher in HR40 than in the wild type, implying that CatR represses transcription of these genes. Transcripts from the catA and catR genes were induced within 10 min of H(2)O(2) treatment, suggesting that the repressor activity of CatR may be directly modulated by H(2)O(2). A putative CatR-binding site containing an inverted repeat of 23 base pairs was localized upstream of the catA and catR gene, on the basis of sequence comparison and deletion analysis. CatR protein purified in the presence of dithiothreitol bound to this region, whereas oxidized CatR, treated with H(2)O(2) or diamide, did not. The redox shift of CatR involved thiol-disulfide exchange as judged by modification of free thiols with 4-acetamido-4'-maleimidylstilbene-2,2'-disulfonate. From these results we propose that CatR regulates its downstream target genes as a repressor whose DNA binding ability is directly modulated by redox changes in the cell.
Hahn
J S
JS
Laboratory of Molecular Microbiology, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul 151-742, Korea.
Oh
S Y
SY
Chater
K F
KF
Cho
Y H
YH
Roe
J H
JH
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001483:Base Sequence; D002374:Catalase / Q000235:genetics*; D003360:Cosmids; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015723:Gene Library; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C068477:ferric uptake regulating proteins, bacterial; C086843:CatR protein, bacteria; D006861:Hydrogen Peroxide; D002374:Catalase