title: Determinants of redox sensitivity in RsrA, a zinc-containing anti-sigma factor for regulating thiol oxidative stress response.
abstract: Various environmental oxidative stresses are sensed by redox-sensitive regulators through cysteine thiol oxidation or modification. A few zinc-containing anti-sigma (ZAS) factors in actinomycetes have been reported to respond sensitively to thiol oxidation, among which RsrA from Streptomyces coelicolor is best characterized. It forms disulfide bonds upon oxidation and releases bound SigR to activate thiol oxidative stress response genes. Even though numerous ZAS proteins exist in bacteria, features that confer redox sensitivity to a subset of these have been uncharacterized. In this study, we identified seven additional redox-sensitive ZAS factors from actinomycetes. Comparison with redox-insensitive ZAS revealed characteristic sequence patterns. Domain swapping demonstrated the significance of the region K(33)FEHH(37)FEEC(41)SPC(44)LEK(47) that encompass the conserved HX(3)CX(2)C (HCC) motif. Mutational effect of each residue on diamide responsive induction of SigR target genes in vivo demonstrated that several residues, especially those that flank two cysteines (E39, E40, L45, E46), contribute to redox sensitivity. These residues are well conserved among redox-sensitive ZAS factors, and hence are proposed as redox-determinants in sensitive ZAS. H37A, C41A, C44A and F38A mutations, in contrast, compromised SigR-binding activity significantly, apparently affecting structural integrity of RsrA. The residue pattern around HCC motif could therefore serve as an indicator to predict redox-sensitive ZAS factors from sequence information.
authors.affiliation: School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul, Korea.
authors.forename: Yong-Gyun
authors.initials: YG
authors.lastname: Jung
authors.forename: Yoo-Bok
authors.initials: YB
authors.lastname: Cho
authors.forename: Min-Sik
authors.initials: MS
authors.lastname: Kim
authors.forename: Ji-Sun
authors.initials: JS
authors.lastname: Yoo
authors.forename: Seok-Hyeon
authors.initials: SH
authors.lastname: Hong
authors.forename: Jung-Hye
authors.initials: JH
authors.lastname: Roe
mesh_terms: D039903:Actinobacteria / Q000235:genetics; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D003958:Diamide / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial; D008667:Metalloproteins / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics*; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D014157:Transcription Factors / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D015032:Zinc / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D008667:Metalloproteins; C121147:RsrA protein, Streptomyces coelicolor; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D014157:Transcription Factors; D003958:Diamide; D015032:Zinc