RRC ID 29313
著者 Teramoto H, Inui M, Yukawa H.
タイトル OxyR acts as a transcriptional repressor of hydrogen peroxide-inducible antioxidant genes in Corynebacterium glutamicum R.
ジャーナル FEBS J
Abstract OxyR, a LysR-type transcriptional regulator, has been established as a redox-responsive activator of antioxidant genes in bacteria. This study shows that OxyR acts as a transcriptional repressor of katA, dps, ftn and cydA in Corynebacterium glutamicum R. katA encodes H2O2-detoxifing enzyme catalase, dps and ftn are implicated in iron homeostasis and cydA encodes a subunit of cytochrome bd oxidase. Quantitative RT-PCR analyses revealed that expression of katA and dps, but not of ftn and cydA, was induced by H2O2. Disruption of the oxyR gene encoding OxyR resulted in a marked increase in katA and dps mRNAs to a level higher than that induced by H2O2, and the oxyR-deficient mutant showed a H2O2-resistant phenotype. This is in contrast to the conventional OxyR-dependent regulatory model. ftn and cydA were also upregulated by oxyR disruption but to a smaller extent. Electrophoretic mobility shift assays revealed that the OxyR protein specifically binds to all four upstream regions of the respective genes under reducing conditions. We observed that the oxidized form of OxyR similarly bound to not only the target promoter regions, but also nonspecific DNA fragments. Based on these findings, we propose that the transcriptional repression by OxyR is alleviated under oxidative stress conditions in a titration mechanism due to the decreased specificity of its DNA-binding activity. DNase I footprinting analyses revealed that the OxyR-binding site in the four target promoters is ~ 50 bp in length and has multiple T-N11-A motifs, a feature of LysR-type transcriptional regulators, but no significant overall sequence conservation.
巻・号 280(14)
ページ 3298-312
公開日 2013-7-1
DOI 10.1111/febs.12312
PMID 23621709
MeSH Bacterial Proteins / physiology* Base Sequence Binding Sites Catalase / metabolism Corynebacterium glutamicum / genetics* Corynebacterium glutamicum / growth & development Corynebacterium glutamicum / metabolism Electrophoretic Mobility Shift Assay Enzyme Induction Gene Expression Regulation, Bacterial* Genes, Bacterial Hydrogen Peroxide / pharmacology* Molecular Sequence Data Oxidants / pharmacology Oxidative Stress Promoter Regions, Genetic Protein Binding Repressor Proteins / physiology* Transcription Initiation Site
IF 4.392
引用数 40
WOS 分野 BIOCHEMISTRY & MOLECULAR BIOLOGY
リソース情報
一般微生物 JCM 18229