The mycobacterial LysR-type regulator OxyS responds to oxidative stress and negatively regulates expression of the catalase-peroxidase gene

• Published in: PloS one 2012-01, Vol.7 (1), p.e30186
• Main Authors: Li, Yuqing, He, Zheng-Guo
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Base Sequence; Binding sites; Binding Sites - genetics; Biology; Catalase; Catalase - genetics; Catalase - metabolism; Cell division; Chromatin Immunoprecipitation; Cysteine; Cysteine - genetics; Cysteine - metabolism; Deoxyribonucleic acid; Dithiothreitol; DNA; DNA polymerase; Drug resistance; E coli; Gene expression; Gene Expression Regulation, Bacterial; Genes; Hydrogen peroxide; Hydrogen Peroxide - pharmacology; KatG gene; Laboratories; Life sciences; Medicine; Models, Molecular; Molecular Sequence Data; Mutation; Mycobacterium bovis; Mycobacterium smegmatis; Mycobacterium smegmatis - genetics; Mycobacterium smegmatis - metabolism; Mycobacterium tuberculosis; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - metabolism; Oxidants - pharmacology; Oxidative Stress; Peroxidase; Promoter Regions, Genetic - genetics; Protein Binding - drug effects; Protein Structure, Tertiary; Proteins; Proteomics; Regulatory mechanisms (biology); Reverse Transcriptase Polymerase Chain Reaction; Sequence Homology, Nucleic Acid; Stress response; Transcription; Transcription factors; Tuberculosis; Vaccines
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0030186

Protection against oxidative stress is one of the primary defense mechanisms contributing to the survival of Mycobacterium tuberculosis in the host. In this study, we provide evidence that OxyS, a LysR-type transcriptional regulator functions as an oxidative stress response regulator in mycobacteria. Overexpression of OxyS lowers expression of the catalase-peroxidase (KatG) gene in M. smegmatis. OxyS binds directly with the katG promoter region and a conserved, GC-rich T-N(11)-A motif for OxyS binding was successfully characterized in the core binding site. Interestingly, the DNA-binding activity of OxyS was inhibited by H(2)O(2), but not by dithiothreitol. Cys25, which is situated at the DNA-binding domain of OxyS, was found to have a regulatory role for the DNA-binding ability of OxyS in response to oxidative stress. In contrast, the other three cysteine residues in OxyS do not appear to have this function. Furthermore, the mycobacterial strain over-expressing OxyS had a higher sensitivity to H(2)O(2). Thus, OxyS responds to oxidative stress through a unique cysteine residue situated in its DNA-binding domain and negatively regulates expression of the katG gene. These findings uncover a specific regulatory mechanism for mycobacterial adaptation to oxidative stress.