MarR-family transcription factors often control antioxidant enzymes, multidrug efflux pumps or virulence factors in bacterial pathogens and confer resistance towards oxidative stress and antibiotics. In this study, we have characterized the function and redox-regulatory mechanism of the MarR-type regulator HypS in Mycobacterium smegmatis. RNA-seq transcriptomics and qRT-PCR analyses of the hypS mutant revealed that hypS is autoregulated and represses transcription of the co-transcribed hypO gene which encodes a multidrug efflux pump. DNA binding activity of HypS to the 8-5-8 bp inverted repeat sequence upstream of the hypSO operon was inhibited under NaOCl stress. However, the HypSC58S mutant protein was not impaired in DNA-binding under NaOCl stress in vitro, indicating an important role of Cys58 in redox sensing of NaOCl stress. HypS was shown to be inactivated by Cys58-Cys58' intersubunit disulfide formation under HOCl stress, resulting in derepression of hypO transcription. Phenotype results revealed that the HypS regulon confers resistance towards HOCl, rifampicin and erythromycin stress. In conclusion, HypS was identified as a novel redox-sensitive repressor that contributes to mycobacterial resistance towards HOCl stress and antibiotics.

中文翻译：

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氧化还原敏感的MarR型阻遏物HypS控制耻垢分枝杆菌中的次氯酸盐和抗菌素耐药性。

MarR家族的转录因子通常控制细菌病原体中的抗氧化酶，多药外排泵或毒力因子，并赋予对氧化应激和抗生素的抗性。在这项研究中，我们表征了耻垢分枝杆菌中的MarR型调节剂HypS的功能和氧化还原调节机制。对hypS突变体的RNA-seq转录组学和qRT-PCR分析表明，hypS是自动调节的，可抑制编码多药外排泵的共转录hypO基因的转录。在NaOCl胁迫下，HypS与hypSO操纵子上游8-5-8 bp反向重复序列的DNA结合活性受到抑制。然而，HypSC58S突变蛋白在体外NaOCl胁迫下的DNA结合中未受到损害，表明Cys58在NaOCl胁迫的氧化还原感测中的重要作用。在HOC1胁迫下，HypS被Cys58-Cys58'亚基二硫键形成灭活，导致hypO转录降低。表型结果表明，HypS调节剂赋予对HOCl，利福平和红霉素胁迫的抗性。总之，HypS被认为是一种新型的氧化还原敏感性阻遏物，其有助于分枝杆菌对HOCl胁迫和抗生素产生抗性。