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首页> 外文期刊>The FEBS journal >OxyR acts as a transcriptional repressor of hydrogen peroxide-inducible antioxidant genes in Corynebacterium glutamicum R.
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OxyR acts as a transcriptional repressor of hydrogen peroxide-inducible antioxidant genes in Corynebacterium glutamicum R.

机译：OxyR充当谷氨酸棒杆菌R中过氧化氢诱导的抗氧化剂基因的转录阻遏物。

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摘要

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. 2013 FEBS.Registry Number/Name of Substance 0 (Bacterial Proteins). 0 (Oxidants). 0 (Repressor Proteins). 7722-84-1 (Hydrogen Peroxide). EC 1-11-1-6 (Catalase).
机译：OxyR，一种LysR型转录调节因子，已被确定为细菌中抗氧化剂基因的氧化还原反应激活剂。这项研究表明OxyR充当谷氨酸棒杆菌R中katA，dps，ftn和cydA的转录阻遏物.katA编码H2O2-解毒酶过氧化氢酶，dps和ftn参与铁体内稳态，而cydA编码细胞色素bd氧化酶的一个亚基。定量RT-PCR分析显示，H2O2诱导了katA和dps的表达，但不引起ftn和cydA的表达。编码OxyR的oxyR基因的破坏导致katA和dps mRNA显着增加，其水平高于H2O2诱导的水平，而oxyR缺陷型突变体表现出抗H2O2的表型。这与常规的OxyR依赖性调节模型相反。 ftn和cydA也被oxyR破坏上调，但程度较小。电泳迁移率变动分析表明，在还原条件下，OxyR蛋白与相应基因的所有四个上游区域特异性结合。我们观察到，OxyR的氧化形式不仅与靶启动子区域相似，而且与非特异性DNA片段相似。基于这些发现，我们提出在氧化应激条件下，由于其DNA结合活性的特异性降低，在氧化应激条件下可减轻OxyR的转录抑制。 DNase I足迹分析表明，四个靶标启动子中的OxyR结合位点长度约为50 bp，具有多个T-N11-A基序，这是LysR型转录调节因子的特征，但没有明显的整体序列保守性。 2013年FEBS。注册号/物质0（细菌蛋白）的名称。 0（氧化剂）。 0（阻遏蛋白）。 7722-84-1（过氧化氢）。 EC 1-11-1-6（过氧化氢酶）。

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