Control of Thioredoxin Reductase Gene (trxB) Transcription by SarA in Staphylococcus aureus
Control of Thioredoxin Reductase Gene (trxB) Transcription by SarA in Staphylococcus aureus
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DOI：
10.1128/jb.01202-09
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发表时间：
2010-01-01
影响因子：
3.2
通讯作者：
Manna, Adhar C.
中科院分区：
文献类型：
--
作者：
Ballal, Anand;Manna, Adhar C.
硫氧还蛋白还原酶(由trxB编码)保护金黄色葡萄球菌免受氧气或二硫化物胁迫，是生长所必需的。在所分析的不同的SarA家族突变体中，在有氧和微需氧生长条件下，SarA突变体中trxB的转录显著上调，表明SarA是trxB表达的负调控因子。凝胶位移分析表明，纯化的SarA蛋白在体外可直接与trxB启动子区域的DNA结合。SARA的DNA结合是金黄色葡萄球菌体内抑制trxB转录所必需的。对纯化的野生型SarA和突变体SarAC9G的Northern印迹分析和DNA结合研究表明，Cys-9的氧化降低了SarA与trxB启动子DNA的结合。氧化剂，特别是联胺，可以进一步增强SarA突变体中trxB基因的转录，这表明存在一种SarA非依赖的trxB诱导模式。对两个氧化应激反应调控靶基因trxB和sodM与不同突变型SARA构建体的分析表明，SARA在体内对上述两个基因的表达具有不同的调控能力。总体而言，数据表明SARA在调节金黄色葡萄球菌氧化应激抵抗相关基因的表达方面发挥了重要作用。
Thioredoxin reductase (encoded by trxB) protects Staphylococcus aureus against oxygen or disulfide stress and is indispensable for growth. Among the different sarA family mutants analyzed, transcription of trxB was markedly elevated in the sarA mutant under conditions of aerobic as well as microaerophilic growth, indicating that SarA acts as a negative regulator of trxB expression. Gel shift analysis showed that purified SarA protein binds directly to the trxB promoter region DNA in vitro. DNA binding of SarA was essential for repression of trxB transcription in vivo in S. aureus. Northern blot analysis and DNA binding studies of the purified wild-type SarA and the mutant SarAC9G with oxidizing agents indicated that oxidation of Cys-9 reduced the binding of SarA to the trxB promoter DNA. Oxidizing agents, in particular diamide, could further enhance transcription of the trxB gene in the sarA mutant, suggesting the presence of a SarA-independent mode of trxB induction. Analysis of two oxidative stress-responsive sarA regulatory target genes, trxB and sodM, with various mutant sarA constructs showed a differential ability of the SarA to regulate expression of the two above-mentioned genes in vivo. The overall data demonstrate the important role played by SarA in modulating expression of genes involved in oxidative stress resistance in S. aureus.