Comparative genomics reveal novel heat shock regulatory mechanisms in Staphylococcus aureus and other Gram-positive bacteria
Comparative genomics reveal novel heat shock regulatory mechanisms in Staphylococcus aureus and other Gram-positive bacteria
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DOI：
10.1046/j.1365-2958.2003.03355.x
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发表时间：
2003-02-01
影响因子：
3.6
通讯作者：
Msadek, T
中科院分区：
文献类型：
--
作者：
Chastanet, A;Fert, J;Msadek, T
低 G+C 革兰氏阳性菌中同时存在多种应对应激的调节机制。其中，HrcA 和 CtsR 阻遏蛋白控制模型生物枯草芽孢杆菌中的不同调节子。我们最近在主要病原体金黄色葡萄球菌中发现了应激反应 CtsR 调节因子的直系同源物。金黄色葡萄球菌基因组的序列分析揭示了潜在的 CtsR 操纵子位点的存在，不仅位于编码 Clp ATP 依赖性蛋白酶亚基的基因上游（如枯草芽孢杆菌中），而且出人意料地位于已知受 HrcA 特异性控制的 dnaK 和 groESL 操纵子的启动子区域内。 CtsR 和 HrcA 操纵子的串联排列提出了这两种抑制子的双重热激调节的新模式。 S 。将金黄色葡萄球菌 ctsR 和 hrcA 基因克隆到 P xylA 木糖诱导型启动子的控制下，并使用 B 来证明 CtsR 和 HrcA 对 dnaK 和 groESL 操纵子的双重调节。枯草芽孢杆菌作为异源宿主。使用纯化的金黄色葡萄球菌 CtsR 和 HrcA 蛋白，通过凝胶迁移率变化和 DNase I 足迹实验在体外显示了两种阻遏蛋白的直接结合。 S 的 Delta ctsR 、 Delta hrcA 和 Delta ctsR Delta hrcA 突变体。构建了金黄色葡萄球菌，表明这两个阻遏蛋白不是多余的，而是协同作用，在没有应激的情况下维持 dnaK 和 groESL 操纵子的低基础表达水平。这种新颖的调节模式似乎是葡萄球菌特有的。
Multiple regulatory mechanisms for coping with stress co-exist in low G+C Gram-positive bacteria. Among these, the HrcA and CtsR repressors control distinct regulons in the model organism, Bacillus subtilis . We recently identified an orthologue of the CtsR regulator of stress response in the major pathogen, Staphylococcus aureus . Sequence analysis of the S aureus genome revealed the presence of potential CtsR operator sites not only upstream from genes encoding subunits of the Clp ATP-dependent protease, as in B subtilis, but also, unexpectedly, within the promoter regions of the dnaK and groESL operons known to be specifically controlled by HrcA. The tandem arrangement of the CtsR and HrcA operators suggests a novel mode of dual heat shock regulation by these two repressors. The S . aureus ctsR and hrcA genes were cloned under the control of the P xylA xylose-inducible promoter and used to demonstrate dual regulation of the dnaK and groESL operons by both CtsR and HrcA, using B . subtilis as a heterologous host. Direct binding by both repressors was shown in vitro by gel mobility shift and DNase I footprinting experiments using purified S aureus CtsR and HrcA proteins. Delta ctsR , Delta hrcA and Delta ctsR Delta hrcA mutants of S . aureus were constructed, indicating that the two repressors are not redundant but, instead, act together synergistically to maintain low basal levels of expression of the dnaK and groESL operons in the absence of stress. This novel regulatory mode appears to be specific to Staphylococci.