A supramolecular complex in the environmental stress signalling pathway of Bacillus subtilis
A supramolecular complex in the environmental stress signalling pathway of Bacillus subtilis
复制标题
DOI：
10.1046/j.1365-2958.2003.03663.x
复制
发表时间：
2003-09-01
影响因子：
3.6
通讯作者：
Delumeau, O
中科院分区：
文献类型：
--
作者：
Chen, CC;Lewis, RJ;Delumeau, O
sigma（B）是枯草芽孢杆菌的另一种sigma因子，介导细胞对各种物理损伤的反应。在环境胁迫信号通路中，RsbU是一种蛋白磷酸酶，通过与蛋白激酶RsbT的相互作用而受到刺激。在不存在应激的情况下，预期RsbT被替代结合配偶体RsbS捕获。在这里，我们已经证明，单独的RsbS不能作为RsbT的替代伴侣，而是需要RsbR的存在，以创建一个高分子量的RsbR：RsbS复合物（类似于1 MDa）能够捕获RsbT。在这种复合物中，RsbS的磷酸化状态，而不是RsbR的磷酸化状态，控制与RsbT的结合，其对RsbS的激酶活性可以通过RsbX的活性来平衡，RsbX是RsbS-P的磷酸酶。RsbR：RsbS复合物从RsbT和RsbU的混合物中招募RsbT。复合物中RsbR的磷酸化形式增强了RsbT对RsbS的激酶活性。因此，这种超分子复合物具有RsbT的替代伴侣的功能特性。电子显微镜下，这种复合物，并从细胞提取物的RsbR：RsbS复合物的纯化提供了证据，这种复合物在体内的存在
sigma(B), an alternative sigma-factor of Bacillus subtilis, mediates the response of the cell to a variety of physical insults. Within the environmental stress signalling pathway RsbU, a protein phosphatase, is stimulated by its interaction with the protein kinase RsbT. In the absence of stress RsbT is expected to be trapped by an alternative binding partner, RsbS. Here, we have demonstrated that RsbS alone cannot act as an alternative partner for RsbT, but instead requires the presence of RsbR to create a high molecular mass RsbR: RsbS complex (similar to1 MDa) able to capture RsbT. In this complex the phosphorylation state of RsbS, and not that of RsbR, controlled the binding to RsbT, whose kinase activity towards RsbS could be counterbalanced by the activity of RsbX, the phosphatase for RsbS-P. The RsbR: RsbS complex recruited RsbT from a mixture of RsbT and RsbU. The phosphorylated form of RsbR in the complex enhanced the kinase activity of RsbT towards RsbS. This supramolecular complex thus has the functional properties of an alternative partner for RsbT. Electron micrographs of this complex are presented, and the purification of the RsbR: RsbS complex from cellular extracts provides evidence for the existence of such a complex in vivo