A multicomponent protein complex mediates environmental stress signaling in Bacillus subtilis
A multicomponent protein complex mediates environmental stress signaling in Bacillus subtilis
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DOI：
10.1016/j.jmb.2004.05.043
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发表时间：
2004-07-30
影响因子：
5.6
通讯作者：
Price, CW
中科院分区：
文献类型：
--
作者：
Kim, TJ;Gaidenko, TA;Price, CW
枯草芽孢杆菌的一般胁迫转录因子Sigma(B)的活性直接受伙伴转换机制的调节，在该机制中，关键蛋白质的相互作用由丝氨酸磷酸化来控制。能量或环境压力的信号通过独立的通路传递给Sigma(B)，每条通路的末端都有一个差异调节的丝氨酸磷酸酶，该酶的活性是控制伴侣转换调节器所必需的。我们提供了遗传和生化证据，证明RsbU环境信号磷酸酶的激活受到第二个非典型伙伴开关的调节，该开关包含大型、多组分信号复合体中多余的负调控蛋白。在目前的模型中，RsbU磷酸酶的负调节完全依赖于RsbS拮抗剂蛋白。在这里，我们进行了一项关键的基因测试，使该模型无效，并证明RsbS拮抗剂本身不足以阻止环境信号传递。还需要四个共拮抗蛋白家族中的一个，这里将其重命名为RsbRA、RsbRB、RsbRC和RsbRD，每个蛋白的羧基末端结构域都与整个RsbS蛋白非常相似。由于RsbR家族中的任何一个成员与RsbS一起足以进行环境信号传递，我们得出结论，RsbR蛋白是RsbS拮抗剂发挥作用所必需的冗余共拮抗剂。此外，通过镍亲和层析和凝胶过滤层析从细胞提取物中纯化RsbRA，发现RsbRA和RsbRB共拮抗剂与RsbS拮抗剂形成了一个多组分的复合体。我们认为，这种复合体作为一台机器将应力信号传递给Sigma(B)，并且复合体的性质可能有助于环境应力传感。(C)2004爱思唯尔有限公司。保留所有权利。
Activity of the general stress transcription factor sigma(B) of Bacillus subtilis is regulated directly by a partner-switching mechanism in which key protein interactions are governed by serine phosphorylation. Signals of energy or environmental stress are conveyed to sigma(B) by independent pathways, each terminating with a differentially regulated serine phosphatase, whose activity is required to control the partner-switching regulators. We present genetic and biochemical evidence that activation of the RsbU environmental signaling phosphatase is modulated by a second, atypical partner switch that comprises redundant negative regulatory proteins in a large, multicomponent signaling complex. In the current model, negative regulation of the RsbU phosphatase depends solely on the RsbS antagonist protein. Here, we perform a critical genetic test that invalidates this model and demonstrates that the RsbS antagonist alone is insufficient to prevent environmental signaling. Also required is one of a family of four co-antagonist proteins, here renamed RsbRA, RsbRB, RsbRC, and RsbRD, each with a carboxyl-terminal domain closely resembling the entire RsbS protein. Because any single member of the RsbR family, together with RsbS, was sufficient for environmental signaling, we conclude that the RsbR proteins serve as redundant co-antagonists necessary for RsbS antagonist function. Moreover, purification of RsbRA from cell extracts by nickel affinity and gel-filtration chromatography found a multicomponent complex containing the RsbRA and RsbRB co-antagonists together with the RsbS antagonist. We propose that this complex serves as a machine to transmit stress signals to sigma(B), and that the properties of the complex may contribute to environmental stress sensing. (C) 2004 Elsevier Ltd. All rights reserved.