Regulatory Role of an Interdomain Linker in the Bacterial Chemotaxis Histidine Kinase CheA
Regulatory Role of an Interdomain Linker in the Bacterial Chemotaxis Histidine Kinase CheA
复制标题
域间连接子在细菌趋化组氨酸激酶 CheA 中的调节作用
DOI：
10.1128/jb.00052-18
复制
发表时间：
2018-05-01
影响因子：
3.2
通讯作者：
Wang, Xiqing
中科院分区：
文献类型：
--
作者：
Ding, Xueye;He, Qiang;Wang, Xiqing
组氨酸激酶CheA在细菌趋化信号转导途径中的信号整合、转换和放大中发挥着核心作用。激酶活性在趋化信号复合物中受到调节，该复合物是通过 CheA 调节域 (P5)、偶联蛋白 CheW 和跨膜化学感受器之间的相互作用形成的。尽管最近对信号复合物结构的理解取得了进展，但这种调节背后的分子机制仍然难以捉摸。连接 CheA 的催化 (P4) 和调节域的域间接头可以介导从 P5-CheW-受体相互作用到催化域的调节信号。为了研究该域间接头是否能够激活和抑制 CheA，我们进行了体内筛选，以寻找导致不同 CheA 自激酶活性的 P4-P5 接头突变。已鉴定出几种 CheA 变体，其激酶活性范围为野生型 CheA 活性的 30% 至 670%。所有这些 CheA 变体在受体介导的激酶激活方面均存在缺陷，表明天然受体介导的信号传递途径同时受到这些突变的影响。即使在没有 P5 结构域的情况下，改变的 P4-P5 连接体也足以使激酶活性发生显着变化。因此，域间连接子是一个活性模块，能够对P4域的催化活性施加调节作用。这些结果表明，化学感受器可能操纵P4-P5连接子的构象，以实现信号复合物平台中CheA的调节。¶¶重要性由组氨酸激酶CheA的调节域、偶联蛋白CheW和化学感受器形成的细菌趋化性信号复合物中激酶调节的分子机制仍然未知。我们分离并表征了连接 CheA 催化域和调节域的域间接头中的突变，发现接头突变在调节域不存在和存在的情况下导致不同的 CheA 自激酶活性以及受体介导的激酶激活缺陷。这些结果表明，域间连接子是一个活性模块，能够对 CheA 活性施加调节作用。化学感受器可以操纵该域间连接子的构象，以实现信号复合物平台中的 CheA 调节。
The histidine kinase CheA plays a central role in signal integration, conversion, and amplification in the bacterial chemotaxis signal transduction pathway. The kinase activity is regulated in chemotaxis signaling complexes formed via the interactions among CheA's regulatory domain (P5), the coupling protein CheW, and transmembrane chemoreceptors. Despite recent advancements in the understanding of the architecture of the signaling complex, the molecular mechanism underlying this regulation remains elusive. An interdomain linker that connects the catalytic (P4) and regulatory domains of CheA may mediate regulatory signals from the P5-CheW-receptor interactions to the catalytic domain. To investigate whether this interdomain linker is capable of both activating and inhibiting CheA, we performed in vivo screens to search for P4-P5 linker mutations that result in different CheA autokinase activities. Several CheA variants were identified with kinase activities ranging from 30% to 670% of the activity of wild-type CheA. All of these CheA variants were defective in receptor-mediated kinase activation, indicating that the natural receptor-mediated signal transmission pathway was simultaneously affected by these mutations. The altered P4-P5 linkers were sufficient for making significant changes in the kinase activity even in the absence of the P5 domain. Therefore, the interdomain linker is an active module that has the ability to impose regulatory effects on the catalytic activity of the P4 domain. These results suggest that chemoreceptors may manipulate the conformation of the P4-P5 linker to achieve CheA regulation in the platform of the signaling complex.& para;& para;IMPORTANCE The molecular mechanism underlying kinase regulation in bacterial chemotaxis signaling complexes formed by the regulatory domain of the histidine kinase CheA, the coupling protein CheW, and chemoreceptors is still unknown. We isolated and characterized mutations in the interdomain linker that connects the catalytic and regulatory domains of CheA and found that the linker mutations resulted in different CheA autokinase activities in the absence and presence of the regulatory domain as well as a defect in receptor-mediated kinase activation. These results demonstrate that the interdomain linker is an active module that has the ability to impose regulatory effects on CheA activity. Chemoreceptors may manipulate the conformation of this interdomain linker to achieve CheA regulation in the platform of the signaling complex.