Analysis of chimeric chemoreceptors in Bacillus subtilis reveals a role for CheD in the function of the McpC HAMP domain
Analysis of chimeric chemoreceptors in Bacillus subtilis reveals a role for CheD in the function of the McpC HAMP domain
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DOI：
10.1128/jb.186.17.5950-5955.2004
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发表时间：
2004-09-01
影响因子：
3.2
通讯作者：
Ordal, GW
中科院分区：
文献类型：
--
作者：
Kristich, CJ;Ordal, GW
能动的原核生物使用感觉回路来控制运动装置，其中配体响应性化学感受器通过修饰的双组分信号转导系统来调节磷酰基通量。化学感受器表现出模块化结构，包括N-末端感觉模块、C-末端输出模块和HAMP结构域，HAMP结构域连接N-和C-末端模块并通过未知机制在它们之间传递感觉信息。本文详细研究了枯草芽孢杆菌两种化学感受器介导的感觉回路。已知McpB以Che D独立的方式调节对引诱物天冬酰胺的趋化性，而McpC需要Che D调节对引诱物脯氨酸的趋化性。虽然CheD是一种遗传学上广泛分布的趋化蛋白，但对其功能的了解有限。我们构建了McpB和McpC之间的嵌合体，以探讨CheD在促进McpC的感觉转导中的作用。我们发现，McpC可以被转换为一个CheD-独立的受体，其RAMP结构域的一半与相应的序列从McpB的替换，这表明McpC RAMP结构域的功能是复杂的，可能需要与CheD蛋白的分子间相互作用。当结合先前的观察结果考虑时，即CheD催化B的C-末端模块的共价修饰。枯草杆菌受体，这些结果表明，CheD可能与化学受体在多个，功能不同的网站。
Motile prokaryotes use a sensory circuit for control of the motility apparatus in which ligand-responsive chemoreceptors regulate phosphoryl flux through a modified two-component signal transduction system. The chemoreceptors exhibit a modular architecture, comprising an N-terminal sensory module, a C-terminal output module, and a HAMP domain that connects the N- and C-terminal modules and transmits sensory information between them via an unknown mechanism. The sensory circuits mediated by two chemoreceptors of Bacillus subtilis have been studied in detail. McpB is known to regulate chemotaxis towards the attractant asparagine in a CheD-independent manner, whereas McpC requires CheD to regulate chemotaxis towards the attractant proline. Although CheD is a phylogenetically widespread chemotaxis protein, there exists only a limited understanding of its function. We have constructed chimeras between McpB and McpC to probe the role of CheD in facilitating sensory transduction by McpC. We found that McpC can be converted to a CheD-independent receptor by the replacement of one-half of its RAMP domain with the corresponding sequence from McpB, suggesting that McpC RAMP domain function is complex and may require intermolecular interactions with the CheD protein. When considered in combination with the previous observation that CheD catalyzes covalent modification of the C-terminal modules of B. subtilis receptors, these results suggest that CheD may interact with chemoreceptors at multiple, functionally distinct sites.