细菌鞭毛马达转换的分子机制。
A molecular mechanism of bacterial flagellar motor switching.
作者信息
Dyer Collin M, Vartanian Armand S, Zhou Hongjun, Dahlquist Frederick W
机构信息
Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.
出版信息
J Mol Biol. 2009 Apr 24;388(1):71-84. doi: 10.1016/j.jmb.2009.02.004.
The high-resolution structures of nearly all the proteins that comprise the bacterial flagellar motor switch complex have been solved; yet a clear picture of the switching mechanism has not emerged. Here, we used NMR to characterize the interaction modes and solution properties of a number of these proteins, including several soluble fragments of the flagellar motor proteins FliM and FliG, and the response-regulator CheY. We find that activated CheY, the switch signal, binds to a previously unidentified region of FliM, adjacent to the FliM-FliM interface. We also find that activated CheY and FliG bind with mutual exclusivity to this site on FliM, because their respective binding surfaces partially overlap. These data support a model of CheY-driven motor switching wherein the binding of activated CheY to FliM displaces the carboxy-terminal domain of FliG (FliGC) from FliM, modulating the FliGC-MotA interaction, and causing the motor to switch rotational sense as required for chemotaxis.
几乎所有构成细菌鞭毛马达开关复合体的蛋白质的高分辨率结构都已解析出来；然而，关于开关机制的清晰图景尚未形成。在这里，我们利用核磁共振（NMR）来表征其中一些蛋白质的相互作用模式和溶液性质，包括鞭毛马达蛋白FliM和FliG的几个可溶性片段，以及响应调节蛋白CheY。我们发现，作为开关信号的活化CheY与FliM上一个先前未被识别的区域结合，该区域毗邻FliM-FliM界面。我们还发现，活化的CheY和FliG相互排斥地结合在FliM上的这个位点，因为它们各自的结合表面部分重叠。这些数据支持了一种由CheY驱动的马达开关模型，其中活化的CheY与FliM的结合将FliG的羧基末端结构域（FliGC）从FliM上置换下来，调节FliGC-MotA相互作用，并使马达根据趋化作用的需要切换旋转方向。
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