Interactions between C ring proteins and export apparatus components:: a possible mechanism for facilitating type III protein export
Interactions between C ring proteins and export apparatus components:: a possible mechanism for facilitating type III protein export
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DOI：
10.1111/j.1365-2958.2006.05149.x
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发表时间：
2006-05-01
影响因子：
3.6
通讯作者：
Namba, K
中科院分区：
文献类型：
--
作者：
González-Pedrajo, B;Minamino, T;Namba, K
沙门氏菌鞭毛开关蛋白FliG、FliM和FliN参与电机旋转、扭矩产生和鞭毛组装/输出的开关。FliN与鞭毛出口过程有关。为了解决这种可能性，我们在FliN的c端结构域上构建了10个氨基酸扫描缺失和更大的截断。除了最后一个缺失变异外，所有其他变异都不能补充fliN缺失菌株或恢复鞭毛蛋白的输出。大多数缺失对野生型细胞表现出强烈的负显性效应。FliN被发现与FliH相关，FliH是一种鞭毛输出成分，调节FliI的atp酶活性。FliM与FliN的结合不会干扰这种FliN- flih相互作用。此外，通过镍亲和层析纯化了由FliG、his标记的FliM、FliN、FliH和FliI组成的五蛋白复合物。即使在没有FliH的情况下，假定的一般伴侣FliJ也必然会与FliM结合。讨论了C环作为出口底物、伴侣和通过FliH的FliI的可能对接位点的重要性，以便它们有效地传递到出口装置的膜组分。
The flagellar switch proteins of Salmonella, FliG, FliM and FliN, participate in the switching of motor rotation, torque generation and flagellar assembly/export. FliN has been implicated in the flagellar export process. To address this possibility, we constructed 10-amino-acid scanning deletions and larger truncations over the C-terminal domain of FliN. Except for the last deletion variant, all other variants were unable to complement a fliN null strain or to restore the export of flagellar proteins. Most of the deletions showed strong negative dominance effects on wild-type cells. FliN was found to associate with FliH, a flagellar export component that regulates the ATPase activity of FliI. The binding of FliM to FliN does not interfere with this FliN-FliH interaction. Furthermore, a five-protein complex consisting of FliG, His-tagged FliM, FliN, FliH and FliI was purified by nickel-affinity chromatography. FliJ, a putative general chaperone, is bound to FliM even in the absence of FliH. The importance of the C ring as a possible docking site for export substrates, chaperones and FliI through FliH for their efficient delivery to membrane components of the export apparatus is discussed.