The oligomeric state and arrangement of the active bacterial translocon.
The oligomeric state and arrangement of the active bacterial translocon.
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DOI：
10.1074/jbc.m110.175638
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发表时间：
2011-02-11
期刊：
影响因子：
--
通讯作者：
Collinson I
中科院分区：
文献类型：
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作者：
Deville K;Gold VA;Robson A;Whitehouse S;Sessions RB;Baldwin SA;Radford SE;Collinson I
细菌中的蛋白质分泌通过ATP酶SecA通过无处不在的SecYEG复合物驱动。单独的SecYEG或作为与SecA在洗涤剂中的复合物的结构揭示了包围中心蛋白通道的单体异源三聚体，然而在膜中它是二聚体。我们已经解决了使用单分子和集成方法的蛋白质易位的SecYEG的寡聚状态的功能意义。结果表明，虽然单体足以使SecYEG与前蛋白质发生SecA和ATP依赖性结合，但主动转运需要SecYEG二聚体以背靠背构象排列。这种二聚体结构的分子建模，结合新的功能数据，提供了一个合理的存在的SecYEG的主动和被动拷贝的功能性易位子。
Protein secretion in bacteria is driven through the ubiquitous SecYEG complex by the ATPase SecA. The structure of SecYEG alone or as a complex with SecA in detergent reveal a monomeric heterotrimer enclosing a central protein channel, yet in membranes it is dimeric. We have addressed the functional significance of the oligomeric status of SecYEG in protein translocation using single molecule and ensemble methods. The results show that while monomers are sufficient for the SecA- and ATP-dependent association of SecYEG with pre-protein, active transport requires SecYEG dimers arranged in the back-to-back conformation. Molecular modeling of this dimeric structure, in conjunction with the new functional data, provides a rationale for the presence of both active and passive copies of SecYEG in the functional translocon.