du Plessis David J F, Nouwen Nico, Driessen Arnold J M
Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Materials, University of Groningen, 9751NN Haren, The Netherlands.
Biochim Biophys Acta. 2011 Mar;1808(3):851-65. doi: 10.1016/j.bbamem.2010.08.016. Epub 2010 Aug 27.
The vast majority of proteins trafficking across or into the bacterial cytoplasmic membrane occur via the translocon. The translocon consists of the SecYEG complex that forms an evolutionarily conserved heterotrimeric protein-conducting membrane channel that functions in conjunction with a variety of ancillary proteins. For posttranslational protein translocation, the translocon interacts with the cytosolic motor protein SecA that drives the ATP-dependent stepwise translocation of unfolded polypeptides across the membrane. For the cotranslational integration of membrane proteins, the translocon interacts with ribosome-nascent chain complexes and membrane insertion is coupled to polypeptide chain elongation at the ribosome. These processes are assisted by the YidC and SecDF(yajC) complex that transiently interacts with the translocon. This review summarizes our current understanding of the structure-function relationship of the translocon and its interactions with ancillary components during protein translocation and membrane protein insertion. This article is part of a Special Issue entitled Protein translocation across or insertion into membranes.
绝大多数穿过或进入细菌细胞质膜的蛋白质是通过转运体进行运输的。转运体由SecYEG复合物组成，该复合物形成一个进化上保守的异源三聚体蛋白质传导膜通道，并与多种辅助蛋白协同发挥作用。对于翻译后蛋白质转运，转运体与胞质动力蛋白SecA相互作用，SecA驱动未折叠多肽跨膜的ATP依赖性逐步转运。对于膜蛋白的共翻译整合，转运体与核糖体-新生链复合物相互作用，膜插入与核糖体上的多肽链延伸偶联。这些过程由YidC和SecDF（yajC）复合物辅助，它们与转运体短暂相互作用。本综述总结了我们目前对转运体的结构-功能关系及其在蛋白质转运和膜蛋白插入过程中与辅助成分相互作用的理解。本文是名为“蛋白质跨膜转运或插入膜”的特刊的一部分。
