期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：13
页码：4844-4849
DOI：10.1073/pnas.1315901111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The SecY/61 complex forms the protein-channel component of the ubiquitous protein secretion and membrane protein insertion apparatus. The bacterial version SecYEG interacts with the highly conserved YidC and SecDF-YajC subcomplex, which facilitates translocation into and across the membrane. Together, they form the holo-translocon (HTL), which we have successfully overexpressed and purified. In contrast to the homo-dimeric SecYEG, the HTL is a hetero-dimer composed of single copies of SecYEG and SecDF-YajC-YidC. The activities of the HTL differ from the archetypal SecYEG complex. It is more effective in cotranslational insertion of membrane proteins and the posttranslational secretion of a {beta}-barreled outer-membrane protein driven by SecA and ATP becomes much more dependent on the proton-motive force. The activity of the translocating copy of SecYEG may therefore be modulated by association with different accessory subcomplexes: SecYEG (forming SecYEG dimers) or SecDF-YajC-YidC (forming the HTL). This versatility may provide a means to refine the secretion and insertion capabilities according to the substrate. A similar modularity may also be exploited for the translocation or insertion of a wide range of substrates across and into the endoplasmic reticular and mitochondrial membranes of eukaryotes.
