The plug domain of the SecY protein stabilizes the closed state of the translocation channel and maintains a membrane seal
The plug domain of the SecY protein stabilizes the closed state of the translocation channel and maintains a membrane seal
复制标题
DOI：
10.1016/j.molcel.2007.05.002
复制
发表时间：
2007-05-25
期刊：
影响因子：
16
通讯作者：
Rapoport, Tom A.
中科院分区：
文献类型：
--
作者：
Li, Weikai;Schulman, Sol;Rapoport, Tom A.
蛋白质通过由原核SecY或真核Sec61复合物形成的通道跨膜转运。对M. Jannaschii揭示了一个塞子结构域，该结构域似乎将通道密封在其闭合状态。然而，塞的作用仍然不清楚，特别是因为塞缺失突变体在S。cerevisiae酿酒酵母are functional功能.在这里，我们证明了大肠杆菌SecY中的插入缺失突变体也是功能性的，甚至有效地易位具有缺陷或缺失信号序列的蛋白质。对M. Jannaschii表明，尽管保持了整体结构，但形成了新的塞子。它们缺乏许多通常稳定封闭通道的相互作用，这解释了为什么通道可以为具有信号序列突变的蛋白质打开。我们的数据表明，插头域需要保持通道的封闭状态，并建议通道门控的机制。
Proteins are translocated across membranes through a channel that is formed by the prokaryotic SecY or eukaryotic Sec61 complex. The crystal structure of the SecY channel from M. jannaschii revealed a plug domain that appears to seal the channel in its closed state. However, the role of the plug remains unclear, particularly because plug deletion mutants in S. cerevisiae are functional. Here, we demonstrate that plug deletion mutants in E coli SecY are also functional and even efficiently translocate proteins with defective or missing signal sequences. The crystal structures of equivalent plug deletions in SecY of M. jannaschii show that, although the overall structures are maintained, new plugs are formed. These lack many interactions that normally stabilize the closed channel, explaining why the channels can open for proteins with signal-sequence mutations. Our data show that the plug domain is required to maintain a closed state of the channel and suggest a mechanism for channel gating.