SECA PROMOTES PREPROTEIN TRANSLOCATION BY UNDERGOING ATP-DRIVEN CYCLES OF MEMBRANE INSERTION AND DEINSERTION
SECA PROMOTES PREPROTEIN TRANSLOCATION BY UNDERGOING ATP-DRIVEN CYCLES OF MEMBRANE INSERTION AND DEINSERTION
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DOI：
10.1016/s0092-8674(94)90582-7
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发表时间：
1994-09-09
期刊：
影响因子：
64.5
通讯作者：
WICKNER, W
中科院分区：
文献类型：
--
作者：
ECONOMOU, A;WICKNER, W
SecA 是大肠杆菌前蛋白转位酶的外周亚基，作为前蛋白转位催化循环的一部分，在膜插入和脱插入状态之间交替。当 SecA 与 SecY/E 和前蛋白复合时，ATP 驱动深刻的构象变化，导致 SecA 的 30 kDa 结构域插入膜。插入的结构域是蛋白酶无法从膜的胞质侧进入的，但在膜破裂后就可以进入。伴随着 30 kDa 结构域的插入，类似于前蛋白的 20 个氨酰残基发生了易位。额外的 ATP 可在 SecA 的第二个 ATP 位点水解，释放易位的前蛋白并允许 30 kDa 结构域脱插入，从而与胞质 SecA 交换。因此，SecA 是完整膜转运蛋白的移动亚基，在其催化循环的插入和脱插入阶段消耗 ATP，同时引导前蛋白片段穿过膜。
SecA, the peripheral subunit of E. coli preprotein translocase, alternates between a membrane inserted and a deinserted state as part of the catalytic cycle of preprotein translocation. When SecA is complexed with SecY/E and preprotein, ATP drives a profound conformational change, leading to membrane insertion of a 30 kDa domain of SecA. The inserted domain is protease-inaccessible from the cytosolic side of the membrane, but becomes accessible upon membrane disruption. Concomitant with 30 kDa domain insertion, similar to 20 aminoacyl residues of the preprotein are translocated. Additional ATP, which may be hydrolyzed at the second ATP site of SecA, releases the translocated preprotein and allows the 30 kDa domain to deinsert, whence it can exchange with cytosolic SecA. Thus, SecA is the mobile subunit of an integral membrane transporter, consuming ATP during both the insertion and deinsertion phases of its catalytic cycle while guiding preprotein segments across the membrane.