Multiple SecA molecules drive protein translocation across a single translocon with SecG inversion
Multiple SecA molecules drive protein translocation across a single translocon with SecG inversion
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多个 SecA 分子通过 SecG 反转驱动蛋白质易位跨单个易位子
DOI：
10.1074/jbc.m111.301754
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
K.
中科院分区：
文献类型：
--
作者：
Morita;K.;Tokuda;H. and Nishiyama;K.
SecA是一种易位atp酶，它驱动蛋白质易位。D209N SecA是一种显性阴性突变体，能结合ATP，但不能水解ATP。该突变体对proOmpA易位无活性。然而，它产生了一个18 kDa的易位中间体。进一步添加野生型SecA导致其易位为成熟的OmpA或另一种28 kDa的中间体，可以通过质子动力易位为成熟的OmpA。在易位过程中添加过量的D209N SecA导致SecG的拓扑反转。此外，当使用相同数量的野生型和D209N SecA时，发现了SecG转化的中间产物。这些结果表明，多个SecA分子通过SecG反转驱动单个易位的易位。在这里，我们提出了一种修正的proOmpA易位模型，其中SecA的单一催化循环导致10-13 kDa的易位与ATP结合和水解，当下一个SecA循环开始时，需要SecG倒置，并且需要额外的ATP水解。
SecA is a translocation ATPase that drives protein translocation. D209N SecA, a dominant-negative mutant, binds ATP but is unable to hydrolyze it. This mutant was inactive to proOmpA translocation. However, it generated a translocation intermediate of 18 kDa. Further addition of wild-type SecA caused its translocation into either mature OmpA or another intermediate of 28 kDa that can be translocated into mature by a proton motive force. The addition of excess D209N SecA during translocation caused a topology inversion of SecG. Moreover, an intermediate of SecG inversion was identified when wild-type and D209N SecA were used in the same amounts. These results indicate that multiple SecA molecules drive translocation across a single translocon with SecG inversion. Here, we propose a revised model of proOmpA translocation in which a single catalytic cycle of SecA causes translocation of 10–13 kDa with ATP binding and hydrolysis, and SecG inversion is required when the next SecA cycle begins with additional ATP hydrolysis.