The SecDFyajC domain of preprotein translocase controls preprotein movement by regulating SecA membrane cycling
The SecDFyajC domain of preprotein translocase controls preprotein movement by regulating SecA membrane cycling
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DOI：
10.1093/emboj/16.16.4871
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发表时间：
1997-08-15
期刊：
影响因子：
11.4
通讯作者：
Wickner, W
中科院分区：
文献类型：
--
作者：
Duong, F;Wickner, W
大肠杆菌前蛋白转位酶由 SecY、SecE、SecG、SecD、SecF 和 YajC (SecYEGDFyajC) 的膜嵌入六聚体复合物和外周 ATP 酶 SecA 组成，ATP 结合和水解的能量促进 SecA 的膜插入和脱插入循环，并催化前蛋白跨膜运动。质子动力（PMF）虽然不是必需的，但极大地加速了易位的后期阶段。我们现在报道，转位酶的 SecDFyajC 结构域减慢了前蛋白在运输过程中的运动，以防止反向和正向易位，并通过稳定插入形式的 SecA 来发挥这种控制作用。这种机制允许特定易位中间体的积累，然后在 PMF 的驱动力下完成易位。这些发现建立了 SecA 膜插入和前蛋白易位之间的功能关系，并表明 SecDFyajC 控制 SecG 膜循环来调节易位前蛋白的运动。
Escherichia coli preprotein translocase comprises a membrane-embedded hexameric complex of SecY, SecE, SecG, SecD, SecF and YajC (SecYEGDFyajC) and the peripheral ATPase SecA, The energy of ATP binding and hydrolysis promotes cycles of membrane insertion and deinsertion of SecA and catalyzes the movement of the preprotein across the membrane. The proton motive force (PMF), though not essential, greatly accelerates late stages of translocation. We now report that the SecDFyajC domain of translocase slows the movement of preprotein in transit against both reverse and forward translocation and exerts this control through stabilization of the inserted form of SecA. This mechanism allows the accumulation of specific translocation intermediates which can then complete translocation under the driving force of the PMF, These findings establish a functional relationship between SecA membrane insertion and preprotein translocation and show that SecDFyajC controls SecG membrane cycling to regulate the movement of the translocating preprotein.