SecM facilitates translocase function of SecA by localizing its biosynthesis
SecM facilitates translocase function of SecA by localizing its biosynthesis
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DOI：
10.1101/gad.1259505
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发表时间：
2005-02-15
影响因子：
10.5
通讯作者：
Ito, K
中科院分区：
文献类型：
--
作者：
Nakatogawa, H;Murakanti, A;Ito, K
大肠杆菌SecM的“阻滞序列”与核糖体出口通道相互作用，并阻止其自身的翻译延伸，这是由新生的SecM链的共翻译输出释放的。SecM的这一特性对于SecA的基础和调控表达至关重要。在这里，我们报告说，SecM还有一个促进SecA活动的额外作用。系统测定不同SecA含量细胞的SecA丰度-蛋白输出关系发现，当SecM - SecA信息的上游区域缺少SecM时，当SecM具有捕获缺陷突变时，以及当SecM缺乏信号序列时，SecA的功能较差。这些结果表明，将新生SecM靶向转座子在促进功能性SecA分子形成方面发挥了以前未被认识到的作用。膜和Sec易位附近的生物合成将有利于这种多构象atp酶采用现成的功能构象。
"Arrest sequence" of Escherichia coli SecM interacts with the ribosomal exit tunnel and arrests its own translation elongation, which is released by cotranslational export of the nascent SecM chain. This property of SecM is essential for the basal and regulated expression of SecA. Here we report that SecM has an additional role of facilitating SecA activities. Systematic determinations of the SecA-abundance-protein export relationships of cells with different SecA contents revealed that SecA was less functional when SecM was absent from the upstream region of the secM-secA message, when SecM had the arrest-defective mutation, and also when SecM lacked the signal sequence. These results suggest that cotranslational targeting of nascent SecM to the translocon plays previously unrecognized roles of facilitating the formation of functional SecA molecules. Biosynthesis in the vicinity of the membrane and the Sec translocon will be beneficial for this multiconformation ATPase to adopt ready-to-function conformations.