Dynamic coupling of fast channel gating with slow ATP-turnover underpins protein transport through the Sec-translocon

The Sec-translocon is a highly conserved membrane complex for polypeptide transport across, or into, lipid bilayers. In bacteria, the core protein-channel complex SecYEG resides in the inner-membrane, through which secretion is powered by the cytosolic ATPase SecA. Here, we present a single-molecule FRET dataset which shows that the SecYEG-channel fluctuates between open and closed states much faster than ATP turnover, while the nucleotide status of SecA modulates the rates of opening and closure.

Sec转运子（Sec-translocon）是一种高度保守的膜复合物，负责多肽跨脂质双分子层（lipid bilayers）转运或进入脂质双分子层。在细菌中，SecYEG核心蛋白通道复合物（SecYEG）定位于内膜（inner membrane），其分泌过程由胞质ATP酶SecA（cytosolic ATPase SecA）提供能量。本文呈现了一组单分子荧光共振能量转移（FRET）数据集，结果显示SecYEG通道在开放与关闭状态间的波动速度远快于ATP周转（ATP turnover），而SecA的核苷酸状态（nucleotide status of SecA）则调节通道的开合速率。