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.