The SecA protein deeply penetrates into the SecYEG channel during insertion, contacting most channel transmembrane helices and periplasmic regions.

ABSTRACT: The bacterial Sec-dependent system is the major protein-biogenic pathway for protein secretion across the cytoplasmic membrane or insertion of integral membrane proteins into the phospholipid bilayer. The mechanism of SecA-driven protein transport across the SecYEG channel complex has remained controversial with conflicting claims from biochemical and structural studies regarding the depth and extent of SecA insertion into SecYEG during ongoing protein transport. Here we utilized site-specific in vivo photo-crosslinking to thoroughly map SecY regions that are in contact with SecA during its insertion cycle. An arabinose-inducible, rapidly folding OmpA-GFP chimera was utilized to jam the SecYEG channels with an arrested substrate protein to "freeze" them in their SecA-inserted state.

SUBMITTER: Banerjee T 

PROVIDER: S-EPMC5712611 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature