Analysis of polypeptide movement in the SecY channel during SecA-mediated protein translocation.

ABSTRACT: In bacteria most secretory proteins are transported across the plasma membrane by the interplay of the ATPase SecA with the translocation channel formed by the SecY complex; SecA uses cycles of ATP hydrolysis to "push" consecutive segments of a polypeptide substrate through the channel. Here we have addressed the mechanism of this process by following the fate of stalled translocation intermediates. These were generated by using a polypeptide substrate containing a bulky disulfide-bonded loop, thus preventing the final residues from passing through the channel. Protease protection experiments showed that the intermediates were stable in the presence of ATP and could complete translocation once the block was removed. The translocation intermediate was also stable when SecA associated with A

SUBMITTER: Erlandson KJ 

PROVIDER: S-EPMC2409214 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature