Lateral opening of a translocon upon entry of protein suggests the mechanism of insertion into membranes.

ABSTRACT: The structure of the protein-translocating channel SecYEβ from Pyrococcus furiosus at 3.1-Å resolution suggests a mechanism for chaperoning transmembrane regions of a protein substrate during its lateral delivery into the lipid bilayer. Cytoplasmic segments of SecY orient the C-terminal α-helical region of another molecule, suggesting a general binding mode and a promiscuous guiding surface capable of accommodating diverse nascent chains at the exit of the ribosomal tunnel. To accommodate this putative nascent chain mimic, the cytoplasmic vestibule widens, and a lateral exit portal is opened throughout its entire length for partition of transmembrane helical segments to the lipid bilayer. In this primed channel, the central plug still occludes the pore while the lateral gate is opened, ena

SUBMITTER: Egea PF 

PROVIDER: S-EPMC2951439 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature