3MP7

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

Summary for 3MP7

• Entry DOI: 10.2210/pdb3mp7/pdb
• Related: 1RH5 2YXQ 2YXR 2ZJS 3DKN
• Descriptor: Preprotein translocase subunit secY, Preprotein translocase subunit secE (2 entities in total)
• Functional Keywords: protein transport, membrane protein complex, preprotein translocase, membrane insertion, structural genomics, psi-2, protein structure initiative, center for structures of membrane proteins, csmp
• Biological source: Pyrococcus furiosus; More
• Cellular location: Cell membrane ; Multi-pass membrane protein : Q8U019; Cell membrane ; Single-pass membrane protein : Q8TZK2
• Total number of polymer chains: 2
• Total formula weight: 60883.81

Authors

Egea, P.F.,Stroud, R.M.,Center for Structures of Membrane Proteins (CSMP) (deposition date: 2010-04-26, release date: 2010-10-06, Last modification date: 2023-09-06)

Primary citation

Egea, P.F.,Stroud, R.M.
Lateral opening of a translocon upon entry of protein suggests the mechanism of insertion into membranes.
Proc.Natl.Acad.Sci.USA, 107:17182-17187, 2010

PubMed 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, enabling topological arbitration during early protein insertion. In vivo, a 15 amino acid truncation of the cytoplasmic C-terminal helix of SecY fails to rescue a secY-deficient strain, supporting the essential role of this helix as suggested from the structure.

PubMed: 20855604
DOI: 10.1073/pnas.1012556107

Experimental method

X-RAY DIFFRACTION (2.9 Å)