6ITC

Structure of a substrate engaged SecA-SecY protein translocation machine

Summary for 6ITC

• Entry DOI: 10.2210/pdb6itc/pdb
• EMDB information: 9731
• Descriptor: Protein translocase subunit SecA, ADENOSINE-5'-DIPHOSPHATE, (1R)-2-{[{[(2S)-2,3-DIHYDROXYPROPYL]OXY}(HYDROXY)PHOSPHORYL]OXY}-1-[(PALMITOYLOXY)METHYL]ETHYL (11E)-OCTADEC-11-ENOATE, ... (11 entities in total)
• Functional Keywords: seca, secy, translocation, cryo-em, protein transport
• Biological source: Bacillus subtilis (strain 168); More
• Total number of polymer chains: 7
• Total formula weight: 204075.55

Authors

Ma, C.Y.,Wu, X.F.,Sun, D.J.,Park, E.Y.,Rapoport, T.A.,Gao, N.,Long, L. (deposition date: 2018-11-21, release date: 2019-06-12, Last modification date: 2023-11-15)

Primary citation

Ma, C.,Wu, X.,Sun, D.,Park, E.,Catipovic, M.A.,Rapoport, T.A.,Gao, N.,Li, L.
Structure of the substrate-engaged SecA-SecY protein translocation machine.
Nat Commun, 10:2872-2872, 2019

PubMed Abstract: The Sec61/SecY channel allows the translocation of many proteins across the eukaryotic endoplasmic reticulum membrane or the prokaryotic plasma membrane. In bacteria, most secretory proteins are transported post-translationally through the SecY channel by the SecA ATPase. How a polypeptide is moved through the SecA-SecY complex is poorly understood, as structural information is lacking. Here, we report an electron cryo-microscopy (cryo-EM) structure of a translocating SecA-SecY complex in a lipid environment. The translocating polypeptide chain can be traced through both SecA and SecY. In the captured transition state of ATP hydrolysis, SecA's two-helix finger is close to the polypeptide, while SecA's clamp interacts with the polypeptide in a sequence-independent manner by inducing a short β-strand. Taking into account previous biochemical and biophysical data, our structure is consistent with a model in which the two-helix finger and clamp cooperate during the ATPase cycle to move a polypeptide through the channel.

PubMed: 31253804
DOI: 10.1038/s41467-019-10918-2

Experimental method

ELECTRON MICROSCOPY (3.45 Å)