title: Cryo-EM structure of the ribosome-SecYE complex in the membrane environment.
abstract: The ubiquitous SecY-Sec61 complex translocates nascent secretory proteins across cellular membranes and integrates membrane proteins into lipid bilayers. Several structures of mostly detergent-solubilized Sec complexes have been reported. Here we present a single-particle cryo-EM structure of the SecYEG complex in a membrane environment, bound to a translating ribosome, at subnanometer resolution. Using the SecYEG complex reconstituted in a so-called Nanodisc, we could trace the nascent polypeptide chain from the peptidyltransferase center into the membrane. The reconstruction allowed for the identification of ribosome-lipid interactions. The rRNA helix 59 (H59) directly contacts the lipid surface and appears to modulate the membrane in immediate vicinity to the proposed lateral gate of the protein-conducting channel (PCC). On the basis of our map and molecular dynamics simulations, we present a model of a signal anchor-gated PCC in the membrane.
authors.affiliation: Gene Center, Department for Biochemistry, University of Munich, Munich, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Frauenfeld
authors.forename: James
authors.initials: J
authors.lastname: Gumbart
authors.forename: Eli O van der
authors.initials: EO
authors.lastname: Sluis
authors.forename: Soledad
authors.initials: S
authors.lastname: Funes
authors.forename: Marco
authors.initials: M
authors.lastname: Gartmann
authors.forename: Birgitta
authors.initials: B
authors.lastname: Beatrix
authors.forename: Thorsten
authors.initials: T
authors.lastname: Mielke
authors.forename: Otto
authors.initials: O
authors.lastname: Berninghausen
authors.forename: Thomas
authors.initials: T
authors.lastname: Becker
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
authors.forename: Roland
authors.initials: R
authors.lastname: Beckmann
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D020285:Cryoelectron Microscopy; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D021381:Protein Transport; D012270:Ribosomes / Q000737:chemistry*; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle / Q000502:physiology
chemical_list: D029968:Escherichia coli Proteins; D008075:Lipoproteins, HDL; D008565:Membrane Proteins; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C057841:SecY protein, E coli; D018271:Signal Recognition Particle