title: Membrane protein insertion and assembly by the bacterial holo-translocon SecYEG-SecDF-YajC-YidC.
abstract: Protein secretion and membrane insertion occur through the ubiquitous Sec machinery. In this system, insertion involves the targeting of translating ribosomes via the signal recognition particle and its cognate receptor to the SecY (bacteria and archaea)/Sec61 (eukaryotes) translocon. A common mechanism then guides nascent transmembrane helices (TMHs) through the Sec complex, mediated by associated membrane insertion factors. In bacteria, the membrane protein 'insertase' YidC ushers TMHs through a lateral gate of SecY to the bilayer. YidC is also thought to incorporate proteins into the membrane independently of SecYEG. Here, we show the bacterial holo-translocon (HTL) - a supercomplex of SecYEG-SecDF-YajC-YidC - is a bona fide resident of the Escherichia coli inner membrane. Moreover, when compared with SecYEG and YidC alone, the HTL is more effective at the insertion and assembly of a wide range of membrane protein substrates, including those hitherto thought to require only YidC.
authors.affiliation: School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K.
authors.forename: Joanna
authors.initials: J
authors.lastname: Komar
authors.affiliation: School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K.
authors.forename: Sara
authors.initials: S
authors.lastname: Alvira
authors.affiliation: School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Schulze
authors.affiliation: School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K.
authors.forename: Remy
authors.initials: R
authors.lastname: Martin
authors.affiliation: European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, Grenoble 38042, France.
authors.forename: Jelger A
authors.initials: JA
authors.lastname: Lycklama A Nijeholt
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham B15 2TT, U.K.
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Lee
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham B15 2TT, U.K.
authors.forename: Tim R
authors.initials: TR
authors.lastname: Dafforn
authors.affiliation: Arbeitsgruppe Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück D-49069, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Deckers-Hebestreit
authors.affiliation: School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K. European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, Grenoble 38042, France.
authors.forename: Imre
authors.initials: I
authors.lastname: Berger
authors.affiliation: School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K. European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, Grenoble 38042, France.
authors.forename: Christiane
authors.initials: C
authors.lastname: Schaffitzel
authors.affiliation: School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K.
authors.forename: Ian
authors.initials: I
authors.lastname: Collinson
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins
keywords: SecY; YidC; holo-translocon; insertion; membrane protein