title: YidC and SecYEG form a heterotetrameric protein translocation channel.
abstract: The heterotrimeric SecYEG complex cooperates with YidC to facilitate membrane protein insertion by an unknown mechanism. Here we show that YidC contacts the interior of the SecY channel resulting in a ligand-activated and voltage-dependent complex with distinct ion channel characteristics. The SecYEG pore diameter decreases from 8 Å to only 5 Å for the YidC-SecYEG pore, indicating a reduction in channel cross-section by YidC intercalation. In the presence of a substrate, YidC relocates to the rim of the pore as indicated by increased pore diameter and loss of YidC crosslinks to the channel interior. Changing the surface charge of the pore by incorporating YidC into the channel wall increases the anion selectivity, and the accompanying change in wall hydrophobicity is liable to alter the partition of helices from the pore into the membrane. This could explain how the exit of transmembrane domains from the SecY channel is facilitated by YidC.
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, Freiburg, 79104, Germany.|Fakultät für Biologie, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, 79104, Freiburg, Germany.
authors.forename: Ilie
authors.initials: I
authors.lastname: Sachelaru
authors.affiliation: Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020, Linz, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Winter
authors.affiliation: Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020, Linz, Austria.
authors.forename: Denis G
authors.initials: DG
authors.lastname: Knyazev
authors.affiliation: Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020, Linz, Austria.
authors.forename: Mirjam
authors.initials: M
authors.lastname: Zimmermann
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, Freiburg, 79104, Germany.|Fakultät für Biologie, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, 79104, Freiburg, Germany.|Spemann-Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-Universität Freiburg, 79104, Freiburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Vogt
authors.affiliation: Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020, Linz, Austria.
authors.forename: Roland
authors.initials: R
authors.lastname: Kuttner
authors.affiliation: Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020, Linz, Austria.
authors.forename: Nicole
authors.initials: N
authors.lastname: Ollinger
authors.affiliation: Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020, Linz, Austria.
authors.forename: Christine
authors.initials: C
authors.lastname: Siligan
authors.affiliation: Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020, Linz, Austria. Peter.Pohl@jku.at.
authors.forename: Peter
authors.identifier: 0000-0002-1792-2314
authors.initials: P
authors.lastname: Pohl
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, Freiburg, 79104, Germany. Hans-Georg.Koch@biochemie.uni-freiburg.de.|Spemann-Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-Universität Freiburg, 79104, Freiburg, Germany. Hans-Georg.Koch@biochemie.uni-freiburg.de.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Koch
mesh_terms: D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D000069284:Protein Translocation Systems / Q000737:chemistry / Q000378:metabolism; D000069816:SEC Translocation Channels / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D000069284:Protein Translocation Systems; D000069816:SEC Translocation Channels; C412443:YIDC protein, E coli