title: YidC mediates membrane protein insertion in bacteria.
abstract: The basic machinery for the translocation of proteins into or across membranes is remarkably conserved from Escherichia coli to humans. In eukaryotes, proteins are inserted into the endoplasmic reticulum using the signal recognition particle (SRP) and the SRP receptor, as well as the integral membrane Sec61 trimeric complex (composed of alpha, beta and gamma subunits). In bacteria, most proteins are inserted by a related pathway that includes the SRP homologue Ffh, the SRP receptor FtsY, and the SecYEG trimeric complex, where Y and E are related to the Sec61 alpha and gamma subunits, respectively. Proteins in bacteria that exhibit no dependence on the Sec translocase were previously thought to insert into the membrane directly without the aid of a protein machinery. Here we show that membrane insertion of two Sec-independent proteins requires YidC. YidC is essential for E. coli viability and homologues are present in mitochondria and chloroplasts. Depletion of YidC also interferes with insertion of Sec-dependent membrane proteins, but it has only a minor effect on the export of secretory proteins. These results provide evidence for an additional component of the translocation machinery that is specialized for the integration of membrane proteins.
authors.affiliation: Department of Chemistry, The Ohio State University, Columbus 43210, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Samuelson
authors.forename: M
authors.initials: M
authors.lastname: Chen
authors.forename: F
authors.initials: F
authors.lastname: Jiang
authors.forename: I
authors.initials: I
authors.lastname: Möller
authors.forename: M
authors.initials: M
authors.lastname: Wiedmann
authors.forename: A
authors.initials: A
authors.lastname: Kuhn
authors.forename: G J
authors.initials: GJ
authors.lastname: Phillips
authors.forename: R E
authors.initials: RE
authors.lastname: Dalbey
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D001692:Biological Transport; D002213:Capsid / Q000378:metabolism; D036022:Capsid Proteins; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents; D003576:Electron Transport Complex IV; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D009004:Monosaccharide Transport Proteins; D009687:Nuclear Proteins / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012697:Serine Endopeptidases / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D036022:Capsid Proteins; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D009004:Monosaccharide Transport Proteins; D009687:Nuclear Proteins; C090858:OXA1 protein; C490210:ProW protein, E coli; D011498:Protein Precursors; C412443:YIDC protein, E coli; C025668:coat protein, Bacteriophage M13; C461599:maltose transport system, E coli; C078167:OMPA outer membrane proteins; D003576:Electron Transport Complex IV; D012697:Serine Endopeptidases; C026515:type I signal peptidase