title: Protein insertion into the mitochondrial inner membrane by a twin-pore translocase.
abstract: The mitochondrial inner membrane imports numerous proteins that span it multiple times using the membrane potential Deltapsi as the only external energy source. We purified the protein insertion complex (TIM22 complex), a twin-pore translocase that mediated the insertion of precursor proteins in a three-step process. After the precursor is tethered to the translocase without losing energy from the Deltapsi, two energy-requiring steps were needed. First, Deltapsi acted on the precursor protein and promoted its docking in the translocase complex. Then, Deltapsi and an internal signal peptide together induced rapid gating transitions in one pore and closing of the other pore and drove membrane insertion to completion. Thus, protein insertion was driven by the coordinated action of a twin-pore complex in two voltage-dependent steps.
authors.affiliation: Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Rehling
authors.forename: Kirstin
authors.initials: K
authors.lastname: Model
authors.forename: Katrin
authors.initials: K
authors.lastname: Brandner
authors.forename: Peter
authors.initials: P
authors.lastname: Kovermann
authors.forename: Albert
authors.initials: A
authors.lastname: Sickmann
authors.forename: Helmut E
authors.initials: HE
authors.lastname: Meyer
authors.forename: Werner
authors.initials: W
authors.lastname: Kühlbrandt
authors.forename: Richard
authors.initials: R
authors.lastname: Wagner
authors.forename: Kaye N
authors.initials: KN
authors.lastname: Truscott
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Pfanner
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism*; D029382:Dicarboxylic Acid Transporters / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D015640:Ion Channel Gating; D008051:Lipid Bilayers; D008081:Liposomes; D008564:Membrane Potentials; D026901:Membrane Transport Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008954:Models, Biological; D011498:Protein Precursors / Q000378:metabolism*; D021382:Protein Sorting Signals; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D029382:Dicarboxylic Acid Transporters; D008051:Lipid Bilayers; D008081:Liposomes; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; D029701:Saccharomyces cerevisiae Proteins; C102549:TIM22 protein, S cerevisiae