title: Mgr2 promotes coupling of the mitochondrial presequence translocase to partner complexes.
abstract: Many mitochondrial proteins are synthesized with N-terminal presequences in the cytosol. The presequence translocase of the inner mitochondrial membrane (TIM23) translocates preproteins into and across the membrane and associates with the matrix-localized import motor. The TIM23 complex consists of three core components and Tim21, which interacts with the translocase of the outer membrane (TOM) and the respiratory chain. We have identified a new subunit of the TIM23 complex, the inner membrane protein Mgr2. Mitochondria lacking Mgr2 were deficient in the Tim21-containing sorting form of the TIM23 complex. Mgr2 was required for binding of Tim21 to TIM23(CORE), revealing a binding chain of TIM23(CORE)-Mgr2/Tim21-respiratory chain. Mgr2-deficient yeast cells were defective in growth at elevated temperature, and the mitochondria were impaired in TOM-TIM23 coupling and the import of presequence-carrying preproteins. We conclude that Mgr2 is a coupling factor of the presequence translocase crucial for cell growth at elevated temperature and for efficient protein import.
authors.affiliation: Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Fakultät für Biologie, Funktionelle Proteomik, Universität Freiburg, 79104 Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Gebert
authors.forename: Sandra G
authors.initials: SG
authors.lastname: Schrempp
authors.forename: Carola S
authors.initials: CS
authors.lastname: Mehnert
authors.forename: Anna K
authors.initials: AK
authors.lastname: Heißwolf
authors.forename: Silke
authors.initials: S
authors.lastname: Oeljeklaus
authors.forename: Raffaele
authors.initials: R
authors.lastname: Ieva
authors.forename: Maria
authors.initials: M
authors.lastname: Bohnert
authors.forename: Karina
authors.initials: K
authors.lastname: von der Malsburg
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wiese
authors.forename: Thomas
authors.initials: T
authors.lastname: Kleinschroth
authors.forename: Carola
authors.initials: C
authors.lastname: Hunte
authors.forename: Helmut E
authors.initials: HE
authors.lastname: Meyer
authors.forename: Ilka
authors.initials: I
authors.lastname: Haferkamp
authors.forename: Bernard
authors.initials: B
authors.lastname: Guiard
authors.forename: Bettina
authors.initials: B
authors.lastname: Warscheid
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Pfanner
authors.forename: Martin
authors.initials: M
authors.lastname: van der Laan
mesh_terms: D049109:Cell Proliferation; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism*; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature
chemical_list: D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C574457:Mgr2 protein, S cerevisiae; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D046912:Multiprotein Complexes; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C083081:TIM23 protein, S cerevisiae