title: Assembly of β-barrel proteins in the mitochondrial outer membrane.
abstract: Mitochondria evolved through endosymbiosis of a Gram-negative progenitor with a host cell to generate eukaryotes. Therefore, the outer membrane of mitochondria and Gram-negative bacteria contain pore proteins with β-barrel topology. After synthesis in the cytosol, β-barrel precursor proteins are first transported into the mitochondrial intermembrane space. Folding and membrane integration of β-barrel proteins depend on the mitochondrial sorting and assembly machinery (SAM) located in the outer membrane, which is related to the β-barrel assembly machinery (BAM) in bacteria. The SAM complex recognizes β-barrel proteins by a β-signal in the C-terminal β-strand that is required to initiate β-barrel protein insertion into the outer membrane. In addition, the SAM complex is crucial to form membrane contacts with the inner mitochondrial membrane by interacting with the mitochondrial contact site and cristae organizing system (MICOS) and shares a subunit with the endoplasmic reticulum-mitochondria encounter structure (ERMES) that links the outer mitochondrial membrane to the endoplasmic reticulum (ER).
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany.
authors.forename: Alexandra I C
authors.initials: AI
authors.lastname: Höhr
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany.
authors.forename: Sebastian P
authors.initials: SP
authors.lastname: Straub
authors.affiliation: BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany; Abteilung Biochemie und Funktionelle Proteomik, Institut für Biologie II, Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Warscheid
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Becker
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany. Electronic address: Nils.Wiedemann@biochemie.uni-freiburg.de.
authors.forename: Nils
authors.initials: N
authors.lastname: Wiedemann
mesh_terms: D004721:Endoplasmic Reticulum / Q000737:chemistry; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry*; D051336:Mitochondrial Membranes / Q000737:chemistry*; D018272:Porins / Q000737:chemistry; D017433:Protein Structure, Secondary; D021381:Protein Transport; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D018272:Porins; D029701:Saccharomyces cerevisiae Proteins; C066555:Tom40 protein, S cerevisiae
keywords: Bacteria; Beta-barrel; Mitochondria; Outer membrane; Protein assembly; Protein import