title: Multispan mitochondrial outer membrane protein Ugo1 follows a unique Mim1-dependent import pathway.
abstract: The mitochondrial outer membrane (MOM) harbors several multispan proteins that execute various functions. Despite their importance, the mechanisms by which these proteins are recognized and inserted into the outer membrane remain largely unclear. In this paper, we address this issue using yeast mitochondria and the multispan protein Ugo1. Using a specific insertion assay and analysis by native gel electrophoresis, we show that the import receptor Tom70, but not its partner Tom20, is involved in the initial recognition of the Ugo1 precursor. Surprisingly, the import pore formed by the translocase of the outer membrane complex appears not to be required for the insertion process. Conversely, the multifunctional outer membrane protein mitochondrial import 1 (Mim1) plays a central role in mediating the insertion of Ugo1. Collectively, these results suggest that Ugo1 is inserted into the MOM by a novel pathway in which Tom70 and Mim1 contribute to the efficiency and selectivity of the process.
authors.affiliation: Interfaculty Institute of Biochemistry, University of Tübingen, Germany.
authors.forename: Drazen
authors.initials: D
authors.lastname: Papic
authors.forename: Katrin
authors.initials: K
authors.lastname: Krumpe
authors.forename: Jovana
authors.initials: J
authors.lastname: Dukanovic
authors.forename: Kai S
authors.initials: KS
authors.lastname: Dimmer
authors.forename: Doron
authors.initials: D
authors.lastname: Rapaport
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; C492709:MIM1 protein, S cerevisiae; D008565:Membrane Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; C489350:TOM20 protein, S cerevisiae; C489039:TOM70 protein, S cerevisiae; C423986:UGO1 protein, S cerevisiae