title: A yeast mitochondrial membrane methyltransferase-like protein can compensate for oxa1 mutations.
abstract: Members of the Oxa1p/Alb3/YidC family mediate the insertion of various organelle or bacterial hydrophobic proteins into membranes. They present at least five transmembrane segments (TM) linked by hydrophilic domains located on both sides of the membrane. To examine how Oxa1p structure relates to its function, we have introduced point mutations and large deletions into various domains of the yeast mitochondrial protein. These mutants allowed us to show the importance of the first TM domain as well as a synergistic interaction between the first loop and the C-terminal tail, which both protrude into the matrix. These mutants also led to the isolation of a high copy suppressor, OMS1, which encodes a member of the methyltransferase family. Overexpression of OMS1 seems to increase the steady-state level of both the mutant and wild-type Oxa1p. We show that Oms1p is a mitochondrial inner membrane protein inserted independently of Oxa1p. Oms1p presents one TM and a N-in C-out topology with the C-terminal domain carrying the methyltransferase-like domain. A conserved motif within this domain is essential for the suppression of oxa1 mutations. We discuss the possible role of Oms1p on Oxa1p intermembrane space domain.
authors.affiliation: Centre de Génétique Moléculaire, CNRS Gif-sur-Yvette, UPR 2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Lemaire
authors.forename: Florence
authors.initials: F
authors.lastname: Guibet-Grandmougin
authors.forename: Diane
authors.initials: D
authors.lastname: Angles
authors.forename: Geneviève
authors.initials: G
authors.lastname: Dujardin
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bonnefoy
mesh_terms: D000818:Animals; D019069:Cell Respiration / Q000502:physiology; D004579:Electron Transport / Q000502:physiology; D003576:Electron Transport Complex IV; D015966:Gene Expression Regulation, Fungal; D008780:Methyltransferases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D017354:Point Mutation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes; D009687:Nuclear Proteins; C090858:OXA1 protein; D029701:Saccharomyces cerevisiae Proteins; D003576:Electron Transport Complex IV; D008780:Methyltransferases; C495319:OMS1 protein, S cerevisiae