title: Mba1, a membrane-associated ribosome receptor in mitochondria.
abstract: The genome of mitochondria encodes a small number of very hydrophobic polypeptides that are inserted into the inner membrane in a cotranslational reaction. The molecular process by which mitochondrial ribosomes are recruited to the membrane is poorly understood. Here, we show that the inner membrane protein Mba1 binds to the large subunit of mitochondrial ribosomes. It thereby cooperates with the C-terminal ribosome-binding domain of Oxa1, which is a central component of the insertion machinery of the inner membrane. In the absence of both Mba1 and the C-terminus of Oxa1, mitochondrial translation products fail to be properly inserted into the inner membrane and serve as substrates of the matrix chaperone Hsp70. We propose that Mba1 functions as a ribosome receptor that cooperates with Oxa1 in the positioning of the ribosome exit site to the insertion machinery of the inner membrane.
authors.affiliation: Institut für Physiologische Chemie, Universität München, München, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Ott
authors.forename: Martin
authors.initials: M
authors.lastname: Prestele
authors.forename: Heike
authors.initials: H
authors.lastname: Bauerschmitt
authors.forename: Soledad
authors.initials: S
authors.lastname: Funes
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bonnefoy
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Herrmann
mesh_terms: D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018840:HSP70 Heat-Shock Proteins; C100490:MBA1 protein, S cerevisiae; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; C090858:OXA1 protein; C090869:SSA3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D003576:Electron Transport Complex IV