title: OM14 is a mitochondrial receptor for cytosolic ribosomes that supports co-translational import into mitochondria.
abstract: It is well established that import of proteins into mitochondria can occur after their complete synthesis by cytosolic ribosomes. Recently, an additional model was revived, proposing that some proteins are imported co-translationally. This model entails association of ribosomes with the mitochondrial outer membrane, shown to be mediated through the ribosome-associated chaperone nascent chain-associated complex (NAC). However, the mitochondrial receptor of this complex is unknown. Here, we identify the Saccharomyces cerevisiae outer membrane protein OM14 as a receptor for NAC. OM14Δ mitochondria have significantly lower amounts of associated NAC and ribosomes, and ribosomes from NAC[Δ] cells have reduced levels of associated OM14. Importantly, mitochondrial import assays reveal a significant decrease in import efficiency into OM14Δ mitochondria, and OM14-dependent import necessitates NAC. Our results identify OM14 as the first mitochondrial receptor for ribosome-associated NAC and reveal its importance for import. These results provide a strong support for an additional, co-translational mode of import into mitochondria.
authors.affiliation: Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
authors.forename: Chen
authors.initials: C
authors.lastname: Lesnik
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Yifat
authors.initials: Y
authors.lastname: Cohen
authors.affiliation: Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
authors.forename: Avigail
authors.initials: A
authors.lastname: Atir-Lande
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Maya
authors.initials: M
authors.lastname: Schuldiner
authors.affiliation: Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
authors.forename: Yoav
authors.initials: Y
authors.lastname: Arava
mesh_terms: D000818:Animals; D001692:Biological Transport; D003600:Cytosol / Q000378:metabolism*; D005816:Genetic Complementation Test; D047468:Immunoprecipitation; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D021381:Protein Transport; D011817:Rabbits; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D018832:Molecular Chaperones; C000600009:OM14 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins