title: The voltage-dependent anion channel, a major component of the tRNA import machinery in plant mitochondria.
abstract: In plants, as in most eukaryotic cells, import of nuclear-encoded cytosolic tRNAs is an essential process for mitochondrial biogenesis. Despite its broad occurrence, the mechanisms governing RNA transport into mitochondria are far less understood than protein import. This article demonstrates by Northwestern and gel-shift experiments that the plant mitochondrial voltage-dependent anion channel (VDAC) protein interacts with tRNA in vitro. It shows also that this porin, known to play a key role in metabolite transport, is a major component of the channel involved in the tRNA translocation step through the plant mitochondrial outer membrane, as supported by inhibition of tRNA import into isolated mitochondria by VDAC antibodies and Ruthenium red. However VDAC is not a tRNA receptor on the outer membrane. Rather, two major components from the TOM (translocase of the outer mitochondrial membrane) complex, namely TOM20 and TOM40, are important for tRNA binding at the surface of mitochondria, suggesting that they are also involved in tRNA import. Finally, we show that proteins and tRNAs are translocated into plant mitochondria by different pathways. Together, these findings identify unexpected components of the tRNA import machinery and suggest that the plant tRNA import pathway has evolved by recruiting multifunctional proteins.
authors.affiliation: Institut de Biologie Moléculaire des Plantes, Unité Propre de Recherche 2357, Conventionné avec l'Université Louis Pasteur (Strasbourg1), Centre National de la Recherche Scientifique, 67084 Strasbourg Cedex, France.
authors.forename: Thalia
authors.initials: T
authors.lastname: Salinas
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Duchêne
authors.forename: Ludovic
authors.initials: L
authors.lastname: Delage
authors.forename: Stefan
authors.initials: S
authors.lastname: Nilsson
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Glaser
authors.forename: Marlyse
authors.initials: M
authors.lastname: Zaepfel
authors.forename: Laurence
authors.initials: L
authors.lastname: Maréchal-Drouard
mesh_terms: D000906:Antibodies / Q000276:immunology; D002467:Cell Nucleus / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism; D011485:Protein Binding; D034443:RNA Transport; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism*; D012430:Ruthenium Red; D011198:Solanum tuberosum / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D050994:Voltage-Dependent Anion Channels / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D026901:Membrane Transport Proteins; D050994:Voltage-Dependent Anion Channels; D012430:Ruthenium Red; D012343:RNA, Transfer