title: Biological significance of 5S rRNA import into human mitochondria: role of ribosomal protein MRP-L18.
abstract: 5S rRNA is an essential component of ribosomes of all living organisms, the only known exceptions being mitochondrial ribosomes of fungi, animals, and some protists. An intriguing situation distinguishes mammalian cells: Although the mitochondrial genome contains no 5S rRNA genes, abundant import of the nuclear DNA-encoded 5S rRNA into mitochondria was reported. Neither the detailed mechanism of this pathway nor its rationale was clarified to date. In this study, we describe an elegant molecular conveyor composed of a previously identified human 5S rRNA import factor, rhodanese, and mitochondrial ribosomal protein L18, thanks to which 5S rRNA molecules can be specifically withdrawn from the cytosolic pool and redirected to mitochondria, bypassing the classic nucleolar reimport pathway. Inside mitochondria, the cytosolic 5S rRNA is shown to be associated with mitochondrial ribosomes.
authors.affiliation: "Génétique Moléculaire, Génomique, Microbiologie" (GMGM), Université de Strasbourg-CNRS, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Smirnov
authors.forename: Nina
authors.initials: N
authors.lastname: Entelis
authors.forename: Robert P
authors.initials: RP
authors.lastname: Martin
authors.forename: Ivan
authors.initials: I
authors.lastname: Tarassov
mesh_terms: D003600:Cytosol / Q000378:metabolism; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D018832:Molecular Chaperones; D011485:Protein Binding; D034443:RNA Transport / Q000502:physiology*; D012341:RNA, Ribosomal, 5S / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism; D013884:Thiosulfate Sulfurtransferase / Q000378:metabolism
chemical_list: D018832:Molecular Chaperones; D012341:RNA, Ribosomal, 5S; D012269:Ribosomal Proteins; C029609:ribosomal protein L18; D013884:Thiosulfate Sulfurtransferase