title: tRNAs and proteins are imported into mitochondria of Trypanosoma brucei by two distinct mechanisms.
abstract: Import of tRNA into the mitochondrial matrix of Trypanosoma brucei was reconstituted in vitro. Efficient import required the hydrolysis of externally added ATP and was shown to be a carrier-mediated process depending on proteinaceous receptors on the surface of mitochondria. A partly synthetic tRNA(Tyr) as well as a physiological tRNA(Lys) were imported along the same pathway. Contrary to import of all matrix-localized proteins, tRNA import does not require a membrane potential. Furthermore, addition of an excess of import-competent tRNA had no effect on import of a mitochondrial matrix protein. In summary, these results show that tRNAs and proteins in T. brucei are imported by fundamentally different mechanisms.
authors.affiliation: University of Fribourg, Institute of Zoology, Pérolles, CH-1700 Fribourg, Switzerland.
authors.forename: C E
authors.initials: CE
authors.lastname: Nabholz
authors.forename: E K
authors.initials: EK
authors.lastname: Horn
authors.forename: A
authors.initials: A
authors.lastname: Schneider
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D005095:Exoribonucleases / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D008967:Molecular Biology / Q000379:methods; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000378:metabolism*; D016053:RNA, Protozoan / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism*; D012357:RNA, Transfer, Lys / Q000378:metabolism; D012365:RNA, Transfer, Tyr / Q000737:chemistry / Q000378:metabolism; D012259:Ribonuclease, Pancreatic / Q000737:chemistry / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins; D016053:RNA, Protozoan; D012357:RNA, Transfer, Lys; D012365:RNA, Transfer, Tyr; D000255:Adenosine Triphosphate; D012343:RNA, Transfer; C020145:formaldehyde dehydrogenase (glutathione); D000445:Aldehyde Oxidoreductases; D005095:Exoribonucleases; C042081:exoribonuclease T; D012259:Ribonuclease, Pancreatic