tRNAs and Proteins Are Imported into Mitochondria of Trypanosoma brucei by Two Distinct Mechanisms |
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Authors: | Christoph E Nabholz Elke K Horn and Andr Schneider |
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Institution: | University of Fribourg, Institute of Zoology, Pérolles, CH-1700 Fribourg, Switzerland. |
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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. |
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