tRNAs and proteins use the same import channel for translocation across the mitochondrial outer membrane of trypanosomes

Niemann, Moritz; Harsman, Anke Judith; Mani, Jan; Peikert, Christian D.; Oeljeklaus, Silke; Warscheid, Bettina; Wagner, Richard; Schneider, André (2017). tRNAs and proteins use the same import channel for translocation across the mitochondrial outer membrane of trypanosomes. Proceedings of the National Academy of Sciences of the United States of America - PNAS, 114(37), E7679-E7687. National Academy of Sciences NAS 10.1073/pnas.1711430114

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Mitochondrial tRNA import is widespread, but the mechanism by which tRNAs are imported remains largely unknown. The mitochondrion of the parasitic protozoan Trypanosoma brucei lacks tRNA genes, and thus imports all tRNAs from the cytosol. Here we show that in T. brucei in vivo import of tRNAs requires four subunits of the mitochondrial outer membrane protein translocase but not the two receptor subunits, one of which is essential for protein import. The latter shows that it is possible to uncouple mitochondrial tRNA import from protein import. Ablation of the intermembrane space domain of the translocase subunit, archaic translocase of the outer membrane (ATOM)14, on the other hand, while not affecting the architecture of the translocase, impedes both protein and tRNA import. A protein import intermediate arrested in the translocation channel prevents both protein and tRNA import. In the presence of tRNA, blocking events of single-channel currents through the pore formed by recombinant ATOM40 were detected in electrophysiological recordings. These results indicate that both types of macromolecules use the same import channel across the outer membrane. However, while tRNA import depends on the core subunits of the protein import translocase, it does not require the protein import receptors, indicating that the two processes are not mechanistically linked.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Niemann, Moritz; Harsman, Anke Judith; Mani, Jan and Schneider, André

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

0027-8424

Publisher:

National Academy of Sciences NAS

Language:

English

Submitter:

Christina Schüpbach

Date Deposited:

29 Nov 2017 10:15

Last Modified:

10 Sep 2018 11:59

Publisher DOI:

10.1073/pnas.1711430114

Related URLs:

BORIS DOI:

10.7892/boris.107336

URI:

https://boris.unibe.ch/id/eprint/107336

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