Dataset Information

Homologue replacement in the import motor of the mitochondrial inner membrane of trypanosomes.

ABSTRACT: Many mitochondrial proteins contain N-terminal presequences that direct them to the organelle. The main driving force for their translocation across the inner membrane is provided by the presequence translocase-associated motor (PAM) which contains the J-protein Pam18. Here, we show that in the PAM of Trypanosoma brucei the function of Pam18 has been replaced by the non-orthologous euglenozoan-specific J-protein TbPam27. TbPam27 is specifically required for the import of mitochondrial presequence-containing but not for carrier proteins. Similar to yeast Pam18, TbPam27 requires an intact J-domain to function. Surprisingly, T. brucei still contains a bona fide Pam18 orthologue that, while essential for normal growth, is not involved in protein import. Thus, during evolution of kinetoplastids, Pam18 has been replaced by TbPam27. We propose that this replacement is linked to the transition from two ancestral and functionally distinct TIM complexes, found in most eukaryotes, to the single bifunctional TIM complex present in trypanosomes.

SUBMITTER: von Kanel C

PROVIDER: S-EPMC7064343 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Homologue replacement in the import motor of the mitochondrial inner membrane of trypanosomes.

von Känel Corinne C Muñoz-Gómez Sergio A SA Oeljeklaus Silke S Wenger Christoph C Warscheid Bettina B Wideman Jeremy G JG Harsman Anke A Schneider Andre A

eLife 20200227

Many mitochondrial proteins contain N-terminal presequences that direct them to the organelle. The main driving force for their translocation across the inner membrane is provided by the presequence translocase-associated motor (PAM) which contains the J-protein Pam18. Here, we show that in the PAM of <i>Trypanosoma brucei</i> the function of Pam18 has been replaced by the non-orthologous euglenozoan-specific J-protein TbPam27. TbPam27 is specifically required for the import of mitochondrial pre ...[more]

PMID: 32105215

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Project description:Trypanosomatids are unicellular parasitic protozoa. Many of the species of this genera cause severe diseases in human, such as Leishmaniasis, African trypanosomiasis and Chagas disease. These parasites possess a single reticular mitochondrion with a concatenated structure of mitochondrial DNA known as kinetoplast or kDNA. kDNA encodes few essential mitochondrial proteins but no tRNAs. Therefore, trypanosomatid mitochondrion import a full set of nucleus-encoded tRNAs for mitochondrial translation. Recent advances indicated that mitochondrial protein translocases, particularly the subunits of the ATOM complex, are involved in the import of a tRNA in Trypanosoma brucei. However, the global picture and the role of the translocase components of the mitochondrial inner membrane (TbTims) are not well understood. Here we investigated the relative abundance of 16 different tRNAs in the cytosolic and mitochondrial fractions isolated from the six TbTims knockdown cell lines. We found that knockdown of TbTim17, one of the primary components of the TbTIM complex, reduced the abundance of all of these tRNAs into mitochondria and increased their abundance in the cytosol. Depletion of TbTim62, a TbTim17 associated proteins, also reduced the relative abundance of most of these tRNAs into mitochondria except for tRNAleu, tRNAmet, and tRNAglu. Whereas, knockdown of other TbTims, like TbTim50 and two small TbTims, TbTim10 and TbTim8/13, didn't have any effect on tRNA abundance either in the cytosol or mitochondria. Depletion of any of these TbTims showed minimal effect on the levels of total tRNAs in T. brucei. Absolute quantification of tRNA levels revealed that TbTim17 knockdown reduced the levels of different tRNAs in mitochondria from 3-6% to 0.8-1.4%, which is equivalent to ~70% reduction in average. Whereas, TbTim62 depletion showed somewhat selective effect. Overall, our results suggest that TbTim17 and TbTim62 are essential for tRNA import that further makes a connection between the tRNA and protein import into mitochondria in T. brucei.

Dataset Information

Homologue replacement in the import motor of the mitochondrial inner membrane of trypanosomes.

Publications

Homologue replacement in the import motor of the mitochondrial inner membrane of trypanosomes.

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