Decision letter: Homologue replacement in the import motor of the mitochondrial inner membrane of trypanosomes [peer_review]

Patrick R D' Silva, Dominique Soldati-Favre, Agnieszka Chacinska
2019 unpublished
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 Here, we show that in the PAM of Trypanosoma brucei the function of Pam18 has been replaced by the non-orthologous euglenozoan-specific J-protein TbPam27.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
more » ... chondrial 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 Thus, during evolution of kinetoplastids, Pam18 has been replaced by TbPam27.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. von Kä nel et al. eLife 2020;9:e52560. DOI: 1 of 27 RESEARCH ARTICLE Results Identification of J domain-containing putative PAM subunits in T. brucei We searched for J domain-containing proteins that could be part of the PAM complex that cooperates with the single bifunctional TIM complex of T. brucei. To do so, we first built a protein similarity von Kä nel et al. eLife 2020;9:e52560.
doi:10.7554/elife.52560.sa1 fatcat:hvikkqhjazajza2ail4gjbllmm