title: The non-canonical mitochondrial inner membrane presequence translocase of trypanosomatids contains two essential rhomboid-like proteins.
abstract: Mitochondrial protein import is essential for all eukaryotes. Here we show that the early diverging eukaryote Trypanosoma brucei has a non-canonical inner membrane (IM) protein translocation machinery. Besides TbTim17, the single member of the Tim17/22/23 family in trypanosomes, the presequence translocase contains nine subunits that co-purify in reciprocal immunoprecipitations and with a presequence-containing substrate that is trapped in the translocation channel. Two of the newly discovered subunits are rhomboid-like proteins, which are essential for growth and mitochondrial protein import. Rhomboid-like proteins were proposed to form the protein translocation pore of the ER-associated degradation system, suggesting that they may contribute to pore formation in the presequence translocase of T. brucei. Pulldown of import-arrested mitochondrial carrier protein shows that the carrier translocase shares eight subunits with the presequence translocase. This indicates that T. brucei may have a single IM translocase that with compositional variations mediates import of presequence-containing and carrier proteins.
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland.
authors.forename: Anke
authors.initials: A
authors.lastname: Harsman
authors.affiliation: Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Schänzlestraße 18, Freiburg 79104, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Oeljeklaus
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Wenger
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland.
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Huot
authors.affiliation: Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Schänzlestraße 18, Freiburg 79104, Germany.|BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestraße 18, Freiburg 79104, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Warscheid
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland.
authors.forename: André
authors.initials: A
authors.lastname: Schneider
mesh_terms: D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D051336:Mitochondrial Membranes; D021122:Protein Subunits; D021381:Protein Transport; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D033681:Mitochondrial Membrane Transport Proteins; D021122:Protein Subunits; D015800:Protozoan Proteins