The non-canonical mitochondrial inner membrane presequence translocase of trypanosomatids contains two essential rhomboid-like proteins

Nat Commun. 2016 Dec 19:7:13707. doi: 10.1038/ncomms13707.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Membrane Proteins / metabolism
  • Mitochondria / enzymology*
  • Mitochondrial Membrane Transport Proteins / metabolism*
  • Mitochondrial Membranes
  • Protein Subunits
  • Protein Transport
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • RNA Interference
  • Trypanosoma brucei brucei / enzymology*
  • Trypanosoma brucei brucei / metabolism

Substances

  • Membrane Proteins
  • Mitochondrial Membrane Transport Proteins
  • Protein Subunits
  • Protozoan Proteins