Independent evolution of functionally exchangeable mitochondrial outer membrane import complexes

Elife. 2018 Jun 20:7:e34488. doi: 10.7554/eLife.34488.


Assembly and/or insertion of a subset of mitochondrial outer membrane (MOM) proteins, including subunits of the main MOM translocase, require the fungi-specific Mim1/Mim2 complex. So far it was unclear which proteins accomplish this task in other eukaryotes. Here, we show by reciprocal complementation that the MOM protein pATOM36 of trypanosomes is a functional analogue of yeast Mim1/Mim2 complex, even though these proteins show neither sequence nor topological similarity. Expression of pATOM36 rescues almost all growth, mitochondrial biogenesis, and morphology defects in yeast cells lacking Mim1 and/or Mim2. Conversely, co-expression of Mim1 and Mim2 restores the assembly and/or insertion defects of MOM proteins in trypanosomes ablated for pATOM36. Mim1/Mim2 and pATOM36 form native-like complexes when heterologously expressed, indicating that additional proteins are not part of these structures. Our findings indicate that Mim1/Mim2 and pATOM36 are the products of convergent evolution and arose only after the ancestors of fungi and trypanosomatids diverged.

Keywords: MIM complex; S. cerevisiae; biochemistry; biogenesis; chemical biology; mitochondria; outer membrane; trypanosome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Coevolution
  • Gene Deletion
  • Gene Expression Regulation, Fungal*
  • Genetic Complementation Test
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism
  • Mitochondria / genetics
  • Mitochondria / metabolism
  • Mitochondrial Membrane Transport Proteins / genetics*
  • Mitochondrial Membrane Transport Proteins / metabolism
  • Mitochondrial Membranes / metabolism*
  • Organelle Biogenesis
  • Phosphorylation
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protozoan Proteins / genetics*
  • Protozoan Proteins / metabolism
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism
  • Trypanosoma brucei brucei / genetics*
  • Trypanosoma brucei brucei / metabolism


  • MIM1 protein, S cerevisiae
  • Membrane Proteins
  • Mitochondrial Membrane Transport Proteins
  • Protein Isoforms
  • Protozoan Proteins
  • Saccharomyces cerevisiae Proteins