title: Mitochondrial preprotein translocase of trypanosomatids has a bacterial origin.
abstract: Mitochondria are found in all eukaryotic cells and derive from a bacterial endosymbiont [1, 2]. The evolution of a protein import system was a prerequisite for the conversion of the endosymbiont into a true organelle. Tom40, the essential component of the protein translocase of the outer membrane, is conserved in mitochondria of almost all eukaryotes but lacks bacterial orthologs [3-6]. It serves as the gateway through which all mitochondrial proteins are imported. The parasitic protozoa Trypanosoma brucei and its relatives do not have a Tom40-like protein, which raises the question of how proteins are imported by their mitochondria [7, 8]. Using a combination of bioinformatics and in vivo and in vitro studies, we have discovered that T. brucei likely employs a different import channel, termed ATOM (archaic translocase of the outer mitochondrial membrane). ATOM mediates the import of nuclear-encoded proteins into mitochondria and is essential for viability of trypanosomes. It is not related to Tom40 but is instead an ortholog of a subgroup of the Omp85 protein superfamily that is involved in membrane translocation and insertion of bacterial outer membrane proteins [9]. This suggests that the protein import channel in trypanosomes is a relic of an archaic protein transport system that was operational in the ancestor of all eukaryotes.
authors: Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.
authors: Mascha
authors: M
authors: Pusnik
authors: Oliver
authors: O
authors: Schmidt
authors: Andrew J
authors: AJ
authors: Perry
authors: Silke
authors: S
authors: Oeljeklaus
authors: Moritz
authors: M
authors: Niemann
authors: Bettina
authors: B
authors: Warscheid
authors: Trevor
authors: T
authors: Lithgow
authors: Chris
authors: C
authors: Meisinger
authors: André
authors: A
authors: Schneider
mesh_terms: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D005057:Eukaryotic Cells / Q000378:metabolism; D019143:Evolution, Molecular; D008727:Methotrexate / Q000494:pharmacology; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D011487:Protein Conformation; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D050994:Voltage-Dependent Anion Channels / Q000235:genetics / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C503914:BamA protein, E coli; D029968:Escherichia coli Proteins; D033681:Mitochondrial Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C066555:Tom40 protein, S cerevisiae; D050994:Voltage-Dependent Anion Channels; D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate