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Mitochondrial preprotein translocase of trypanosomatids has a bacterial origin.

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2011
Author Pusnik Mascha, Schmidt Oliver, Perry Andrew J, Oeljeklaus Silke, Niemann Moritz, Warscheid Bettina, Lithgow Trevor, Meisinger Chris, Schneider André,
Project Mitochondrial biogenesis in T. brucei: import of macromolecules and organellar gene expression
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Original article (peer-reviewed)

Journal Current biology : CB
Volume (Issue) 21(20)
Page(s) 1738 - 43
Title of proceedings Current biology : CB
DOI 10.1016/j.cub.2011.08.060


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.