Mitochondrial Preprotein Translocase of Trypanosomatids Has a Bacterial Origin

作者：Pusnik Mascha; Schmidt Oliver; Perry Andrew J; Oeljeklaus Silke; Niemann Moritz; Warscheid Bettina; Lithgow Trevor; Meisinger Chris; Schneider Andre^*

来源：Current Biology, 2011, 21(20): 1738-1743.

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 mitochondria! 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 0mp85 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.

• 出版日期2011-10-25