An essential novel component of the noncanonical mitochondrial outer membrane protein import system of trypanosomatids

Mascha Pusnik, Jan Mani, Oliver I Schmidt, Moritz Niemann, Silke Oeljeklaus, Felix Schnarwiler, Bettina Warscheid, Trevor J Lithgow, Chris Meisinger, Andre Schneider

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20 Citations (Scopus)


The mitochondrial outer membrane protein Tom40 is the general entry gate for imported proteins in essentially all eukaryotes. Trypanosomatids however lack Tom40 and use instead a protein termed the archaic translocase of the outer mitochondrial membrane (ATOM). Here we report the discovery of pATOM36, a novel essential component of the trypanosomal outer membrane protein import system that interacts with ATOM. pATOM36 is not related to known Tom proteins from other organisms and mediates the import of matrix proteins. However, there is a group of precursor proteins whose import is independent of pATOM36. Domain swapping experiments indicate that the N-terminal presequence-containing domain of the substrate proteins at least in part determines the dependence on pATOM36. Secondary structure profiling suggests pATOM36 is composed largely of alpha-helices and its assembly into the outer membrane is independent of the SAM complex. Taken together, these results show that pATOM36 is a novel component associated with the ATOM complex that promotes the import of a subpopulation of proteins into the mitochondrial matrix.
Original languageEnglish
Pages (from-to)3420 - 3428
Number of pages9
JournalMolecular Biology of the Cell
Issue number17
Publication statusPublished - 2012

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