title: The Import of Proteins into the Mitochondrion of Toxoplasma gondii.
abstract: Outside of well characterized model eukaryotes, relatively little is known about the translocons that transport proteins across the two membranes that surround the mitochondrion. Apicomplexans are a phylum of intracellular parasites that cause major diseases in humans and animals and are evolutionarily distant from model eukaryotes such as yeast. Apicomplexans harbor a mitochondrion that is essential for parasite survival and is a validated drug target. Here, we demonstrate that the apicomplexan Toxoplasma gondii harbors homologues of proteins from all the major mitochondrial protein translocons present in yeast, suggesting these arose early in eukaryotic evolution. We demonstrate that a T. gondii homologue of Tom22 (TgTom22), a central component of the translocon of the outer mitochondrial membrane (TOM) complex, is essential for parasite survival, mitochondrial protein import, and assembly of the TOM complex. We also identify and characterize a T. gondii homologue of Tom7 (TgTom7) that is important for parasite survival and mitochondrial protein import. Contrary to the role of Tom7 in yeast, TgTom7 is important for TOM complex stability, suggesting the role of this protein has diverged during eukaryotic evolution. Together, our study identifies conserved and modified features of mitochondrial protein import in apicomplexan parasites.
authors.affiliation: From the Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia, giel.vandooren@anu.edu.au.
authors.forename: Giel G
authors.identifier: 0000-0003-2455-9821
authors.initials: GG
authors.lastname: van Dooren
authors.affiliation: the School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia, and.
authors.forename: Lee M
authors.initials: LM
authors.lastname: Yeoh
authors.affiliation: the Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602.
authors.forename: Boris
authors.initials: B
authors.lastname: Striepen
authors.affiliation: the School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia, and.
authors.forename: Geoffrey I
authors.initials: GI
authors.lastname: McFadden
mesh_terms: D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D015800:Protozoan Proteins / Q000378:metabolism*; D014122:Toxoplasma / Q000378:metabolism*
chemical_list: D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D015800:Protozoan Proteins
keywords: Toxoplasma gondii; intracellular trafficking; mitochondria; parasite; protein import