Thursday, July 28, 2016

The Import of Proteins into the Mitochondrion of Toxoplasma gondii

 2016 Jul 25. pii: jbc.M116.725069. [Epub ahead of print]

Abstract

Outside of well-characterized model eukaryotes, there is relatively little 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 harbour a mitochondrion that is essential for parasite survival, and is a validated drug target. Here, we demonstrate that the apicomplexan Toxoplasma gondii harbours 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.
Copyright © 2016, The American Society for Biochemistry and Molecular Biology.

KEYWORDS: 

Toxoplasma gondii; intracellular trafficking; mitochondria; parasite; protein import

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