title: The aconitase C-terminal domain is an independent dual targeting element.
abstract: The tricarboxylic acid cycle enzyme aconitase in yeast is a single translation product, which is dual targeted and distributed between the mitochondria and the cytosol by a unique mechanism involving reverse translocation. There is limited understanding regarding the precise mechanism of reverse translocation across the mitochondrial membranes. Here, we examined the contribution of the mature part of aconitase to its dual targeting. We created a set of aconitase mutants harboring two kinds of alterations: (1) point mutations or very small deletions in conserved sites and (2) systematic large deletions. These mutants were screened for their localization by a α-complementation assay, which revealed that the aconitase fourth domain that is at the C-terminus (amino acids 517-778) is required for aconitase distribution. Moreover, fusion of this C-terminal domain to mitochondria-targeted passenger proteins such as dihydrofolate reductase and orotidine-5'-phosphate decarboxylase, conferred dual localization on them. These results indicate that the aconitase C-terminal domain is both necessary and sufficient for dual targeting, thereby functioning as an "independent signal". In addition, the same C-terminal domain was shown to be necessary for aconitase efficient posttranslational import into mitochondria.
authors: Department of Microbiology and Molecular Genetics, Institute of Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel.
authors: Reut
authors: R
authors: Ben-Menachem
authors: Neta
authors: N
authors: Regev-Rudzki
authors: Ophry
authors: O
authors: Pines
mesh_terms: D000154:Aconitate Hydratase / Q000235:genetics / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D005816:Genetic Complementation Test; D047468:Immunoprecipitation; D008928:Mitochondria / Q000378:metabolism*; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation / Q000235:genetics; D021382:Protein Sorting Signals; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D013347:Subcellular Fractions; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics / Q000378:metabolism
chemical_list: D050505:Mutant Proteins; D021382:Protein Sorting Signals; D029701:Saccharomyces cerevisiae Proteins; C554167:URA3 protein, S cerevisiae; D013762:Tetrahydrofolate Dehydrogenase; D000154:Aconitate Hydratase