title: Mia40 combines thiol oxidase and disulfide isomerase activity to efficiently catalyze oxidative folding in mitochondria.
abstract: Mia40 (a mitochondrial import and assembly protein) catalyzes disulfide bond formation in proteins in the mitochondrial intermembrane space. By using Cox17 (a mitochondrial copper-binding protein) as a natural substrate, we discovered that, in the presence of Mia40, the formation of native disulfides is strongly favored. The catalytic mechanism of Mia40 involves a functional interplay between the chaperone site and the catalytic disulfide. Mia40 forms a specific native disulfide in Cox17 much more rapidly than other disulfides, in particular, non-native ones, which originates from the recently described high affinity for hydrophobic regions near target cysteines and the long lifetime of the mixed disulfide. In addition to its thiol oxidase function, Mia40 is active also as a disulfide reductase and isomerase. We found that species with inadvertently formed incorrect disulfides are rebound by Mia40 and reshuffled, revealing a proofreading mechanism that is steered by the conformational folding of the substrate protein.
authors.affiliation: Laboratorium für Biochemie und Bayreuther Zentrum für Molekulare Biologie, Universität Bayreuth, 95440 Bayreuth, Germany.
authors.forename: Johanna R
authors.initials: JR
authors.lastname: Koch
authors.affiliation: Laboratorium für Biochemie und Bayreuther Zentrum für Molekulare Biologie, Universität Bayreuth, 95440 Bayreuth, Germany. Electronic address: fx.schmid@uni-bayreuth.de.
authors.forename: Franz X
authors.initials: FX
authors.lastname: Schmid
mesh_terms: D055162:Biocatalysis; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000079922:Copper Transport Proteins; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007536:Isomerism; D007700:Kinetics; D033681:Mitochondrial Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: C100359:COX17 protein, S cerevisiae; D027682:Cation Transport Proteins; D000079922:Copper Transport Proteins; D004220:Disulfides; C495320:MIA40 protein, S cerevisiae; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; D013438:Sulfhydryl Compounds; D010088:Oxidoreductases; D019704:Protein Disulfide-Isomerases
keywords: disulfide relay; mitochondrial disulfide formation; mitochondrial import; mitochondrial intermembrane space; oxidative protein folding