title: Identification and characterization of mitochondrial Mia40 as an iron-sulfur protein.
abstract: Mia40 is a highly conserved mitochondrial protein that plays an essential role in the import and oxidative folding of many proteins of the mitochondrial intermembrane space. Mia40 uses its redox active CPC motif to shuttle disulfides between its client proteins (newly imported proteins) and the thiol oxidase Erv1. As a thiol oxidoreductase, no cofactor was found in Mia40, nor is a cofactor required for this function. In the present study we, for the first time based on both in vitro and in vivo studies, show that yeast Mia40 can exist as an Fe-S (iron-sulfur) protein as well. We show that Mia40 binds a [2Fe-2S] cluster in a dimer form with the cluster co-ordinated by the cysteine residues of the CPC motifs. The biological relevance of the cofactor binding was confirmed in vivo by cysteine redox state and iron uptake analyses, which showed that a significant amount of cellular Mia40 binds iron in vivo. Furthermore, our oxygen consumption results suggested that the Fe-S-containing Mia40 is not an electron donor for Erv1. Thus we conclude that Mia40 is a novel Fe-S protein with a new cluster-binding motif (CPC), and apart from the thiol oxidoreductase activity, Mia40 may have another important, as yet undefined, function in cells.
authors.affiliation: *Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Spiller
authors.forename: Swee Kim
authors.initials: SK
authors.lastname: Ang
authors.forename: Efrain
authors.initials: E
authors.lastname: Ceh-Pavia
authors.forename: Karl
authors.initials: K
authors.lastname: Fisher
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Stephen E J
authors.initials: SE
authors.lastname: Rigby
authors.forename: Hui
authors.initials: H
authors.lastname: Lu
mesh_terms: D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010084:Oxidation-Reduction; D011485:Protein Binding; D055503:Protein Multimerization; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D007506:Iron-Sulfur Proteins; C495320:MIA40 protein, S cerevisiae; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D007501:Iron