title: The disease-associated mutation of the mitochondrial thiol oxidase Erv1 impairs cofactor binding during its catalytic reaction.
abstract: Erv1 (essential for respiration and viability 1) is an FAD-dependent thiol oxidase of the Erv/ALR (augmenter of liver regeneration) sub-family. It is an essential component of the mitochondrial import and assembly (MIA) pathway, playing an important role in the oxidative folding of the mitochondrial intermembrane space (IMS) proteins and linking the MIA pathway to the mitochondrial respiratory chain via cytochrome c (cyt c). The importance of the Erv/ALR enzymes was also demonstrated in a recent study where a single mutation in the human ALR (R194H) leads to autosomal recessive myopathy [Di Fonzo, Ronchi, Lodi, Fassone, Tigano, Lamperti, Corti, Bordoni, Fortunato, Nizzardo et al. (2009) Am. J. Hum. Genet. 84, 594-604]. However, the molecular mechanism of the disease is still unclear. In the present study, we use yeast Erv1 as a model to provide clear evidence for a progressive functional defect in the catalytic activity of the corresponding Erv1 R182H mutant. We show that the FAD cofactor was released from Erv1 R182H during its catalytic cycle, which led to the inactivation of the enzyme. We also characterized the effects of the mutation on the folding and stability of Erv1 and tested our in vitro findings in vivo using a yeast genetic approach. The results of the present study allow us to provide a model for the functional defect in Erv1 R182H, which could potentially be extended to human ALR R194H and provides insights into the molecular basis of autosomal recessive myopathy.
authors.affiliation: *Faculty of Life Sciences, Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
authors.forename: Efrain
authors.initials: E
authors.lastname: Ceh-Pavia
authors.affiliation: *Faculty of Life Sciences, Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
authors.forename: Swee Kim
authors.initials: SK
authors.lastname: Ang
authors.affiliation: *Faculty of Life Sciences, Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Spiller
authors.affiliation: *Faculty of Life Sciences, Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
authors.forename: Hui
authors.initials: H
authors.lastname: Lu
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D002384:Catalysis; D020134:Catalytic Domain / Q000235:genetics; D003067:Coenzymes / Q000378:metabolism; D003579:Cytochrome Reductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009135:Muscular Diseases / Q000235:genetics*; D020125:Mutation, Missense; D050862:Oxidoreductases Acting on Sulfur Group Donors; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D003067:Coenzymes; D003579:Cytochrome Reductases; C500897:GFER protein, human; D050862:Oxidoreductases Acting on Sulfur Group Donors