title: A role for cytochrome c and cytochrome c peroxidase in electron shuttling from Erv1.
abstract: Erv1 is a flavin-dependent sulfhydryl oxidase in the mitochondrial intermembrane space (IMS) that functions in the import of cysteine-rich proteins. Redox titrations of recombinant Erv1 showed that it contains three distinct couples with midpoint potentials of -320, -215, and -150 mV. Like all redox-active enzymes, Erv1 requires one or more electron acceptors. We have generated strains with erv1 conditional alleles and employed biochemical and genetic strategies to facilitate identifying redox pathways involving Erv1. Here, we report that Erv1 forms a 1:1 complex with cytochrome c and a reduced Erv1 can transfer electrons directly to the ferric form of the cytochrome. Erv1 also utilized molecular oxygen as an electron acceptor to generate hydrogen peroxide, which is subsequently reduced to water by cytochrome c peroxidase (Ccp1). Oxidized Ccp1 was in turn reduced by the Erv1-reduced cytochrome c. By coupling these pathways, cytochrome c and Ccp1 function efficiently as Erv1-dependent electron acceptors. Thus, we propose that Erv1 utilizes diverse pathways for electron shuttling in the IMS.
authors.affiliation: Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Deepa V
authors.initials: DV
authors.lastname: Dabir
authors.forename: Edward P
authors.initials: EP
authors.lastname: Leverich
authors.forename: Sung-Kun
authors.initials: SK
authors.lastname: Kim
authors.forename: Frederick D
authors.initials: FD
authors.lastname: Tsai
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hirasawa
authors.forename: David B
authors.initials: DB
authors.lastname: Knaff
authors.forename: Carla M
authors.initials: CM
authors.lastname: Koehler
mesh_terms: D000483:Alleles; D001671:Biochemistry / Q000379:methods; D003578:Cytochrome-c Peroxidase / Q000502:physiology*; D045304:Cytochromes c / Q000502:physiology*; D004583:Electrons; D006861:Hydrogen Peroxide / Q000737:chemistry; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000502:physiology*; D008954:Models, Biological; D008957:Models, Genetic; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000502:physiology*; D013997:Time Factors
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D003578:Cytochrome-c Peroxidase; D050862:Oxidoreductases Acting on Sulfur Group Donors; C073790:ERV1 protein, S cerevisiae; D010100:Oxygen