title: Reaction of wild-type and Glu243Asp variant yeast cytochrome c oxidase with O2.
abstract: We have studied internal electron transfer during the reaction of Saccharomyces cerevisiae mitochondrial cytochrome c oxidase with dioxygen. Similar absorbance changes were observed with this yeast oxidase as with the previously studied Rhodobacter sphaeroides and bovine mitochondrial oxidases, which suggests that the reaction proceeds along the same trajectory. However, notable differences were observed in rates and electron-transfer equilibrium constants of specific reaction steps, for example the ferryl (F) to oxidized (O) reaction was faster with the yeast (0.4ms) than with the bovine oxidase (~1ms) and a larger fraction CuA was oxidized with the yeast than with the bovine oxidase in the peroxy (PR) to F reaction. Furthermore, upon replacement of Glu243, located at the end of the so-called D proton pathway, by Asp the PR→F and F→O reactions were slowed by factors of ~3 and ~10, respectively, and electron transfer from CuA to heme a during the PR→F reaction was not observed. These data indicate that during reduction of dioxygen protons are transferred through the D pathway, via Glu243, to the catalytic site in the yeast mitochondrial oxidase. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.
authors.affiliation: Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Linda
authors.initials: L
authors.lastname: Näsvik Öjemyr
authors.affiliation: Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Amandine
authors.initials: A
authors.lastname: Maréchal
authors.affiliation: Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Vestin
authors.affiliation: Centre de Génétique Moléculaire du CNRS, UPR 3404, avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Meunier
authors.affiliation: Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Rich
authors.affiliation: Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden. Electronic address: peterb@dbb.su.se.
authors.forename: Peter
authors.initials: P
authors.lastname: Brzezinski
mesh_terms: D000595:Amino Acid Sequence; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D003576:Electron Transport Complex IV; D010100:Oxygen
keywords: Cytochrome aa(3); Electron transfer; Membrane protein; Metalloprotein; Redox reaction; Respiration