title: Characterization of the peroxide sensitivity of COX-deficient yeast strains reveals unexpected relationships between COX assembly proteins.
abstract: A number of distinct cuproproteins of the mitochondrial inner membrane are required for the assembly of cytochrome oxidase (COX), thought to function in a "bucket brigade" fashion to provide copper to the Cu(A) and Cu(B) sites. In yeast, the loss of two these proteins, Sco1p and Cox11p, leads to respiratory deficiency and a specific inability to survive exposure to hydrogen peroxide (H(2)O(2)). Using a quantitative assay, we have identified subtle differences in the peroxide-sensitive phenotypes between sco1 and cox11 mutant strains. Interestingly, the peroxide sensitivity of the sco1 null strain can be suppressed by overexpressing either SCO2 or COX11, although overexpression of neither SCO1 nor SCO2 can rescue the cox11 null strain. We also find that overexpression of either CTT1, encoding the cytosolic catalase T, or CTA1, encoding the mitochondrial matrix catalase, suppresses the peroxide sensitivity in both the sco1 and the cox11 null mutants. Direct measurement of peroxide metabolism shows that sco1 and cox11 null strains fail to degrade a significant amount of exogenously provided H(2)O(2). Taken together, our data demonstrate that although Cox11p and Sco1p play distinct roles in COX assembly, they seem to play overlapping or related roles in peroxide metabolism that require further investigation.
authors.affiliation: Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada.
authors.forename: Simona
authors.initials: S
authors.lastname: Veniamin
authors.forename: Luanne G
authors.initials: LG
authors.lastname: Sawatzky
authors.forename: Graham S
authors.initials: GS
authors.lastname: Banting
authors.forename: D Moira
authors.initials: DM
authors.lastname: Glerum
mesh_terms: D002374:Catalase / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D003300:Copper / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D030781:Organisms, Genetically Modified; D012119:Respiration / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes / Q000235:genetics; D015003:Yeasts / Q000502:physiology*
chemical_list: C086106:COX11 protein, S cerevisiae; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes; C066384:SCO1 protein, S cerevisiae; C498516:SCO2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D003300:Copper; D006861:Hydrogen Peroxide; D002374:Catalase