title: COX23, a homologue of COX17, is required for cytochrome oxidase assembly.
abstract: Deletion of reading frame YHR116W of the Saccharomyces cerevisiae nuclear genome elicits a respiratory deficiency. The encoded product, here named Cox23p, is shown to be required for the expression of cytochrome oxidase. Cox23p is homologous to Cox17p, a water-soluble copper protein previously implicated in the maturation of the Cu(A) center of cytochrome oxidase. The respiratory defect of a cox23 null mutant is rescued by high concentrations of copper in the medium but only when the mutant harbors COX17 on a high copy plasmid. Overexpression of Cox17p by itself is not a sufficient condition to rescue the mutant phenotype. Cox23p, like Cox17p, is detected in the intermembrane space of mitochondria and in the postmitochondrial supernatant fraction, the latter consisting predominantly of cytosolic proteins. Because Cox23p and Cox17p are not part of a complex, the requirement of both for cytochrome oxidase assembly suggests that they function in a common pathway with Cox17p acting downstream of Cox23p.
authors.affiliation: Department of Genetics Instituto de Biociencias de Botucatu-Universidade Estadual Paulista, Botucatu, São Paulo, Brazil 18607-741.
authors.forename: Mario H
authors.initials: MH
authors.lastname: Barros
authors.forename: Alisha
authors.initials: A
authors.lastname: Johnson
authors.forename: Alexander
authors.initials: A
authors.lastname: Tzagoloff
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000494:pharmacology; D000079922:Copper Transport Proteins; D004271:DNA, Fungal / Q000235:genetics; D003576:Electron Transport Complex IV / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005800:Genes, Fungal; D008928:Mitochondria / Q000378:metabolism; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: C100359:COX17 protein, S cerevisiae; D027682:Cation Transport Proteins; D000079922:Copper Transport Proteins; D004271:DNA, Fungal; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; D003300:Copper; D003576:Electron Transport Complex IV