title: The effect of amino acid substitutions in the conserved aromatic region of subunit II of cytochrome c oxidase in Saccharomyces cerevisiae.
abstract: Mitochondrial encoded subunit II of cytochrome c oxidase carries the metal center, which acts as the initial acceptor of electrons from cytochrome c. Among the conserved features of this protein is a region in which five aromatic and three non-aromatic amino acids are conserved in a wide variety of organisms. This aromatic region has been postulated to be involved in transfer of electrons from the copper center in subunit II to the remaining metal centers of cytochrome oxidase in subunit I. To test the functional importance of two conserved, aromatic tryptophan residues and one conserved, non-aromatic glycine residue, yeast strains with alterations at these positions were characterized. The strains with altered codons were tested for their ability to carry out cellular respiration, for their growth rates on non-fermentable carbon sources, and for their cytochrome c oxidase activity. The results demonstrate that the aromatic character of the tryptophan residues appears necessary for subunit II function, while the conserved glycine can be replaced with other, small, uncharged residues.
authors.affiliation: Biology Department, Ithaca College, New York, 14850, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Overholtzer
authors.forename: P S
authors.initials: PS
authors.lastname: Yakowec
authors.forename: V
authors.initials: V
authors.lastname: Cameron
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003062:Codon; D017124:Conserved Sequence; D003574:Cytochrome c Group / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D046911:Macromolecular Substances; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010101:Oxygen Consumption; D010641:Phenotype; D017354:Point Mutation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000502:physiology
chemical_list: D003062:Codon; D003574:Cytochrome c Group; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D003576:Electron Transport Complex IV