9317071 Cameron Subunit II of cytochrome c oxidase is a highly conserved protein required for respiration in all eucaryotes and some procaryotes. The enzyme complex is the terminal member of the electron transport chain responsible for transferring electrons from cytochrome c to oxygen. Subunit II binds to cytochrome c and accepts electrons via the CuA redox center. The protein has several highly conserved features including two hydrophobic regions, a conserved aromatic region, a number of negatively charged amino acids thought to interact with lysines on cytochrome c and a copper binding site like those found in blue copper proteins. To understand the function of this protein, yeast mutants defective in subunit II have been generated. We have identified strains defective in function due to alterations in the CuA binding region and due to codon substitutions in the aromatic region. We are finishing our analysis of the mutants and to extend our investigation to revertants of these strains that have recovered function. We expect to find true revertants that restore that wild type sequence; pseudo revertants where one amino acid is substituted for another and strains carrying extra- genic suppressors. Among the latter group, we expect to identify gene products, both nuclear and mitochondrial, that interact directly with subunit II. This analysis will yield information concerning functionally critical amino acids in the protein and possibly about interactions between oxidase subunits. %%% This is a continuation of the genetic studies on the yeast protein, subunit II of cytochrome c oxidase. This protein is a highly conserved protein required for respiration in all higher organisms. This research has the potential to broaden our understanding of respiration. In addition, the project is providing college undergraduates with the opportunity to understand the process of scientific research and to participate in it. ***
