Eukaryotic cytochrome oxidases are composed of up to 13 subunits, of which three, subunits 1, 2 and 3, are mitochondrially encoded. In this study, yeast mutants were used to investigate the role of subunits 1 and 3 domains on the enzyme assembly. Mutation S203L in subunit 3 which abolished the respiratory growth, decreased cytochrome oxidase content, as measured by optical spectroscopy and immunodetection. Secondary mutations in subunits 1 and 3 restored (partly) the enzyme level. Two reversions reintroduced residues with a hydroxyl group at the primary mutation site (S203T) or in a subunit 3 transmembrane helix close to subunit 1 (G104S). These residues may be involved in hydrogen bonding which strengthen subunits 1-3 interaction. Two other reversions (A224V and Q137K) are located in P-side loops in subunit 1, which may be involved in the enzyme assembly. A mutation in residue A224 has been reported in a family presenting with encephalomyopathy. Surprisingly, the introduction of the 'human' mutation A224S and of a more drastic change A224F had no effect on the yeast enzyme. This might be explained by differences in local folding in the two enzymes.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|