The aromatic nature of residue 66 of the 11-kDa subunit of ubiquinol-cytochrome <i>c</i> oxidoreductase of the yeast <i>Saccharomyces cerevisiae</i> is important for the assembly of a functional enzyme

AbstractTransformation of multi- and single-copy plasmids carrying a mutated version (LTN2, region 66-YWYWW-70 replaced by SASAA) of QCR8, the gene encoding the 11-kDa subunit of ubiquinol-cytochrome c oxidoreductase of Saccharomyces cerevisiae, to a QCR80 strain indicated the importance of this aromatic region for the assembly of a functional enzyme. Sequencing of plasmids giving spontaneous restoration of growth to some colonies among the single-copy LTN2 transformants showed that changing the sequence SASAA into the sequence FASAA could, to a large extent, overcome the observed assembly defect, indicating the importance of the aromatic nature of residue 66