LEVEL OF ATP SYNTHASE ACTIVITY REQUIRED FOR YEAST SACCHAROMYCES-CEREVISIAE TO GROW ON GLYCEROL MEDIA

Two independent cold-sensitive pet mutants in the gene (ATP5) coding f or the oligomycin sensitivity conferring protein (OSCP) have been isol ated in the yeast Saccharomyces cerevisiae. The mutations in both stra ins alter the initiating methionine codon in the ATP5 gene: ATG to ATA (Ile) and AAG (Lys). Western blot analysis of total yeast protein aft er the cells were grown at 18 degrees C, 30 degrees C, and 37 degrees C, indicates that the level of OSCP decreased 80% relative to the wild type strain. In addition, the level of the oligomycin-sensitive ATPas e decreased 85% relative to the wild type strain, after growth at 30 d egrees C. These findings indicate that for S. cerevisiae, the level of oxidative phosphorylation can decrease 85% without showing a large gr owth defect on media containing glycerol at 30 degrees C, but not at 1 8 degrees C.