Carbon and Energy Uncoupling Associated with Cell Cycle Arrest of cdc Mutants of Saccharomyces cerevisiae May Be Linked to Glucose-Induced Catabolite Repression

Several cell division cycle (cdc) mutants of Saccharomyces cerevisiae (cdc28, cdc35, cdc19, cdc21, and cdc17) at the restrictive temperature (37°C) in the presence of 1% glucose and defined medium divert most of the carbon (∼50%) to ethanol production with low biomass growth yields (Y_glc) that correlate with carbon and energy uncoupling and arrest of cell proliferation. The cdc mutants studied are shown to be glucose-repressed, while this was not the case for the wild-type A364A (WT). At 37°C, in the presence of 1% glycerol, derepressed cdc28 mutant cells did not show arrest of cell division and carbon and energy uncoupling since the Y_glc levels measured were similar to these of the WT strain. These results suggest that the increased fermentative ability and carbon and energy uncoupling exhibited in the presence of glucose by cdc mutants with respect to those exhibited by the WT may be due to catabolite repression.