Decrease in glycolytic flux in Saccharomyces cerevisiae cdc35-1 cells at restrictive temperature correlates with a decrease in glucose transport

Abstract

The glycolytic flux was investigated in the thermosensitive Saccharomyces cerevisiae adenylate cyclase mutant cdc35-1. Directly after a shift to restrictive temperature, the specific CO₂ production rate increased from about 250 nmol min⁻¹ (mg protein)⁻¹ to more than 400 nmol min⁻¹ (mg protein)⁻¹, but then the CO₂ production gradually fell to about 70 nmol min⁻¹ (mg protein)⁻¹ after 5 h. O₂ consumption at restrictive temperature continued at more or less the same rate as at permissive temperature. The temperature shift in the mutant resulted in an increase in the estimated intracellular cAMP concentration from about 1.1 μM to 1.8 μM. This indicates that high cAMP levels are not sufficient for cell cycle progression and high glycolytic activity. The decrease in glycolytic activity at restrictive temperature was not paralleled by a similar decrease in the specific activity of any of the glycolytic enzymes, but correlated with a decrease in hexose transport. A drop in intracellular concentrations of the early metabolites of glycolysis further indicated a defect in transport at restrictive temperature. Our data suggest that glucose transport has a high control on glycolytic flux.