IDENTIFICATION AND CHARACTERIZATION OF REGULATORY ELEMENTS IN THE PHOSPHOENOLPYRUVATE CARBOXYKINASE GENE PCK1 OF SACCHAROMYCES-CEREVISIAE

Phosphoenolpyruvate carboxykinase is a key enzyme in gluconeogenesis. The expression of the PCK1 gene in Saccharomyces cerevisiae is strictl y regulated and dependent on the carbon source provided. Two upstream activation sites (UAS1(PCK1) and UAS2(PCK1)) and one upstream repressi on site (URS(PCK1)) were localized by detailed deletion analysis. The efficacy of these three promoter elements when separated from each oth er was confirmed by investigations using heterologous promoter test pl asmids. Activation mediated by UAS1(PCK1) or UAS2(PCK1) did not occur in the presence of glucose, indicating that these elements are essenti al for glucose derepression. The repressing effect caused by URS(PCK1) was much stronger in glucose-grown cells than in ethanol-grown cells.