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 strictly regulated and dependent on the carbon source provided. Two upstream activation sites (UAS1(PCK1) and UAS2(PCK1)) and one upstream repression site (URS(PCK1)) were localized by detailed deletion analysis. The efficacy of these three promoter elements when separated from each other was confirmed by investigations using heterologous promoter test plasmids. Activation mediated by UAS1(PCK1) or UAS2(PCK1) did not occur in the presence of glucose, indicating that these elements are essential for glucose derepression. The repressing effect caused by URS(PCK1) was much stronger in glucose-grown cells than in ethanol-grown cells.