The CCAAT box-binding factor stimulates ammonium assimilation in Saccharomyces cerevisiae, defining a new cross-pathway regulation between nitrogen and carbon metabolisms

The GDH1 gene in Saccharomyces cerevisiae needs the CCAAT box-binding activator (HAP complex) for optimal expression. Expression of GDH1 is also controlled by the carbon source. Hence, expression is higher on lactate than on ethanol, glycerol or galactose. The hap2 mutation does not affect expression of other genes which control nitrogen metabolism. The function of the HAP complex in the gene expression regulation indicates a cross-pathway regulation between carbon and nitrogen metabolisms.