Glucose repression of the inducible catabolic pathway for N-acetylglucosamine in yeast

In order to investigate the mechanism of glucose repression of the N-acetylglucosamine metabolic enzymes in Candida albicans, an obligatory aerobic yeast, the activities of the following inducible enzymes were assayed: the N-acetylglucosamine uptake, N-acetylglucosamine kinase and glucosamine-6-phosphate deaminase. In the presence of glucose or other sugars e.g. succinate and glycerol, synthesis of these enzymes took place at a normal rate, suggesting that the hexose produces no catabolite repression in this organism. On the contrary, strong inhibition by glucose was observed on the activities of N-acetylglucosamine uptake and deaminase in N-acetylglucosamine-grown cells of Saccharomyces cerevisiae, a facultative aerobe. From the results, it is concluded that "glucose effect" or catabolite repression is absent in Candida albicans, a pathogenic strain of yeast.