Metabolic Interconversion of Yeast Fractose-1,6-Bisphosphatase

Abstract

After the addition of glucose to acetate- or ethanol-grown yeast cells a small group of enzymes is rapidly inactivated. This phenomenon has been called “catabolite inactivation” (Holzer 1976). Among other enzymes participating in gluconeogenesis, fructose-1,6-bisphosphatase is inactivated during catabolite inactivation (Harris and Ferguson 1967; Gancedo 1971). As shown in Fig. 1, the simultaneous presence of phosphofructokinase and fructose-1,6-bisphosphatase would lead after addition of glucose to a “futile cycle” which continously splits ATP to ADP and inorganic phosphate. The rapid inactivation of fructose-1,6-bisphosphatase after addition of glucose therefore protects the cells from ATP depletion. Experiments with specific antibodies have shown that catabolite inactivation of cytoplasmic malate dehydrogenase (Neeff et al. 1978), aminopeptidase I (Frey and Röhm 1979), fructose-1,6-bisphosphatase (Funayama et al. 1980), and phosphoenolpyruvate carboxykinase (Müller et al. 1981), is the result of proteolytic degradation of the respective enzymes.