Inactivation of Gluconegenic Enzymes in Glycolytic Mutants of Saccharomyces cervisiae

Yeast mutants blocked at different steps of the glycolytic pathway have been used to study the inactivation of several gluconeogenic enzymes upon addition of sugars. While phosphorylation of the sugars appears a requisite for the inactivation of fructose 1,6-bisphosphatase and phosphoeenol-pyruvate carboxykinase, malate dehydrogenase is inactivated by fructose in mutants lacking hexokinase. The normal inactivation elicited by glucose in a mutant lacking phosphofructokinase indicates that the process does not require metabolism of the sugar beyond hexose monophosphates. A possible role for ATP in the inactivation process is suggested.This work was partially sup- ported by the Comisión Asesora de Investigación Científica y Técnica.Peer reviewe