Genetic control of invertase formation in Saccharomyces cerevisiae. I. Isolation and characterization of mutants affecting sucrose utilization.

Nine sucrose nonfermenting mutants have been isolated from yeast strain EK-6B, carrying the tightly linked SUC3 and MAL3 genes. These mutants are allelic to the SUC3 gene recessive in nature and none of them has detectable levels of either internal or external invertase. A single point mutation leading to the loss of both invertases suggests that either SUC3 is a control gene or codes for a polypeptide which is shared by both invertases.