The cdc30 Mutation in Saccharomyces cerevisiae Results in a Temperature-sensitive Isoenzyme of Phosphoglucose Isomerase

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Abstract
The cdc30 mutation in the yeast Saccharomyces cerevisiae causes cell cycle arrest late in nuclear division when cells are shifted from the permissive temperature of 25.degree. C to the restrictive temperature of 36.5.degree. C. Cell cycle arrest at 36.5.degree. C is dependent upon the carbon source used: a shift-up in glucose containing media results in cell cycle blockade, whereas a shift-up in ethanol, fructose, glycerol, glycerol plus ethanol, or mannose does not. Metabolite analyses showed accumulation of glucose 6-phosphate in a cdc30-bearing strain after a temperature shift-up in glucose-containing medium. Thermal denaturation studies and kinetic measurements indicate the existence of two isoenzymes of phosphoglucose isomerase (EC 5.3.1.9); one of which is apparently altered in the temperature-sensitive cell cycle mutant. We propose that the gene products of both the CDC30 and PG11 genes are required for cell cycle progression in glucose media and that the PG11 gene product has a regulatory function over the CDC30 gene product.