The cdc30 mutation in Saccharomyces cerevisiae affects phosphoglucose isomerase, the cell cycle and sporulation

Spontaneous revertants of the cdc30 mutation in Saccharomyces cerevisiae simultaneously regained the ability to grow and divide at 36.5 degrees C on glucose-containing media along with a more thermostable phosphoglucose isomerase (PGI). An independently isolated allele of cdc30 gave a similar phenotype to that previously described including temperature-sensitivity of PGI. Isoelectric focussing allowed the separation of two isoenzymes of PGI. These results all support the idea that two genes--PGI1 and CDC30--are responsible for PGI activity in yeast. Diploid strains homozygous for the cdc30 mutation sporulated poorly in potassium acetate irrespective of whether the cells had previously been cultured at a temperature that was permissive or restrictive for cell cycle progression. This was not surprising because a strain defective in PGI would not be expected to be able to complete the gluconeogenic events of sporulation.