CELL-CYCLE MUTATIONS AMONG THE COLLECTION OF SACCHAROMYCES-CEREVISIAEDNA MUTANTS

The temperature-sensitive dna mutants of the budding yeast Saccharomyc es cerevisiae (Dumas et al. (1982) Mol. Gen. Genet. 187, 42-46) are mo re inhibited in DNA synthesis than in protein synthesis. These propert ies are also characteristic of many yeast mutations that inhibit progr ess through the cell cycle. Therefore we surveyed the collection of dn a mutants for cell-cycle mutations. By genetic complementation we foun d that dna1 = cdc22, dna6 = cdc34, dna19 = cdc36, and dna39 = dbf3. Fu rthermore, by direct gene cloning we found that the dna26 mutation is allelic to prt1 mutations, which are known to exert primary inhibition on protein synthesis. This protein-synthesis mutation exerts a dna ph enotype due to cell-cycle inhibition: prt1 mutations can block the reg ulatory step of the cell cycle while allowing significant amounts of p rotein synthesis to continue. Our non-exhaustive screening suggests th at the dna mutants may house other mutations that affect the yeast cel l cycle.