HYS2, AN ESSENTIAL GENE REQUIRED FOR DNA REPLICATION IN SACCHAROMYCES CEREVISIAE

摘要

To investigate cell cycle regulation at the S or G2 phase in Saccharomyces cerevisiae, we have isolated mutants displaying supersensitivity to hydroxyurea (HU), a chemical that inhibits DNA replication, Such mutants, which we have named hydroxyurea sensitive (hys), defined four linkage groups and we characterized the hys2 mutation in this study, The hys2-1 mutant displays temperature sensitive growth and a constellation of phenotypes indicating defective DNA metabolism, At the restrictive temperature, hys2-1 cells arrest as large budded cells with a single nucleus at the neck of the bud and a short spindle, The hys2-1 mutant exhibits increased rates of chromosome loss and recombination, Additionally, hys2-1 appears to accumulate incompletely replicated DNA that can be detected by a pulse field electrophoresis assay, Finally, deletion of RADS in a hys2-1 strain decreases the percentage of arrested cells, suggesting that an intact RAD9-checkpoint is required for the cell cycle arrest in hys2-1 cells, HYS2 encodes a 55 kDa protein that is essential for viability at all temperatures, Taken together, these data suggest that Hys2 plays a role in DNA replication.