THE FISSION YEAST CDC19(+) GENE ENCODES A MEMBER OF THE MCM FAMILY OFREPLICATION PROTEINS

We have cloned and characterized the fission yeast cdc19(+) gene. We d emonstrate that it encodes a structural homologue of the budding yeast MCM2 protein. In fission yeast, the cdc19(+) gene is constitutively e xpressed, and essential for viability. Deletion delays progression thr ough S phase, and cells arrest in the first cycle with an apparent 2C DNA content, with their checkpoint control intact. The temperature-sen sitive cdc19-P1 mutation is synthetically lethal with cdc21-M68. In ad dition, we show by classical and molecular genetics that cdc19(+) is a llelic to the nda1(+) locus. We conclude that cdc19p plays a potential ly conserved role in S phase.