NOVEL ALLELES OF CDC13 AND CDC2 ISOLATED AS SUPPRESSORS OF MITOTIC CATASTROPHE IN SCHIZOSACCHAROMYCES-POMBE

Cell cycle control in the fission yeast Schizosaccharomyces pombe invo lves interplay amongst a number of regulatory molecules, including the cdc2 cdc13, cdc25, wee1, and mik1 gene products. Cdc2, Cdc13, and Cdc 25 act as positive regulators of cell cycle progression at the G2/M bo undary, while Wee1 and Mik1 play a negative regulatory role. Here, we have screened for suppressors of the lethal premature entry into mitos is, termed mitotic catastrophe, which results from simultaneous loss o f function of both Wee1 and Mik1. Through such a screen, we hoped to i dentify additional components of the cell cycle regulatory network, an d/or G2/M-specific substrates of Cdc2. Although we did not identify su ch molecules, we isolated a number of alleles of both cdc2 and cdc13, including a novel wee allele of cdc2, cdc2-5w. Here, we characterize c dc2-5w and two alleles of cdc13, which have implications for the under standing of details of the interactions amongst Cdc2, Cdc13, and Wee1.