MUTATIONS OF THE CDC28 GENE AND THE RADIATION SENSITIVITY OF SACCHAROMYCES-CEREVISIAE

cdc28-srm, a non-temperature-sensitive (ts) mutation in the CDC28 gene of Saccharomyces cerevisiae that affects fidelity of mitotic transmis sion of both mitochondrial and nuclear genetic structures (Devin et al ., 1990), also affected cell growth and sensitivity to lethal effects of ionizing radiation. Al 30 degrees C cdc28-13, a is mutation, was wi thout appreciable effects on spontaneous mitochondrial rho(-)-mutagene sis, cell growth and radiation sensitivity, whereas all three cell cha racteristics mentioned were affected (although to a lesser degree than by cdc28-srm) by cdc28-1, another is mutation. cdc28-srm was without any significant effect on the rates of spontaneous nuclear gene mutati ons and gamma-ray-induced mitotic recombination. An analysis of double mutants as regards their radiation sensitivity has revealed additive or even synergistic interactions between the cdc28-srm mutation and ev ery one of the rad6-1 and rad52-1 mutations. The rad9 Delta allele was found to be epistatic to cdc28-srm. These data suggest that the p34(C DC28) protein is involved in the RAD9-dependent feedback control of DN A integrity operating at the cell cycle checkpoints. (C) 1998 John Wil ey & Sons, Ltd.