DNA-repair characterization of cdc40-1, a cell-cycle mutant of Saccharomyces cerevisiae

The cell-cycle specific mutation cdc40-1, which has been previously shown to be sensitive to MMS at the restrictive temperature, was further characterized as a DNA-repair-deficient mutation. cdc40-1 mutants shown only slight sensitivity to UV irradiation. Double mutant studies shown that rad6-l is epistatic to cdc40-1 with respect to sensitivity to UV irradiation and MMS. rad50-1 is epistatic to cdc40-1 with respect to MMS sensitivity in G1 stationary cells, but not in logarithmic cultures. An additive effect is seen between cdc40-1 and rad50-1 with respect to UV irradiation. cdc40-1 mutants are defective in UV-induced mutagenesis at the restrictive temperature. UV-induced levels of recombination are normal at both temperatures, while MMS-induced recombination is enhanced at the restrictive temperature.