A. Cells with the rad54-AA mutation are as sensitive to DNA damaging agents as the null mutant. Shown are 10-fold dilutions of cells spotted onto plates treated with methylmethane sulfonate (MMS), hydroxyurea (HU) or ultraviolet (UV) light, at the indicated doses. The spot assay was performed as described in the methods. B.
The
rad54
PIP-box mutant is defective in mitotic recombination and genome stability functions. Results from wild type, rad54Δ and rad54-AA mutant strains in recombination assays are shown, and the fold change from the wild type is shown in parentheses. Gene conversion and deletion (single-strand annealing) event rates were determined by fluctuation tests with the leu2-EcoRI::URA3-leu2-BstEII reporter as described in the methods. The mean of the rates from three independent experiments are shown with standard deviations. Spontaneous mutagenesis rates in the rad54-AA mutant were determined two or three times by fluctuation tests, as described. Significance was determined using a t-test (p<0.05). For spore viability, diploids homozygous for RAD54, rad54Δ, or rad54-AA were sporulated and dissected, and the surviving spores quantified. At least 100 spores were analyzed for each strain.