Figure 3.

UV and bleomycin survival are impaired in chk1-S345A cells. (a) chk1-S345A cells are UV sensitive. Wild type (chk1⁺), chk1Δ, and mutants of all of the SQ/TQ motifs were tested in a UV survival assay. With the exception of chk1-S345A cells, all SQ/TQ motif mutants displayed UV resistance equivalent to that of wild type. The chk1-S345A and chk1Δ cells were equally sensitive to UV. (b) A similar damage survival assay was performed with bleomycin. Cells were exposed to the indicated doses of bleomycin for 1 h. The chk1-S345A and chk1Δ cells were sensitive to bleomycin, whereas all other strains were indistinguishable from wild type.