FIG. 1.

Cells deficient in Yng2 are highly sensitive to replication associated DNA damage. The wild type (YNG2), yng2 mutants, and several well-characterized DNA damage mutants were treated with DNA-damaging agents. While MMS and HU predominantly induce S-phase lesions, both UV and gamma irradiation can generate DNA breaks in all phases of the cell cycle. Strikingly, yng2 mutants are most sensitive to S-phase lesions. Mutants defective in several DNA damage repair pathways were used for comparison: rad50 mutants are defective for DSB repair; yku70 mutants are deficient in nonhomologous end-joining; pol2-11 mutants are defective in the intra-S-phase checkpoint response; rad14 mutants have defects in excision repair of UV-induced damage. Cells were serially diluted 10-fold and spotted onto plates. Photographs were taken after 4 to 5 days of growth at 25°C.