Fig 3.

Sensitivity of the uvrD1 and uvrA uvrD1 mutant strains to DNA damage. Survival of the uvrD1 and uvrA uvrD1 strains following DNA damage caused by UV irradiation (A) or mitomycin C (B) was compared with that of the wild type, the uvrD1 complement, and a uvrA mutant. Survival following exposure to the indicated agent was assessed as described in Materials and Methods. In each case the surviving fraction was calculated by comparison with an untreated control. The data shown are the means of duplicate (UV) or triplicate (mitomycin C) assays from three biological replicates; the error bars represent standard deviations. One hundred percent survival in each case corresponds to approximately 10⁷ CFU. The data in panel A for the uvrA and uvrA uvrD1 strains at all UV doses were significantly different from the wild type (P < 0.001; ANOVA). Survival of each mutant strain in panel B was significantly different from the wild type (*, P < 0.05; **, P < 0.01; ANOVA).