Figure 2. Mutational effects of nucS deletion.

(a) Rates of spontaneous mutations conferring rifampicin, Rif-R (red), and streptomycin resistance, Str-R (grey) of M. smegmatis mc² 155 (WT), its ΔnucS derivative and the ΔnucS strain complemented with nucS from M. smegmatis mc² 155 (nucS_Sm). (b) Mutational spectrum of M. smegmatis mc² 155 (green) and its ΔnucS derivative (red). Bars represent the frequency of the types of change found in rpoB. (c) Rates of spontaneous mutations conferring Rif-R (red) and Str-R (grey) of S. coelicolor A3(2) M145 (WT), its ΔnucS derivative and the ΔnucS strain complemented with the wild-type nucS from S. coelicolor (nucS_Sco). Error bars represent 95% confidence intervals (n=20). Asterisks denote statistical significance (Likelihood ratio test under Luria-Delbruck model, Bonferroni corrected, P value <10⁻⁴ in all cases). Mutation rate: mutations per cell per generation.