Fig 3.

Weakening the interaction between CarD and the RNAP compromises the survival of mycobacteria during oxidative stress. (A and B) Survival of M. smegmatis strains during oxidative stress. The log-phase M. smegmatis ΔcarD attB∷tet-carD strains expressing CarD^WT, CarD^R25E, or CarD^R47E in LB were treated for 1 h with either 10 mM or 25 mM H₂O₂. After treatment, dilutions were plated on LB. Panel A shows one such experiment, and B graphically represents survival as a ratio of CFU in treated cultures to that in untreated cultures. (C) Survival of the M. tuberculosis strains during oxidative stress. The log-phase M. tuberculosis ΔcarD attB∷tet-carD strains expressing CarD^WT or CarD^R47E growing in 7H9 broth were treated for 75 h with 25 mM H₂O₂. After treatment, dilutions were plated on 7H10 agar, and survival is graphically represented as the ratio of CFU in treated cultures to that in untreated cultures. The graphs in panels B and C show the mean± standard error of the mean (SEM), and each sample is represented by a black circle. The significance levels in panels B and C were determined by calculating P values by Student's t test; an asterisk indicates significance with a P value of <0.05, two asterisks indicate significance with a P value of <0.01, and three asterisks indicate significance with a P value of <0.005.