FIG. 3.

Confirmation of the PDS microarray data. (A) qPCR-based interrogation of the PDS expression levels of certain genes with perturbed expression in wild-type M. tuberculosis relative to the level for the Δ-σ^H mutant at different time points. Results are shown for trxB2, hsp, ctpG, bpoB, Rv2745c, clpP1, and mce1A. Values represent mean differences (n-fold) ± standard deviations of results from quadruplicate experiments. Statistically significant changes in expression are denoted by * (P < 0.05), ** (P < 0.01), or *** (P < 0.005). (B) Western blot of M. tuberculosis wild-type and Δ-σ^H mutant lysates obtained from cultures treated pre-diamide stress and PDS shows a σ^H-dependent expression of Rv2745c. Lysates were probed with an affinity-purified polyclonal antibody raised against an epitope on the protein encoded by the M. tuberculosis Rv2745c gene. Lane A, prestained protein ladder (Invitrogen); lane B, lysate from log-phase pre-diamide stress M. tuberculosis culture; lane C, lysate from log-phase pre-diamide stress Δ-σ^H culture; lanes D, F, H, and J, lysates from 0-, 30-, 60-, and 90-min-PDS M. tuberculosis cultures; lanes E, G, I, and K, lysates from 0-, 30-, 60-, and 90-min-PDS Δ-σ^H cultures.