FIG 3.

PhoP regulates expression of redox-inducible genes associated with the SigH regulon. (A) RNA-seq-derived heat-map of upregulated (≥2.0-fold; P < 0.05) genes in the WT H37Rv and phoP::Kan^r mutant strains incubated in the presence of 5 mM diamide relative to their expression levels under normal conditions of growth. (Only the top 15 genes are shown.) The data show a list of significantly induced genes, most of which belong to the SigH regulon. Notably, thioredoxin (trx) genes representing one of the major mycobacterial antioxidant systems are found to be part of the redox-active PhoP regulon. (B and C) Expression of redox-active thioredoxin genes in the WT, phoP::Kan^r, and complemented phoP::Kan^r strains, grown (B) in the presence of 5 mM diamide or (C) under acidic pH conditions, were investigated by RT-qPCR measurements, and fold differences in expression levels with standard deviations from replicate experiments were determined from at least three independent RNA preparations (*, P < 0.05; **, P < 0.01).