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. 2022 Aug 1;18(8):e1010331. doi: 10.1371/journal.pgen.1010331

Fig 5. STPK phosphorylation of PrrA is important for Mtb response to pH and Cl-.

Fig 5

(A) Blocking STPK phosphorylation of PrrA significantly alters Mtb transcriptional profile in standard 7H9, pH 7.0 growth conditions. PrrA-DUC/ΔprrA and PrrA-T6A-DUC/ΔprrA Mtb were grown in 7H9, pH 7.0 media for four hours before RNA was extracted for RNA sequencing analysis. Log2-fold change compares gene expression in the PrrA-T6A-DUC/ΔprrA (“PrrA-T6A”) versus PrrA-DUC/ΔprrA strain (p<0.05, FDR<0.01). (B and C) A STPK-phosphoablative PrrA variant alters Mtb response to acidic pH and high [Cl-]. PrrA-DUC/ΔprrA and PrrA-T6A-DUC/ΔprrA strains were grown in 7H9, pH 7.0 or 7H9, pH 5.7 + 250 mM NaCl for four hours, and RNA extracted for RNA sequencing analysis (B) or qRT-PCR (C). In (B), log2-fold change compares gene expression in the 7H9, pH 5.7 + 250 mM NaCl condition versus the 7H9, pH 7 control condition for each of the PrrA-DUC/ΔprrA or PrrA-T6A-DUC/ΔprrA strains. Genes marked in purple had a log2-fold change difference ≥0.25 between the PrrA-T6A-DUC/ΔprrA and PrrA-DUC/ΔprrA strains (p<0.05, FDR<0.01 in both sets, with log2-fold change ≥1 in the PrrA-DUC/ΔprrA set). In (C), fold change compares the 7H9, pH 5.7 + 250 mM NaCl condition to the control 7H9, pH 7.0 condition for each strain. sigA was used as the control gene, and data are shown as means ± SD from 3 technical replicates. p-values were obtained with an unpaired t-test. N.S. not significant, * p<0.05, *** p<0.001, **** p<0.0001.