FIG 9.

Transcriptional regulatory activity of PprB is phosphorylation independent. (A) Analysis of the phosphorylation site in the REC domain of PprB. D15 and D16 are the two acidic residues within the loop that connects β1 and α1, which are involved in Mg²⁺ ion binding, and D60 is the phosphorylation site at the end of the third β-strand. (B) Expression values of flp, cupE, and rcpC transcriptional reporters in PAO1, PApprB1, or PApprB(D60A) strains. (C) SfGFP images of flp transcriptional reporter in E. coli (TOP10 strain) with or without pprB overexpression. (D) Expression levels of flp transcriptional reporter in E. coli (strain TOP10) with or without pprB overexpression. Statistical analysis was based on pairwise strain comparisons (t test). *, P < 0.05; **, P < 0.01; ns, not significant.