Fig. 5: GrpP/GrpQ is activated in response to D-serine.

A Fold changes in the mRNA levels of grpP and grpQ in CFT073-infected BALB/c mouse bladders compared to that in CFT073 inoculum at 2 h p.i. (n = 5 mice). The mouse experiments were repeated thrice. B Fold changes in the mRNA levels of grpP and grpQ in CFT073 cultured in M9 medium with the indicated concentrations of D-serine compared to that without D-serine for 2 h (n = 3 independent experiments). C Phos-tag™ SDS-PAGE analysis of phosphorylation status of GrpQ in CFT073 cultured in M9 medium containing 0, 0.02, 0.1, 0.5, and 1 mM D-serine. Representative image from three independent experiments (upper). The bar graph shows the relative GrpQ-P/GrpQ. GrpQ-P phosphorylated GrpQ, GrpQ non-phosphorylated GrpQ (bottom). D qRT-PCR analysis of the mRNA levels of grpP, grpQ, fimA, or fimH in WT in the presence or absence of 1 mM D-serine (n = 3 independent experiments). E qRT-PCR analysis of the mRNA levels of fimA or fimH in WT, ΔgrpP/grpQ, or ΔgrpP/grpQ+ in the presence of 1 mM D-serine (n = 3 independent experiments). F Regulation of type 1 fimbria expression by GrpP/GrpQ in the presence or absence of 1 mM D-serine in vitro. GFP activation visualized in WT and ΔgrpP/grpQ carried a fimS-GFP fusion reporter plasmid. Images are representative of three independent experiments. DIC, differential interference contrast. Scale bars, 5 μm. Data were obtained from three independent experiments and presented as mean ± SD (A, B, C, D, and E). P values were determined using a two-way analysis of variance (A, B, D, and E) or two-tailed Student’s t-test (C). Significance was indicated by a P value. n.s., No significant difference. A P = 0.000091; B P = 0.000003 (0 mM vs 0.1 mM); C P = 0.00000088 (0 mM vs 0.02 mM), P = 0.000077 (0 mM vs 0.1 mM); D P = 0.000093 (grpP), P = 0.000049 (fimH); E P = 0.000001 (fimA), P = 0.0000006 (fimH). Source data are provided as a Source data file.