Fig. 6: GrpP/GrpQ is activated in response to D-serine in the urine to promote UPEC invasion.

A, B Bacterial titers in 5637 cells infected with WT or ΔgrpP/grpQ at 2 h p.i., in the presence or absence of 1 (A) or 0.02 mM (B) D-serine (n = 3 independent experiments). C Fold changes in the mRNA levels of fimH in WT, or ΔgrpP/grpQ that infected 5637 cells at 2 h p.i., with 0.02, 1 mM or without D-serine (n = 3 independent experiments). D Total bacterial titers in WT- or ΔgrpP/grpQ-infected BALB/c mouse bladders pretreated with siRNA targeting PHGDH or control siRNA at 24 h p.i. (n = 10 mice). E Intracellular bacterial titers in WT- or ΔgrpP/grpQ-infected BALB mouse bladders pretreated with siRNA targeting PHGDH or control siRNA at 2 h p.i. (n = 10 mice). 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 (C) or two-tailed Student’s t-test (A and B) or two-tailed Mann–Whitney U test (D and E). Significance was indicated by a P value. n.s., No significant difference. A P = 0.000077 (0 mM), P = 0.00000009 (1 mM); E P = 0.000011 (WT vs ΔgrpP/grpQ) P = 0.000076 (Control siRNA WT vs PHGDH siRNA WT). Source data are provided as a Source data file.