Fig. 8: Multiple hvKp strains regulate mucoidy through the ARG box in response to arginine and host conditions.

A Hypervirulent K. pneumoniae (hvKp) strains NTUH-K2044, Kp4289, Kp4585, and Kp6557 carrying either the P_rmp-GFP reporter plasmid or a mutated ARG box (P_rmp∆ARG-GFP) were cultured in M9+All and M9-Arg. GFP expression measured promoter activity. B NTUH-K2044, Kp4289, Kp4585, and Kp6557 were cultured in M9+All or M9-Arg. Mucoidy was assessed by sedimentation assay. C 20% pooled human heat-inactivated serum was supplemented into 10x M9 salts (M9 + HI Serum). Both M9 + HI Serum and human urine samples were centrifuged to remove debris and proteinase-treated prior to arginine quantification. D KPPR1 carrying either the P_rmp-GFP reporter plasmid or P_rmp∆ARG-GFP was cultured in either M9 + HI Serum or sterile-filtered pooled human urine. Promoter activity was measured by GFP expression. E KPPR1 and ∆argR was cultured in M9 + HI Serum or sterile-filtered pooled human urine and mucoidy was assessed via a sedimentation assay. Data presented are the mean, and error bars represent the standard error of the mean. Statistical significance was determined in panel (A) using a two-way ANOVA with Tukey’s post-test, while in panel (B) a two-tailed t-test was used. In panel (C) a two-tailed Mann-Whitney test was performed and in panels (D and E) a one-way ANOVA with Bonferroni’s post-test was applied. p-values are displayed above each comparison: *p < 0.05; **p < 0.01; ***p < 0.001; #p < 0.0001. Exact P-values: (A), left to right above data bars: <0.0001, <0.0001, 0029; connected by lines: <0.0001, 0.0010, <0.0001, 0.0003, <0.0001, 0.0067, <0.0001, <0.0001; (B), left to right: <0.0001, 0.0019, <0.0001, <0.0001; (C), left to right: <0.0001; (D), left to right; <0.0001, 0.0138; (E), left to right: <0.0001, <0.0001. Experiments were performed > 3 independent times, each in biological triplicate (n = 9). Source data are provided as a Source Data file.