Fig. 2: The regulation of ammonia production and C. elegans chemoattraction in PA14. | Nature Communications

Fig. 2: The regulation of ammonia production and C. elegans chemoattraction in PA14.

From: Pseudomonas aeruginosa modulates both Caenorhabditis elegans attraction and pathogenesis by regulating nitrogen assimilation

Fig. 2

a Model of PA14 nitrogen assimilation mechanism. When preferred nitrogen sources are limited, the two-component NtrCB system is activated, thus promoting expression at the start of P11. NasS binds to inorganic nitrates, and NasT inhibition is relieved. NasT binds to P11, allowing for anti-termination at the leader sequence and expression of the nitrogen assimilation operon. b Choice assays between WT PA14 ΔP11 and PA14 mutants in nitrite reductase (nirBTn) and nitrate reductase (nasCTn). c Relative expression of P11 and nirB in PA14 nasSTn/nasTTn to WT PA14. Normalized to 5S expression. The dotted line represents the limit of detection. P = < 0.001. d Choice assays between WT PA14ΔP11 and PA14 mutants in the partner-switching genes (nasSTn and nasTTn). CI = (# on WT PA14 or ∆P11 PA14 gene mutants)/(Total). e Choice assays between WT PA14 and nirBTn with Wild type, che-2(e1033), che-1(p627), and odr-7(ky4) worm mutants (left) or odr-1(n1936), ceh-36(ky646), and ceh-37(ok642) (right). CI = (# on WT PA14–PA14 nirBTn)/(Total). f Addition of ammonia (ammonium acetate and ammonium hydroxide) to choice assay between WT PA14 and nirBTn. CI = (# on WT PA14–PA14 nirBTn)/(Total). g WT PA14 and gene mutants ammonia production measured using an ammonia colorimetric assay. Colorimetric fluorescence intensity (ex = 360 nm/em = 450 nm) normalized to CFU and multiplied by 105. p values using WT as control: nirBTn = 0.0032, nasCTn = 0.0007, nasTTn = 0.0013. Box Plots: center line = median, box range 25th–75th percentile, minimum/maximum denoted by whiskers, individual choice assay plates are represented by dots and are technical replicates (10 plates/technical replicates for (b, d, e (left), f) and 20 plates/technical replicates for (e, right). Bar graph error bars denote SD, center denotes mean, and each dot represents a biological replicate (3 total). One-Way ANOVA, (b, d–f) Tukey’s multiple comparison test, c, g Dunett’s multiple comparison test using WT as control. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001, ns = not significant (Prism 9). For exact sample size (n), all biological replicates, and p values see source data file.

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