FIG 1.

PilU levels affect surface-dependent cAMP production and T4P-related phenotypes. (A) Images of phage sensitivity plates (top panel) and images of twitch zones stained with crystal violet (bottom panel). “+” indicates a phage-susceptible strain, which forms a clear plaque at the center of the plate where the lysate is spotted, and “–” indicates a phage-resistant strain. Below is the quantification of the twitch zone diameter for each strain. Data are from four biological replicates. (B) Quantification of the PaQa reporter as a surrogate for cAMP levels as measured by flow cytometry after 5 h of growth on agar. Data are from six biological replicates. (C) Quantification of the PaQa reporter as measured by flow cytometry after 5 h of growth for the WT and ΔpilU mutant expressing the pilU gene from a multicopy plasmid or carrying the empty vector (EV) control. Growth was on M8 agar supplemented with 1 mM or no IPTG and the appropriate antibiotics. (D) Quantification of the normalized PilU protein levels of the cells in panel C. Values were normalized to a cross-reacting band. Data are from three biological replicates. Bars and error bars in all panels are the mean and standard deviation, and statistical significance was determined by one-way analysis of variance (ANOVA), followed by Tukey's post hoc test, **, P ≤ 0.001; ***, P ≤ 0.0001; ****, P ≤ 0.00001; ns, not significant.