FIG 1.

Activity of the RbdA protein. (A) Bacterial colony morphologies and biofilm phenotypes of P. aeruginosa PAO1 and the rbdA^{E585A,L586A,L587A} chromosomal mutant. (B) Visualization of biofilm formation on polystyrene tubes. (C) Quantitative comparison of biofilm formation levels. The data shown are means of triplicate values. Standard deviations are shown by error bars (*, P < 0.05; two-tailed t test). (D) Comparative growth curves of P. aeruginosa PAO1 and the rbdA^{E585A,L586A,L587A} chromosomal mutant (RbdA mutant). (E) Allosteric activation of PDE enzymatic activity of the cRbdA protein at 25°C in the presence of increasing concentrations of GMPPNP (ranging from 5 to 500 μM). (F) DGC enzymatic activity of RbdA. The PDE mutant bears the 585-ELL-587 → ALL single mutation, the PDE + I site double mutant has both 585-ELL-587 → ALL and 444-REGD-447 → AEGD mutations, and the A site mutant (453-GGDEF-457 → GGAAF) is the negative control. Reaction conditions are described in Materials and Methods.