FIG 4.

Regulation of CdrAB-dependent biofilm growth by LapG in P. aeruginosa. (A) Assessment of biofilm formation in response to CdrAB and LapG expression in static cultures of the P. aeruginosa PAO1 ΔcdrA strain (9) as measured by crystal violet staining (see Materials and Methods). Top, Western blot of CdrA released into the supernatant of these cultures using an anti-CdrA antibody developed previously (9). (B) Biofilm formation in P. aeruginosa expressing CdrAB and LapG (+Ara), including a plasmid in which the TAAG cleavage site of CdrA has been mutated to TRRG. Above the plots are Western blots of CdrA from whole-cell and supernatant fractions of these cultures, demonstrating that the TRRG mutation prevents LapG-dependent release of CdrA into the supernatant fraction. Asterisks indicate P values of <0.01 (*), <0.001 (**), <0.0001 (***), and <0.00001 (****) between the indicated samples.