FIG. 8.
The Chp system regulates pilA transcription by mediating intracellular levels of PilA. (A) The indicated strains harboring the PpilA-lacZ fusion and PAO1 harboring a promoterless lacZ gene (CTX-lacZ) integrated into the chromosome at the attB site were cultured in liquid (A and B) or on solid (A) medium for 16 h. The β-galactosidase activity of samples was measured, and the specific activities relative to the OD600 were calculated. Shown are the means ± the SD (n = 3). *, P < 0.05. (C) Surface structures (SS) and intracellular (WC) preparations of the indicated strains cultured in liquid (broth) or on solid (plate) medium were immunoblotted with a polyclonal antibody to PilA (α-pilA) or to FliC (α-FliC), as described in Fig. 2. The higher-molecular-weight band above pilin in the whole-cell lysates represents a cross-reactive band present in all samples.