Figure 4. Effect of Lrp-binding motif mutations in P_fimA on type 1 fimbriae production and β-galactosidase synthesis directed by P_fimA promoter fusions in the indicated Salmonella strains.

Salmonella strains each harboring one of the P_fimA mutations were statically grown in LB broth at 37°C for one day (24 h) or 3 days. Mannose-sensitive yeast agglutination assay and western blot analysis were performed to monitor fim expression in the single mutants (A). Agglutination was scored as follows: -, none; ++, good; +++, strong; and ++++, very strong. Immunoblots using anti-FimA serum in each panel determine the level of FimA synthesized in each mutant. (B) β-galactosidase assay for a each lacZ fusion strain is shown. *, P<0.05; N.S., not significant.