FIG. 2.

Inactivation of the lrp gene reverses the response of the fim switch to DNA relaxation. (A) Treatment with increasing concentrations of novobiocin results in a strong on-to-off bias in an lrp::Tn10 knockout mutant, the opposite of the pattern seen in the wild type. (B) Complementation of the lrp knockout mutation with a functional copy of the lrp gene restores the wild-type pattern of response to novobiocin treatment. Densitometric data from PCR switch assay gels (insets) were used to plot the graphs. Numbers above each gel lane are μg/ml of novobiocin. Bands corresponding to phase-on or -off are labeled.