FIG 3.

Induction of the two-component system operon by bacitracin. The promoter region of the two-component system operon EF0926-0927 was fused to lacZ and introduced into wild-type E. faecalis JH2-2 (WT) and mutant backgrounds. The resulting strains were assayed for β-galactosidase activity, expressed in Miller units (MU), after 1 h exposure of exponentially growing cultures to 0 μg ml⁻¹ (white bars) or 4 μg ml⁻¹ (gray bars) bacitracin. The genes deleted in each strain are indicated by locus tags below the bars. Results are means plus standard deviations for three biological replicates. The significance of induction and strain differences was calculated across the entire data set by two-way analysis of variance (ANOVA). Significant effects of bacitracin compared to uninduced cells are indicated by three asterisks (P < 0.001); the different mutant backgrounds caused significant differences between strains (P = 0.018; not depicted in the graph).