FIGURE 5.

Deletion analysis of the P_cabA regulatory region. (A) PCR fragments carrying the P_cabA regulatory region with 5′-end deletions were subcloned into pBBR-lux to create each pSH reporter. The wild-type P_cabA regulatory region is shown on top with the proposed –10 and –35 regions, and the binding sites for BrpS (BRPSB; gray box) and BrpT (BRPTB; white box) were determined later in this study (Figures 6C,D). Solid lines, the upstream region of cabA; black blocks, the cabA coding region; white blocks, luxCDABE. (B–D) Cellular luminescence was determined from the parent strain (B, black bars), brpS mutant (C, gray bars), and brpT mutant (D, white bars) containing each pSH reporter as indicated. Cultures grown to an A₆₀₀ of 2.0 were used to measure the cellular luminescence. Error bars represent the SD from three independent experiments. ^∗∗, p < 0.005 relative to the strain containing pSH1704; ns, not significant. RLUs, relative light units. Parent, parent strain; ΔbrpS, brpS mutant; ΔbrpT, brpT mutant.