Figure 2.

Competition between VanR and PhoB. Expression of phoA (encoding bacterial alkaline phosphatase, Bap) and a P_vanH-lacZ fusion report on PhoB and VanR_a activation, respectively. VanS_a or PhoR were synthesized under P_rhaB control in cells expressing phoB, vanR_a, or both behind its native promoter. Bap and BG were assayed as in Table 1 in medium with rhamnose and 2 mM (Excess) or 0.1 mM (Limited) P_i. Arrows on the right are in proportion to Sp Act values (nmol product made per min per OD₄₂₀). With no rhamnose, Bap and BG Sp Act values of all strains were ca. 0.1 ± 0.1 and 1.0 ± 0.2, respectively. Strains are integrants of BW25053 (ΔphoBR) or BW25124 (ΔphoR): JCS289 (pJS126, pMP1), JCS297 (pMP3), JCS304 (pJS126, pMP3), JCS338 (pMP1), and JCS342 (pMP3).