Fig. 6.
PhoA activity levels in the V. cholerae ΔphoBR mutant complemented with low-copy-number plasmids containing the phoBR operon under the control of different versions of its regulatory region. PhoA activity was measured in cells grown under high (HP) and low (LP) Pi conditions. ΔphoBR cells and ΔphoBR cells transformed with the empty vector were used as negative controls, and the wild-type strain was used as a positive control. Ø, no plasmid; vector, empty plasmid; 1,2,3, boxes 1, 2, and 3 fused to phoBR; 1,2 M,3, box 1, mutated box 2, and box 3 fused to phoBR; 1,2 M, box 1 and mutated box 2 fused to phoBR; 1,2, boxes 1 and 2 fused to phoBR; 1, box 1 fused to phoBR.