FIG 1.

Schematic of operon structures and promoter regions in the resistance circuit. (A) Operons for the ABC transporters. In each, the first gene encodes the ATPase and the second gene the permease; the bent arrow indicates the promoter. The nucleotide sequences of the promoter regions are given below the respective schematics. The proposed response regulator binding site is highlighted in gray, the −10 and −35 elements are boxed, the transcriptional start site (+1) determined by 5′ RACE is shown as an underlined capital letter, and the translational start is shown in italicized capitals. Vertical lines show the beginning of fragments used to construct transcriptional reporter fusions, and the numbers of the derived constructs are given. (B) Operon for the two-component system. The first gene encodes the response regulator, and the second gene encodes the sensor kinase; the promoter region is indicated by a bent arrow. No putative regulator binding site was identified in the promoter, and therefore no sequence is shown.