Fig. 2.

ToxT–activated promoters. A schematic representation of the tcpA and ctxA promoter regions to which ToxT binds to activate transcription. (A). The tcpA promoter contains two “toxboxes” (underlined). The “A/T” triplets within the boxes are critical nucleotides for ToxT-dependent transcription. (B). The ctxA promoter represented in this figure is sufficient for ToxT-dependent transcriptional activation and therefore should contain two “toxboxes”. The boxes outline “A/T” triplets that are spaced identically to the triplets in the tcpA promoter, which suggests that ToxT is oriented in the opposite direction with respect to RNA polymerase in ctxA promoter as compared to the tcpA promoter