Figure 5. Synthesized compounds inhibit ToxT-DNA binding interactions.

(a) ToxT EMSA in the presence of virstatin and the compounds. All lanes contain a DIG labeled, 84-bp segment of the tcpA promoter. All lanes except lane 1 contain 0.78 μM ToxT. The solvent (DMSO) does not inhibit DNA binding (lane 3). A 100 molar excess of the unlabeled “cold” DNA segment competes for binding (lane 4). The presence of 100 μM virstatin (vir) or 100 μM compounds inhibits DNA binding (lanes 5–15). (b) ToxT does not shift the negative control CJ2.6 DNA³⁵, a mutated segment of the tcpA promoter which ToxT cannot bind. (c) ToxT EMSA in the presence of virstatin and four lead compounds. All lanes contain labeled DNA. Virstatin is tested at 100, 10, 1, and 0.1 μM concentrations. Compounds 4a, 5a, 3b and 4b are each tested at 10, 1, and 0.1 μM. The EMSAs shown are representative of three or more independent experiments.