FIG 6 .

Model of the virulence cascade in V. cholerae and targets of the toxtazins. The virulence cascade in V. cholerae is tightly regulated. AphA and AphB activate transcription of tcpPH. TcpPH form an inner membrane complex with ToxR and ToxS to activate transcription of toxT. ToxT activates the transcription of tcpA-F, which encode the toxin coregulated pilus, and ctxAB, which encode the cholera toxin subunits. Based on our experiments, we propose that toxtazin A inhibits toxT transcription, while toxtazin inhibits tcpPH transcription.