FIGURE 13.

Putative model of ToxP/AntitoxP TA system. The toxP/antitoxP operon has a nonconical “reverse” TA gene organization. The first gene encodes the putative mRNA interferase and corepressor toxin ToxP (red) and the second gene encodes the AntitoxP antitoxin. The location of the toxP promoter (PtoxP) is depicted upstream of toxP. Consistent with the HigB2 toxin from V. cholerae, the ToxP toxin is predicted to interact with the ribosome A site, where it would cleave mRNA and prevent the translation from the corresponding mRNA. The AntitoxP antitoxin binds ToxP, thereby preventing translation inhibition, and this complex can then bind to the PtoxP promoter resulting in repression of transcription from PtoxP. AntitoxP also binds PtoxP in the absence of ToxP. Gray arrows represent interactions between components of the model. Black arrows represent the production of protein from toxP and antitoxP