Fig 7. Model of ToxR mediated co-activation of the toxT promoter.

A) Prior to activation, the toxT promoter is silenced by H-NS [35]. B) ToxR-TcpP interaction between the N-terminal β-sheet of ToxR and the wing of TcpP recruits TcpP to the toxT promoter. C) Upon ToxR binding to the toxT promoter, ToxR and TcpP no longer interact. ToxR binding to the promoter results in relieving H-NS repression, possibly bending the DNA to make the TcpP binding site more accessible [34], and recruiting the toxT promoter to the membrane [37]. D) This results in enhanced TcpP binding to the toxT promoter and transcriptional activation via TcpP interaction with RNA polymerase.