FIG 7.

VpsR uses at least three different mechanisms to activate transcription. With σ⁷⁰-RNAP, VpsR and c-di-GMP (cdG) together activate P_rbmA and P_rbmF using a class I mechanism and activate P_vpsL and P_vpsU using a class II mechanism. In vivo ChIP-seq analyses suggest a third mechanism: VpsR is an antirepressor of H-NS at P_vpsT (38). Promoters, which we tested but did not activate transcription in vitro under our conditions, are labeled with an asterisk. Though direct VpsR binding has been demonstrated for P_vpsT, P_tfoY, P_epsC, and P_aphA in EMSAs and or DNase I footprinting (30, 32, 36, 40, 41), transcription mechanisms for these four promoters have not been recapitulated and determined in vitro.