Figure 3.
Activation of PA-PD by GvpE (a) and repression by GvpD (b). Schematic representation of the region between gvpA and gvpD and the two oppositely-oriented promoters PA and PD. TATA-box and BRE are shown in grey, and the two UAS elements are partly overlapping in the center in light grey. The reading frames gvpD and gvpA are represented by dark arrows. (a) Activation of transcription by GvpE should involve binding of GvpE, presumably as a dimer, at the respective UAS element and recruitment of TFB, TBP and of the RNA polymerase. (b) In the presence of GvpD, the interaction of GvpE-GvpD leads to a strong reduction in the amount of GvpE and the repression of gas vesicle formation.