FIG. 3.

A model for three-way signal convergence in Vibrio harveyi. The three recognized signals are indicated prior to association with their cognate transmembrane receptors. In the absence of signal, receptors initiate the LuxU-LuxO phosphorelay, resulting in elevated levels of the Qrr regulatory RNAs, which block LuxR translation, thus preventing activation of lux genes and other target functions. Signal perception reverses phosphate flow, limiting qrr expression and allowing LuxR activation of target genes (see model in reference 32 for details).