Scheme 2.
Simplified schematic of the QS signaling circuit in P. aeruginosa. The LuxI-type synthases, LasI and RhlI, generate the AHL ligands OdDHL and C4-HL, respectively. LasR is the dominant system, and together with the RhlR system controls a host of QS controlled genes. QscR negatively regulates lasI in addition to controlling its own regulon.[40, 41] The Las system also regulates production of the Pseudomonas quinolone signal (PQS), which is involved in siderophore production and other processes.[42]