Fig. 2
From: Pseudomonas aeruginosa’s greenish-blue pigment pyocyanin: its production and biological activities
The QS systems in P. aeruginosa and their role in pyocyanin production. Pyocyanin is synthesized via multiple gene products encoded by the phenazine synthesis operon, which is regulated by four QS systems in P. aeruginosa. The PqsR and RhlR directly control pyocyanin production by activating the phenazine synthesis operon, while the LasR and IqsR indirectly affect pyocyanin production via their activation effects on the PqsR and RhlR (the black arrows)