Fig. 2.
An overview of QS hierarchy model in P. aeruginosa. P. aeruginosa has three quorum-sensing systems, Las, Rhl and PQS. In the Las system, a receptor, LasR, is activated by its cognate AHL, 3-oxo-C12-HSL, synthesized by LasI, and the complex activates Las, PQS and Rhl systems. PQS binds its receptor, PqsR, and the complex regulates PQS and Rhl systems. The Rhl system consists of RhlR and its cognate signal, C4-HSL, synthesized by RhlI and the complex autoregulates the Rhl system. These quorum-sensing systems control the production of a range of virulence factors and various behaviors.