Pseudomonas quinolone signal

The QS system of Pseudomonas aeruginosa has been studied extensively because of its importance as a human pathogen. P. aeruginosa has a unique system of QS that consists of las, rhl, and Pseudomonas quinolone signal (PQS) circuits (Fig. 2a). The first two circuits, las and rhl, have a set of proteins (synthase and receptor) and AI-1 like the typical luxIR circuit. The las circuit is composed of LasI and LasR along with 3-oxo-Ci2-HSL (Fig. 2b) as its cognate AI, whereas in the rhl... 

McGrath S, Wade DS, Pesci EC. Dueling quorum sensing systems in Pseudomonas aeruginosa control the production of the Pseudomonas quinolone signal (PQS). ELMS Microbiol. Lett. 2004 230 27-34. 

McKnight SL, Iglewski BH, Pesci EC. The Pseudomonas quinolone signal regulates rhl quorum sensing in Pseudomonas aeruginosa. J. Bacteriol. 2000 182 2702-2708. 

Calfee MW, Coleman JP, Pesci EC (2001) Interference with Pseudomonas quinolone signal synthesis inhibits virulence factor expression by Pseudomonas aeruginosa. Proc Natl Acad Sci USA 98 11633-11637... 

Gallagher LA, McKnight SL, Kuznetsova MS, Pesci EC, Manoil C (2002) Functions required for extracellular quinolone signaling by Pseudomonas aeruginosa. J Bacteriol 184 6472-6480... 

Besides AHLs (Table 1), the opportunistic human pathogen Pseudomonas aeruginosa also produces another chemically distinct QS signal molecule, 2-n-heptyl-3-hydroxy-4(lH)-quinolone (PQS 5) [18]. PQS is an integral component of the QS hierarchy and plays an important role in regulating virulence gene expression [19]. 

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