FIG. 4.

PQS synthesis and regulation. The genomic organization of the pqs genes and a model for PQS biosynthesis and regulation are shown. We propose that PQS is synthesized from chorismate via anthranilate by the phnAB, pqsABCD, and pqsH gene products as indicated. Points of regulation by PqsR, LasI/R, np20, and PqsE based on the results presented in this and a previous report (5) are shown. The PqsR (MvfR) regulation of pqsABCDE is suggested by the finding that a plasmid carrying pqsABCDE complements a phnA mutant but not a pqsR mutant for PQS production (Fig. 3C).