Required for the biosynthesis of the quorum-sensing signaling molecules 2-heptyl-4(1H)-quinolone (HHQ) and 2-heptyl-3-hydroxy-4(1H)-quinolone (Pseudomonas quinolone signal or PQS), which are important for biofilm formation and virulence. The PqsC/PqsB complex catalyzes the condensation of 2-aminobenzoylacetate (2-ABA) and octanoyl-CoA to form HHQ. PqsB, together with PqsC, catalyzes the coupling of 2-ABA with the octanoate group, leading to decarboxylation and dehydration, and resulting in closure of the quinoline ring. PqsB is probably required for the proper folding of PqsC rather than for a direct enzymatic role in the process. Activity of the complex is inhibited by 2-aminoacetophenone (2-AA). Forms a tight complex with PqsC. Belongs to the thiolase-like superfamily. FabH family.