Accepted name: 2-heptyl-4(1H)-quinolone synthase
Reaction: octanoyl-CoA + (2-aminobenzoyl)acetate = 2-heptyl-4-quinolone + CoA + CO2 + H2O (overall reaction)
(1a) octanoyl-CoA + L-cysteinyl-[PqsC protein] = S-octanoyl-L-cysteinyl-[PqsC protein] + CoA
(1b) S-octanoyl-L-cysteinyl-[PqsC protein] + (2-aminobenzoyl)acetate = 1-(2-aminophenyl)decane-1,3-dione + CO2 + L-cysteinyl-[PqsC protein]
(1c) 1-(2-aminophenyl)decane-1,3-dione = 2-heptyl-4-quinolone + H2O
Glossary: 2-heptyl-4-quinolone = 2-heptylquinolin-4(1H)-one
Other name(s): pqsBC (gene names); malonyl-CoA:anthraniloyl-CoA C-acetyltransferase (decarboxylating)
Systematic name: octanoyl-CoA:(2-aminobenzoyl)acetate octanoyltransferase
Comments: The enzyme, characterized from the bacterium Pseudomonas aeruginosa, is a heterodimeric complex. The PqsC subunit acquires an octanoyl group from octanoyl-CoA and attaches it to an internal cysteine residue. Together with the PqsB subunit, the proteins catalyse the coupling of the octanoyl group with (2-aminobenzoyl)acetate, leading to decarboxylation and dehydration events that result in closure of the quinoline ring.
1.  Dulcey, C.E., Dekimpe, V., Fauvelle, D.A., Milot, S., Groleau, M.C., Doucet, N., Rahme, L.G., Lepine, F. and Deziel, E. The end of an old hypothesis: the pseudomonas signaling molecules 4-hydroxy-2-alkylquinolines derive from fatty acids, not 3-ketofatty acids. Chem. Biol. 20 (2013) 1481–1491. [PMID: 24239007]
2.  Drees, S.L., Li, C., Prasetya, F., Saleem, M., Dreveny, I., Williams, P., Hennecke, U., Emsley, J. and Fetzner, S. PqsBC, a condensing enzyme in the biosynthesis of the Pseudomonas aeruginosa quinolone signal: crystal structure, inhibition, and reaction mechanism. J. Biol. Chem. 291 (2016) 6610–6624. [PMID: 26811339]
[EC created 2013, modified 2017]

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