IUBMB Enzyme Nomenclature


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-aminobenzoylacetate = 1-(2-aminophenyl)decane-1,3-dione + CO2 + L-cysteinyl-[PqsC protein]
(1c) 1-(2-aminophenyl)decane-1,3-dione = 2-heptyl-4(1H)-quinolone + H2O

Glossary: 2-heptyl-4-hydroxyquinoline = 2-heptyl-4(1H)-quinolone

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.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:


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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