IUBMB Enzyme Nomenclature


Accepted name: 2-heptyl-1-hydroxyquinolin-4(1H)-one methyltransferase

Reaction: S-adenosyl-L-methionine + 2-heptyl-1-hydroxyquinolin-4(1H)-one = S-adenosyl-L-homocysteine + 2-heptyl-1-methoxyquinolin-4(1H)-one

Other name(s): htm (gene name)

Systematic name: S-adenosyl-L-methionine:2-heptyl-1-hydroxyquinolin-4(1H)-one methyltransferase

Comments: The enzyme, found in mycobacteria, is a member of a family of heterocyclic toxin methyltransferases. It is involved in defense against several antimicrobial natural compounds and drugs. 4-Hydroxyquinolin-2(1H)-one, 2-heptylquinolin-4(1H)-one, 2-heptyl-3-hydroxyquinolin-4(1H)-one (the "Pseudomonas quinolone signal", PQS) and the flavonol quercetin are also O-methylated, albeit with lower activity [2]. The enzyme also N-methylates the bactericidal compound 3-methyl-1-oxo-2-[3-oxo-3-(pyrrolidin-1-yl)propyl]-1,5-dihydrobenzo[4,5]imidazo[1,2-a]pyridine-4-carbonitrile [1].

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


1. Warrier, T., Kapilashrami, K., Argyrou, A., Ioerger, T.R., Little, D., Murphy, K.C., Nandakumar, M., Park, S., Gold, B., Mi, J., Zhang, T., Meiler, E., Rees, M., Somersan-Karakaya, S., Porras-De Francisco, E., Martinez-Hoyos, M., Burns-Huang, K., Roberts, J., Ling, Y., Rhee, K.Y., Mendoza-Losana, A., Luo, M. and Nathan, C.F. N-methylation of a bactericidal compound as a resistance mechanism in Mycobacterium tuberculosis. Proc. Natl. Acad. Sci. USA 113 (2016) E4523-E4530. [PMID: 27432954]

2. Sartor, P., Bock, J., Hennecke, U., Thierbach, S. and Fetzner, S. Modification of the Pseudomonas aeruginosa toxin 2-heptyl-1-hydroxyquinolin-4(1H)-one and other secondary metabolites by methyltransferases from mycobacteria. FEBS J. (2020) . [PMID: 33064871]

[EC created 2020]

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