Reaction: (1) ATP + a (2E)-N-acyl-2-dehydrotryptophan = AMP + diphosphate + an alkyltryptazolone
(2) ATP + a (2E)-N-acyl-2-dehydrotyrosine = AMP + diphosphate + an alkyltyrazolone
(3) ATP + a (2E)-N-acyl-2-dehydrophenylalanine = AMP + diphosphate + an alkylphenazolone;
Glossary: an alkyltryptazolone = a (4E)-2-alkyl-4-(1H-indol-3-ylmethylidene)-1,3-oxazol-5-one
an alkyltyrazolone = a (4E)-4-[(4-hydroxyphenyl)methylidene]-2-alkyl-1,3-oxazol-5-one
an alkylphenazolone = a (4E)-4-(phenylmethylidene)-2-alkyl-1,3-oxazol-5-one
Other name(s): tyzB (gene name); oxzB (gene name); trzS (gene name)
Systematic name: (2E)-N-acyl-2-dehydroaromatic amino acid cyclase (oxazolone-forming)
Comments: The enzyme, found in Gram-negative and Gram-positive bacteria, has sequence similarity to EC 2.7.7.73, sulfur carrier protein ThiS adenylyltransferase. The enzyme uses ATP to activate the carboxylate moiety of its substrate, resulting in dehydration and formation of an oxazolone ring. The enzyme acts along EC 1.3.3.19, N-acyl-aromatic-amino-acid desaturase, and the order in which the two enzymes act has not been determined conclusively. In some organisms the two enzymes form a fusion protein.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. de Rond, T., Asay, J.E. and Moore, B.S. Co-occurrence of enzyme domains guides the discovery of an oxazolone synthetase. Nat. Chem. Biol. 17 (2021) 794-799. [PMID: 34099916]
2. Grigg, J.C., Copp, J.N., Krekhno, J.MC., Liu, J., Ibrahimova, A. and Eltis, L.D. Deciphering the biosynthesis of a novel lipid in Mycobacterium tuberculosis expands the known roles of the nitroreductase superfamily. J. Biol. Chem. 299 (2023) 104924. [PMID: 37328106]
3. Kleetz, J., Grigg, J.C., Hassan, A.A., Ibtisam, A., Copp, J.N., Lian, J., Liu, J. and Eltis, L.D. The biosynthesis of N-acylated tryptazolone in Mycobacterium tuberculosis and related bacteria. J. Biol. Chem. 302 (2026) 111079. [PMID: 41429352]