IUBMB Enzyme Nomenclature


Accepted name: methylornithine synthase

Reaction: L-lysine = (3R)-3-methyl-D-ornithine

Glossary: (3R)-3-methyl-D-ornithine = (2R,3R)-2,5-diamino-3-methylpentanoate

Other name(s): PylB

Systematic name: L-lysine carboxy-aminomethylmutase

Comments: The enzyme is a member of the superfamily of S-adenosyl-L-methionine-dependent radical (radical AdoMet) enzymes. Binds a [4Fe-4S] cluster that is coordinated by 3 cysteines and an exchangeable S-adenosyl-L-methionine molecule. The reaction is part of the biosynthesis pathway of pyrrolysine, a naturally occurring amino acid found in some archaeal methyltransferases.

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


1. Gaston, M.A., Zhang, L., Green-Church, K.B. and Krzycki, J.A. The complete biosynthesis of the genetically encoded amino acid pyrrolysine from lysine. Nature 471 (2011) 647-650. [PMID: 21455182]

2. Quitterer, F., List, A., Eisenreich, W., Bacher, A. and Groll, M. Crystal structure of methylornithine synthase (PylB): insights into the pyrrolysine biosynthesis. Angew. Chem. Int. Ed. Engl. 51 (2012) 1339-1342. [PMID: 22095926]

[EC created 2012]

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