IUBMB Enzyme Nomenclature


Accepted name: MMP 1-O-methyltransferase

Reaction: S-adenosyl-L-methionine + 3,3'-di-O-methyl-4α-mannobiose = S-adenosyl-L-homocysteine + 1,3,3'-tri-O-methyl-4α-mannobiose

Glossary: 3,3'-di-O-methyl-4α-mannobiose = 3-O-methyl-α-D-mannopyranosyl-(1→4)-3-O-methyl-α-D-mannopyranose

Other name(s): MeT1; 3-O-methylmannose polysaccharide 1-O-methyltransferase

Systematic name: S-adenosyl-L-methionine:3,3'-di-O-methyl-4α-mannobiose 1-O-methyltransferase

Comments: Requires Mg2+. The enzyme, characterized from the bacterium Mycolicibacterium hassiacum, participates in the biosynthesis of 3-O-methylmannose polysaccharides (MMP), which are intracellular polymethylated polysaccharides implicated in the modulation of fatty acid metabolism in nontuberculous mycobacteria. The methylation catalysed by this enzyme was shown to block the reducing end of 3,3'-di-O-methyl-α-mannobiose, a probable early precursor of the 3-O-methylmannose polysaccharides.

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


1. Ripoll-Rozada, J., Costa, M., Manso, J.A., Maranha, A., Miranda, V., Sequeira, A., Ventura, M.R., Macedo-Ribeiro, S., Pereira, P.JB. and Empadinhas, N. Biosynthesis of mycobacterial methylmannose polysaccharides requires a unique 1-O-methyltransferase specific for 3-O-methylated mannosides. Proc. Natl. Acad. Sci. USA 116 (2019) 835-844. [PMID: 30606802]

[EC created 2020]

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