Reaction: GDP-α-D-mannose + [3-O-methyl-α-D-mannosyl-(1→4)]n-3-O-methyl-α-D-mannose = α-D-mannosyl-(1→4)-[3-O-methyl-α-D-mannosyl-(1→4)]n-3-O-methyl-α-D-mannose + GDP
Glossary: MMP = α-D-mannosyl-(1→4)-[3-O-methyl-α-D-mannosyl-(1→4)]n-1-O,3-O-dimethyl-α-D-mannose
Other name(s): manT (gene name)
Systematic name: GDP-α-D-mannose:[3-O-methyl-α-D-mannosyl-(1→4)]n-3-O-methyl-α-D-mannose [(1→4)-α-D-mannosyl]transferase
Comments: The enzyme, present in mycobacterial species that produce a 3-O-methylmannose polysaccharide (MMP), is involved in recycling and biosynthesis of the polymer. The enzyme has the highest activity with 3-O-methylated mannosides with 4-6 residues. The residue at the reducing end of the substrate is often dimethylated, with the second methyl group attached at the O-1 position.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Maranha, A., Costa, M., Ripoll-Rozada, J., Manso, J.A., Miranda, V., Mendes, V.M., Manadas, B., Macedo-Ribeiro, S., Ventura, M.R., Pereira, P.JB. and Empadinhas, N. Self-recycling and partially conservative replication of mycobacterial methylmannose polysaccharides. Commun Biol 6 (2023) 108. [PMID: 36707645]