Reaction: 2 GDP-α-D-mannose + α-D-mannosyl-(1→3)-N-acetyl-α-D-glucosaminyl-diphospho-ditrans,octacis-undecaprenol = 2 GDP + α-D-mannosyl-(1→3)-α-D-mannosyl-(1→3)-α-D-mannosyl-(1→3)-N-acetyl-α-D-glucosaminyl-diphospho-ditrans,octacis-undecaprenol
Other name(s): WbdB
Systematic name: GDP-α-D-mannose:α-D-mannosyl-(1→3)-N-acetyl-α-D-glucosaminyl-diphospho-ditrans,octacis-undecaprenol 3-α-mannosyltransferase (configuration-retaining)
Comments: The enzyme is involved in the biosynthesis of the linker region of the polymannose O-polysaccharide in the outer leaflet of the membrane of Escherichia coli serotypes O8, O9 and O9a. It has no activity with N-acetyl-α-D-glucosaminyl-diphospho-ditrans,octacis-undecaprenol (cf. EC 184.108.40.2068, N-acetyl-α-D-glucosaminyl-diphospho-ditrans,octacis-undecaprenol 3-α-mannosyltransferase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
1. Greenfield, L.K., Richards, M.R., Li, J., Wakarchuk, W.W., Lowary, T.L. and Whitfield, C. Biosynthesis of the polymannose lipopolysaccharide O-antigens from Escherichia coli serotypes O8 and O9a requires a unique combination of single- and multiple-active site mannosyltransferases. J. Biol. Chem. 287 (2012) 35078-35091. [PMID: 22875852]