Reaction: GDP-mannose + D-fructose 6-phosphate = GDP + β-D-fructofuranosyl-α-D-mannopyranoside 6F-phosphate
Glossary: mannosylfructose = β-D-fructofuranosyl-α-D-mannopyranoside
Other name(s): mannosylfructose-6-phosphate synthase; MFPS
Systematic name: GDP-mannose:D-fructose-6-phosphate 2-α-D-mannosyltransferase
Comments: This enzyme, from the soil proteobacterium and plant pathogen Agrobacterium tumefaciens strain C58, requires Mg2+ or Mn2+ for activity. GDP-mannose can be replaced by ADP-mannose but with a concomitant decrease in activity. The product of this reaction is dephosphorylated by EC 3.1.3.79 (mannosylfructose-phosphate phosphatase) to form the non-reducing disaccharide mannosylfructose, which is the major endogenous osmolyte produced by several α-proteobacteria in response to osmotic stress. The F in the product name is used to indicate that the fructose residue of sucrose carries the substituent.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
References:
1. Torres, L.L. and Salerno, G.L. A metabolic pathway leading to mannosylfructose biosynthesis in Agrobacterium tumefaciens uncovers a family of mannosyltransferases. Proc. Natl. Acad. Sci. USA 104 (2007) 14318–14323. [PMID: 17728402]