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 18.104.22.168 (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.
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. USA104 (2007) 14318–14323. [PMID: 17728402]