Synthesis of GDP-Mannose in Recombinant Escherichia coli

Three recombinant Escherichia coli strains were constructed to produce guanosine 5'-diphosphate (GDP)-mannose, donor of GDP-fucose, which is an essential substrate for synthesis of fucosyloligosaccharides. Glucokinase (glk), phosphomannomutase (manB), and mannose-1-phosphate guanylytransferase (manC), are three crucial enzymes for the de novo GDP-mannose biosynthesis, were overexpressed in recombinant E.coli by constructing inducible overexpression vectors. The optimum expression conditions for GLK, ManB, and ManC in recombinant E.coli BL21 (DE3) were 25°C and 0.1 mM isopropyl-β-D-thioglucopyranoside. In this condition, the conversion rate was 30% from mannose to GDP-mannose.