A novel N-acetylglucosamine-1-phosphate pyrophosphorylase was identified from Campylobacter jejuni NCTC 11168. An unprecedented degree of substrate promiscuity has been revealed by systematic studies on its substrate specificities towards sugar-1-P and NTP. The yields of the synthetic reaction of seven kinds of sugar nucleotides catalyzed by the enzyme were up to 60%. In addition, the yields of the other nine were around 20%. With this enzyme, three novel sugar nucleotide analogs were synthesized on a preparative scale and well characterized.

Nucleotide sugars are essential glycosyl donors for Leloir-type glycosyltransferases. The UDP-N-acetylgalactosamine pyrophosphorylase (UDP-GalNAc PP; AGX1) from Homo sapiens catalyzes the synthesis of UDP-N-acetylgalactosamine from N-acetylgalactosamine 1-phosphate and UTP. In this Letter, we systematically studied nucleotide substrate specificity of AGX1 during its uridyltransfer reaction, and described the capability of AGX1 to catalyze dUTP and dTTP to their corresponding nucleotide sugars for the first time. Furthermore, using such a eukaryotic enzyme, we synthesized dUDP-GalNAc and dTDP-GalNAc in multiple mg scale in vitro efficiently and rapidly.

•The salvage pathway for GDP-fucose biosynthesis from Bacterioides fragilis was introduced into Escherichia coli.•The biosynthesis of guanosine 5′-triphosphate (GTP), an essential substrate for GDP-fucose biosynthesis, was enhanced.•The production capacities of metabolically engineered strains bearing different combinations of recombinant enzymes were compared.•The recombinant strain containing enzymes Fkp, Gpt, Gmk and Ndk have a better productivity.•The established schemes in this work also have the advantage to be a potential avenue to GDP-fucose analogs.Guanosine 5′-diphosphate (GDP)-fucose is the indispensible donor substrate for fucosyltransferase-catalyzed synthesis of fucose-containing biomolecules, which have been found involving in various biological functions. In this work, the salvage pathway for GDP-fucose biosynthesis from Bacterioides fragilis was introduced into Escherichia coli. Besides, the biosynthesis of guanosine 5′-triphosphate (GTP), an essential substrate for GDP-fucose biosynthesis, was enhanced via overexpression of enzymes involved in the salvage pathway of GTP biosynthesis. The production capacities of metabolically engineered strains bearing different combinations of recombinant enzymes were compared. The shake flask fermentation of the strain expressing Fkp, Gpt, Gmk and Ndk obtained the maximum GDP-fucose content of 4.6 ± 0.22 μmol/g (dry cell mass), which is 4.2 fold that of the strain only expressing Fkp. Through fed-batch fermentation, the GDP-fucose content further rose to 6.6 ± 0.14 μmol/g (dry cell mass). In addition to a better productivity than previous fermentation processes based on the de novo pathway for GDP-fucose biosynthesis, the established schemes in this work also have the advantage to be a potential avenue to GDP-fucose analogs encompassing chemical modification on the fucose residue.