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Background  Nucleotide sugars serve as sugar donors for the synthesis of various glycones. The biological and chemical properties of glycones can be altered depending which sugar is attached. Bacteria synthesize unusual nucleotide sugars. A novel nucleotide sugar can be synthesized in  Escherichia coli  by introducing nucleotide biosynthetic genes from other microorganisms into  E. coli . The engineered  E. coli  strains can be used as a platform for the synthesis of novel glycones.    Results  Four genes,  Pdeg  (UDP- N -acetylglucosamine C4,6-dehydratase),  Preq  (UDP-4-reductase),  UDP - GlcNAc 6 - DH  (UDP- N -acetylglucosamine 6-dehydrogenase), and  UXNAcS  (UDP- N -acetylxylosamine synthase), were employed to synthesize UDP-quinovosamine, UDP- N -acetylglucosaminuronic acid, and UDP- N -acetylxylosamine in  E. coli . We engineered an  E. coli  nucleotide sugar biosynthetic pathway to increase the pool of substrate for the target nucleotide sugars. Uridine diphosphate dependent glycosyltransferase (UGT) was also selected and introduced into  E. coli . Using engineered  E. coli , high levels of three novel flavonoid glycosides were obtained; 158.3 mg/L quercetin 3- O -( N -acetyl)quinovosamine, 172.5 mg/L luteolin 7- O -( N -acetyl)glucosaminuronic acid, and 160.8 mg/L quercetin 3- O -( N -acetyl)xylosamine.    Conclusions  We reconstructed an  E. coli  nucleotide pathway for the synthesis of UDP-quinovosamine, UDP- N -acetylglucosaminuronic acid and UDP- N -acetylxylosamine in an  E. coli galU  (UDP-glucose 1-phosphate uridylyltransferase) or  pgm  (phosphoglucomutase) deletion mutant. Using engineered  E. coli  strains harboring a specific UGT, three novel flavonoids glycones were synthesized. The  E. coli  strains used in this study can be used for the synthesis of diverse glycones.    Electronic supplementary material  The online version of this article (doi:10.1186/s12934-016-0582-8) contains supplementary material, which is available to authorized users.

Biosynthesis of three N-acetylaminosugar-conjugated flavonoids using engineered Escherichia coli