Synthesis of α-galactosyl epitopes by metabolically engineered Escherichia coli

► E. coli strains expressed genes for β-3GlcNAcT, β-4GalT and α-3GalT. ► α-Gal epitopes ranging from DP5 to DP13 were produced using H. pylori β-3GlcNAcT. ► The N. meningitidis β-3GlcNAcT has a higher affinity for α-galactosides than for β-galactosides. ► Unusual molecules were formed by the repeated addition of [Galβ-4GlcNAcβ-3Galα-3] motif onto LNnT. ► Structures of oligosaccharides were elucidated by 1H and 13C NMR analyses.