FIGURE 1.
Strategy for the generation of Lex-glycoproteins. The initiating glycosyltransferase WecA from E. coli was employed for the addition of the first GlcNAc residue onto the lipid carrier UndPP. Glycosyltransferase from the H. influenzae LOS biosynthesis cluster are introduced to the E. coli expression strain for the completion of the precursor glycolipid Galβ1-4GlcNAcβ1–3Galβ1–3GlcNAc-UndPP. The glycan is then conjugated in the same E. coli cells by the C. jejuni oligosaccharyltransferase PglB onto one of its protein acceptors, AcrA. The addition of the fucose residue in an α1–3 linkage onto the exterior GlcNAc residue by H. pylori FucT in vitro completes the synthesis of the Lex-glycoprotein. Squares indicate GlcNAc residues, circles the Gal residues, and triangles the Fuc residues. Sugar residues added by E. coli WecA are dark colored, by the H. influenzae Lsg proteins are light colored, and by the H. pylori FucT are gray colored.