The biosynthesis of Lewis X in Helicobacter pylori

The biosynthesis of the Lewis X determinant (Gal beta 1-4 [Fuc alpha 1-3]GlcNAc beta-) in three strains of Helicobacter pylori has been investigated. Strains UA 861, UA 802 and UA 1182 contain alpha 1,3 fucosyltransferase and beta 1,4 galactosyltransferase activities that synthesize the Lewis X structure by the transfer of monosaccharides from GDP-fucose and UDP-galactose donors, respectively. The enzyme reaction products that formed were characterized by capillary zone electrophoresis and by 1H-NMR spectroscopy. The biosynthetic pathway is therefore identical to that found in humans. In the three strains, the fucosyltransferase and galactosyltransferase activities differed in various cellular fractions. Km values for their donor and acceptor substrates also differed.