Synthesis of mono- and di-fucosylated type I Lewis blood group antigen by Helicobacter pylori

The identification of Helicobacter pylori isolates that expresses exclusive ly type I Lewis antigens is necessary to determine the biosynthetic pathway of these antigens. Fast-atom bombardment MS provides evidence that the H. pylori isolate UA1111 expresses predominantly Le(b), with H type I and Le(a ) in lesser amounts. Cloning and expression of the H. pylori fucosyltransfe rases (FucTs) allow comparisons with previously identified H. pylori enzyme s and determination of the enzyme specificities. Although all FucTs, one al pha(1,2) FucT and two alpha(1,3/4) FucTs, appear to be functional in this i solate, their activities are lower and enzyme specificities are different t o other H. pylori FucTs previously characterized. Studies of the cloned enz yme activities and mutational analysis indicate that Le(a) acts as the subs trate for the synthesis of Le(b). This is different from the human Le(b) bi osynthetic pathway, but analogous to the biosynthetic pathway utilized by H . pylori for the production of Le(y).