FUCOSYLATION OF COMPLEX GLYCOSPHINGOLIPIDS BY RECOMBINANT FUCOSYL-TRANSFERASE-VII

Fucosyltransferase VII (FucT-VII) is one of five known alpha 1-->3fuco syltransferases capable of transferring fucose to the C-3 position of N-acetylglucosamine residues found in lactosamine based glycans, Previ ous studies have indicated that FucT-VII has a very restricted specifi city, capable of fucosylating only terminally alpha 2-->3sialylated ca rbohydrate substrates, resulting in the synthesis of the sialyl Lewis x (sLe(x)) epitope, Although FucT-VII is expressed in cells of myeloid origin, the monosialylganglioside fraction of HL60 cells contains onl y internally and/or multiply fucosylated polylactosamine structures; n o monofucosylated sLe(x) derivatives are detected. We now report that the structure of the final product formed by the action of FucT-VII on sialynorhexaosylceramide (a glycosphingolipid substrate having multip le fucosylation sites) is extended monofucosyl sLe(x) and fucosylation is restricted to the terminal GlcNAc-V, This indicates that the biosy nthesis of all fucosylated monosialylated gangliosides found in HL60 c ells (including the E-selectin binding fractions) involves at least on e additional alpha-->3fucosyltransferase. (C) 1997 Academic Press.