Plant members of the α1 → 3/4-fucosyltransferase gene family encode an α1 → 4-fucosyltransferase, potentially involved in Lewisa biosynthesis, and two core α1 → 3-fucosyltransferases

Three putative α1 → 3/4-fucosyltransferase (α1 → 3/4-FucT) genes have been detected in the Arabidopsis thaliana genome. The products of two of these genes have been identified in vivo as core α1 → 3-FucTs involved in N-glycosylation. An orthologue of the third gene was isolated from a Beta vulgaris cDNA library. The encoded enzyme efficiently fucosylates Galβ1 → 3GlcNAcβ1 → 3Galβ1 → 4Glc. Analysis of the product by 400 MHz 1H-nuclear magnetic resonance spectroscopy showed that the product is α1 → 4-fucosylated at the N-acetylglucosamine residue. In vitro, the recombinant B. vulgaris α1 → 4-FucT acts efficiently only on neutral type 1 chain-based glycan structures. In plants the enzyme is expected to be involved in Lewisa formation on N-linked glycans. © 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.