Molecular cloning and functional expression of beta 1,2-xylosyltransferasecDNA from Arabidopsis thaliana

The transfer of xylose from UDP-xylose to the core beta-linked mannose of N -linked oligosaccharides by beta 1,2-xylosyl-transferase (XylT) is a widesp read feature of plant glycoproteins which renders them immunogenic and alle rgenic in man. Here, we report the isolation of the Arabidopsis thaliana Xy lT gene, which contains two introns and encodes a 60.2 kDa protein with a p redicted type II transmembrane protein topology typical for Golgi glycosylt ransferases, Upon expression of A. thaliana XylT cDNA in the baculovirus/in sect cell system, a recombinant protein was produced that exhibited XylT ac tivity in vitro. Furthermore, the recombinant enzyme displayed XylT activit y in vivo in the insect cells, as judged by the acquired cross-reaction of cellular glycoproteins with antibodies against the beta 1,2-xylose epitope, The cloned XylT cDNA as well as the recombinant enzyme are essential tools to study the role of beta 1,2-xylose in the immunogenicity and allergenici ty of plant glycoproteins at the molecular level. (C) 2000 Federation of Eu ropean Biochemical Societies.