The recent draft sequencing of the rice (
Oryza sativa) genome has enabled a genetic analysis of the glycosylation capabilities of an agroeconomically important group of plants, the monocotyledons. In this study, we have not only identified genes putatively encoding enzymes involved in
N-glycosylation, but have examined by MALDI-TOF MS the structures of the
N-glycans of rice and other monocotyledons (maize, wheat and dates;
Zea mays,
Triticum aestivum and
Phoenix dactylifera); these data show that within the plant kingdom the types of
N-glycans found are very similar between monocotyledons, dicotyledons and gymnosperms. Subsequently, we constructed expression vectors for the key enzymes forming plant-typical structures in rice,
N-acetylglucosaminyltransferase I (GlcNAc-TI; EC 2.4.1.101), core

1,3-fucosyltransferase (FucTA; EC 2.4.1.214) and

1,2-xylosyltransferase (EC 2.4.2.38) and successfully expressed them in
Pichia pastoris. Rice GlcNAc-TI, FucTA and xylosyltransferase are therefore the first monocotyledon glycosyltransferases involved in
N-glycan biosynthesis to be characterised in a recombinant form.
fucosyltransferase - glycan - glucosyltransferase - monocotyledon -
N-acetylglucosaminyltransferase - oligosaccharide - rice - xylosyltransferase