<i>Nicotiana tabacum</i> contains two alpha1,3-fucosyltransferase types, one of which is able to catalyze core fucosylation of high-mannose <i>N</i>-glycans

N-glycosylation is a critical quality attribute to consider when expressing recombinant glycoproteins in eukaryotic cells including plant cells. N-acetylglucosaminyltransferase I (GnTI) initiates complex N-glycan maturation in the Golgi apparatus by transferring a single N-acetylglucosamine (GlcNAc) residue on the alpha1,3-arm of a Man5 N-glycan acceptor. This step is required for the processing of high mannose into hybrid and complex N-glycans. Therefore, Arabidopsis mutants lacking GnTI activity display accumulation of Man5 N-glycans instead of complex N-glycans and do not synthesise N-glycans containing core alpha1,3-fucose residue. In contrast, GnTI knockout cell line of Nicotiana tabacum BY-2 still displays a little core alpha1,3-fucose signal on western blotting. Here, we show that N. tabacum contains two alpha1,3-fucosyltransferase types, one of which is able to transfer a core alpha1,3-fucose on a Man5 substrate when no Man5Gn substrate is available such as in BY-2 GnTI knock-out cell lines.