Glycosylation of the cationic peanut peroxidase gene expressed in transgenic tobacco

The major cationic peanut (Arachis hypogaea) peroxidase, secreted into the extracellular space, is a glycoprotein with three N-linked glycans (polysac charides) which are connected to the peptide backbone at Asn-60, Asn-144 an d Asn-185. In this report, a C-terminal histidine-tagged cationic peanut pe roxidase gene was expressed in transgenic tobacco (Nicotiana tabacum). Tiss ue of the transgenic tobacco was cultured in suspension culture and the his -tagged peroxidase was purified in large quantities from 14-day-old suspens ion culture. The number of glycans, glycosylation sites and the chemical na ture of glycan moieties attached to cationic peanut peroxidase expressed in transgenic tobacco were examined. Cationic peanut peroxidase isolated From the above transgenic tobacco had the identical number of complex glycans, attached at the same glycosylation sites as on cationic peanut peroxidase i solated from peanut suspension culture. Monosaccharide components of these glycans are N-acetylglucosamine (GlcNAc), mannose (Man), fucose (Fuc), xylo se (Xyl) and galactose (Gal), the same sugars as found in native cationic p eanut peroxidase. (C) 2000 Elsevier Science Ireland Ltd. All rights reserve d.