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 (polysaccharides) which are connected to the peptide backbone at Asn-60, Asn-144 and Asn-185. In this report, a C-terminal histidine-tagged cationic peanut peroxidase gene was expressed in transgenic tobacco (Nicotiana tabacum). Tissue of the transgenic tobacco was cultured in suspension culture and the his-tagged peroxidase was purified in large quantities from 14-day-old suspension culture. The number of glycans, glycosylation sites and the chemical nature 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 isolated from peanut suspension culture. Monosaccharide components of these glycans are N-acetylglucosamine (GlcNAc), mannose (Man), fucose (Fuc), xylose (Xyl) and galactose (Gal), the same sugars as found in native cationic peanut peroxidase.