title: N-glycosylation and N-glycan moieties of CTB expressed in rice seeds.
abstract: Cholera toxin B subunit (CTB) is widely used as a carrier molecule and mucosal adjuvant and for the expression of fusion proteins of interest. CTB-fusion proteins are also expressed in plants, but the N-glycan structures of CTB have not been clarified. To gain insights into the N-glycosylation and N-glycans of CTB expressed in plants, we expressed CTB in rice seeds with an N-terminal glutelin signal and a C-terminal KDEL sequence and analyzed its N-glycosylation and N-glycan structures. CTB was successfully expressed in rice seeds in two forms: a form with N-glycosylation at Asn32 that included both plant-specific N-glycans and small oligomannosidic N-glycans and a non-N-glycosylated form. N-Glycan analysis of CTB showed that approximately 50 % of the N-glycans had plant-specific M3FX structures and that almost none of the N-glycans was of high-mannose-type N-glycan even though the CTB expressed in rice seeds contains a C-terminal KDEL sequence. These results suggest that the CTB expressed in rice was N-glycosylated through the endoplasmic reticulum (ER) and Golgi N-glycosylation machinery without the ER retrieval.
authors.affiliation: International Center for Biotechnology, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kajiura
authors.forename: Masashi
authors.initials: M
authors.lastname: Wasai
authors.forename: Saori
authors.initials: S
authors.lastname: Kasahara
authors.forename: Fumio
authors.initials: F
authors.lastname: Takaiwa
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Fujiyama
mesh_terms: D001216:Asparagine / Q000737:chemistry / Q000378:metabolism; D001709:Biotechnology; D002772:Cholera Toxin / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006031:Glycosylation; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000378:metabolism*
chemical_list: D011134:Polysaccharides; D001216:Asparagine; D002772:Cholera Toxin