1. N-Glycosylation of cholera toxin B subunit in Nicotiana benthamiana: impacts on host stress response, production yield and vaccine potential
- Author
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Kazuhito Fujiyama, Adam S. Husk, Krystal Teasley Hamorsky, Lauren J. Moore, Bailey Nelson, Hiroyuki Kajiura, Jessica M. Jurkiewicz, J. Calvin Kouokam, and Nobuyuki Matoba
- Subjects
Cholera Toxin ,Agroinfiltration ,Glycosylation ,Immunogen ,Genetic Vectors ,Gene Expression ,Nicotiana benthamiana ,G(M1) Ganglioside ,Endoplasmic Reticulum ,medicine.disease_cause ,complex mixtures ,Article ,Mice ,N-linked glycosylation ,Polysaccharides ,medicine ,Animals ,Immunity, Mucosal ,Multidisciplinary ,biology ,Protein Stability ,Tobamovirus ,Cholera toxin ,Cholera Vaccines ,ER retention ,Plants ,Endoplasmic Reticulum Stress ,Plants, Genetically Modified ,biology.organism_classification ,Antibodies, Bacterial ,Molecular biology ,Recombinant Proteins ,Unfolded protein response ,Thermodynamics ,Female ,Cholera vaccine ,Protein Binding - Abstract
Plant-based transient overexpression systems enable rapid and scalable production of subunit vaccines. Previously, we have shown that cholera toxin B subunit (CTB), an oral cholera vaccine antigen, is N-glycosylated upon expression in transgenic Nicotiana benthamiana. Here, we found that overexpression of aglycosylated CTB by agroinfiltration of a tobamoviral vector causes massive tissue necrosis and poor accumulation unless retained in the endoplasmic reticulum (ER). However, the re-introduction of N-glycosylation to its original or an alternative site significantly relieved the necrosis and provided a high CTB yield without ER retention. Quantitative gene expression analysis of PDI, BiP, bZIP60, SKP1, 26Sα proteasome and PR1a and the detection of ubiquitinated CTB polypeptides revealed that N-glycosylation significantly relieved ER stress and hypersensitive response and facilitated the folding/assembly of CTB. The glycosylated CTB (gCTB) was characterized for potential vaccine use. Glycan profiling revealed that gCTB contained approximately 38% plant-specific glycans. gCTB retained nanomolar affinity to GM1-ganglioside with only marginal reduction of physicochemical stability and induced an anti-cholera holotoxin antibody response comparable to native CTB in a mouse oral immunization study. These findings demonstrated gCTB's potential as an oral immunogen and point to a potential role of N-glycosylation in increasing recombinant protein yields in plants.
- Published
- 2015