title: Production of active human glucocerebrosidase in seeds of Arabidopsis thaliana complex-glycan-deficient (cgl) plants.
abstract: There is a clear need for efficient methods to produce protein therapeutics requiring mannose-termination for therapeutic efficacy. Here we report on a unique system for production of active human lysosomal acid β-glucosidase (glucocerebrosidase, GCase, EC 3.2.1.45) using seeds of the Arabidopsis thaliana complex-glycan-deficient (cgl) mutant, which are deficient in the activity of N-acetylglucosaminyl transferase I (EC 2.4.1.101). Gaucher disease is a prevalent lysosomal storage disease in which affected individuals inherit mutations in the gene (GBA1) encoding GCase. A gene cassette optimized for seed expression was used to generate the human enzyme in seeds of the cgl (C5) mutant, and the recombinant GCase was mainly accumulated in the apoplast. Importantly, the enzymatic properties including kinetic parameters, half-maximal inhibitory concentration of isofagomine and thermal stability of the cgl-derived GCase were comparable with those of imiglucerase, a commercially available recombinant human GCase used for enzyme replacement therapy in Gaucher patients. N-glycan structural analyses of recombinant cgl-GCase showed that the majority of the N-glycans (97%) were mannose terminated. Additional purification was required to remove ∼15% of the plant-derived recombinant GCase that possessed potentially immunogenic (xylose- and/or fucose-containing) N-glycans. Uptake of cgl-derived GCase by mouse macrophages was similar to that of imiglucerase. The cgl seed system requires no addition of foreign (non-native) amino acids to the mature recombinant GCase protein, and the dry transgenic seeds represent a stable repository of the therapeutic protein. Other strategies that may completely prevent plant-like complex N-glycans are discussed, including the use of a null cgl mutant.
authors: Department of Biological Sciences,  Simon Fraser University, 8888 University Dr., Burnaby, British Columbia,  V5A 1S6, Canada.
authors: Xu
authors: X
authors: He
authors: Jason D
authors: JD
authors: Galpin
authors: Michael B
authors: MB
authors: Tropak
authors: Don
authors: D
authors: Mahuran
authors: Thomas
authors: T
authors: Haselhorst
authors: Mark
authors: M
authors: von Itzstein
authors: Daniel
authors: D
authors: Kolarich
authors: Nicolle H
authors: NH
authors: Packer
authors: Yansong
authors: Y
authors: Miao
authors: Liwen
authors: L
authors: Jiang
authors: Gregory A
authors: GA
authors: Grabowski
authors: Lorne A
authors: LA
authors: Clarke
authors: Allison R
authors: AR
authors: Kermode
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002478:Cells, Cultured; D004795:Enzyme Stability; D005962:Glucosylceramidase / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007700:Kinetics; D008264:Macrophages / Q000378:metabolism; D008358:Mannose; D051379:Mice; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D012639:Seeds / Q000166:cytology / Q000235:genetics*
chemical_list: D011994:Recombinant Proteins; D005962:Glucosylceramidase; D008358:Mannose; C090568:imiglucerase