A genetically modified plant or plant cell with reduced α1,3-fucosyltransferase and β1,2-xylosyltransferase activity compared to a wild type plant or plant cell, wherein less than 10% of the total glycan on a protein produced by the plant or plant cell is α1,3-fucosylated glycan and less than 3% of the total glycan on the protein is β1,2-xylosylated glycan is provided. In one embodiment, the plant or plant cell comprises three T-DNA insertions expressing five copies of RNAi targeting α1,3-fucosyltranserase and three copies of RNAi targeting β1,2xylosyltransferase.

The invention describes the discovery and novel application of a bacterial ubiquitin transferase (Cap2). Specifically, the invention describes the novel activity of the enzyme Cap2 which is capable of creating a specific fusion between two proteins implementing a standalone catalytic mechanism to create the fusion.

A genetically modified plant or plant cell with reduced 1,3-fucosyltransferase and 1,2-xylosyltransferase activity compared to a wild type plant or plant cell, wherein less than 10% of the total glycan on a protein produced by the plant or plant cell is 1,3-fucosylated glycan and less than 3% of the total glycan on the protein is 1,2-xylosylated glycan is provided. In one embodiment, the plant or plant cell comprises three T-DNA insertions expressing five copies of RNAi targeting 1,3-fucosyltranserase and three copies of RNAi targeting 1,2xylosyltransferase.

The present invention relates to a plant for producing a protein containing a humanized low-mannose N-glycan, and a method for producing a protein containing a customized humanized low-mannose N-glycan using the aforementioned plant.

A quadruple mutant (qm) plant is deficient of functions of core 1,3-fucosyltransferase A (FucTA), core 1,3-fucosyltransferase B (FucTB), 1,2-xylosyltransferase (XylT), and 1,2-N-acetylglucosaminyltransferase II (GnTII), and produces a protein containing hypoallergenic pauci-mannose-type N-glycan that does not include 1,3-fucose and 1,2-xylose residues. A method for producing a transgenic plant for a production of a protein containing hypoallergenic pauci-mannose-type N-glycan that does not include 1,3-fucose and 1,2-xylose residues but includes 1,6-fucose residue includes preparing the quadruple mutant (qm) plant, and transforming the quadruple mutant plant with a recombinant vector containing a gene encoding the human-derived 1,6-fucosyltransferase (FUT8) protein to overexpress FUT8 gene, and selecting a transgenic plant which is deficient of the functions of FucTA, FucTB, XylT and GnTII proteins.