earticle

영어

The predominant N-glycan in plants is paucimannosidic N-glycan with core β1,2-xylose and α 1,3-fucose residues (PNGXF). Here, We hypothesized that additions of the core β1,2-xylose, α 1,3-fucose, and 6-arm β1,2-GlcNAc residues to the common acceptor (GlcNAcMan3GlcNAc2) are relatively determined by the different activity and/or substrate occupancy of the enzymes of the corresponding genes in plants. As a result, we describe a mechanism in Arabidopsis thaliana that effectively form the largest N-glycan in plants. Genetic and biochemical evidence suggest that the addition of the 6-arm β1,2-GlcNAc residue by N-acetylglucosaminyltransferase II (GnTII) is less effective than additions of the core β1,2-xylose and α1,3-fucose residues by XylT, FucTA, and FucTB in Arabidopsis thaliana. Moreover, analysis of gnt2 mutant and 35S: GnTII transgenic plants indicates that the additions of the core β1,2-xylose and α1,3-fucose residues to the common acceptor (GlcNAcMan3GlcNAc2) are partially inhibited by the addition of the 6-arm β1,2-GlcNAc residue. Our findings show that plants control the rate of the addition of the 6-arm GlcNAc residue to the common N-glycan acceptor as a mechanism to facilitate formation of the general N-glycans with Man3XylFucGlcNAc2 and GlcNAc2Man3XylFucGlcNAc2 structures by hexosaminidase activity and the regulated sharing of the common acceptor GlcNAcMan3GlcNAc2.