earticle

영어

The most abundant N-glycan in plants is the paucimannosidic N-glycan with core β 1,2-xylose and α1,3-fucose residues (XylMan3FucGlcNAc2). Here, we investigated the physiological significance in Arabidopsis thaliana of α-1,6-mannosyl-glycoprotein 2--N-acetylglucosaminyltransferase (EC 2.4.1.143, N-acetylglucosaminyltransferase II [GnTII]), which transfers N-acetylglucosamine (GlcNAc) residue from the nucleotide sugar donor UDP-GlcNAc to the α1,6-mannose residue of the di-antennary N-glycan acceptor in the Golgi apparatus. We assessed the phenotypic effects of a loss-of-function mutation (gnt2-1) in GnTII, and used quantitative PCR (qPCR) to examine gene expression and callose deposition assays under stress conditions. Prolonged stress from tunicamycin or NaCl treatment enhanced GnTII expression in the wild type and caused severely disrupted development and abnormal callose deposition in root tissues in the gnt2-1 mutant. Lack of the 6-arm β1,2-linked GlcNAc residue in the N-glycans promoted the unfolded protein response (UPR) upon prolonged endoplasmic reticulum (ER) stress in gnt2-1. Thus, GnTII's promotion of the 6-arm GlcNAc addition to N-glycans is important for plant growth and development under stress conditions.