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Functional analysis of a gycosyltransferase, GNUT during rice development
Thiyagarajan Thulasinathan,Rikno Harmoko,Wahyu Indra Fanata,Jae Yong Yoo,Ki Seong Ko,Nirmal Kumar Ramasamy,Kyung Hwa Kim,Ryun Gyeong Kim,Sang Yeol Lee,Kyun Oh Lee 한국당과학회 2013 한국당과학회 학술대회 Vol.2013 No.1
N-linked Glycosylation is enzymatic process that attaches sugars residue to tripeptide sequence Asparagine-X-Serine /Threonin of nascent polypeptide, where X could be any amino acid except Proline. Extracellular and endomembrane protein are mostly glycosylated by N-linked oligosaccharides in eukaryote. The maturation of N-glycan is modified by glycosidases and glycosyl transferases in the ER and golgi of the secretory pathway. The GNUT is a glycosyltransferases that responsible for the transfer core sugar residues to N-glycans of glycoprotein. To explore the physiological role of alpha GNUT, the mutant gnut1 was isolated in rice. Genetic analysis shows that T-DNA was inserted in the first intron of the GNUT gene. The T-DNA insertion causes loss-of-function mutation of this gene. Biochemical analysis have confirm that sugar residue was absent from core N-glycan in this mutant. The gnut1 shows internodes length retardation in the late vegetative growth. In generative growth, the gnut1 mutant also exhibit short panicles length, grain filling defective and small grains. The result indicates that GNUT is important for normal growth of rice in the generative phase.
Functional characterization of endoplasmic reticulum stress sensors in Arabidopsis thaliana
Jae Yong Yoo,Wahyu Indra Fanata,Rikno Harmoko,Ki Seong Ko,Nirmal Kumar Ramasamy,Kyung Hwa Kim,Thiyagarajan Thulasinathan,Ryun Gyeong Kim,Sang Yeol Lee,Kyun Oh Lee 한국당과학회 2013 한국당과학회 학술대회 Vol.2013 No.1
Environmental or physiological influences that induce accumulation of unfolded proteins in the lumen of endoplasmic reticulum (ER) cause ER stress and activate signaling pathway called unfolded protein response (UPR). An ER-located transmembrane receptor protein kinase/ribonuclease called Ire1 plays an essential role in the UPR in yeasts and mammals. However, it has been unclear whether a similar mechanism is applicable to Arabidopsis. To elucidate the role of Arabidopsis IRE1, we performed functional analyses by isolating loss-of-function mutants of IRE1A and IRE1B. We found that a double mutant of Arabidopsis IRE1A and IRE1B (ire1a ire1b) is more sensitive to the ER stress inducer tunicamycin than the wild-type. ire1a ire1b result in a delayed induction of BiP3 that is well known ER chaperone by tunicamycin treatment, whereas induction of several other ER chaperones in ire1a ire1b was similar with that of WT. Our results indicate that IRE1A and IRE1B are implicated in unfolded protein response signaling in plants.
Jae Yong Yoo,Bo Hwa Son,Wahyu Indra Fanata,Rikno Harmoko,Ki Seong Ko,Nirmal Kumar Ramasamy,Thiyagarajan Thulasinathan,Kyung Hwa Kim,Sang Yeol Lee,Kyun Oh Lee 한국당과학회 2012 한국당과학회 학술대회 Vol.2012 No.1
Environmental or physiological influences that induce accumulation of unfolded proteins in the lumen of endoplasmic reticulum (ER) cause ER stress and activate signaling pathway called unfolded protein response (UPR). An ER-located transmembrane receptor protein kinase/ribonuclease called Ire1 plays an essential role in the UPR in yeasts and mammals. However, it has been unclear whether a similar mechanism is applicable to Arabidopsis. To elucidate the role of Arabidopsis IRE1, we performed functional analyses by isolating loss-of-function mutants of IRE1A and IRE1B. We found that a double mutant of Arabidopsis IRE1A and IRE1B (ire1a/ire1b) is more sensitive to the ER stress inducer tunicamycin than the wild-type. ire1a/ire1b result in a delayed induction of BiP3 which is well known ER chaperone by DTT treatment, whereas induction of BiP1 in ire1a/ire1b was similar with that of WT. Our result indicate that IRE1A and IRE1B are implicated in unfolded protein response signaling in plants.
Glycoengineering for production of biopharmaceuticals
Ryun Gyeong Kim,Ki Seong Ko,Wahyu Indra Fanata,Jae Yong Yoo,Rikno Harmoko,Nirmal Kumar Ramasamy,Kyung Hwa Kim,Thiyagarajan Thulasinathan,Sang Yeol Lee,Kyun Oh Lee 한국당과학회 2013 한국당과학회 학술대회 Vol.2013 No.1
N-glycosylation is one of the major post-translational protein modifications, which alters physicochemical properties of the protein, affecting the folding, distribution, stability and thus biological function and efficiency of protein. Although the earlier steps in the N-glycosylation pathway leading to the formation of oligomannosidic structures are conserved in plants and mammals, the later steps in the formation of complex N-glycans are quite different from each other. In particular, plant type complex N-glycans are distinctive from those found in mammalian because they contain β 1,2-xylose and core α1,3-fucose residues attached to pentasaccharide (Man3GlcNAc2) core structure but no sialic acid residues. The presence of β1,2-xylose and core α1,3-fucose residues on plant type complex N-glycans has long been an irritating limitation in the use of plant-made pharmaceuticals (PMPs) in human therapy, as these N-glycan epitopes are potentially immunogenic in mammals. In this study, to remove the plant specific sugar residues and humanize the N-glycosylation in plant, we isolated mutants of the corresponding plant specific glycosyltransferase genes and used for multiple-mutants construction. The resulting mutants will be transformed by human glycosyltransferases genes to accomplish humanized N-glycosylation in plant.