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RNA-dependent RNA polymerase 6 is required for efficient hpRNA-induced gene silencing in plants
Harmoko, Rikno,Fanata, Wahyu Indra Duwi,Yoo, Jae Yong,Ko, Ki Seong,Rim, Yeong Gil,Uddin, Mohammad Nazim,Siswoyo, Tri Agus,Lee, Seung Sik,Kim, Dool Yi,Lee, Sang Yeol,Lee, Kyun Oh Springer-Verlag 2013 Molecules and cells Vol.35 No.3
Rikno Harmoko,Jae Yong Yoo,Ki Seong Ko,Nirmal Kumar Ramasamy,Bo Young Hwang,Eun Ji Lee,Ho Soo Kim,Kyung Jin Lee,Doo-Byoung Oh,Dool-Yi Kim,Sanghun Lee,Yang Li,Sang Yeol Lee,Kyun Oh Lee 한국당과학회 2016 한국당과학회 학술대회 Vol.2016 No.07
In plants, α1,3-fucosyltransferase (FucT) catalyzes the transfer of fucose from GDP-fucose to asparagine-linked GlcNAc of the N-glycan core in the medial Golgi. To explore the physiological significance of this processing, we isolated two Oryza sativa (rice) mutants (fuct-1 and fuct-2) with loss of FucT function. Biochemical analyses of the N-glycan structure confirmed that α1,3-fucose is missing from the N-glycans of allelic fuct-1 and fuct-2. Compared with the wild-type cv Kitaake, fuct-1 displayed a larger tiller angle, shorter internode and panicle lengths, and decreased grain filling as well as an increase in chalky grains with abnormal shape. The mutant allele fuct-2 gave rise to similar developmental abnormalities, although they were milder than those of fuct-1. Restoration of a normal tiller angle in fuct-1 by complementation demonstrated that the phenotype is caused by the loss of FucT function. Both fuct-1 and fuct-2 plants exhibited reduced gravitropic responses. Expression of the genes involved in tiller and leaf angle control was also affected in the mutants. We demonstrate that reduced basipetal auxin transport and low auxin accumulation at the base of the shoot in fuct-1 account for both the reduced gravitropic response and the increased tiller angle.
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.
Eun Ji Lee,Jae Yong Yoo,Rikno Harmoko,Ki Seong Ko,Nirmal Kumar Ramasamy,Bo Young Hwang,Sang Yeol Lee,Kyun Oh Lee 한국당과학회 2016 한국당과학회 학술대회 Vol.2016 No.01
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.
Expression of a human glucocerebrosidase in a customized N-glycan producing plant
Bo Young Hwang,Ki Seong Ko,Jae Yong Yoo,Rikno Harmoko,Nirmal Kumar Ramasamy,Eun Ji Lee,Sang Yeol Lee,Kyun Oh Lee 한국당과학회 2016 한국당과학회 학술대회 Vol.2016 No.01
Gaucher’s disease is a lysosomal storage disorder by mutations in the gene encoding glucocerebrosidase (GC). Gaucher’s disease is currently treated by enzyme replacement therapy using recombinant GC (CerezymeⓇ) expressed in Chinese hamster ovary (CHO) cells. As complex glycans in mammalian cells have not terminate in mannose residues, which are essential for the biological absorption of GC via macrophage mannose receptors in human patient with Gaucher’s disease, glycan modification in vitro is required in order to expose the mannose residues on the glycans of CerezymeⓇ. Notably, the recombinant human GC (rhGC) expressed in the plant cells unaffectedly contains terminal mannose residues on its complex glycan. Hence, the plant-produced rhGC does not require exposure of mannose residues in vitro, which is a requirement for the production of CerezymeⓇ. However, The presence of β1,2-xylose and core α1,3-fucose residues on plant type complex N-glycans are potentially allergic in mammals. In this study, to remove the plant specific sugar residues and customize the N-glycan structure in plant, we isolated mutants of the corresponding plant specific glycosyltransferase genes and used for multiple-mutants construction. The resulting mutants was transformed by a human α 1,6-fucosyltransferase gene to accomplish customized N-glycosylation in plant. In consequence, the production of a rhGC in a humanized N-glycosylation plant is described.