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Kang, Chang Ho,Park, Joung Hun,Lee, Eun Seon,Paeng, Seol Ki,Chae, Ho Byoung,Chi, Yong Hun,Lee, Sang Yeol MDPI 2019 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.20 No.1
<P>In our previous study, we found that Ypt1p, a Rab family small GTPase protein, exhibits a stress-driven structural and functional switch from a GTPase to a molecular chaperone, and mediates thermo tolerance in <I>Saccharomyces cerevisiae</I>. In the current study, we focused on the temperature-sensitive <I>ypt1-G80D</I> mutant, and found that the mutant cells are highly sensitive to heat-shock, due to a deficiency in the chaperone function of Ypt1p<SUP>G80D</SUP>. This defect results from an inability of the protein to form high molecular weight polymers, even though it retains almost normal GTPase function. The heat-stress sensitivity of <I>ypt1-G80D</I> cells was partially recovered by treatment with 4-phenylbutyric acid, a chemical chaperone. These findings indicate that loss of the chaperone function of Ypt1p<SUP>G80D</SUP> underlies the heat sensitivity of <I>ypt1-G80D</I> cells. We also compared the proteomes of <I>YPT1</I> (wild-type) and <I>ypt1-G80D</I> cells to investigate Ypt1p-controlled proteins under heat-stress conditions. Our findings suggest that Ypt1p controls an abundance of proteins involved in metabolism, protein synthesis, cellular energy generation, stress response, and DNA regulation. Finally, we suggest that Ypt1p essentially regulates fundamental cellular processes under heat-stress conditions by acting as a molecular chaperone.</P>
Universal Stress Protein (USP) Enhances Plant Growth and Development by Promoting Cell Expansion
Lee Eun Seon,Phan Kieu Anh Thi,Jun Sang Eun,박정훈,Paeng Seol Ki,Chae Ho Byoung,Wi Seong Dong,Bae Su Bin,Kang Kee Ryeon,김경태,이상열 한국식물학회 2022 Journal of Plant Biology Vol.65 No.3
Plants are exposed to various environmental stimuli, including abiotic and biotic stresses, during their life cycle. In Arabidopsis thaliana, the Universal Stress Protein (AtUSP) acts as a protein chaperone and RNA chaperone to protect plants from heat shock and cold shock, respectively. This study aimed to explore the role of AtUSP in plant growth and development. We conducted morphological analyses of wild-type (WT; Col-0), AtUSP overexpression (AtUSPOE), and atusp knockout mutant plants during their vegetative growth, and measured the total leaf number, leaf size, and root length. Compared with the WT, AtUSPOE plants displayed enhanced growth, whereas atusp plants displayed reduced growth of all examined organs. To investigate whether these growth phenotypes were caused by changes in cell expansion and proliferation, we analyzed the mature leaves of all genotypes at the cellular level. The enlarged leaves of AtUSPOE plants showed an increase in cell size, but not in cell number, indicating that AtUSP promotes cell expansion. Moreover, expression analysis of cell growth-related genes revealed that AtUSP is involved in cell expansion rather than cell proliferation. These findings suggest that AtUSP acts as a positive regulator of cell expansion, and provide novel insights into its role in plant growth and development.
Melencion, Sarah Mae Boyles,Chi, Yong Hun,Pham, Thuy Thi,Paeng, Seol Ki,Wi, Seong Dong,Lee, Changyu,Ryu, Seoung Woo,Koo, Sung Sun,Lee, Sang Yeol MDPI AG 2017 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.18 No.12
<P>The physiological function of <I>Arabidopsis thaliana</I> universal stress protein (AtUSP) in plant has remained unclear. Thus, we report here the functional role of the <I>Arabidopsis</I> universal stress protein, AtUSP (At3g53990). To determine how AtUSP affects physiological responses towards cold stress, AtUSP overexpression (AtUSP OE) and T-DNA insertion knock-out (<I>atusp</I>, SALK_146059) mutant lines were used. The results indicated that AtUSP OE enhanced plant tolerance to cold stress, whereas <I>atusp</I> did not. AtUSP is localized in the nucleus and cytoplasm, and cold stress significantly affects RNA metabolism such as by misfolding and secondary structure changes of RNA. Therefore, we investigated the relationship of AtUSP with RNA metabolism. We found that AtUSP can bind nucleic acids, including single- and double-stranded DNA and luciferase mRNA. AtUSP also displayed strong nucleic acid-melting activity. We expressed AtUSP in RL211 <I>Escherichia coli</I>, which contains a hairpin-loop RNA structure upstream of chloramphenicol acetyltransferase (<I>CAT</I>), and observed that AtUSP exhibited anti-termination activity that enabled <I>CAT</I> gene expression. AtUSP expression in the cold-sensitive <I>Escherichia coli (E. coli)</I> mutant BX04 complemented the cold sensitivity of the mutant cells. As these properties are typical characteristics of RNA chaperones, we conclude that AtUSP functions as a RNA chaperone under cold-shock conditions. Thus, the enhanced tolerance of AtUSP OE lines to cold stress is mediated by the RNA chaperone function of AtUSP.</P>
Nucleoredoxin2 (NRX2) Promotes Jasmonate-Mediated Trichome Formation in Arabidopsis
Lee Eun Seon,Joung Hun Park,Gwang Yong Hwang,Yong Hun Chi,Chang Ho Kang,Ho Byoung Chae,Seol Ki Paeng,Seong Dong Wi,Su Bin Bae,Kieu Anh Thi Phan,이상열 한국식물학회 2020 Journal of Plant Biology Vol.63 No.6
Thioredoxin (Trx) proteins are essential for the maintenance of cellular redox balance through thiol/disulfide exchange modification. In Arabidopsis, the Trx superfamily consists of multiple protein isotypes distributed in most cellular compartments. Although the functions of chloroplastic and cytosolic Trxs have been investigated in plants, the physiological role of nuclear Trx proteins remains elusive. Nucleoredoxin (NRX) is a nuclear Trx first identified in eukaryotic organisms. Arabidopsis possesses two NRX genes (AtNRX1 and AtNRX2), and the function of AtNRX2 has not been elucidated to date. In this study, we characterized the function of AtNRX2 using the atnrx2 knockout mutant, based on its comparison with the atnrx1 mutant. In atnrx2 knockout mutant plants, trichome number was significantly reduced compared with the wild type (WT; Col-0) and the atnrx1 mutant. In response to JA induction of trichome, trichome formation was markedly diminished in the atnrx2 mutant. In addition, expression levels of genes involved in trichome formation were reduced in the atnrx2 mutant compared with the WT and atnrx1 mutant. Overall, our results suggest that AtNRX2 plays a physiological role in JA-mediated trichome formation in Arabidopsis.
Jung, Young Jun,Chi, Yong Hun,Chae, Ho Byoung,Shin, Mi Rim,Lee, Eun Seon,Cha, Joon-Yung,Paeng, Seol Ki,Lee, Yuno,Park, Jin Ho,Kim, Woe Yeon,Kang, Chang Ho,Lee, Kyun Oh,Lee, Keun Woo,Yun, Dae-Jin,Lee, Biochemical Society 2013 Biochemical journal Vol.456 No.1
<P>Multiple isoforms of Arabidopsis thaliana h-type thioredoxins (AtTrx-hs) have distinct structural and functional specificities. AtTrx-h3 acts as both a disulfide reductase and as a molecular chaperone. We prepared five representative AtTrx-hs and compared their protein structures and disulfide reductase and molecular chaperone activities. AtTrx-h2 with an N-terminal extension exhibited distinct functional properties with respect to other AtTrx-hs. AtTrx-h2 formed low-molecular-mass structures and exhibited only disulfide reductase activity, whereas the other AtTrx-h isoforms formed high-molecular-mass complexes and displayed both disulfide reductase and molecular chaperone activities. The domains that determine the unique structural and functional properties of each AtTrx-hs protein were determined by constructing a domain-swap between the N- and C-terminal regions of AtTrx-h2 and AtTrx-h3 (designated AtTrx-h-2N3C and AtTrx-h-3N2C respectively), an N-terminal deletion mutant of AtTrx-h2 [AtTrx-h2-N(?19)] and site-directed mutagenesis of AtTrx-h3. AtTrx-h2-N(?19) and AtTrx-h-3N2C exhibited similar properties to those of AtTrx-h2, but AtTrx-h-2N3C behaved more like AtTrx-h3, suggesting that the structural and functional specificities of AtTrx-hs are determined by their C-terminal regions. Hydrophobicity profiling and molecular modelling revealed that Ala100 and Ala106 in AtTrx-h3 play critical roles in its structural and functional regulation. When these two residues in AtTrx-h3 were replaced with lysine, AtTrx-h3 functioned like AtTrx-h2. The chaperone function of AtTrx-hs conferred enhanced heat-shock-resistance on a thermosensitive trx1/2-null yeast mutant.</P>
Molecular and Functional Properties of Three Different Peroxiredoxin Isotypes in Chinese Cabbage
Sun Young Kim,이상열,정영준,Mi Rim Shin,Jung Hoon Park,Ganesh M. Nawkar,Punyakishore Maibam,Eun Seon Lee,Kang-San Kim,Seol Ki Paeng,김외연,이균오,윤대진,강창호 한국분자세포생물학회 2012 Molecules and cells Vol.33 No.1
Peroxiredoxins (Prxs), which are classified into three isotypes in plants, play important roles in protection systems as peroxidases or molecular chaperones. The three Prx isotypes of Chinese cabbage, namely C1C-Prx, C2C-Prx, and C-PrxII, have recently been identified and characterized. The present study compares their molecular properties and biochemical functions to gain insights into their concerted roles in plants. The three Prx isotype genes were differentially expressed in tissue- and developmental stage-specific manners. The transcript level of the C1C-Prx gene was abundant at the seed stage, but rapidly decreased after imbibitions. In contrast, the C2C-Prx transcript was not detected in the seeds, but its expression level increased at germination and was maintained thereafter. The C-PrxII transcript level was mild at the seed stage, rapidly increased for 10 days after imbibitions, and gradually disappeared thereafter. In the localization analysis using GFP-fusion proteins, the three isotypes showed different cellular distributions. C1C-Prx was localized in the cytosol and nucleus, whereas C2C-Prx and C-Prx were found mainly in the chloroplast and cytosol, respectively. In vitro thiol-dependent antioxidant assays revealed that the relative peroxidase activities of the isotypes were C-PrxII > C2C-Prx > C1C-Prx. C1C-Prx and C2C-Prx, but not C-PrxII, prevented aggregation of malate dehydrogenase as a molecular chaperone. Taken together, these results suggest that the three isotypes of Prx play specific roles in the cells in timely and spatially different manners, but they also cooperate with each other to protect the plant.
Molecular and functional properties of three different peroxiredoxin isotypes in Chinese cabbage
Kim, Sun Young,Jung, Young Jun,Shin, Mi Rim,Park, Jung Hoon,Nawkar, Ganesh M.,Maibam, Punyakishore,Lee, Eun Seon,Kim, Kang-San,Paeng, Seol Ki,Kim, Woe Yeon,Lee, Kyun Oh,Yun, Dae-Jin,Kang, Chang Ho,Lee Springer-Verlag 2012 Molecules and cells Vol.33 No.1