• BMB Reports
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• v.32 no.1
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• pp.1-5
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• 1999

In order to understand the biological role of calmodulin in plants, transgenic tobacco plants expressing a calmodulin mutant (VU-4 calmodulin, lys to ile-115) gene have been analyzed. SDS-PAGE and Western-blot analyses showed that the foreign calmodulin mutant is stably and highly expressed in the transgenic tobacco plants. The levels of $H_2O_2$were elevated approximately 2-fold in the transgenic plants. Furthermore, the transgenic tobacco plants have more than 6-fold higher levels of NADPH compared to control tobacco plants. The present findings, combined with previous data showing differences in the susceptibility of the transgenic tobacco seeds and normal tobacco seeds to fungal contamination (Oh and Yang, 1996), suggest that the expression of the calmodulin derivative gene in tobacco plants could increase resistance to infection by fungal pathogens.

• International Journal of Molecular Medicine
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• v.44 no.1
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• pp.125-134
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• 2019

Mutations in myelin protein zero (MPZ) cause inherited peripheral neuropathies, including Charcot-Marie-Tooth disease (CMT) and Dejerine-Sottas neuropathy. Mutant MPZ proteins have previously been reported to cause CMT via enhanced endoplasmic reticulum (ER) stress and Schwann cell (SC) death, although the pathological mechanisms have not yet been elucidated. In this study, we generated an in vitro model of rat SCs expressing mutant MPZ (MPZ V169fs or R98C) proteins and validated the increase in cell death and ER stress induced by the overexpression of the MPZ mutants. Using this model, we examined the efficacy of 3 different aminosalicylic acids (ASAs; 4-ASA, sodium 4-ASA and 5-ASA) in alleviating pathological phenotypes. FACS analysis indicated that the number of apoptotic rat SCs, RT4 cells, induced by mutant MPZ overexpression was significantly reduced following treatment with each ASA. In particular, treatment with 4-ASA reduced the levels of ER stress markers in RT4 cells induced by V169fs MPZ mutant overexpression and relieved the retention of V169fs mutant proteins in the ER. Additionally, the level of an apoptotic signal mediator (p-JNK) was only decreased in the RT4 cells expressing R98C MPZ mutant protein following treatment with 4-ASA. Although 4-ASA is known as a free radical scavenger, treatment with 4-ASA in the in vitro model did not moderate the level of reactive oxygen species, which was elevated by the expression of mutant MPZ proteins. On the whole, the findings of this study indicate that treatment with 4-ASA reduced the ER stress and SC death caused by 2 different MPZ mutants and suggest that ASA may be a potential therapeutic agent for CMT.

• Korean Journal of Pharmacognosy
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• v.35 no.1 s.136
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• pp.28-34
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• 2004

DNA damage induced by reactive oxygen species (ROS) seems to play an important role in the induction of mutation and cancer. Hydrogen peroxide $(H_2O_2)$ has been shown to induce a variety of genetic alterations, probably by the generation of hydroxyl radicals via Fenton reaction. In this study, we examined the ability of medicinal herbs in the suppression of $H_2O_2$-induced mutagenesis. Human fibroblast GM00637 cells were treated with $H_2O_2$ in the presence or absence of medicinal herbs, and $H_2O_2$-induced mutant frequency was measured at the hypoxanthine guanine phosphoribosyl transferase (HPRT) locus. Treatment of cells with various doses of $H_2O_2$ caused a significant increase of the HPRT mutant frequency. However, pretreatment of cells with several medicinal herbs reduced $H_2O_2$-induced mutant frequency. The strong antimutagenic effects were observed from the methylene chloride and ethyl acetate fractions of Selaginella tamariscina, Panax ginseng, and Angelica acutiloba; ethyl acetate fractions of Rehmania glutinosa, Leonurus sibiricus, Curcuma zedoaria and Commiphora molmol; butanol fractions of Scutellaria barbata, Tribulus terrestris, Curcuma zedoaria, Cyperus rotundus and Carthamus tinctorius, which were more than 60% inhibition of $H_2O_2$-induced mutant frequency at the HPRT locus.

• The Plant Pathology Journal
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• v.26 no.2
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• pp.159-169
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• 2010

Lesion mimic mutant (LMM) plants display spontaneous necrotic lesions on their leaves without any pathogenic infection. Specific rice LMMs designated as spotted leaf (spl) including spl1, spl3, spl4, spl5 and spl6 are genetically known as lesion resembling disease (lrd) mutant. The inheritance patterns in the $F_1$ and $F_2$ progenies of these mutants are controlled by recessive genetic factors. Lesion development in the rice LMMs were controlled by both development stages and environmental factors. The rice LMMs exhibited higher numbers of spots under $45^{\circ}C$ temperature than those under $30^{\circ}C$. Contents of chlorophyll were drastically reduced at 60 days old LMM leaves when the spot formation was severe. The levels of endogenous hydrogen peroxide were highest at 45 days old mutants but reduced at 60 days old. Transcription levels of stress related genes including thioredoxin peroxidase and protein disulfide isomerase were reduced in spotted leaves than those of non spotted leaves. It could be suggested that scavenging system against reactive oxygen species induced by either stresses or innate metabolisms may not work properly in the rice LMMs. As these rice LMMs autonomously expressed clear lesions of lrd phenotype without pathogen infection, it could be useful to understand stresses responses in plants.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.604-612
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• 1999

A puc-deleted cell of Rhodobacter sphaeroides grows with a doubling time longer than 160 h under light-limiting photoheterotrophic (3 Watts [W]/㎡) conditions due to an absence of the peripheral light-harvesting B800-850 complex. A spontaneous fast-growing mutant, R. sphaeroides SK101, was isolated from the puc-deleted cells cultured photoheterotrophically at 3 W/㎡. This mutant grew with an approximately 40-h doubling time. The growth of the mutant, however, was indistinguishable from its parental strain during photoheterotrophic growth at 10 W/㎡ as well as during aerobic growth. The membrane of SK101 grown aerobically did not reveal the presence of any spectral complex, while the amounts of the B875 complex and photosynthetic pigments of SK101 grown anaerobiclly in the dark with dimethylsulfoxide (DMSO) were the same as those of the parental cell. These results indicate that the oxygen control of the photosynthetic complex formation remained unaltered in the mutant. The B875 complex of SK101 under light-limiting conditions was elevated by 20％ to 30％ compared with that of the parental cell, which reflected the parallel increase of the bacteriochlorophyll and carotenoid contents of the mutant. When the puc was restored in SK101, the B875 complex level remained unchanged, but that of the B800-850 complex increased. The mutated phenotype of SK101 was complemented with orfQ encoding a putative bacteriochlorophyll-mobilizing protein. Accordingly, it is proposed that the mutated OrfQ of SK101 should have an altered affinity towards the assembly factor specific to the most peripheral light-harvesting complex, which could be either the B875 or the B800-850 complex.

• Microbiology and Biotechnology Letters
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• v.19 no.5
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• pp.491-496
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• 1991

To maximize the production of aminoglycoside-3'-phosphotransferase of E. coli ATCC 21990 carrying R factor which encodes aminoglycoside-3'-phosphotransferase (APH(3')) phosphorylating the 3'-hydroxyl group of aminoglycoside, mutants M1 and M2, media composition and several factors affecting the enzyme production during fermentation were studied. Although the specific activity of APH(3') produced by a mutant M1 was increased as much as four times than that of E. coii ATCC 21990, the growth rate was decreased. The increase of the enzyme production was obtained by increased biomass during fermentation. A mutant M2 was obtained to increase the cell growth rate. Mutant M2 cells were cultivated with optimal media and pure oxygen gas in a fed-batch mode of fermentor operation. The specific activity of APH(3') was decreased, but total enzyme activity of APH(3') was increased as much as two point five times than that of mutant MI.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.1010-1012
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• 2002

In order to isolate carotenoid-hyperproducing yeast, low-dose gamma irradiation was used as means of mutagenesis. Phaffia rhodozyma was treated by gamma irradiation of less than 10 kGy, which is considered to be a wholesome irradiation condition established by the Food and Drug Administration. Through repeated rounds of gamma irradiation and visual screening, mutant 3A4-8 was obtained. It produced a $3,824{\mu}g$ carotenoid/g yeast, 69% higher content than $2,265{\mu}g/g$ yeast of the unirradiated one. This result indicates that low-dose gamma irradiation could be used as means of mutagenesis to obtain carotenoid-hyperproducing strain of Phaffia rhodozyma, since only carotenoid-hyperproducing yeast survived gamma irradiation by scavenging oxygen radicals generated by radiolysis of water.

• BMB Reports
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• v.47 no.1
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• pp.15-20
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• 2014

Intracellular lipid-binding proteins (LBPs) impact fatty acid homeostasis in various ways, including fatty acid transport into mitochondria. However, the physiological consequences caused by mutations in genes encoding LBPs remain largely uncharacterized. Here, we explore the metabolic consequences of lbp-5 gene deficiency in terms of energy homeostasis in Caenorhabditis elegans. In addition to increased fat storage, which has previously been reported, deletion of lbp-5 attenuated mitochondrial membrane potential and increased reactive oxygen species levels. Biochemical measurement coupled to proteomic analysis of the lbp-5(tm1618) mutant revealed highly increased rates of glycolysis in this mutant. These differential expression profile data support a novel metabolic adaptation of C. elegans, in which glycolysis is activated to compensate for the energy shortage due to the insufficient mitochondrial ${\beta}$-oxidation of fatty acids in lbp-5 mutant worms. This report marks the first demonstration of a unique metabolic adaptation that is a consequence of LBP-5 deficiency in C. elegans.

• Molecules and Cells
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• v.39 no.9
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• pp.680-686
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• 2016

Uncoupling proteins (UCPs) are mitochondrial inner membrane proteins that function to dissipate proton motive force and mitochondrial membrane potential. One UCP has been identified in Caenorhabditis elegans (C. elegans), namely UCP-4. In this study, we examined its expression and localization using a GFP marker in C. elegans. ucp-4 was expressed throughout the body from early embryo to aged adult and UCP-4 was localized in the mitochondria. It is known that increased mitochondrial membrane protential leads to a reactive oxygen species (ROS) increase, which is associated with age-related diseases, including neurodegenerative diseases in humans. A ucp-4 mutant showed increased mitochondrial membrane protential in association with increased neuronal defects during aging, and the neurons of ucp-4 overexpressing animals showed decreased neuronal defects during aging. These results suggest that UCP-4 may be involved in neuroprotection during aging via relieving mitochondrial membrane protential. We also investigated the relationship between UCP-4 and innate immunity because increased ROS can affect innate immunity. ucp-4 mutant displayed increased resistance to the pathogen Staphylococcus aureus compared to wild type. The enhanced immunity in the ucp-4 mutant could be related to increased mitochondrial membrane protential, presumably followed by increased ROS. In summary, UCP-4 might have an important role in neuronal aging and innate immune responses through mediating mitochondrial membrane protential.

• International Journal of Oral Biology
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• v.39 no.4
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• pp.207-213
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• 2014

Antimicrobial actions of reactive oxygen/nitrogen species (ROS/RNS) derived from products of NADPH oxidase and inducible nitric oxide (NO) synthase in host phagocytes inactivate various bacterial macromolecules. To cope with these cytotoxic radicals, pathogenic bacteria have evolved to conserve systems necessary for detoxifying ROS/RNS and repairing damages caused by their actions. In response to these stresses, bacteria also induce expression of molecular chaperones to aid in ameliorating protein misfolding. In this study, we explored the function of a newly identified chaperone Spy, that is localized exclusively in the periplasm when bacteria exposed to conditions causing spheroplast formation, in the resistance of Salmonella Typhimurium to ROS/RNS. A spy deletion mutant was constructed in S. Typhimurium by a PCR-mediated method of one-step gene inactivation with ${\lambda}$ Red recombinase, and subjected to ROS/RNS stresses. The spy mutant Salmonella showed a modest decrease in growth rate in NO-producing cultures, and no detectable difference of growth rate in $H_2O_2$ containing cultures, compared with that of wild type Salmonella. Quantitative RT-PCR analysis showed that spy mRNA levels were similar regardless of both stresses, but were increased considerably in Salmonella mutants lacking the flavohemoglobin Hmp, which are incapable of NO detoxification, and lacking an alternative sigma factor RpoS, conferring hypersusceptibility to $H_2O_2$. Results demonstrate that Spy expression can be induced under extreme conditions of both stresses, and suggest that the protein may have supportive roles in maintaining proteostasis in the periplasm where various chaperones may act in concert with Spy, thereby protecting bacteria against toxicities of ROS/RNS.