Myung Hee Nam

Korea Basic Science Institute KBSI, Sŏul, Seoul, South Korea

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Publications (25)91.35 Total impact

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    ABSTRACT: It was previously reported that the amounts of lysophosphatidylcholines (lysoPCs), which are naturally occurring bioactive lipid molecules, significantly increase following pathogen inoculation, as determined using ultraperformance liquid chromatography-quadrupole-time of flight/mass spectrometry analyses. Here, real-time quantitative RT-PCR was performed for the phospholipase A2 (PLA2) genes, Nt1PLA2 and Nt2PLA2, which are responsible for LysoPCs generation. The transcription level of Nt2PLA2 in pathogen-infected tobacco plants transiently peaked at 1h and 36h, whereas induction of Nt1PLA2 transcription peaked at 36h. A prominent biphasic ROS accumulation in lysoPC (C18:1(9Z))-treated tobacco leaves was also observed. Transcription of NtRbohD, a gene member of NADPH oxidase, showed biphasic kinetics upon lysoPC 18:1 treatment, as evidenced by an early transient peak in phase I at 1h and a massive peak in phase II at 12h. Each increase in NtACS2 and NtACS4 transcription, gene members of the ACC synthase family, was followed by biphasic peaks of ethylene production after lysoPC 18:1 treatment. This suggested that lysoPC (C18:1)-induced ethylene production was regulated at the transcriptional level of time-dependent gene members. LysoPC 18:1 treatment also rapidly induced cell damage. LysoPC 18:1-induced cell death was almost completely abrogated in ROS generation-impaired transgenic plants (rbohD-as and rbohF-as), ethylene production-impaired transgenic plants (CAS-AS and CAO-AS), and ethylene signaling-impaired transgenic plants (Ein3-AS), respectively. Taken together, pathogen-induced lysoPCs enhance pathogen susceptibility accompanied by ROS and ethylene biosynthesis, resulting in chlorophyll degradation and cell death. Expression of PR genes (PR1-a, PR-3, and PR-4b) and LOX3 was strongly induced in lysoPC 18:1-treated leaves, indicating the involvement of lysoPC 18:1 in the defense response. However, lysoPC 18:1 treatment eventually resulted in cell death, as evidenced by metacaspase gene expression. Therefore, a hypothesis is proposed that the antipathogenic potential of lysoPC 18:1 is dependent on how quickly it is removed from cells for avoidance of lysoPC toxicity.
    Phytochemistry 05/2014; · 3.05 Impact Factor
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    ABSTRACT: Arabidopsis GDSL lipase 1 (GLIP1) has been shown to modulate systemic immunity through the regulation of ethylene signaling components. Here we demonstrate that the constitutive triple response mutant ctr1-1 requires GLIP1 for the ethylene response, gene expression, and pathogen resistance. The glip1-1 mutant was defective in induced resistance following primary inoculation of necrotrophic pathogens, whereas GLIP1-overexpressing plants showed resistance to multiple pathogens. Necrotrophic infection triggered the downregulation of EIN3 and the activation of ERF1 and SID2 in a GLIP1-dependent manner. These results suggest that GLIP1 positively and negatively regulates ethylene signaling, resulting in an ethylene-associated, necrotroph-induced immune response.
    FEBS letters 03/2014; · 3.54 Impact Factor
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    ABSTRACT: Ethylene is a key signal in the regulation of plant defense responses. It is required for the expression and function of GDSL lipase 1 (GLIP1) in Arabidopsis thaliana, which plays an important role in plant immunity. Here we explore molecular mechanisms underlying the relationship between GLIP1 and ethylene signaling by an epistatic analysis of ethylene response mutants and GLIP1-overexpressing (35S:GLIP1) plants. We show that GLIP1 expression is regulated by ethylene signaling components and, further, that GLIP1 expression or application of petiole exudates from 35S:GLIP1 plants affects ethylene signaling both positively and negatively, leading to ERF1 activation and EIN3 downregulation, respectively. Additionally, 35S:GLIP1 plants or their exudates increase expression of the salicylic acid (SA) biosynthesis gene SID2, known to be inhibited by EIN3 and EIL1. These results suggest that GLIP1 regulates plant immunity through positive and negative feedback regulation of ethylene signaling, and this is mediated by its activity to accumulate a systemic signal(s) in the phloem. We propose a model explaining how GLIP1 regulates the fine-tuning of ethylene signaling and ethylene-SA crosstalk.
    Plant physiology 10/2013; · 6.56 Impact Factor
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    ABSTRACT: Reactive oxygen species (ROS) and ethylene play an important role in determining resistance or susceptibility of plant to pathogen attack. A previous study of the response of tobacco cultivar (Nicotiana tabacum L. cv Wisconsin 38) to a compatible hemibiotroph, Phytophthora parasitica var. nicotianae (Ppn), showed that biphasic bursts of reactive oxygen species (ROS) and ethylene are positively associated with disease severity. The levels of ethylene and ROS might influence the susceptibility of plant to pathogen, with changing the levels of metabolite related to disease resistance or susceptibility. In this study, to obtain more detailed information on the interaction of ROS and ethylene signaling related to resistance and/or susceptibility of plant to pathogen, we compared Ppn-induced metabolic profiles from wild type (WT) and ethylene signaling-impaired transgenic plants that expressed Ein3 antisense (Ein3-AS) using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Non-redundant mass ions (576 in ESI+ mode and 336 in ESI- mode) were selected, and 56 mass ions were identified based on their accurate mass ions and MS/MS spectra. Two-way hierarchical clustering analysis of the selected mass ions revealed that nicotine and phenylpropanoid-polyamine conjugates, such as caffeoyl-dihydrocaffeoyl-spermidine, dicaffeoyl-spermidine, caffeoyl-feruloyl-spermidine and two bis(dihydrocaffeoyl)-spermine isomers, and their intermediates, such as arginine and putrecine, were present at lower levels in Ein3-AS transgenic plants during Ppn-interaction than in WT, whereas galactolipid and oxidized free fatty acid levels were higher in Ein3-AS transgenic plants. Taken together, these results reveal a function for ethylene signaling in tobacco defense responses during Ppn-interaction.
    Journal of Agricultural and Food Chemistry 07/2013; · 3.11 Impact Factor
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    ABSTRACT: Pre-harvest sprouting (PHS) in rice causes poor grain quality and results in significant reductions in yield, leading to significant economic losses. In contrast, deep dormancy can lead to equally unwanted non-uniform germination. Therefore, a suitable level of dormancy is a critically important agronomic trait. In this study, an analysis of PHS in developing seeds of two Korean rice cultivars (vivipary), Gopum and Samgwang, revealed differences in dormancy in caryopses at 25 d after heading (DAH). To assess the transcriptomic characteristics associated with vivipary, we compared RNA profiles at early (3-6 DAH), middle (25 DAH), and late (40 DAH) developmental stages. Transcriptomic differentiation was most pronounced in caryopses at 25 DAH, the developmental stage at which differential dormancy was also the most prominent. A k-means clustering analysis of the two cultivars revealed groups of genes with similar or dissimilar expression profiles. Many of the genes that showed distinct differential expression profiles were those involved in seed maturation. Intriguingly, differential gene expression levels between the two cultivars were positively correlated with fold-changes in their expression during the early half of caryopsis development. This implies that the establishment of seed dormancy is strongly correlated with the altered transcriptomic patterns related to the progression of maturation. Our global RNA profiling suggests that caryopsis development in Gopum proceeds at a greater speed than in the Samgwang cultivar. Thus, a high degree of maturity and early dormancy release may be present in 25 DAH caryopses of Gopum, although we cannot exclude the possibility of genetic defects modifying dormancy. The comparative transcriptomic analysis of the two cultivars did not reveal noticeable differences in RNA profiles with respect to differences in abscisic acid (ABA) content or ABA sensitivity. Therefore, it is unlikely that ABA is directly involved in the differences in dormancy observed between the two cultivars.
    Journal of plant physiology 04/2013; · 2.50 Impact Factor
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    ABSTRACT: A biphasic reactive oxygen species (ROS) production has previously been observed in tobacco at 1 and 48 h after inoculation with the hemibiotrophic compatible pathogen, Phytophthora parasitica var. nicotianae (Ppn). To characterize the response of tobacco to biphasically produced ROS concerning the propagation of Ppn, ultraperformance liquid chromatography–quadrupole–time of flight/ mass spectrometry (UPLC-Q-TOF/MS) based metabolic profiling combined with multivariate statistical analysis was performed. Among the nonredundant 355 mass ions in ESI+ mode and 345 mass ions in ESI– mode that were selected as significantly changed by Ppn inoculation (|p(corr)| > 0.6 on S-plot of orthogonal partial least-squares discriminant analysis (OPLS-DA), fold-change > 2, and p < 0.05 in the independent two-sample t test), 76 mass ions were identified on the basis of their accurate mass ions and MS/MS spectra. Phenolic amino acids, phenylpropanoids, hydroxycinnamic acid amides, linoleic acid, linolenic acid, lysophospholipids, glycoglycerolipids, and trioxidized phospholipids were identified as having changed after Ppn inoculation. On the basis of their quantitative changes, the metabolic responses occurring at each phase of ROS production after Ppn inoculation were investigated in this study.
    Journal of Agricultural and Food Chemistry 11/2012; · 3.11 Impact Factor
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    ABSTRACT: A biphasic reactive oxygen species (ROS) production has previously been observed in tobacco at 1 and 48 h after inoculation with the hemibiotrophic compatible pathogen, Phytophthora parasitica var. nicotianae (Ppn). To characterize the response of tobacco to biphasically produced ROS concerning the propagation of Ppn, ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) based metabolic profiling combined with multivariate statistical analysis was performed. Among the non-redundant 355 mass ions in ESI+ mode and 345 mass ions in ESI- mode that were selected as significantly changed by Ppn inoculation (|p(corr)|>0.6 on S-plot of orthogonal partial least discriminant analysis (OPLS-DA), fold-change > 2, and p < 0.05 in the independent two-sample t-test), 76 mass ions were identified based on their accurate mass ions and MS/MS spectra. Phenolic amino acids, phenylpropanoids, hydroxycinnamic acid amides, linoleic acid, linolenic acid, lysophospholipids, glycoglycerolipids, and trioxidized phospholipids were identified as having changed after Ppn inoculation. Based on their quantitative changes, the metabolic responses occurring at each phase of ROS production after Ppn inoculation were investigated in this study.
    Journal of Agricultural and Food Chemistry 10/2012; · 3.11 Impact Factor
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    ABSTRACT: The rice roots are highly salt-sensitive organ and primary root growth is rapidly suppressed by salt stress. Sucrose nonfermenting 1-related protein kinase2 (SnRK2) family is one of the key regulator of hyper-osmotic stress signalling in various plant cells. To understand early salt response of rice roots and identify SnRK2 signaling components, proteome changes of transgenic rice roots over-expressing OSRK1, a rice SnRK2 kinase were investigated. Proteomes were analyzed by two-dimensional electrophoresis and protein spots were identified by LC-MS/MS from wild type and OSRK1 transgenic rice roots exposed to 150 mM NaCl for either 3 h or 7 h. Fifty two early salt -responsive protein spots were identified from wild type rice roots. The major up-regulated proteins were enzymes related to energy regulation, amino acid metabolism, methylglyoxal detoxification, redox regulation and protein turnover. It is noted that enzymes known to be involved in GA-induced root growth such as fructose bisphosphate aldolase and methylmalonate semialdehyde dehydrogenase were clearly down-regulated. In contrast to wild type rice roots, only a few proteins were changed by salt stress in OSRK1 transgenic rice roots. A comparative quantitative analysis of the proteome level indicated that forty three early salt-responsive proteins were magnified in transgenic rice roots at unstressed condition. These proteins contain single or multiple potential SnRK2 recognition motives. In vitro kinase assay revealed that one of the identified proteome, calreticulin is a good substrate of OSRK1. Our present data implicate that rice roots rapidly changed broad spectrum of energy metabolism upon challenging salt stress, and suppression of GA signaling by salt stress may be responsible for the rapid arrest of root growth and development. The broad spectrum of functional categories of proteins affected by over-expression of OSRK1 indicates that OSRK1 is an upstream regulator of stress signaling in rice roots. Enzymes involved in glycolysis, branched amino acid catabolism, dnaK-type molecular chaperone, calcium binding protein, Sal T and glyoxalase are potential targets of OSRK1 in rice roots under salt stress that need to be further investigated.
    Proteome Science 03/2012; 10:25. · 2.42 Impact Factor
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    ABSTRACT: Pine wilt disease (PWD) is one of the most devastating forest diseases in Asia and Europe. The pine wood nematode, Bursaphelenchus xylophilus, has been identified as the pathogen underlying PWD, although the pathology is not completely understood. At present, diagnosis and confirmation of PWD are time consuming tasks that require nematode extraction and microscopic examination. To develop a more efficient detection method for B. xylophilus, we first generated monoclonal antibodies (MAbs) specific to B. xylophilus. Among 2304 hybridoma fusions screened, a hybridoma clone named 3-2A7-2H5 recognized a single protein from B. xylophilus specifically, but not those from other closely related nematodes. We finally selected the MAb clone 3-2A7-2H5-D9-F10 (D9-F10) for further studies. To identify the antigenic target of MAb-D9-F10, we analyzed proteins in spots, fractions, or bands isolated from SDS-PAGE, two-dimensional electrophoresis, anion exchange chromatography, and immunoprecipitation via nano liquid chromatography electrospray ionization quadrupole ion trap mass spectrometry (nano-LC-ESI-Q-IT-MS). Peptides of galactose-binding lectin-1 of B. xylophilus (Bx-LEC-1) were commonly detected in several proteomic analyses, demonstrating that this LEC-1 is the antigenic target of MAb-D9-F10. The localization of MAb-D9-F10 immunoreactivities at the area of the median bulb and esophageal glands suggested that the Bx-LEC-1 may be involved in food perception and digestion. The Bx-LEC-1 has two nonidentical galactose-binding lectin domains important for carbohydrate binding. The affinity of the Bx-LEC-1 to D-(+)-raffinose and N-acetyllactosamine were much higher than that to L-(+)-rhamnose. Based on this combination of evidences, MAb-D9-F10 is the first identified molecular biomarker specific to the Bx-LEC-1.
    Molecular &amp Cellular Proteomics 02/2011; 10(2):M900521-MCP200. · 7.25 Impact Factor
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    ABSTRACT: To investigate the molecular and cellular pathogenesis underlying myocarditis, we used an experimental autoimmune myocarditis (EAM)-induced heart failure rat model that represents T cell mediated postinflammatory heart disorders. By performing unbiased 2-dimensional electrophoresis of protein extracts from control rat heart tissues and EAM rat heart tissues, followed by nano-HPLC-ESI-QIT-MS, 67 proteins were identified from 71 spots that exhibited significantly altered expression levels. The majority of up-regulated proteins were confidently associated with unfolded protein responses (UPR), while the majority of down-regulated proteins were involved with the generation of precursor metabolites and energy metabolism in mitochondria. Although there was no difference in AKT signaling between EAM rat heart tissues and control rat heart tissues, the amounts and activities of extracellular signal-regulated kinase (ERK)-1/2 and ribosomal protein S6 (rpS6) were significantly increased. By comparing our data with the previously reported myocardial proteome of the Coxsackie viruses of group B (CVB)-mediated myocarditis model, we found that UPR-related proteins were commonly up-regulated in two murine myocarditis models. Even though only two out of 29 down-regulated proteins in EAM rat heart tissues were also dysregulated in CVB-infected rat heart tissues, other proteins known to be involved with the generation of precursor metabolites and energy metabolism in mitochondria were also dysregulated in CVB-mediated myocarditis rat heart tissues, suggesting that impairment of mitochondrial functions may be a common underlying mechanism of the two murine myocarditis models. UPR, ERK-1/2 and S6RP signaling were activated in both EAM- and CVB-induced myocarditis murine models. Thus, the conserved components of signaling pathways in two murine models of acute myocarditis could be targets for developing new therapeutic drugs or methods aimed at treating enigmatic myocarditis.
    BMC Genomics 01/2011; 12:520. · 4.40 Impact Factor
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    ABSTRACT: Human papilloma virus (HPV) 16 causes cervical cancer. Induction of oncogenesis by HPV 16 is primarily dependent on the function of E6 and E7 proteins, which inactivate the function of p53 and pRB, respectively. Thus, blocking the activity of the E6 and E7 proteins from HPV 16 is critical to inhibiting oncogenesis during infection. We have expressed and purified soluble HPV 16 E6 and E7 fusion immunoglobulin (Ig), which were combined with the constant region of an Ig heavy chain, in a mammalian system. To assess whether soluble E6 and E7 fusion Igs induce effective cellular immune responses, immature dendritic cells (DCs) were treated with these fusion proteins. Soluble E6 and E7 fusion Igs effectively induced maturation of DCs. Furthermore, immunization with soluble E6 and E7 fusion Igs in mice resulted in antigen-specific activation of T helper 1 (Th1) cells. This is the first comprehensive study to show the molecular basis of how soluble HPV 16 E6 or E7 fusion Igs induces Th1 responses through the maturation of DCs. In addition, we show that DC therapy using soluble HPV E6 and E7 fusion Igs may be a valuable tool for controlling the progress of cervical cancer.
    Biotechnology Letters 12/2010; 33(4):663-71. · 1.85 Impact Factor
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    ABSTRACT: OREB1 is a rice ABRE binding factor characterized by the presence of multiple highly-conserved phosphorylation domains (C1, C2, C3, and C4) and two kinase recognition motifs, RXXS/T and S/TXXE/D, within different functional domains. An in vitro kinase assay showed that OREB1 is phosphorylated not only by the SnRK2 kinase, but also by other Ser/Thr protein kinases, such as CaMKII, CKII, and SnRK3. Furthermore, the N-terminal phosphorylation domain C1 was found to be differentially phosphorylated by the SnRK2/SnRK3 kinase and by hyperosmotic/cold stress, suggesting that the C1 domain may function in decoding different signals. The phosphorylation-mediated regulation of OREB1 activity was investigated through mutation of the SnRK2 recognition motif RXXS/T within each phosphorylation module. OREB1 contains a crucial nine-amino acid transactivation domain located near the phosphorylation module C1. Deletion of the C1 domain increased OREB1 activity, whereas mutation of Ser 44, Ser 45, and Ser 48 of the C1 domain to aspartates decreased OREB1 activity. In the C2 domain, a double mutation of Ser 118 and Ser 120 to alanines suppressed OREB1 activity. These findings strongly suggest that selective phosphorylation of the C1 or C2 modules may positively or negatively regulate OREB1 transactivation. In addition, mutation of Ser 385 of the C4 domain to alanines completely abolished the interaction between OREB1 and a rice 14-3-3 protein, GF14d, suggesting that SnRK2-mediated phosphorylation may regulate this interaction. These results indicate that phosphorylation domains of OREB1 are not functionally redundant and regulate at least three different functions, including transactivation activity, DNA binding, and protein interactions. The multisite phosphorylation of OREB1 is likely a key for the fine control of its activity and signal integration in the complex stress signaling network of plant cells.
    Phytochemistry 11/2010; 72(1):27-36. · 3.05 Impact Factor
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    ABSTRACT: In this study, various solvent systems were applied to obtain a high and consistent recovery rate of low molecular weight plasma proteins (LMPP) from human plasma. A buffer system containing 7 M urea, 2 M thiourea, 25 mM NH(4)HCO(3) + 20% ACN (pH 8.2) produced the highest recovery rate of LMPP. To validate the recovery of cut off membrane (COM) obtained using the urea buffer system, 27 different 30 kDa COMs were used to prepare the LMPP sample which were then subjected to 1-D SDS-PAGE. Statistical analysis showed that the buffer system with COM produced a consistent the recovery of LMPP. In addition, 2-DE analysis was also conducted to determine the relative intensity of each protein spot. When molecular weight ranges over 30 kDa and under 30 kDa were evaluated, 953 and 587 protein spots were observed in the gels, respectively, resulting in a total of 1540 protein spots being resolved. Identification of the major proteins were then performed using a nano-LC/MS system comprised of an HPLC system and an ESI-quadrupole IT MS equipped with a nano-ESI source.
    Proteomics 05/2009; 9(7):1827-40. · 4.43 Impact Factor
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    ABSTRACT: Systemic resistance is induced by necrotizing pathogenic microbes and non-pathogenic rhizobacteria and confers protection against a broad range of pathogens. Here we show that Arabidopsis GDSL LIPASE-LIKE 1 (GLIP1) plays an important role in plant immunity, eliciting both local and systemic resistance in plants. GLIP1 functions independently of salicylic acid but requires ethylene signaling. Enhancement of GLIP1 expression in plants increases resistance to pathogens including Alternaria brassicicola, Erwinia carotovora and Pseudomonas syringae, and limits their growth at the infection site. Furthermore, local treatment with GLIP1 proteins is sufficient for the activation of systemic resistance, inducing both resistance gene expression and pathogen resistance in systemic leaves. The PDF1.2-inducing activity accumulates in petiole exudates in a GLIP1-dependent manner and is fractionated in the size range of less than 10 kDa as determined by size exclusion chromatography. Our results demonstrate that GLIP1-elicited systemic resistance is dependent on ethylene signaling and provide evidence that GLIP1 may mediate the production of a systemic signaling molecule(s).
    The Plant Journal 01/2009; 58(2):235-45. · 6.58 Impact Factor
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    ABSTRACT: To explore the effects of power frequency magnetic fields (MF) on cell growth in prostate cancer, DU145, PC3, and LNCaP cells were examined in vitro. The cells were exposed to various intensities and durations of 60-Hz sinusoidal MF in combination with various serum concentrations in the media. To analyze MF effects on cell growth, cell counting, trypan blue exclusion assay, Western blot analysis, flow cytometry, enzyme-linked immunosorbent assay (ELISA), semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), fluorescence microscopy, and spectrofluorometry were used. MF exposure induced significant cell growth inhibition and apoptosis in an intensity- and time-dependent manner, in which cell cycle arrest, cleaved Caspase-3, and reactive oxygen species (ROS) increased. Pretreatment with a Caspase-3 inhibitor or antioxidant, N-acetyl-L-cysteine (NAC), significantly attenuated MF-induced cell growth inhibition and cell death. Media replacement experiments failed to show any notable change in the MF effects. These results demonstrate 60-Hz sinusoidal MF-activated cell growth inhibition of prostate cancer in vitro. Apoptosis together with cell cycle arrest were the dominant causes of the MF-elicited cell growth inhibition, mediated by MF-induced ROS. These results suggest that a possibility of using 60-Hz MF in radiation therapy of prostate cancer could usefully be investigated.
    International Journal of Radiation Biology 12/2008; 84(11):945-55. · 1.84 Impact Factor
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    ABSTRACT: Conventional antimicrobial activity analyses such as the broth dilution method and disk diffusion test are considerably demanding processes for new antimicrobial agent discovery and sensitive diagnosis of infectious diseases. Here, we developed a new antimicrobial activity analysis system using CE-based SSCP (CE-SSCP) combined with 16S rRNA gene-specific PCR (PCR/CE-SSCP). Using this method, the population change in the microbial community in response to specific antimicrobial agents could be quantified with a high sensitivity and accuracy from a small sample amount. Using a mixture of microorganisms comprising Escherichia coli, Corynebacterium glutamicum, Acinetobacter calcoaceticus, and Staphylococcus aureus as a model system, the linear correlation between the genomic DNA concentrations and peak areas in 16S rRNA gene-specific PCR/CE-SSCP was determined; consequently, quantification of cell concentrations could be demonstrated using this method. Compared to the minimum inhibitory concentration (MIC) values from the conventional broth dilution method, this new system provided almost the same MIC values for popular antimicrobial agents such as kanamycin, spectinomycin, and streptomycin. The results demonstrated that the newly developed method can be a substitute for the conventional antimicrobial analysis method and highlighted its high potential in the areas of new antimicrobial agent discovery and clinical diagnosis.
    Electrophoresis 08/2007; 28(14):2416-23. · 3.26 Impact Factor
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    ABSTRACT: Although many reports have been published regarding the pharmacological effects of ginseng, little is known about the biochemical pathways operant in ginsenoside biosynthesis, or the genes involved therein. Proteomics analysis is an approach to elucidate the physiological characteristics and biosynthetic pathways of ginsenosides, main components of ginseng. In this review, we introduced the recent progress in proteomics studies of ginseng (Panax ginseng C.A. Meyer). We briefly reference the genomic analyses of P. ginseng, without which proteomics approaches would have been impossible. Functional genomics studies regarding secondary metabolism in P. ginseng are also introduced here, in order to introduce possible future prospects for further study.
    Journal of Chromatography B 03/2005; 815(1-2):147-55. · 2.49 Impact Factor
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    ABSTRACT: Rhodococcus sp. strain DK17 is able to grow on o-xylene, benzene, toluene, and ethylbenzene. DK17 harbors at least two megaplasmids, and the genes encoding the initial steps in alkylbenzene metabolism are present on the 330-kb pDK2. The genes encoding alkylbenzene degradation were cloned in a cosmid clone and sequenced completely to reveal 35 open reading frames (ORFs). Among the ORFs, we identified two nearly exact copies (one base difference) of genes encoding large and small subunits of an iron sulfur protein terminal oxygenase that are 6 kb apart from each other. Immediately downstream of one copy of the dioxygenase genes (akbA1a and akbA2a) is a gene encoding a dioxygenase ferredoxin component (akbA3), and downstream of the other copy (akbA1b and akbA2b) are genes putatively encoding a meta-cleavage pathway. RT-PCR experiments show that the two copies of the dioxygenase genes are operonic with the downstream putative catabolic genes and that both operons are induced by o-xylene. When expressed in Escherichia coli, AkbA1a-AkbA2a-AkbA3 transformed o-xylene into 2,3- and 3,4-dimethylphenol. These were apparently derived from an unstable o-xylene cis-3,4-dihydrodiol, which readily dehydrates. This indicates a single point of attack of the dioxygenase on the aromatic ring. In contrast, attack of AkbA1a-AkbA2a-AkbA3 on ethylbenzene resulted in the formation of two different cis-dihydrodiols resulting from an oxidation at the 2,3 and the 3,4 positions on the aromatic ring, respectively.
    Applied and Environmental Microbiology 01/2005; 70(12):7086-92. · 3.95 Impact Factor
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    ABSTRACT: Psychrophilicity of Gram-positive bacterium, Bacillus psychrosaccharolyticus was investigated in a proteomic approach. One hundred and thirty-one protein spots were analyzed by electrospray ionization-quadrupole-time of flight-tandem mass spectrometry and identified using an unpublished translated contig database as well as a nonredundant Gram-positive bacteria protein database from NCBI because of the lack of a genome sequence of this organism. Results focused on proteomic behavior of cold-response show that global up-regulation of metabolic functions and protective mechanism by stress responses might play a major role in psychrophilicity of B. psychrosaccharolyticus.
    PROTEOMICS 12/2004; 4(11):3654-9. · 4.13 Impact Factor
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    ABSTRACT: We used two-dimensional electrophoresis (2-DE) and other proteomic approaches to identify proteins expressed in suspension-cultured rice cells in response to the rice blast fungus, Magnaporthe grisea. Proteins were extracted from suspension-cultured cells at 24 and 48 h after rice blast fungus inoculation or treatment with elicitor or other signal molecules such as jasmonic acid (JA), salicylic acid, and H(2)O(2). The proteins were then polyethylene glycol fractionated before separation by 2-DE. Fourteen protein spots were induced or increased by the treatments, which we analyzed by N-terminal or internal amino acid sequencing. Twelve proteins from six different genes were identified. Rice pathogen-related protein class 10 (OsPR-10), isoflavone reductase like protein, beta-glucosidase, and putative receptor-like protein kinase were among those induced by rice blast fungus; these have not previously been reported in suspension-cultured rice cells. Six isoforms of probenazole-inducible protein (PBZ1) and two isoforms of salt-induced protein (SalT) that responded to blast fungus, elicitor, and JA were also resolved on a 2-DE gel and identified by proteome analysis. The expression level of these induced proteins both in suspension-cultured cells and in leaves of whole plants was analyzed by Western blot. PBZ1, OsPR-10, and SalT proteins from incompatible reactions were induced earlier and to a greater extent than those in compatible reactions. Proteome analysis can thus distinguish differences in the timing and amount of protein expression induced by pathogens and other signal molecules in incompatible and compatible interactions.
    PROTEOMICS 01/2004; 3(12):2368-78. · 4.13 Impact Factor

Publication Stats

384 Citations
91.35 Total Impact Points

Institutions

  • 2002–2014
    • Korea Basic Science Institute KBSI
      • Division of Magnetic Resonance Research
      Sŏul, Seoul, South Korea
  • 2010–2013
    • National Academy of Agricultural Science (South Korea)
      Sŏul, Seoul, South Korea
  • 2009
    • Korea University
      Sŏul, Seoul, South Korea
  • 2005
    • Rutgers, The State University of New Jersey
      • School of Environmental and Biological Sciences
      New Brunswick, New Jersey, United States