Song-Gun Kim

Korea Research Institute of Bioscience and Biotechnology KRIBB, Anzan, Gyeonggi Province, South Korea

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Publications (24)67.34 Total impact

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    ABSTRACT: A polyphasic taxonomic study was performed on a Gram-negative, aerobic, non-motile, non-spore-forming, rod-shaped bacterium, designated strain PB156(T), isolated from grass soil. Comparative 16S rRNA gene sequence studies showed the isolate was clearly affiliated with the phylum Bacteroidetes, and most closely related to Hymenobacter soli PB17(T), Hymenobacter antarcticus VUG-A42aa(T), and Hymenobacter glaciei VUG-A130(T) showing 96.4 %, 96.2 %, and 95.9% 16S rRNA gene sequence similarities, respectively, while all other species of the genus share only 89.3-95.2% similarity. The main polyamine present was sym-homospermidine. The predominant menaquinone was MK-7. The major fatty acids were C15:0 iso, summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), C16:1 ω5c, and C15:0 anteiso. The G+C content of the genomic DNA of strain PB156(T) was 61.7 mol%. The combined genotypic and phenotypic data supported the conclusion that strain PB156(T) represents a novel species of the genus Hymenobacter, for which the name Hymenobacter ruber sp. nov. is proposed. The type strain is PB156(T) (=KCTC 32477(T) =JCM 19433(T)).
    INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 12/2013; · 2.11 Impact Factor
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    ABSTRACT: Here, we isolated and characterized a new ginsenoside-transforming β-glucosidase (BglQM) from Mucilaginibacter sp. QM49 that shows biotransformation activity for various major ginsenosides. The gene responsible for this activity, bglQM, consists of 2,346 bp, and is predicted to encode 781 amino acid residues and this enzyme has a molecular mass of 85.6 kDa. Sequence analysis of BglQM revealed that it could be classified into glycoside hydrolase family 3. The enzyme was overexpressed in Escherichia coli BL21(DE3) using a MBP-fused pMAL-c2x (TEV) vector system. Overexpressed recombinant BglQM could efficiently transform the protopanaxatriol-type ginsenosides, Re and Rg1, into Rg2(S) and Rh1(S), respectively, by hydrolyzing one glucose moiety attached to the C20 position at pH 8.0 and 30°C. The Km values for p-nitrophenyl-β-d-glucopyranoside, Re and Rg1 were 37.0 ± 0.4 μM, 3.22 ± 0.15 and 1.48 ± 0.09 mM, and the Vmax values were 33.4 ± 0.6 μmol min(-1) mg(-1) of protein, 19.2 ± 0.2 and 28.8 ± 0.27 nmol min(-1) mg(-1) of protein, respectively. A crude protopanaxatriol-type ginsenoside mixture (PPTGM) was treated with BglQM followed by silica column purification to produce Rh1(S) and Rg2(S) at chromatographic purities of 98±0.5% and 97±1.2%, respectively. This is the first report of gram-scale production of Rh1(S) and Rg2(S) from PPTGM using a novel ginsenoside-transforming β-glucosidase of glycoside hydrolase family 3.
    Applied and Environmental Microbiology 06/2013; · 3.95 Impact Factor
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    ABSTRACT: A novel α-L-arabinofuranosidase (Abf22-3) that could biotransform ginsenoside Rc into Rd was obtained from the ginsenoside converting Leuconostoc sp. strain 22-3, isolated from the Korean fermented food kimchi. The gene, termed abf22-3, consisting of 1,527 bp and encoding a protein with a predicted molecular mass of 58,486 Da was cloned into the pMAL-c2x (TEV) vector. A BLAST search using the Abf22-3's amino acid sequence revealed significant homology to that of family 51 glycoside hydrolases. The over-expressed recombinant Abf22-3 in Escherichia coli BL21 (DE3) catalyzed the hydrolysis of the arabinofuranoside moiety attached to the C-20 position of ginsenoside Rc under optimal conditions of pH 6.0 and 30 °C. This result indicated that Abf22-3 selectively converts ginsenoside Rc into Rd, but did not catalyze the hydrolysis of glucopyranosyl groups from Rc or other ginsenosides such as Rb(1) and Rb(2). Over-expressed recombinant enzymes were purified by two steps with amylose-affinity and DEAE-cellulose chromatography and then characterized. The kinetic parameters for α-L-arabinofuranosidase showed apparent K(m) and V(max) values of 0.95 ± 0.02 μM and 1.2 ± 0.1 μmol min(-1) mg of protein(-1) against p-nitrophenyl-α-L-arabinofuranoside, respectively. Using a purified MBP-Abf22-3 (10 μg/ml), 0.1 % of ginsenoside Rc was completely converted to ginsenoside Rd within 20 min.
    Antonie van Leeuwenhoek 12/2012; · 2.07 Impact Factor
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    ABSTRACT: The molecular basis of fructose-2,6-bisphosphatase (F-2,6-P(2)ase) of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB) was investigated using the crystal structures of the human inducible form (PFKFB3) in a phospho-enzyme intermediate state (PFKFB3-P•F-6-P), in a transition state-analogous complex (PFKFB3•AlF(4)), and in a complex with pyrophosphate (PFKFB3•PP(i)) at resolutions of 2.45, 2.2, and 2.3 Å, respectively. Trapping the PFKFB3-P•F-6-P intermediate was achieved by flash cooling the crystal during the reaction, and the PFKFB3•AlF(4) and PFKFB3•PP(i) complexes were obtained by soaking. The PFKFB3•AlF(4) and PFKFB3•PP(i) complexes resulted in removing F-6-P from the catalytic pocket. With these structures, the structures of the Michaelis complex and the transition state were extrapolated. For both the PFKFB3-P formation and break down, the phosphoryl donor and the acceptor are located within ~5.1 Å, and the pivotal point 2-P is on the same line, suggesting an "in-line" transfer with a direct inversion of phosphate configuration. The geometry suggests that NE2 of His253 undergoes a nucleophilic attack to form a covalent N-P bond, breaking the 2O-P bond in the substrate. The resulting high reactivity of the leaving group, 2O of F-6-P, is neutralized by a proton donated by Glu322. Negative charges on the equatorial oxygen of the transient bipyramidal phosphorane formed during the transfer are stabilized by Arg252, His387, and Asn259. The C-terminal domain (residues 440-446) was rearranged in PFKFB3•PP(i), implying that this domain plays a critical role in binding of substrate to and release of product from the F-2,6-P(2) ase catalytic pocket. These findings provide a new insight into the understanding of the phosphoryl transfer reaction.
    Proteins Structure Function and Bioinformatics 04/2012; 80(4):1143-53. · 3.34 Impact Factor
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    ABSTRACT: The effects of the sonication parameters, including the power and time, were investigated for the effective isolation of Scenedesmus sp. from environmental microalgae communities when using fluorescence-activated cell sorting (FACS). The selectivity, defined as the percentage of Scenedesmus sp. successfully isolated and grown in microplates, appeared as peaks in contour plots spanned by the sonication power and time. For fast screening of the optimal sonication conditions, correlations between the selectivity and the statistical parameters from the FACS analysis were investigated. A graphical comparison analysis of the contour plots showed a pattern similarity of over 82% between the coefficients of variation for the side scatter (SSC-CV) and the selectivity. This predictability of the optimal sonication conditions enabled a Scenedesmus sp. selectivity of ca. 2 times using only one-third of the sonication condition sets arbitrarily chosen around the peaks of the SSC-CV, thereby saving resources and time for subsequent processes.
    Bioresource Technology 03/2012; 114:478-83. · 5.04 Impact Factor
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    ABSTRACT: A novel beta-proteobacterium, designated BXN5-27(T), was isolated from soil of a ginseng field of Baekdu Mountain in China, and was characterized using a polyphasic approach. The strain was Gram-staining-negative, aerobic, motile, non-spore-forming, and rod shaped. Strain BXN5-27(T) exhibited beta-glucosidase activity that was responsible for its ability to transform ginsenoside Rb₁ (one of the dominant active components of ginseng) to compound Rd. Phylogenetic analysis based on 16S rRNA gene sequences showed that this strain belonged to the family Comamonadaceae; it was most closely related to Ramlibacter henchirensis TMB834(T) and Ramlibacter tataouinensis TTB310(T) (96.4% and 96.3% similarity, respectively). The G+C content of the genomic DNA was 68.1%. The major menaquinone was Q-8. The major fatty acids were C₁₆:₀, summed feature 4 (comprising C₁₆:₁ omega7c and/or iso-C₁₅:₀ 2OH), and C₁₇:₀ cyclo. Genomic and chemotaxonomic data supported the affiliation of strain BXN5-27(T) to the genus Ramlibacter. However, physiological and biochemical tests differentiated it phenotypically from the other established species of Ramlibacter. Therefore, the isolate represents a novel species, for which the name Ramlibacter ginsenosidimutans sp. nov. is proposed, with the type strain being BXN5-27(T) (= DSM 23480(T) = LMG 24525(T) = KCTC 22276(T)).
    Journal of Microbiology and Biotechnology 03/2012; 22(3):311-5. · 1.40 Impact Factor
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    ABSTRACT: In this paper, the kinetics of a cloned special glucosidase, named ginsenosidase type III hydrolyzing 3-O-glucoside of multi-protopanaxadiol (PPD)-type ginsenosides, were investigated. The gene (bgpA) encoding this enzyme was cloned from a Terrabacter ginsenosidimutans strain and then expressed in E. coli cells. Ginsenosidase type III was able to hydrolyze 3-O-glucoside of multi-PPD-type ginsenosides. For instance, it was able to hydrolyze the 3-O-β-D-(1-->2)-glucopyranosyl of Rb1 to gypenoside XVII, and then to further hydrolyze the 3-O-β-D-glucopyranosyl of gypenoside XVII to gypenoside LXXV. Similarly, the enzyme could hydrolyze the glucopyranosyls linked to the 3-O- position of Rb2, Rc, Rd, Rb3, and Rg3. With a larger enzyme reaction Km value, there was a slower enzyme reaction speed; and the larger the enzyme reaction Vmax value, the faster the enzyme reaction speed was. The Km values from small to large were 3.85 mM for Rc, 4.08 mM for Rb1, 8.85 mM for Rb3, 9.09 mM for Rb2, 9.70 mM for Rg3(S), 11.4 mM for Rd and 12.9 mM for F2; and Vmax value from large to small was 23.2 mM/h for Rc, 16.6 mM/h for Rb1, 14.6 mM/h for Rb3, 14.3 mM/h for Rb2, 1.81mM/h for Rg3(S), 1.40 mM/h for Rd, and 0.41 mM/h for F2. According to the Vmax and Km values of the ginsenosidase type III, the hydrolysis speed of these substrates by the enzyme was Rc>Rb1>Rb3>Rb2>Rg3(S)>Rd>F2 in order.
    Journal of Microbiology and Biotechnology 03/2012; 22(3):343-51. · 1.40 Impact Factor
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    ABSTRACT: The gene encoding an α-L-arabinofuranosidase that could biotransform ginsenoside Rc {3-O-[β-D-glucopyranosyl-(1-2)-β-D-glucopyranosyl]-20-O-[α-L-arabinofuranosyl-(1-6)-β-D-glucopyranosyl]-20(S)-protopanaxadiol} to ginsenoside Rd {3-O-[β-D-glucopyranosyl-(1-2)-β-D-glucopyranosyl]-20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol} was cloned from a soil bacterium, Rhodanobacter ginsenosidimutans strain Gsoil 3054(T), and the recombinant enzyme was characterized. The enzyme (AbfA) hydrolyzed the arabinofuranosyl moiety from ginsenoside Rc and was classified as a family 51 glycoside hydrolase based on amino acid sequence analysis. Recombinant AbfA expressed in Escherichia coli hydrolyzed non-reducing arabinofuranoside moieties with apparent K (m) values of 0.53 ± 0.07 and 0.30 ± 0.07 mM and V (max) values of 27.1 ± 1.7 and 49.6 ± 4.1 μmol min(-1) mg(-1) of protein for p-nitrophenyl-α-L-arabinofuranoside and ginsenoside Rc, respectively. The enzyme exhibited preferential substrate specificity of the exo-type mode of action towards polyarabinosides or oligoarabinosides. AbfA demonstrated substrate-specific activity for the bioconversion of ginsenosides, as it hydrolyzed only arabinofuranoside moieties from ginsenoside Rc and its derivatives, and not other sugar groups. These results are the first report of a glycoside hydrolase family 51 α-L-arabinofuranosidase that can transform ginsenoside Rc to Rd.
    Applied Microbiology and Biotechnology 12/2011; 94(3):673-82. · 3.69 Impact Factor
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    ABSTRACT: A new β-glucosidase gene (bglSp) was cloned from the ginsenoside converting Sphingomonas sp. strain 2F2 isolated from the ginseng cultivating filed. The bglSp consisted of 1344 bp (447 amino acid residues) with a predicted molecular mass of 49,399 Da. A BLAST search using the bglSp sequence revealed significant homology to that of glycoside hydrolase superfamily 1. This enzyme was overexpressed in Escherichia coli BL21 (DE3) using a pET21-MBP (TEV) vector system. Overexpressed recombinant enzymes which could convert the ginsenosides Rb(1), Rb(2), Rc and Rd to the more pharmacological active rare ginsenosides gypenoside XVII, ginsenoside C-O, ginsenoside C-Mc(1) and ginsenoside F(2), respectively, were purified by two steps with Amylose-affinity and DEAE-Cellulose chromatography and characterized. The kinetic parameters for β-glucosidase showed the apparent K(m) and V(max) values of 2.9±0.3 mM and 515.4±38.3 μmol min(-1)mg of protein(-1) against p-nitrophenyl-β-d-glucopyranoside. The enzyme could hydrolyze the outer C3 glucose moieties of ginsenosides Rb(1), Rb(2), Rc and Rd into the rare ginsenosides Gyp XVII, C-O, C-Mc(1) and F(2) quickly at optimal conditions of pH 5.0 and 37°C. A little ginsenoside F(2) production from ginsenosides Gyp XVII, C-O, and C-Mc(1) was observed for the lengthy enzyme reaction caused by the side ability of the enzyme.
    Journal of Biotechnology 08/2011; 156(2):125-33. · 3.18 Impact Factor
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    ABSTRACT: A novel gammaproteobacterium, designated LnR5-47(T), was isolated from soil of a ginseng field in Liaoning province, China. The isolate was a Gram-negative, aerobic, non-motile, non-spore-forming rod. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain LnR5-47(T) belonged to the genus Rhodanobacter. The isolate was most closely related to Rhodanobacter ginsengisoli GR17-7(T), Rhodanobacter terrae GP18-1(T), Dyella ginsengisoli Gsoil 3046(T), Rhodanobacter soli DCY45(T), Dyella soli JS12-10(T) and Dyella japonica IAM 15069(T) (98.0, 97.9, 97.7, 97.3, 97.2 and 97.1% 16S rRNA gene sequence similarity, respectively). Chemotaxonomic data (Q-8 as the predominant ubiquinone, and iso-C(16:0), iso-C(17:1)ω9c and iso-C(15:0) as the major fatty acids) also supported the affiliation of strain LnR5-47(T) with the genus Rhodanobacter. However, DNA-DNA relatedness between strain LnR5-47(T) and its closest phylogenetic neighbours was <25.8%. Moreover, physiological and biochemical tests phenotypically differentiated the isolate from other members of the genus Rhodanobacter. Therefore, strain LnR5-47(T) represents a novel species, for which the name Rhodanobacter panaciterrae sp. nov. is proposed; the type strain is LnR5-47(T) (=KACC 12826(T)=KCTC 22232(T)=LMG 24460(T)).
    INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 02/2011; 61(Pt 12):3028-32. · 2.11 Impact Factor
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    ABSTRACT: A new beta-glucosidase from a novel strain of Terrabacter ginsenosidimutans (Gsoil 3082(T)) obtained from the soil of a ginseng farm was characterized, and the gene, bgpA (1,947 bp), was cloned in Escherichia coli. The enzyme catalyzed the conversion of ginsenoside Rb1 {3-O-[beta-D-glucopyranosyl-(1-2)-beta-D-glucopyranosyl]-20-O-[beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranosyl]-20(S)-protopanaxadiol} to the more pharmacologically active rare ginsenosides gypenoside XVII {3-O-beta-D-glucopyranosyl-20-O-[beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranosyl]-20(S)-protopanaxadiol}, gypenoside LXXV {20-O-[beta-v-glucopyranosyl-(1-6)-beta-D-glucopyranosyl]-20(S)-protopanaxadiol}, and C-K [20-O-(beta-D-glucopyranosyl)-20(S)-protopanaxadiol]. A BLAST search of the bgpA sequence revealed significant homology to family 3 glycoside hydrolases. Expressed in E. coli, beta-glucosidase had apparent K(m) values of 4.2 +/- 0.8 and 0.14 +/- 0.05 mM and V(max) values of 100.6 +/- 17.1 and 329 +/- 31 micromol x min(-1) x mg of protein(-1) against p-nitrophenyl-beta-D-glucopyranoside and Rb1, respectively. The enzyme catalyzed the hydrolysis of the two glucose moieties attached to the C-3 position of ginsenoside Rb1, and the outer glucose attached to the C-20 position at pH 7.0 and 37 degrees C. These cleavages occurred in a defined order, with the outer glucose of C-3 cleaved first, followed by the inner glucose of C-3, and finally the outer glucose of C-20. These results indicated that BgpA selectively and sequentially converts ginsenoside Rb1 to the rare ginsenosides gypenoside XVII, gypenoside LXXV, and then C-K. Herein is the first report of the cloning and characterization of a novel ginsenoside-transforming beta-glucosidase of the glycoside hydrolase family 3.
    Applied and Environmental Microbiology 09/2010; 76(17):5827-36. · 3.95 Impact Factor
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    ABSTRACT: The relative genetic diversity of microcystin-producing Microcystis in the water and sediment of the Daechung Reservoir, Korea, was investigated over an entire year, including the cyanobacterial bloom season. The cells of potentially toxic Microcystis strains containing mcyJ genotypes and cells containing the genus-specific cpcBA gene were quantified by a real-time PCR. The ratio of cells with mcyJ genotypes to the total Microcystis population in the water body was the highest (68.3%) in August when the cyanobacterial bloom reached its peak and the microcystin concentration in the water began to increase. A denaturing gradient gel electrophoresis profile analysis of the mcyJ genotypes performed to monitor any changes in the toxic Microcystis population showed the appearance of new genotypes and the disappearance of existing genotypes in the reservoir water collected during the summer months, when compared with the profile for the samples collected in spring and autumn. However, very little change was observed over the course of the year as regards the population diversity of the sediment samples.
    FEMS Microbiology Ecology 01/2010; · 3.56 Impact Factor
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    ABSTRACT: The alphaproteobacterial strains GRP21(T) and PH34, which were isolated from coastal sediment of the East Sea, Korea, were subjected to a polyphasic taxonomic investigation. The strains were Gram-negative, non-motile, non-spore-forming, oval-shaped rods that produced creamy-white colonies on tryptic soy agar, required NaCl for growth, contained Q-10 as the predominant ubiquinone, contained 16 : 0, 18 : 1omega7c and 19 : 0 cyclo omega8c as major fatty acids and had polar lipid profiles consisting of phosphatidylcholine, phosphatidylglycerol, an unknown aminolipid, an unknown phospholipid and three unknown lipids. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that the strains were most closely related to Donghicola eburneus KCTC 12735(T), with 94.5 % sequence similarity, but formed a separate lineage within the family Rhodobacteraceae. The combined genotypic and phenotypic data supported the conclusion that the strains represent a novel genus and species, for which the name Pontibaca methylaminivorans gen. nov., sp. nov. is proposed. The type strain of Pontibaca methylaminivorans is GRP21(T) (=KCTC 22497(T) =DSM 21219(T)).
    International journal of systematic and evolutionary microbiology 11/2009; 60(Pt 9):2170-5. · 2.11 Impact Factor
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    ABSTRACT: A Gram-positive, rod-shaped, non-spore-forming bacterium (Gsoil 346(T)) was isolated from the soil of a ginseng field in South Korea and was characterized in order to determine its taxonomic position. On the basis of 16S rRNA gene sequences, strain Gsoil 346(T) was shown to belong to the genus Nocardioides in the family Nocardioidaceae, with the most closely related species being Nocardioides aquiterrae GW-9(T) (96.6 % 16S rRNA gene sequence similarity); however, the strain clustered in a distinct branch of the phylogenetic tree with Nocardioides kongjuensis A2-4(T) (96.2 %), Nocardioides aromaticivorans H-1(T) (96.1 %), Nocardioides nitrophenolicus NSP41(T) (96.1 %) and Nocardioides simplex ATCC 15799(T) (95.9 %). Strain Gsoil 346(T) was characterized chemotaxonomically and found to have ll-2,6-diaminopimelic acid in the cell-wall peptidoglycan, phosphatidylinositol and phosphatidylglycerol as the major polar lipids, MK-8(H(4)) as the predominant menaquinone and iso-C(16 : 0), C(18 : 1)omega9c and C(17 : 1)omega8c as the major fatty acids. The G+C content of the genomic DNA of the novel strain was 73.0 mol%. These chemotaxonomic properties supported the placement of strain Gsoil 346(T) in the genus Nocardioides. The results of physiological and biochemical tests, along with the phylogenetic analysis, allowed strain Gsoil 346(T) to be differentiated genotypically and phenotypically from recognized species of the genus Nocardioides. Therefore, strain Gsoil 346(T) represents a novel species, for which the name Nocardioides panacisoli sp. nov. is proposed, with Gsoil 346(T) (=KCTC 19470(T)=DSM 21348(T)) as the type strain.
    International journal of systematic and evolutionary microbiology 09/2009; 60(Pt 2):387-92. · 2.11 Impact Factor
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    ABSTRACT: A Gram-negative, aerobic, rod-shaped, non-motile, non-spore-forming bacterial strain, designated TR6-06(T), was isolated from a compost sample in South Korea and characterized taxonomically by using a polyphasic approach. The organism grew optimally at 30 degrees C and pH 6.5-7.0. The isolate was positive for catalase and oxidase tests, but negative for gelatinase and urease and for indole and H(2)S production. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain TR6-06(T) was most closely affiliated with members of the genus Pedobacter of the family Sphingobacteriaceae. Strain TR6-06(T) exhibited 16S rRNA gene sequence similarity values of 89.9-93.5 % to the type strains of species of the genus Pedobacter. The G+C content of the genomic DNA of strain TR6-06(T) was 41.9 mol%. The predominant respiratory quinone was MK-7. The major fatty acids were iso-C(15 : 0), iso-C(17 : 0) 3-OH, C(16 : 1)omega7c and anteiso-C(15 : 0). These chemotaxonomic data support the affiliation of strain TR6-06(T) to the genus Pedobacter. However, on the basis of its phenotypic properties and phylogenetic distinctiveness, strain TR6-06(T) (=KCTC 12638(T)=LMG 23490(T)) should be classified as the type strain of a novel species, for which the name Pedobacter composti sp. nov. is proposed.
    International journal of systematic and evolutionary microbiology 03/2009; 59(Pt 2):345-9. · 2.11 Impact Factor
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    ABSTRACT: A novel bacterial strain, designated Dae 13T, was isolated from sediment from a freshwater lake in Daejeon, South Korea, and was characterized taxonomically by using a polyphasic approach. The isolate was Gram-negative, aerobic, non-motile, non-spore-forming and rod-shaped. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belonged to the genus Pedobacter in the family Sphingobacteriaceae but was clearly separate from established species of this genus. The 16S rRNA gene sequence similarities between strain Dae 13(T) and type strains of Pedobacter species with validly published names ranged from 91.6 to 97.5 %. The G+C content of the genomic DNA was 33.8 mol%. Chemotaxonomic data, i.e. the presence of MK-7 as the major menaquinone and iso-C(15 : 0), C(16 : 0) and summed feature 3 (iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c) as the major fatty acids, supported the affiliation of strain Dae 13T to the genus Pedobacter. However, the results of physiological and biochemical tests allowed phenotypic differentiation of the isolate with respect to Pedobacter species with validly published names. Therefore, strain Dae 13T represents a novel species within the genus Pedobacter, for which the name Pedobacter daechungensis sp. nov. is proposed. The type strain is Dae 13T (=KCTC 12637T=LMG 23489T).
    International journal of systematic and evolutionary microbiology 02/2009; 59(Pt 1):69-72. · 2.11 Impact Factor
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    ABSTRACT: A simple protocol to convert sitting-drop vapor-diffusion plating into a hangingdrop vapor-diffusion experiment in protein crystallization is reported. After making a sitting-drop plate, agarose solution was added to solidify the reservoir solution, and the plates were incubated upside down. Crystallization experiments with hen egg white lysozyme, thaumatin and glucose isomerase showed that the ‘upside-down sitting-drop’ method could produce single crystals with all the benefits of the hanging-drop crystallization method.
    Journal of Applied Crystallography 01/2009; 42:975-976. · 3.34 Impact Factor
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    ABSTRACT: To understand the molecular basis of a phosphoryl transfer reaction catalyzed by the 6-phosphofructo-2-kinase domain of the hypoxia-inducible bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3), the crystal structures of PFKFB3AMPPCPfructose-6-phosphate and PFKFB3ADPphosphoenolpyruvate complexes were determined to 2.7 A and 2.25 A resolution, respectively. Kinetic studies on the wild-type and site-directed mutant proteins were carried out to confirm the structural observations. The experimentally varied liganding states in the active pocket cause no significant conformational changes. In the pseudo-substrate complex, a strong direct interaction between AMPPCP and fructose-6-phosphate (Fru-6-P) is found. By virtue of this direct substrate-substrate interaction, Fru-6-P is aligned with AMPPCP in an orientation and proximity most suitable for a direct transfer of the gamma-phosphate moiety to 2-OH of Fru-6-P. The three key atoms involved in the phosphoryl transfer, the beta,gamma-phosphate bridge oxygen atom, the gamma-phosphorus atom, and the 2-OH group are positioned in a single line, suggesting a direct phosphoryl transfer without formation of a phosphoenzyme intermediate. In addition, the distance between 2-OH and gamma-phosphorus allows the gamma-phosphate oxygen atoms to serve as a general base catalyst to induce an "associative" phosphoryl transfer mechanism. The site-directed mutant study and inhibition kinetics suggest that this reaction will be catalyzed most efficiently by the protein when the substrates bind to the active pocket in an ordered manner in which ATP binds first.
    Journal of Molecular Biology 07/2007; 370(1):14-26. · 3.91 Impact Factor
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    ABSTRACT: DNA protection during starvation (Dps) proteins play an important role in protecting cellular macromolecules from damage by reactive oxygen species (ROS). Unlike most orthologs that protect DNA by a combination of DNA binding and prevention of hydroxyl radical formation by ferroxidation and sequestration of iron, Dps-1 from the radiation-resistant Deinococcus radiodurans fails to protect DNA from hydroxyl radical-mediated cleavage through a mechanism inferred to involve continuous release of iron from the protein core. To address the structural basis for this unusual release of Fe(2+), the crystal structure of D. radiodurans Dps-1 was determined to 2.0 Angstroms resolution. Two of four strong anomalous signals per protein subunit correspond to metal-binding sites within an iron-uptake channel and a ferroxidase site, common features related to the canonical functions of Dps homologs. Similar to Lactobacillus lactis Dps, a metal-binding site is found at the N-terminal region. Unlike other metal sites, this site is located at the base of an N-terminal coil on the outer surface of the dodecameric protein sphere and does not involve symmetric association of protein subunits. Intriguingly, a unique channel-like structure is seen featuring a fourth metal coordination site that results from 3-fold symmetrical association of protein subunits through alpha2 helices. The presence of this metal-binding site suggests that it may define an iron-exit channel responsible for the continuous release of iron from the protein core. This interpretation is supported by substitution of residues involved in this ion coordination and the observation that the resultant mutant protein exhibits significantly attenuated iron release. Therefore, we propose that D. radiodurans Dps-1 has a distinct iron-exit channel.
    Journal of Molecular Biology 09/2006; 361(1):105-14. · 3.91 Impact Factor
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    ABSTRACT: The detection and prevention of cyanobacterial blooms are important issues in water quality management. As such, the diversity and community dynamics of cyanobacteria during cyanobacterial bloom in the Daechung Reservoir, Korea, were studied by analyzing the intergenic spacer (IGS) region between phycocyanin subunit genes cpcB and cpcA (cpcBA IGS). To amplify the cpcBA IGS from environmental samples, new PCR primers that could cover a wider range of cyanobacteria than previously known primers were designed. In the samples taken around the bloom peak (2 September 2003), seven groups of cpcBA IGS sequences were detected, and none of the amplified cpcBA IGSs was closely related to the cpcBA IGS from chloroplasts. Apart from the Microcystis-, Aphanizomenon (Anabaena)-, Pseudanabaena-, and Planktothrix (Oscillatoria)-like groups, the three other groups of cpcBA IGS sequences were only distantly related to previously reported sequences (<85% similarity to their closest relatives). The most prominent changes during the bloom were the gradual decrease and eventual disappearance of the Aphanizomenon (Anabaena)-like group before the bloom peak and the gradual increase and sudden disappearance of Planktothrix (Oscillatoria)-like groups right after the bloom peak. The community succession profile obtained based on the cpcBA IGS analysis was also supported by a PCR-denaturing gradient gel electrophoresis analysis of the 16S rRNA genes.
    Applied and Environmental Microbiology 05/2006; 72(5):3252-8. · 3.95 Impact Factor

Publication Stats

180 Citations
67.34 Total Impact Points

Institutions

  • 2003–2013
    • Korea Research Institute of Bioscience and Biotechnology KRIBB
      • • Biological Resource Center
      • • Environmental Biotechnology Research Center
      • • Environmental Biotechnology Laboratory
      Anzan, Gyeonggi Province, South Korea
    • Korea Advanced Institute of Science and Technology
      • Department of Biological Sciences
      Seoul, Seoul, South Korea
  • 2006–2012
    • Louisiana State University
      • Department of Biological Sciences
      Baton Rouge, LA, United States
    • Chungbuk National University
      Chinsen, North Chungcheong, South Korea
  • 2009
    • Chungnam National University
      • Department of Bio Environmental Chemistry
      Daiden, Daejeon, South Korea