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Sang Un Park - One of the best experts on this subject based on the ideXlab platform.

  • Research Article Cloning and Characterization of a Flavonol Synthase Gene from
    2016
    Co-Authors: Scutellaria Baicalensis, Jin Woong Cho, Sang Un Park
    Abstract:

    which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Flavonols are themost abundant of all the flavonoids and play pivotal roles in a variety of plants.We isolated a cDNA clone encoding Flavonol Synthase from Scutellaria baicalensis (SbFLS). The SbFLS cDNA is 1011 bp long, encodes 336 amino acid residues, and belongs to a family of 2-oxoglutarate-dependent dioxygenases. The overall structure of SbFLS is very similar to that of Arabidopsis thaliana anthocyanidin Synthase (AtANS), with

  • Cloning, Characterization, and Activity Analysis of a Flavonol Synthase Gene FtFLS1 and Its Association with Flavonoid Content in Tartary Buckwheat
    2016
    Co-Authors: Yuechen Bai, Hui Chen, Xueyi Han, Haixia Zhao, Jirong Shao, Sang Un Park
    Abstract:

    Evidence from in vitro and in vivo studies indicates that rutin, the main flavonoid in tartary buckwheat (Fagopyrum tataricum), may have high value for medicine and health. This paper reports the finding of a Flavonol Synthase (FLS) gene, cloned and characterized from F. tataricum and designated FtFLS1, that is involved in rutin biosynthesis. The FtFLS1 gene was expressed in Escherichia coli BL21­(DE3), and the recombinant soluble FtFLS1 protein had a relative molecular mass of 40 kDa. The purified recombinant protein showed, with dihydroquercetin as substrate, total and specific activities of 36.55 × 10–3 IU and 18.94 × 10–3 IU/mg, respectively, whereas the total and specific activities were 10.19 × 10–3 IU and 5.28 × 10–3 IU/mg, respectively, with dihydrokaempferol. RT-PCR revealed that during F. tataricum florescence there was an organ-specific expression pattern by the FtFLS1 gene, with similar trends in flavonoid content. These observations suggest that FtFLS1 in F. tataricum encodes a functional protein, which might play a key role in rutin biosynthesis

  • Cloning and Characterization of a Flavonol Synthase Gene from Scutellaria baicalensis
    TheScientificWorldJournal, 2014
    Co-Authors: Yeon Bok Kim, Jin Woong Cho, Kwangsoo Kim, Yeji Kim, Pham Anh Tuan, Haeng Hoon Kim, Sang Un Park
    Abstract:

    Flavonols are the most abundant of all the flavonoids and play pivotal roles in a variety of plants. We isolated a cDNA clone encoding Flavonol Synthase from Scutellaria baicalensis (SbFLS). The SbFLS cDNA is 1011 bp long, encodes 336 amino acid residues, and belongs to a family of 2-oxoglutarate-dependent dioxygenases. The overall structure of SbFLS is very similar to that of Arabidopsis thaliana anthocyanidin Synthase (AtANS), with a β jelly-roll fold surrounded by tens of short and long α-helices. SbFLS was constitutively expressed in the roots, stems, leaves, and flowers, with particularly high expression in the roots and flowers. SbFLS transcript levels in the roots were 376-, 70-, and 2.5-fold higher than in the leaves, stems, and flowers. The myricetin content was significantly higher than that of kaempferol and quercetin. Therefore, we suggest that SbFLS mediates Flavonol formation in the different organs of S. baicalensis. Our study may contribute to the knowledge of the role of FLS in S. baicalensis.

  • Differential stress-response expression of two Flavonol Synthase genes and accumulation of Flavonols in tartary buckwheat.
    Journal of plant physiology, 2013
    Co-Authors: Yeon Bok Kim, Yeji Kim, Haeng Hoon Kim, Shicheng Zhao, Eunsook Chung, Jai-heon Lee, Sang Un Park
    Abstract:

    Flavonoids are ubiquitously present in plants and play important roles in these organisms as well as in the human diet. Flavonol Synthase (FLS) is a key enzyme of the flavonoid biosynthetic pathway, acting at the diverging point into the Flavonol subclass branch. We isolated and characterized a FLS isoform gene, FtFLS2, from tartary buckwheat (Fagopyrum tataricum). FtFLS2 shares 48% identity and 67% similarity with the previously reported FtFLS1, whereas both genes share 47-65% identity and 65-69% similarity with FLSs from other plant species. Using quantitative real-time PCR and high-performance liquid chromatography (HPLC), the expression of FtFLS1/2 and the production of 3 main Flavonols (kaempferol, myricetin and quercetin) was detected in roots, leaves, stems, flowers and different stages of developing seeds. The relationship between the expression of the 2 FLS genes and the accumulation of the 3 basic Flavonols was analyzed in 2 tartary buckwheat cultivars. FtFLS1 and FtFLS2 exhibited differential transcriptional levels between the tartary buckwheat cultivars 'Hokkai T10' and 'Hokkai T8'. Generally, higher transcript levels of FtFLS1 and FtFLS2 and a higher amount of Flavonols were observed in the 'Hokkai T10' cultivar than 'Hokkai T8'. The content of Flavonols showed tissue-specific accumulation between the 2 cultivars. The transcription of FtFLS1 was inhibited by the exogenous application of abscisic acid (ABA), salicylic acid (SA) and sodium chloride (NaCl), while FtFLS2 was not affected by ABA but up-regulated by SA and NaCl. These data indicate that the 2 FtFLS isoforms of buckwheat have different functions in the response of buckwheat to environmental stress.

  • Cloning, characterization, and activity analysis of a Flavonol Synthase gene FtFLS1 and its association with flavonoid content in tartary buckwheat.
    Journal of agricultural and food chemistry, 2012
    Co-Authors: Yuechen Bai, Hui Chen, Xueyi Han, Haixia Zhao, Jirong Shao, Sang Un Park
    Abstract:

    Evidence from in vitro and in vivo studies indicates that rutin, the main flavonoid in tartary buckwheat (Fagopyrum tataricum), may have high value for medicine and health. This paper reports the finding of a Flavonol Synthase (FLS) gene, cloned and characterized from F. tataricum and designated FtFLS1, that is involved in rutin biosynthesis. The FtFLS1 gene was expressed in Escherichia coli BL21(DE3), and the recombinant soluble FtFLS1 protein had a relative molecular mass of 40 kDa. The purified recombinant protein showed, with dihydroquercetin as substrate, total and specific activities of 36.55 × 10–3 IU and 18.94 × 10–3 IU/mg, respectively, whereas the total and specific activities were 10.19 × 10–3 IU and 5.28 × 10–3 IU/mg, respectively, with dihydrokaempferol. RT-PCR revealed that during F. tataricum florescence there was an organ-specific expression pattern by the FtFLS1 gene, with similar trends in flavonoid content. These observations suggest that FtFLS1 in F. tataricum encodes a functional prot...

Ulrich S Schubert - One of the best experts on this subject based on the ideXlab platform.

  • spatial and temporal localization of flavonoid metabolites in strawberry fruit fragaria ananassa
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Anna C Crecelius, Manfred Hanke, Thilo C. Fischer, Henryk Flachowsky, Wilfried Schwab, Dirk Holscher, T. K. Hoffmann, Bernd Schneider, Ulrich S Schubert
    Abstract:

    Flavonoids are important metabolites in strawberries (Fragaria × ananassa) because they accomplish an extensive collection of physiological functions and are valuable for human health. However, their localization within the fruit tissue has not been extensively explored. Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to shed light on the spatial distribution of flavonoids during fruit development. One wild-type (WT) and two transgenic lines were compared, wherein the transgenic enzymes anthocyanidin reductase (ANRi) and Flavonol Synthase (FLSi), respectively, were down-regulated using an RNAi-based silencing approach. In most cases, fruit development led to a reduction of the investigated flavonoids in the fruit tissue; as a consequence, they were exclusively present in the skin of mature red fruits. In the case of (epi)catechin dimer, both the ANRi and the WT phenotypes revealed low levels in mature red fruits, whereas the ANRi line bore the lowest relativ...

  • Spatial and Temporal Localization of Flavonoid Metabolites in Strawberry Fruit (Fragaria × ananassa)
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Anna C Crecelius, Manfred Hanke, Thilo C. Fischer, Henryk Flachowsky, Wilfried Schwab, Dirk Holscher, T. K. Hoffmann, Bernd Schneider, Ulrich S Schubert
    Abstract:

    Flavonoids are important metabolites in strawberries (Fragaria × ananassa) because they accomplish an extensive collection of physiological functions and are valuable for human health. However, their localization within the fruit tissue has not been extensively explored. Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to shed light on the spatial distribution of flavonoids during fruit development. One wild-type (WT) and two transgenic lines were compared, wherein the transgenic enzymes anthocyanidin reductase (ANRi) and Flavonol Synthase (FLSi), respectively, were down-regulated using an RNAi-based silencing approach. In most cases, fruit development led to a reduction of the investigated flavonoids in the fruit tissue; as a consequence, they were exclusively present in the skin of mature red fruits. In the case of (epi)catechin dimer, both the ANRi and the WT phenotypes revealed low levels in mature red fruits, whereas the ANRi line bore the lowest relativ...

Anna C Crecelius - One of the best experts on this subject based on the ideXlab platform.

  • spatial and temporal localization of flavonoid metabolites in strawberry fruit fragaria ananassa
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Anna C Crecelius, Manfred Hanke, Thilo C. Fischer, Henryk Flachowsky, Wilfried Schwab, Dirk Holscher, T. K. Hoffmann, Bernd Schneider, Ulrich S Schubert
    Abstract:

    Flavonoids are important metabolites in strawberries (Fragaria × ananassa) because they accomplish an extensive collection of physiological functions and are valuable for human health. However, their localization within the fruit tissue has not been extensively explored. Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to shed light on the spatial distribution of flavonoids during fruit development. One wild-type (WT) and two transgenic lines were compared, wherein the transgenic enzymes anthocyanidin reductase (ANRi) and Flavonol Synthase (FLSi), respectively, were down-regulated using an RNAi-based silencing approach. In most cases, fruit development led to a reduction of the investigated flavonoids in the fruit tissue; as a consequence, they were exclusively present in the skin of mature red fruits. In the case of (epi)catechin dimer, both the ANRi and the WT phenotypes revealed low levels in mature red fruits, whereas the ANRi line bore the lowest relativ...

  • Spatial and Temporal Localization of Flavonoid Metabolites in Strawberry Fruit (Fragaria × ananassa)
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Anna C Crecelius, Manfred Hanke, Thilo C. Fischer, Henryk Flachowsky, Wilfried Schwab, Dirk Holscher, T. K. Hoffmann, Bernd Schneider, Ulrich S Schubert
    Abstract:

    Flavonoids are important metabolites in strawberries (Fragaria × ananassa) because they accomplish an extensive collection of physiological functions and are valuable for human health. However, their localization within the fruit tissue has not been extensively explored. Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to shed light on the spatial distribution of flavonoids during fruit development. One wild-type (WT) and two transgenic lines were compared, wherein the transgenic enzymes anthocyanidin reductase (ANRi) and Flavonol Synthase (FLSi), respectively, were down-regulated using an RNAi-based silencing approach. In most cases, fruit development led to a reduction of the investigated flavonoids in the fruit tissue; as a consequence, they were exclusively present in the skin of mature red fruits. In the case of (epi)catechin dimer, both the ANRi and the WT phenotypes revealed low levels in mature red fruits, whereas the ANRi line bore the lowest relativ...

Wilfried Schwab - One of the best experts on this subject based on the ideXlab platform.

  • spatial and temporal localization of flavonoid metabolites in strawberry fruit fragaria ananassa
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Anna C Crecelius, Manfred Hanke, Thilo C. Fischer, Henryk Flachowsky, Wilfried Schwab, Dirk Holscher, T. K. Hoffmann, Bernd Schneider, Ulrich S Schubert
    Abstract:

    Flavonoids are important metabolites in strawberries (Fragaria × ananassa) because they accomplish an extensive collection of physiological functions and are valuable for human health. However, their localization within the fruit tissue has not been extensively explored. Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to shed light on the spatial distribution of flavonoids during fruit development. One wild-type (WT) and two transgenic lines were compared, wherein the transgenic enzymes anthocyanidin reductase (ANRi) and Flavonol Synthase (FLSi), respectively, were down-regulated using an RNAi-based silencing approach. In most cases, fruit development led to a reduction of the investigated flavonoids in the fruit tissue; as a consequence, they were exclusively present in the skin of mature red fruits. In the case of (epi)catechin dimer, both the ANRi and the WT phenotypes revealed low levels in mature red fruits, whereas the ANRi line bore the lowest relativ...

  • Spatial and Temporal Localization of Flavonoid Metabolites in Strawberry Fruit (Fragaria × ananassa)
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Anna C Crecelius, Manfred Hanke, Thilo C. Fischer, Henryk Flachowsky, Wilfried Schwab, Dirk Holscher, T. K. Hoffmann, Bernd Schneider, Ulrich S Schubert
    Abstract:

    Flavonoids are important metabolites in strawberries (Fragaria × ananassa) because they accomplish an extensive collection of physiological functions and are valuable for human health. However, their localization within the fruit tissue has not been extensively explored. Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to shed light on the spatial distribution of flavonoids during fruit development. One wild-type (WT) and two transgenic lines were compared, wherein the transgenic enzymes anthocyanidin reductase (ANRi) and Flavonol Synthase (FLSi), respectively, were down-regulated using an RNAi-based silencing approach. In most cases, fruit development led to a reduction of the investigated flavonoids in the fruit tissue; as a consequence, they were exclusively present in the skin of mature red fruits. In the case of (epi)catechin dimer, both the ANRi and the WT phenotypes revealed low levels in mature red fruits, whereas the ANRi line bore the lowest relativ...

  • Feedback inhibition of the general phenylpropanoid and Flavonol biosynthetic pathways upon a compromised Flavonol-3-O-glycosylation
    Journal of experimental botany, 2012
    Co-Authors: Ruohe Yin, Wilfried Schwab, Burkhard Messner, Theresa Faus-kessler, Thomas Hoffmann, Mohammad-reza Hajirezaei, Veronica Von Saint Paul, Werner Heller, Anton R. Schäffner
    Abstract:

    Flavonols, phenylalanine-derived secondary metabolites, have protective and regulatory functions in plants. In Arabidopsis thaliana, they are consecutively glycosylated at their 3-OH and 7-OH groups. UGT78D1 and UGT78D2 are the major Flavonol 3-O-glycosyltransferases in Arabidopsis leaves. The ugt78d1 ugt78d2 double mutant, which was strongly compromised in the initial 3-O-glycosylation, showed a severe and specific repression of Flavonol biosynthesis, retaining only one-third of the wild-type level. This metabolic phenotype was associated with a repressed transcription of several Flavonol biosynthetic genes including the committed step chalcone Synthase [(CHS) or TRANSPARENT TESTA 4 (TT4)]. Furthermore, the committed step of the upstream, general phenylpropanoid pathway, phenylalanine ammonia-lyase (PAL), was down-regulated in its enzyme activity and in the transcription of the Flavonol-related PAL1 and PAL2. However, a complete blocking of flavonoid biosynthesis at CHS released PAL inhibition in a tt4 ugt78d1 ugt78d2 line. PAL activity was even enhanced in the Flavonol Synthase 1 mutant, which compromises the final formation of Flavonol aglycones. The dependence of the PAL feedback inhibition on Flavonols was confirmed by chemical complementation of tt4 ugt78d1 ugt78d2 using naringenin, a downstream flavonoid intermediate, which restored the PAL repression. Although aglycones were not analytically detectable, this study provides genetic evidence for a novel, Flavonol-dependent feedback inhibition of the Flavonol biosynthetic pathway and PAL. It was conditioned by the compromised Flavonol-3-O-conjugation and a decrease in Flavonol content, yet dependent on a residual, Flavonol Synthase 1 (FLS1)-related capacity to form Flavonol aglycones. Thus, this regulation would not react to a reduced metabolic flux into Flavonol biosynthesis, but it might prevent the accumulation of non-glycosylated, toxic Flavonols.

Ulrich Matern - One of the best experts on this subject based on the ideXlab platform.

  • three 2 oxoglutarate dependent dioxygenase activities of equisetum arvense l forming flavone and Flavonol from 2s naringenin
    Phytochemistry, 2011
    Co-Authors: Miriam Bredebach, Ulrich Matern, Stefan Martens
    Abstract:

    Equisetum arvense L. (Equisetaceae-horsetail) accumulates various flavones and Flavonols in infertile shoot. Enzyme assays conducted with crude extracts of the green tissue revealed chalcone Synthase activity and also three further activities assigned to flavonoid biosynthesis and identified as flavone Synthase I, flavanone 3β-hydroxylase and Flavonol Synthase. The latter three activities were characterized as soluble, 2-oxoglutarate-dependent dioxygenases by their typical cofactor requirements and peculiar inhibition. Notably, this is the first report of flavone Synthase I which had been considered to be restricted solely to species of the Apiaceae from a distant plant taxon.

  • multifunctional flavonoid dioxygenases Flavonol and anthocyanin biosynthesis in arabidopsis thaliana l
    Phytochemistry, 2010
    Co-Authors: Stefan Martens, Anja Preuss, Ulrich Matern
    Abstract:

    Flavonols and conditionally also anthocyanins, aside from Flavonols, are the predominant polyphenols accumulated in various tissues of the model plant Arabidopsis thaliana L. In vitro experiments suggested that the dioxygenases involved in their biosynthesis, Flavonol Synthase and anthocyanidin Synthase, are "multifunctional" enzymes showing distinct side activities. The in vivo relevance of the additional activities attributed to these enzymes, however, has remained obscure. In this review we summarize the most recent results and present final proof of the complementing activities of these Synthases for Flavonol and anthocyanidin formation in the model plant A. thaliana. The impact of their modification on the biosynthetic pathway and the pattern of flavonoids in different plant tissues are discussed.

  • Arabidopsis thaliana expresses a second functional Flavonol Synthase
    FEBS letters, 2009
    Co-Authors: Anja Preuss, Ulrich Matern, Ralf Stracke, Bernd Weisshaar, Alexander Hillebrecht, Stefan Martens
    Abstract:

    Arabidopsis thaliana L. produces flavonoid pigments, i.e. Flavonols, anthocyanidins and proanthocyanidins, from dihydroFlavonol substrates. A small family of putative Flavonol Synthase (FLS) genes had been recognized in Arabidopsis, and functional activity was attributed only to FLS1. Nevertheless, other FLS activities must be present, because A. thalianafls1 mutants still accumulate significant amounts of Flavonols. The recombinant FLSs and leucoanthocyanidin dioxygenase (LDOX) proteins were therefore examined for their enzyme activities, which led to the identification of FLS3 as a second active FLS. This enzyme is therefore likely responsible for the formation of Flavonols in the ldox/fls1-2 double mutant. These double mutant and biochemical data demonstrate for the first time that LDOX is capable of catalyzing the in planta formation of Flavonols.

  • Flavonol Synthase from citrus unshiu is a bifunctional dioxygenase
    Phytochemistry, 2003
    Co-Authors: Richard Lukacin, Frank Wellmann, Lothar Britsch, Stefan Martens, Ulrich Matern
    Abstract:

    Flavonol Synthase was classified as a 2-oxoglutarate-dependent dioxygenase converting natural (2R,3R)-dihydroFlavonols, i.e. dihydrokaempferol, to the corresponding Flavonols (kaempferol). Flavonol Synthase from Citrus unshiu (Satsuma mandarin), expressed in Escherichia coli and purified to homogeneity, was shown to accept also (2S)-naringenin as a substrate, producing kaempferol in high yield and assigning sequential flavanone 3b-hydroxylase and Flavonol Synthase activities to the enzyme. In contrast, dihydrokaempferol was identified as the predominant product from assays performed with the unnatural (2R)-naringenin as substrate. The product which was not converted any further on repeated incubations was identified by 1 H NMR and CD spectroscopies as ()-trans-dihydrokaempferol. The data demonstrate that Citrus Flavonol Synthase encompasses an additional non

  • Functional expression and mutational analysis of Flavonol Synthase from Citrus unshiu
    European journal of biochemistry, 2002
    Co-Authors: Frank Wellmann, Lothar Britsch, Richard Lukacin, Takaya Moriguchi, Emile Schiltz, Ulrich Matern
    Abstract:

    Flavonols are produced by the desaturation of flavanols catalyzed by Flavonol Synthase. The enzyme belongs to the class of intermolecular dioxygenases which depend on molecular oxygen and FeII/2-oxoglutarate for activity, and have been in focus of structural studies recently. Flavonol Synthase cDNAs were cloned from six plant species, but none of the enzymes had been studied in detail. Therefore, a cDNA from Citrus unshiu (Satsuma mandarin) designated as Flavonol Synthase was expressed in Escherichia coli, and the purified recombinant enzyme was subjected to kinetic and mutational chacterizations. The integrity of the recombinant Synthase was revealed by a molecular ion from MALDI-TOF mass spectrometry at m/z 37888 +/- 40 (as compared to 37899 Da calculated for the translated polypeptide), and by partial N-terminal sequencing. Maximal Flavonol Synthase activity was observed in the range of pH 5-6 with dihydroquercetin as substrate and a temperature optimum at about 37 degrees C. Km values of 272, 11 and 36 micro m were determined for dihydroquercetin, FeII and 2-oxoglutarate, respectively, with a sixfold higher affinity to dihydrokaempferol (Km 45 micro m). Flavonol Synthase polypeptides share an overall sequence similarity of 85% (47% identity), whereas only 30-60% similarity were apparent with other dioxygenases. Like the other dioxygenases of this class, Citrus Flavonol Synthase cDNA encodes eight strictly conserved amino-acid residues which include two histidines (His221, His277) and one acidic amino acid (Asp223) residue for FeII-coordination, an arginine (Arg287) proposed to bind 2-oxoglutarate, and four amino acids (Gly68, His75, Gly261, Pro207) with no obvious functionality. Replacements of Gly68 and Gly261 by alanine reduced the catalytic activity by 95%, while the exchange of these Gly residues for proline completely abolished the enzyme activity. Alternatively, the substitution of Pro207 by glycine hardly affected the activity. The data suggest that Gly68 and Gly261, at least, are required for proper folding of the Flavonol Synthase polypeptide.