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Karl Gruber - One of the best experts on this subject based on the ideXlab platform.

  • oxidation of monolignols by members of the berberine bridge enzyme family suggests a role in plant cell wall metabolism
    Journal of Biological Chemistry, 2015
    Co-Authors: Bastian Daniel, Silvia Wallner, Tea Pavkovkeller, Barbara Steiner, Andela Dordic, Alexander Gutmann, Bernd Nidetzky, Christoph Wilhelm Sensen, Eric Van Der Graaff, Karl Gruber
    Abstract:

    Plant genomes contain a large number of genes encoding for berberine bridge enzyme (BBE)-like enzymes. Despite the widespread occurrence and abundance of this protein family in the plant kingdom, the biochemical function remains largely unexplored. In this study, we have expressed two members of the BBE-like enzyme family from Arabidopsis thaliana in the host organism Komagataella pastoris. The two proteins, termed AtBBE-like 13 and AtBBE-like 15, were purified, and their catalytic properties were determined. In addition, AtBBE-like 15 was crystallized and structurally characterized by x-ray crystallography. Here, we show that the enzymes catalyze the oxidation of aromatic allylic Alcohols, such as coumaryl, sinapyl, and Coniferyl Alcohol, to the corresponding aldehydes and that AtBBE-like 15 adopts the same fold as vanillyl Alcohol oxidase as reported previously for berberine bridge enzyme and other FAD-dependent oxidoreductases. Further analysis of the substrate range identified coniferin, the glycosylated storage form of Coniferyl Alcohol, as a substrate of the enzymes, whereas other glycosylated monolignols were rather poor substrates. A detailed analysis of the motifs present in the active sites of the BBE-like enzymes in A. thaliana suggested that 14 out of 28 members of the family might catalyze similar reactions. Based on these findings, we propose a novel role of BBE-like enzymes in monolignol metabolism that was previously not recognized for this enzyme family.

  • oxidation of monolignols by members of the berberine bridge enzyme family suggests a role in plant cell wall metabolism
    Journal of Biological Chemistry, 2015
    Co-Authors: Bastian Daniel, Silvia Wallner, Tea Pavkovkeller, Barbara Steiner, Andela Dordic, Alexander Gutmann, Bernd Nidetzky, Christoph Wilhelm Sensen, Eric Van Der Graaff, Karl Gruber
    Abstract:

    Plant genomes contain a large number of genes encoding for berberine bridge enzyme (BBE)-like enzymes. Despite the widespread occurrence and abundance of this protein family in the plant kingdom, the biochemical function remains largely unexplored. In this study, we have expressed two members of the BBE-like enzyme family from Arabidopsis thaliana in the host organism Komagataella pastoris. The two proteins, termed AtBBE-like 13 and AtBBE-like 15, were purified, and their catalytic properties were determined. In addition, AtBBE-like 15 was crystallized and structurally characterized by x-ray crystallography. Here, we show that the enzymes catalyze the oxidation of aromatic allylic Alcohols, such as coumaryl, sinapyl, and Coniferyl Alcohol, to the corresponding aldehydes and that AtBBE-like 15 adopts the same fold as vanillyl Alcohol oxidase as reported previously for berberine bridge enzyme and other FAD-dependent oxidoreductases. Further analysis of the substrate range identified coniferin, the glycosylated storage form of Coniferyl Alcohol, as a substrate of the enzymes, whereas other glycosylated monolignols were rather poor substrates. A detailed analysis of the motifs present in the active sites of the BBE-like enzymes in A. thaliana suggested that 14 out of 28 members of the family might catalyze similar reactions. Based on these findings, we propose a novel role of BBE-like enzymes in monolignol metabolism that was previously not recognized for this enzyme family.

John Ralph - One of the best experts on this subject based on the ideXlab platform.

  • suppression of ccr impacts metabolite profile and cell wall composition in pinus radiata tracheary elements
    Plant Molecular Biology, 2013
    Co-Authors: Armin Wagner, Yuki Tobimatsu, Geert Goeminne, Lorelle Phillips, Heather Flint, Diane Steward, Kirk M Torr, Lloyd Donaldson, Wout Boerjan, John Ralph
    Abstract:

    Suppression of the lignin-related gene cinnamoyl-CoA reductase (CCR) in the Pinus radiata tracheary element (TE) system impacted both the metabolite profile and the cell wall matrix in CCR-RNAi lines. UPLC-MS/MS-based metabolite profiling identified elevated levels of p-coumaroyl hexose, caffeic acid hexoside and ferulic acid hexoside in CCR-RNAi lines, indicating a redirection of metabolite flow within phenylpropanoid metabolism. Dilignols derived from Coniferyl Alcohol such as G(8-5)G, G(8-O-4)G and isodihydrodehydrodiConiferyl Alcohol (IDDDC) were substantially depleted, providing evidence for CCR's involvement in Coniferyl Alcohol biosynthesis. Severe CCR suppression almost halved lignin content in TEs based on a depletion of both H-type and G-type lignin, providing evidence for CCR's involvement in the biosynthesis of both lignin types. 2D-NMR studies revealed minor changes in the H:G-ratio and consequently a largely unchanged interunit linkage distribution in the lignin polymer. However, unusual cell wall components including ferulate and unsaturated fatty acids were identified in TEs by thioacidolysis, pyrolysis-GC/MS and/or 2D-NMR in CCR-RNAi lines, providing new insights into the consequences of CCR suppression in pine. Interestingly, CCR suppression substantially promoted pyrolytic breakdown of cell wall polysaccharides, a phenotype most likely caused by the incorporation of acidic compounds into the cell wall matrix in CCR-RNAi lines.

  • synthesis and characterization of new 5 linked pinoresinol lignin models
    Chemistry: A European Journal, 2012
    Co-Authors: Fengxia Yue, Runcang Sun, John Ralph
    Abstract:

    Pinoresinol structures, featur- ing a b-b'-linkage between lignin monoA units, are important in soft- wood lignins and in dicots and mono- cots, particularly those that are down- regulated in syringyl-specific genes. Al- though readily detected by NMR spec- troscopy, pinoresinol structures largely escaped detection by b-ether-cleaving degradation analyses presumably due to the presence of the linkages at the 5 positions, in 5-5' -o r 5-O-4'-structures. In this study, which is aimed at helping better understand 5-linked pinoresinol structures by providing the required data for NMR characterization, new lignin model compounds were synthe- sized through biomimetic peroxidase- mediated oxidative coupling reactions between pre-formed (free-phenolic) Coniferyl Alcohol 5-5' -o r 5-O-4'-linked dimers and a Coniferyl Alcohol mono- mer. It was found that such dimers con- taining free-phenolic Coniferyl Alcohol moieties can cross-couple with the co- AA Alcohol producing pinoresinol- containing trimers (and higher oligo- A in addition to other homo- and cross-coupled products. Eight new lignin model compounds were obtained and characterized by NMR spectrosco- py, and one tentatively identified cross- coupled b-O-4'-product was formed from a Coniferyl Alcohol 5-O-4'-linked dimer. It was demonstrated that the 5- 5'- and 5-O-4'-linked pinoresinol struc- tures could be readily differentiated by using heteronuclear multiple-bond cor- relation (HMBC) NMR spectroscopy. With appropriate modification (etheri- fication or acetylation) to the newly obtained model compounds, it would be possible to identify the 5-5' -o r 5-O- 4'-linked pinoresinol structures in soft- wood lignins by 2D HMBC NMR spec- troscopic methods. Identification of the cross-coupled dibenzodioxocin from a Coniferyl Alcohol 5-5'-linked moiety suggested that thioacidolysis or deriva- tization followed by reductive cleavage (DFRC) could be used to detect and identify whether the Coniferyl Alcohol itself undergoes 5-5'-cross-linking during lignification.

  • fluorescence tagged monolignols synthesis and application to studying in vitro lignification
    Biomacromolecules, 2011
    Co-Authors: Yuki Tobimatsu, Christy L Davidson, John H Grabber, John Ralph
    Abstract:

    Fluorescence-tagged Coniferyl Alcohols, Coniferyl Alcohol γ-coupled by ethylenediamine spacers to dimethylaminocoumarin or nitrobenzofuran fluorophores, were tested as photoprobes to study the oxidase-mediated polymerization of monolignols. The fluorescent Coniferyl Alcohol derivatives readily underwent peroxidase-catalyzed in vitro copolymerization with Coniferyl Alcohol to yield fluorescent dehydrogenation polymers, the backbone polymers of which were structurally indistinguishable from polymers formed solely from Coniferyl Alcohol. To illustrate the use of the photoprobes, we successfully monitored in real time the complexation of Coniferyl Alcohol with horseradish apoperoxidase by Forster resonance energy transfer (FRET) using the protein-tryptophan near the active site and a dimethylaminocoumarin moiety as donor and acceptor fluorophores. Furthermore, mixtures of fluorescence-tagged and normal Coniferyl Alcohols readily diffused into isolated maize cell walls and reacted with wall-bound peroxidases to form in muro artificial lignins that could be visualized by fluorescence microscopy. Thus we anticipate that fluorescence-tagged monolignols will be useful for in vitro and in vivo studies of cell wall lignification.

  • lignins and ferulate Coniferyl Alcohol cross coupling products in cereal grains
    Journal of Agricultural and Food Chemistry, 2004
    Co-Authors: Mirko Bunzel, John Ralph, Ronald D. Hatfield, Hans Steinhart
    Abstract:

    Plant cell walls containing suberin or lignin in the human diet are conjectured to protect against colon cancer. To confirm the existence of authentic lignin in cereal grain dietary fibers, the DFRC (derivatization followed by reductive cleavage) method was applied to different cereal grain dietary fibers. By cleavage of diagnostic arylglycerol-β-aryl (β-O-4) ether linkages and identification of the liberated monolignols, it was ascertained that lignins are truly present in cereal grains. From the ratios of the liberated monolignols Coniferyl Alcohol and sinapyl Alcohol, it is suggested that lignin compositions vary among cereals. Furthermore, dimeric cross-coupling products, comprising ferulate and Coniferyl Alcohol, were identified in most cereal fibers investigated. These ferulate 4-O-β- and 8-β-Coniferyl Alcohol cross-coupled structures indicate radical cross-coupling of polysaccharides to lignin precursors via ferulate. Keywords: Cereal dietary fiber; lignin; DFRC method; cross-coupling; ferulic acid...

  • NMR characterization of altered lignins extracted from tobacco plants down-regulated for lignification enzymes cinnamylAlcohol dehydrogenase and cinnamoyl-CoA reductase
    Proceedings of the National Academy of Sciences of the United States of America, 1998
    Co-Authors: John Ralph, Joel Piquemal, Ronald D. Hatfield, Nabila Yahiaoui, Michel Pean, Alain M. Boudet
    Abstract:

    Homologous antisense constructs were used to down-regulate tobacco cinnamyl-Alcohol dehydrogenase (CAD; EC 1.1.1.195) and cinnamoyl-CoA reductase (CCR; EC 1.2.1.44) activities in the lignin monomer biosynthetic pathway. CCR converts activated cinnamic acids (hydroxycinnamoyl–SCoAs) to cinnamaldehydes; cinnamaldehydes are then reduced to cinnamyl Alcohols by CAD. The transformations caused the incorporation of nontraditional components into the extractable tobacco lignins, as evidenced by NMR. Isolated lignin of antisense-CAD tobacco contained fewer Coniferyl and sinapyl Alcohol-derived units that were compensated for by elevated levels of benzaldehydes and cinnamaldehydes. Products from radical coupling of cinnamaldehydes, particularly sinapaldehyde, which were barely discernible in normal tobacco, were major components of the antisense-CAD tobacco lignin. Lignin content was reduced in antisense-CCR tobacco, which displayed a markedly reduced vigor. That lignin contained fewer Coniferyl Alcohol-derived units and significant levels of tyramine ferulate. Tyramine ferulate is a sink for the anticipated build-up of feruloyl–SCoA, and may be up-regulated in response to a deficit of Coniferyl Alcohol. Although it is not yet clear whether the modified lignins are true structural components of the cell wall, the findings provide further indications of the metabolic plasticity of plant lignification. An ability to produce lignin from alternative monomers would open new avenues for manipulation of lignin by genetic biotechnologies.

Kenghong Tan - One of the best experts on this subject based on the ideXlab platform.

  • transport of methyl eugenol derived sex pheromonal components in the male fruit fly bactrocera dorsalis
    Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2006
    Co-Authors: Alvin Kahwei Hee, Kenghong Tan
    Abstract:

    Abstract Males of Bactrocera dorsalis (Diptera: Tephritidae) are attracted strongly to and feed compulsively on methyl eugenol (1,2-dimethoxy- 4 -(2-propenyl)benzene), a highly potent male attractant. Pharmacophagy of methyl eugenol results in the production of phenylpropanoids 2-allyl-4,5-dimethoxyphenol and (E)-Coniferyl Alcohol that are sequestered and stored in the rectal gland prior to release as sex pheromonal components during mating at dusk. While these pheromonal components have also been detected in the hemolymph and crop of methyl eugenol-fed males, there is currently little information on the transport of these compounds from the crop to rectal gland in male B. dorsalis. Therefore, using physiological techniques such as parabiosis, rectal gland transplantation and hemolymph transfusion coupled with gas chromatography–mass spectrometry (GC-MS) analyses, we were able to ascertain and confirm the role of the hemolymph in the transport of these sex pheromonal components from the crop to the rectal gland. Further, the temporal profile of these methyl eugenol-derived bioactive compounds in the hemolymph also shows an increase with time post-methyl eugenol-feeding, i.e., 2-allyl-4,5-dimethoxyphenol attaining maximum amounts 15 min after ME consumption and decreasing thereafter, while for (E)-Coniferyl Alcohol—the increase and decrease are more gradual. These results further demonstrate the ability of insect hemolymph to transport many diverse forms of bioactive molecules including attractant-derived sex pheromonal components.

  • attraction of female and male bactrocera papayae to conspecific males fed with methyl eugenol and attraction of females to male sex pheromone components
    Journal of Chemical Ecology, 1998
    Co-Authors: Alvin Kahwei Hee, Kenghong Tan
    Abstract:

    The attraction of female and male Bactrocera papayae to conspecific males fed with methyl eugenol (ME) and female attraction to male synthetic sex pheromone, trans-Coniferyl Alcohol (CF), were evaluated in a wind tunnel. Earlier and greater attraction were exhibited by both females and males to ME-fed than to non-ME-fed males as dusk approaches. Males increased their precopulatory behavior (i.e., wing fanning and mounting) during the period of higher attractancy. These data confirm that the consumption of ME enhances the mating competitiveness of males and suggest that ME also functions as a precursor to the male sex and aggregation pheromones. Three phenylpropanoid compounds biosynthesized from ME, Coniferyl Alcohol, 2-allyl-4,5-dimethoxyphenol, and 3,4-dimethoxycinnamyl Alcohol, were detected in male rectal gland along with an endogenous rectal compound, N-(3-methylbutyl) acetamide. When offered singly to the females, Coniferyl Alcohol was found to be most attractive.

Bastian Daniel - One of the best experts on this subject based on the ideXlab platform.

  • oxidation of monolignols by members of the berberine bridge enzyme family suggests a role in plant cell wall metabolism
    Journal of Biological Chemistry, 2015
    Co-Authors: Bastian Daniel, Silvia Wallner, Tea Pavkovkeller, Barbara Steiner, Andela Dordic, Alexander Gutmann, Bernd Nidetzky, Christoph Wilhelm Sensen, Eric Van Der Graaff, Karl Gruber
    Abstract:

    Plant genomes contain a large number of genes encoding for berberine bridge enzyme (BBE)-like enzymes. Despite the widespread occurrence and abundance of this protein family in the plant kingdom, the biochemical function remains largely unexplored. In this study, we have expressed two members of the BBE-like enzyme family from Arabidopsis thaliana in the host organism Komagataella pastoris. The two proteins, termed AtBBE-like 13 and AtBBE-like 15, were purified, and their catalytic properties were determined. In addition, AtBBE-like 15 was crystallized and structurally characterized by x-ray crystallography. Here, we show that the enzymes catalyze the oxidation of aromatic allylic Alcohols, such as coumaryl, sinapyl, and Coniferyl Alcohol, to the corresponding aldehydes and that AtBBE-like 15 adopts the same fold as vanillyl Alcohol oxidase as reported previously for berberine bridge enzyme and other FAD-dependent oxidoreductases. Further analysis of the substrate range identified coniferin, the glycosylated storage form of Coniferyl Alcohol, as a substrate of the enzymes, whereas other glycosylated monolignols were rather poor substrates. A detailed analysis of the motifs present in the active sites of the BBE-like enzymes in A. thaliana suggested that 14 out of 28 members of the family might catalyze similar reactions. Based on these findings, we propose a novel role of BBE-like enzymes in monolignol metabolism that was previously not recognized for this enzyme family.

  • oxidation of monolignols by members of the berberine bridge enzyme family suggests a role in plant cell wall metabolism
    Journal of Biological Chemistry, 2015
    Co-Authors: Bastian Daniel, Silvia Wallner, Tea Pavkovkeller, Barbara Steiner, Andela Dordic, Alexander Gutmann, Bernd Nidetzky, Christoph Wilhelm Sensen, Eric Van Der Graaff, Karl Gruber
    Abstract:

    Plant genomes contain a large number of genes encoding for berberine bridge enzyme (BBE)-like enzymes. Despite the widespread occurrence and abundance of this protein family in the plant kingdom, the biochemical function remains largely unexplored. In this study, we have expressed two members of the BBE-like enzyme family from Arabidopsis thaliana in the host organism Komagataella pastoris. The two proteins, termed AtBBE-like 13 and AtBBE-like 15, were purified, and their catalytic properties were determined. In addition, AtBBE-like 15 was crystallized and structurally characterized by x-ray crystallography. Here, we show that the enzymes catalyze the oxidation of aromatic allylic Alcohols, such as coumaryl, sinapyl, and Coniferyl Alcohol, to the corresponding aldehydes and that AtBBE-like 15 adopts the same fold as vanillyl Alcohol oxidase as reported previously for berberine bridge enzyme and other FAD-dependent oxidoreductases. Further analysis of the substrate range identified coniferin, the glycosylated storage form of Coniferyl Alcohol, as a substrate of the enzymes, whereas other glycosylated monolignols were rather poor substrates. A detailed analysis of the motifs present in the active sites of the BBE-like enzymes in A. thaliana suggested that 14 out of 28 members of the family might catalyze similar reactions. Based on these findings, we propose a novel role of BBE-like enzymes in monolignol metabolism that was previously not recognized for this enzyme family.

Takeshi Katayama - One of the best experts on this subject based on the ideXlab platform.

  • Enzymatic Formation of Guaiacylglycerol 8-O-4´- (Coniferyl Alcohol) Ether from Coniferyl Alcohol with Enzyme Preparations of Eucommia ulmoides
    2015
    Co-Authors: Md. Shameul Alam, Toshisada Suzuki, Takeshi Katayama, Deeder Sultana, Saima Sultana, Md. Daud Hossain
    Abstract:

    Lignans and neolignans are optically active plant secondary metabolites. Research on biosynthesis of lignans has already been advanced especially for the formation of (+) pinoresinol but information on the biosynthesis of 8-O-4´- neolignans is still limited. Moreover, the chemical structure (position of substituents on aromatic rings) and stereochemistry of 8-O-4 ´ neolignans is not clear. Katayama and Kado discovered that incubation of cell-free extracts from E. ulmoides with Coniferyl Alcohol in the presence of hydro-gen peroxide gave (+)-erythro- and (-)-threo- guaiacylglycerol 8-O-4´-(Coniferyl Alcohol) ether (GGCE) (diastereomeric ratio, 3:2) which is the first report on enzymatic formation of optically active-8-O-4 ´ neolignans from an achiral monolignol. In this aspect, enzymatic formation of guaiacyl 8-O-4 ´ neolignan is noteworthy to clarify its stereochemistry from incubation of Coniferyl Alcohol with enzyme prepared from Eucommia ulmoides. In this experiment, soluble and insoluble enzymes prepared from E. ulmoides were incubated with 30 mM Coniferyl Alcohol (CA) for 60 min. The enzyme catalyzed GGCE, dehydrodiConiferyl Alcohol (DHCA), and pinoresinol identified by reversed phase HPLC. Consequently, diastereomeric compositions of GGCE were determined as erythro and threo isomer. Enantiomeric composition was determined by the chiral column HPLC. Both enzyme preparations enantioselec-tively formed (-)-erythro, (+)-erythro and (+)-threo, (-)-threo-GGCEs respectively

  • an extraordinary accumulation of pinoresinol in cell free extracts of forsythia intermedia evidence for enantiospecific reduction of pinoresinol
    Phytochemistry, 1992
    Co-Authors: Takeshi Katayama
    Abstract:

    Abstract Stereoselective and enantiospecific transformation mechanisms in lignan biogenesis are only now yielding to scientific inquiry: it has been shown that soluble cell-free preparations from Forsythia intermedia catalyse the formation of the enantiomerically pure lignan, (−)-secoisolariciresinol, when incubated with Coniferyl Alcohol in the presence of NAD(P)H and H 2 O 2 . Surprisingly, (−)-pinoresinol also accumulates in this soluble cell-free assay mixture in > 96 % enantiomeric excess, even though it is not the naturally occurring antipode present in Forsythia sp. But these soluble cell-free preparations do not engender stereoselective coupling; instead, racemic pinoresinols are first formed, catalysed by an H 2 O 2 -dependent peroxidase reaction. An enantiospecific NAD(P)H reductase then converts (+)-pinoresinol, and not the (−)-antipode, into (−)-secoisolariciresinol. Stereoselective syntheis of (+)-pinoresinol from E -Coniferyl Alcohol is, however, catalysed by an insoluble enzyme preparation in F. suspensa , obtained following removal of readily soluble and ionically bound enzymes; no exogenously supplied cofactors were required other than oxygen, although the reaction was stimulated by NAD-malate addition. Thus, the overall biochemical pathway to enantiomerically pure (−)-secoisolariciresinol has been delineated.

  • on the stereoselective synthesis of pinoresinol in forsythia suspensa from its achiral precursor Coniferyl Alcohol
    Phytochemistry, 1992
    Co-Authors: Diana L Bedgar, Takeshi Katayama
    Abstract:

    The residue from Forsythia suspensa stems, upon removal of soluble enzymes, has provided the first evidence for a stereoselective coupling enzyme in lignan biosynthesis. This preparation catalyses the preferred formation (ca 65%) of (+)-[8,8′-14C]pinoresinol from [8-14C]Coniferyl Alcohol in the absence of exogenously provided cofactors; addition of H2O2 had little effect on enantiomeric composition. However, when NAD and malate were supplied, the stereoselectivity of the coupling reaction was significantly enhanced and pinoresinol consisting of ca 80% of the (+)-antipode was obtained. Clearly, the insoluble residue contains a specific coupling enzyme which catalyses (+)-pinoresinol formation from Coniferyl Alcohol. By contrast, when [8-14C]sinapyl Alcohol was employed as substrate, only racemic syringaresinols were formed: this non-stereoselective peroxidase-catalysed coupling reaction presumably accounts for the low levels of (−)-pinoresinol encountered in this system when Coniferyl Alcohol is used as a substrate.