The Experts below are selected from a list of 119490 Experts worldwide ranked by ideXlab platform
Richard A. Dixon - One of the best experts on this subject based on the ideXlab platform.
-
distinct cinnamoyl coa reductases involved in parallel routes to lignin in medicago truncatula
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Rui Zhou, Fang Chen, Lisa Jackson, Gail Shadle, Jin Nakashima, Stephen Temple, Richard A. DixonAbstract:Cinnamoyl CoA reductases (CCR) convert hydroxycinnamoyl CoA esters to their corresponding cinnamyl aldehydes in monolignol biosynthesis. We identified two CCR genes in the model legume Medicago truncatula. CCR1 exhibits preference for feruloyl CoA, but CCR2 prefers caffeoyl and 4-coumaroyl CoAs, exhibits sigmoidal kinetics with these substrates, and is substrate-inhibited by feruloyl and sinapoyl CoAs. M. truncatula lines harboring transposon insertions in CCR1 exhibit drastically reduced growth and lignin content, whereas CCR2 knockouts grow normally with moderate reduction in lignin levels. CCR1 fully and CCR2 partially complement the irregular xylem gene 4 CCR mutation of Arabidopsis. The expression of caffeoyl CoA 3-O-methyltransferase (CCoAOMT) is up-regulated in CCR2 knockout lines; conversely, knockout of CCoAOMT up-regulates CCR2. These observations suggest that CCR2 is involved in a route to monolignols in Medicago whereby coniferaldehyde is formed via caffeyl aldehyde which then is 3-O-methylated by caffeic acid O-methyltransferase.
-
switchgrass panicum virgatum possesses a divergent family of cinnamoyl coa reductases with distinct biochemical properties
New Phytologist, 2010Co-Authors: Luis Escamillatrevino, Hui Shen, Yuhong Tang, Srinivasa Rao Uppalapati, Tui Ray, Timothy Hernandez, Yanbin Yin, Richard A. DixonAbstract:Summary • The down-regulation of enzymes of the monolignol pathway results in reduced recalcitrance of biomass for lignocellulosic ethanol production. Cinnamoyl CoA reductase (CCR) catalyzes the first step of the phenylpropanoid pathway specifically dedicated to monolignol biosynthesis. However, plants contain multiple CCR-like genes, complicating the selection of lignin-specific targets. This study was undertaken to understand the complexity of the CCR gene family in tetraploid switchgrass (Panicum virgatum) and to determine the biochemical properties of the encoded proteins. • Four switchgrass cDNAs (most with multiple variants) encoding putative CCRs were identified by phylogenetic analysis, heterologously expressed in Escherichia coli, and the corresponding enzymes were characterized biochemically. • Two cDNAs, PvCCR1 and PvCCR2, encoded enzymes with CCR activity. They are phylogenetically distinct, differentially expressed, and the corresponding enzymes exhibited different biochemical properties with regard to substrate preference. PvCCR1 has higher specific activity and prefers feruloyl CoA as substrate, whereas PvCCR2 prefers caffeoyl and 4-coumaroyl CoAs. Allelic variants of each cDNA were detected, but the two most diverse variants of PvCCR1 encoded enzymes with similar catalytic activity. • Based on its properties and expression pattern, PvCCR1 is probably associated with lignin biosynthesis during plant development (and is therefore a target for the engineering of improved biomass), whereas PvCCR2 may function in defense.
-
Improving Saccharification Efficiency of Alfalfa Stems Through Modification of the Terminal Stages of Monolignol Biosynthesis
BioEnergy Research, 2008Co-Authors: Lisa A. Jackson, Fang Chen, Rui Zhou, Jin Nakashima, Gail L. Shadle, Richard A. DixonAbstract:A series of transgenic lines of alfalfa ( Medicago sativa ) were generated in which either one of the two potentially terminal enzymes of the monolignol pathway, cinnamoyl CoA reductase (CCR) or cinnamyl alcohol dehydrogenase (CAD) was down-regulated by expression of antisense transgenes. Levels of CCR enzymatic activity were reduced to between 10% to 65% of the control level, and levels of CAD activity were similarly reduced to between 5% to 40% of the control. Biomass yields were reduced in the most strongly down-regulated lines for both transgenes, but many of the lines exhibited reduced lignin levels but normal biomass and flowering time. In vitro dry matter digestibility was increased for most transgenic lines compared to controls. Saccharification efficiency was determined by measuring the release of sugars from cell walls directly, or after sulfuric acid pre-treatment and subsequent digestion with a mixture of cellulase and cellobiase. Several CCR down-regulated lines had significantly enhanced saccharification efficiency with both pre-treated and untreated tissues, whereas CAD down-regulation had less impact on sugar release when compared to that from CCR lines with similar lignin contents. One CCR line with a 50–60% improvement in saccharification efficiency exhibited normal biomass production, indicating the potential for producing high yielding, improved feedstocks for bioethanol production through genetic modification of the monolignol pathway.
Rui Zhou - One of the best experts on this subject based on the ideXlab platform.
-
structural studies of cinnamoyl coa reductase and cinnamyl alcohol dehydrogenase key enzymes of monolignol biosynthesis
The Plant Cell, 2014Co-Authors: Rui Zhou, Richard A Dixo, Gordo V Louie, Joelle K Muhlema, Eri K Omati, Marianne E Owma, Natalia Dudareva, Joseph P NoelAbstract:The enzymes Cinnamoyl-CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) catalyze the two key reduction reactions in the conversion of cinnamic acid derivatives into monolignol building blocks for lignin polymers in plant cell walls. Here, we describe detailed functional and structural analyses of CCRs from Medicago truncatula and Petunia hybrida and of an atypical CAD (CAD2) from M. truncatula. These enzymes are closely related members of the short-chain dehydrogenase/reductase (SDR) superfamily. Our structural studies support a reaction mechanism involving a canonical SDR catalytic triad in both CCR and CAD2 and an important role for an auxiliary cysteine unique to CCR. Site-directed mutants of CAD2 (Phe226Ala and Tyr136Phe) that enlarge the phenolic binding site result in a 4- to 10-fold increase in activity with sinapaldehyde, which in comparison to the smaller coumaraldehyde and coniferaldehyde substrates is disfavored by wild-type CAD2. This finding demonstrates the potential exploitation of rationally engineered forms of CCR and CAD2 for the targeted modification of monolignol composition in transgenic plants. Thermal denaturation measurements and structural comparisons of various liganded and unliganded forms of CCR and CAD2 highlight substantial conformational flexibility of these SDR enzymes, which plays an important role in the establishment of catalytically productive complexes of the enzymes with their NADPH and phenolic substrates.
-
distinct cinnamoyl coa reductases involved in parallel routes to lignin in medicago truncatula
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Rui Zhou, Fang Chen, Lisa Jackson, Gail Shadle, Jin Nakashima, Stephen Temple, Richard A. DixonAbstract:Cinnamoyl CoA reductases (CCR) convert hydroxycinnamoyl CoA esters to their corresponding cinnamyl aldehydes in monolignol biosynthesis. We identified two CCR genes in the model legume Medicago truncatula. CCR1 exhibits preference for feruloyl CoA, but CCR2 prefers caffeoyl and 4-coumaroyl CoAs, exhibits sigmoidal kinetics with these substrates, and is substrate-inhibited by feruloyl and sinapoyl CoAs. M. truncatula lines harboring transposon insertions in CCR1 exhibit drastically reduced growth and lignin content, whereas CCR2 knockouts grow normally with moderate reduction in lignin levels. CCR1 fully and CCR2 partially complement the irregular xylem gene 4 CCR mutation of Arabidopsis. The expression of caffeoyl CoA 3-O-methyltransferase (CCoAOMT) is up-regulated in CCR2 knockout lines; conversely, knockout of CCoAOMT up-regulates CCR2. These observations suggest that CCR2 is involved in a route to monolignols in Medicago whereby coniferaldehyde is formed via caffeyl aldehyde which then is 3-O-methylated by caffeic acid O-methyltransferase.
-
Improving Saccharification Efficiency of Alfalfa Stems Through Modification of the Terminal Stages of Monolignol Biosynthesis
BioEnergy Research, 2008Co-Authors: Lisa A. Jackson, Fang Chen, Rui Zhou, Jin Nakashima, Gail L. Shadle, Richard A. DixonAbstract:A series of transgenic lines of alfalfa ( Medicago sativa ) were generated in which either one of the two potentially terminal enzymes of the monolignol pathway, cinnamoyl CoA reductase (CCR) or cinnamyl alcohol dehydrogenase (CAD) was down-regulated by expression of antisense transgenes. Levels of CCR enzymatic activity were reduced to between 10% to 65% of the control level, and levels of CAD activity were similarly reduced to between 5% to 40% of the control. Biomass yields were reduced in the most strongly down-regulated lines for both transgenes, but many of the lines exhibited reduced lignin levels but normal biomass and flowering time. In vitro dry matter digestibility was increased for most transgenic lines compared to controls. Saccharification efficiency was determined by measuring the release of sugars from cell walls directly, or after sulfuric acid pre-treatment and subsequent digestion with a mixture of cellulase and cellobiase. Several CCR down-regulated lines had significantly enhanced saccharification efficiency with both pre-treated and untreated tissues, whereas CAD down-regulation had less impact on sugar release when compared to that from CCR lines with similar lignin contents. One CCR line with a 50–60% improvement in saccharification efficiency exhibited normal biomass production, indicating the potential for producing high yielding, improved feedstocks for bioethanol production through genetic modification of the monolignol pathway.
Raquel Mateos - One of the best experts on this subject based on the ideXlab platform.
-
exhaustive qualitative lc dad msn analysis of arabica green coffee beans cinnamoyl glycosides and cinnamoylshikimic acids as new polyphenols in green coffee
Journal of Agricultural and Food Chemistry, 2016Co-Authors: Gema Baeza, Beatriz Sarria, Laura Bravo, Raquel MateosAbstract:Coffee is one of the most consumed beverages in the world, due to its unique aroma and stimulant properties. Although its health effects are controversial, moderate intake seems to be beneficial. The present work deals with the characterization and quantification of polyphenols and methylxanthines in four Arabica green coffee beans from different geographical origins. The antioxidant activity was also evaluated. Forty-three polyphenols (cinnamic acid, cinnamoyl-amide, 5 cinammoyl-glycosides, and 36 cinnamate esters) were identified using LC-MSn. Among these, cinnamate esters of six different chemical groups (including two dimethoxycinnamoylquinic acid isomers, three caffeoyl-feruloylquinic acid isomers, caffeoyl-sinapoylquinic acid, p-coumaroyl-feruloylquinic acid, two caffeoylshikimic acid isomers, and trimethoxycinnamoylshikimic acid) in addition to five isomers of cinnamoyl-glycosides called caffeoyl-2,7-anhydro-3-deoxy-2-octulopyranosic acid (CDOA) are described for the first time in Arabica green cof...
Zhongfeng Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Dynamics of antioxidant activities, metabolites, phenolic acids, flavonoids, and phenolic biosynthetic genes in germinating Chinese wild rice (Zizania latifolia).
Food chemistry, 2020Co-Authors: Cheng Chu, Zhongfeng Zhang, Hongbo Zhang, John Shi, Xiao-long Yuan, Xinmin Liu, Yanhua Liu, Ning YanAbstract:Abstract In this study, the antioxidant activity of germinating Chinese wild rice was found to decline initially, after which it increased. The largest difference in antioxidant activity was observed between the 36-h (G36) and the 120-h germination (G120) stage. We further assessed the dynamic changes in metabolites, phenolic acids, flavonoids, and phenolic biosynthetic genes in germinating Chinese wild rice. Ultra-high performance liquid chromatography–triple quadrupole mass spectrometry revealed that 315 metabolites were up-regulated and 28 were down-regulated between G36 and G120. Levels of p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillin, p-coumaric acid, ferulic acid, and epigallocatechin increased significantly during germination. Gene expression of four phenylalanine ammonia-lyases, one 4-coumarate-CoA ligase, one Cinnamoyl-CoA reductase, two cinnamyl alcohol dehydrogenases, one chalcone synthase, and one chalcone isomerase was significantly higher at G120 than at G36 and promoted phenolics accumulation. This study elucidated the biochemical mechanisms involved in antioxidant activity and phenolic profile changes during Chinese wild rice germination.
-
iTRAQ-based proteomic analysis reveals the accumulation of bioactive compounds in Chinese wild rice (Zizania latifolia) during germination
Food Chemistry, 2019Co-Authors: Yongmei Du, Hongbo Zhang, Zhongfeng ZhangAbstract:Abstract Polyphenols and γ-aminobutyric acid (GABA) accumulate during seed germination, but the mechanisms involved are poorly understood. The objective of this study was to elucidate the accumulation of these bioactive compounds in Chinese wild rice during germination. The greatest differences in the phenolic content were at 36-h (G36) and 120-h germination (G120) stages. An iTRAQ-based proteomic analysis revealed 7031 proteins, and a comparison of the G120 and G36 stages revealed 956 upregulated and 188 downregulated proteins. The KEGG analysis revealed significant protein enrichment in the “metabolic pathways”, “biosynthesis of secondary metabolites” and “phenylpropanoid biosynthesis”. Four phenylalanine ammonia-lyases, one 4-coumarate-CoA ligase, one Cinnamoyl-CoA reductase, two cinnamyl alcohol dehydrogenases, and four glutamate decarboxylases exhibited higher expression at the G120 than at the G36 stage and promoted phenolics and GABA accumulation. This study revealed bioactive compound accumulation in germinating Chinese wild rice, and the finding may help develop functional foods derived from this cereal.
Fang Chen - One of the best experts on this subject based on the ideXlab platform.
-
MOESM8 of Loss of function of folylpolyglutamate synthetase 1 reduces lignin content and improves cell wall digestibility in Arabidopsis
2015Co-Authors: Avinash Srivastava, Fang Chen, Tui Ray, Sivakumar Pattathil, Maria PeĂąa, Utku Avci, David Huhman, Jason Backe, Breeanna UrbanowiczAbstract:Additional file 8: Fig. S6. Schematic representation of C1 metabolism association with the monolignol biosynthetic pathway (Adapted from Humphreys and Chapple [91], Ravanel et al. [56]; van den Broeck et al. [16]. Arrows represent enzymatic reactions and abbreviations depicted next to arrows are the name of the enzyme that catalyzes the associated reaction. (PAL) l-Phenylalanine ammonia lyase; (C4H) Cinnamate 4-hydroxylase; (4-CL) 4-coumarate:coenzyme A ligase; (CCR) Cinnamoyl-CoA reductase; (HCT) Hydroxycinnamoyl CoA: shikimate hydroxycinnamoyltransferase; (C3â˛H) 4-Coumaroyl-shikimate 3â˛-hydroxylase; (CCoAOMT) Caffeoyl-CoA-3-O-methyltransferase; (CAD) Cinnamyl alcohol dehydrogenase; (Lac 4) Laccase 4; (F5H) Ferulate 5-hydroxylase; (COMT) Caffeic acid 3-O-methyltransferase; (FPGS1) Folypolyglutamate synthetase 1; (SHMT) Serine hydroxymethyltransferase; (5,10-Met-THF) 5,10-Methylene-tetrahydrofolate reductase; (Met-Syn) Methionine synthase; (SAM-Syn) S-Adenosyl methionine-Synthase; (SAM-MT) S-Adenosyl methionine dependent Methyl transferase; (SAM-HCT) S-adenosyl homocysteinase; (SAHH) S-Adenosyl-L-homocysteine hydrolase; (Cys) Cysteine; (Cys-Syn) Cystathionine synthase; (Cys-Lys) Cystayhioninelyase
-
distinct cinnamoyl coa reductases involved in parallel routes to lignin in medicago truncatula
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Rui Zhou, Fang Chen, Lisa Jackson, Gail Shadle, Jin Nakashima, Stephen Temple, Richard A. DixonAbstract:Cinnamoyl CoA reductases (CCR) convert hydroxycinnamoyl CoA esters to their corresponding cinnamyl aldehydes in monolignol biosynthesis. We identified two CCR genes in the model legume Medicago truncatula. CCR1 exhibits preference for feruloyl CoA, but CCR2 prefers caffeoyl and 4-coumaroyl CoAs, exhibits sigmoidal kinetics with these substrates, and is substrate-inhibited by feruloyl and sinapoyl CoAs. M. truncatula lines harboring transposon insertions in CCR1 exhibit drastically reduced growth and lignin content, whereas CCR2 knockouts grow normally with moderate reduction in lignin levels. CCR1 fully and CCR2 partially complement the irregular xylem gene 4 CCR mutation of Arabidopsis. The expression of caffeoyl CoA 3-O-methyltransferase (CCoAOMT) is up-regulated in CCR2 knockout lines; conversely, knockout of CCoAOMT up-regulates CCR2. These observations suggest that CCR2 is involved in a route to monolignols in Medicago whereby coniferaldehyde is formed via caffeyl aldehyde which then is 3-O-methylated by caffeic acid O-methyltransferase.
-
Improving Saccharification Efficiency of Alfalfa Stems Through Modification of the Terminal Stages of Monolignol Biosynthesis
BioEnergy Research, 2008Co-Authors: Lisa A. Jackson, Fang Chen, Rui Zhou, Jin Nakashima, Gail L. Shadle, Richard A. DixonAbstract:A series of transgenic lines of alfalfa ( Medicago sativa ) were generated in which either one of the two potentially terminal enzymes of the monolignol pathway, cinnamoyl CoA reductase (CCR) or cinnamyl alcohol dehydrogenase (CAD) was down-regulated by expression of antisense transgenes. Levels of CCR enzymatic activity were reduced to between 10% to 65% of the control level, and levels of CAD activity were similarly reduced to between 5% to 40% of the control. Biomass yields were reduced in the most strongly down-regulated lines for both transgenes, but many of the lines exhibited reduced lignin levels but normal biomass and flowering time. In vitro dry matter digestibility was increased for most transgenic lines compared to controls. Saccharification efficiency was determined by measuring the release of sugars from cell walls directly, or after sulfuric acid pre-treatment and subsequent digestion with a mixture of cellulase and cellobiase. Several CCR down-regulated lines had significantly enhanced saccharification efficiency with both pre-treated and untreated tissues, whereas CAD down-regulation had less impact on sugar release when compared to that from CCR lines with similar lignin contents. One CCR line with a 50–60% improvement in saccharification efficiency exhibited normal biomass production, indicating the potential for producing high yielding, improved feedstocks for bioethanol production through genetic modification of the monolignol pathway.
-
conversion of guaiacyl to syringyl moieties on the cinnamyl alcohol pathway during the biosynthesis of lignin in angiosperms
Planta, 2000Co-Authors: Naoyuki Matsui, Seiichi Yasuda, Fang Chen, Kazuhiko FukushimaAbstract:Aglycons derived from 4-O-β-D-glucosides of both caffeyl and 5-hydroxyconiferyl alcohols were incorporated into guaiacyl (G) and syringyl (S) units in the lignin of newly formed xylem of several angiosperms. It is likely that these aglycons enter the cinnamyl alcohol pathway as intermediates in the introduction of methoxyl groups onto aromatic rings, and serve as precursors for the biosynthesis of lignin. The S/G ratio in this pathway was coincident with the ratio in the cell wall lignin of each tree. Our results indicate that the cinnamyl alcohol pathway involves the same mechanisms as the cinnamic acid and cinnamyl CoA pathways and they suggest that this novel pathway might be part of a metabolic grid in the biosynthesis of lignin.