Syringyl

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Vincent L Chiang - One of the best experts on this subject based on the ideXlab platform.

  • chemical and spatial differentiation of Syringyl and guaiacyl lignins in poplar wood via time of flight secondary ion mass spectrometry
    Analytical Chemistry, 2011
    Co-Authors: Chuanzhen Zhou, Quanzi Li, Vincent L Chiang, Lucian A Lucia, D P Griffis
    Abstract:

    As a major component in plant cell walls, lignin is an important factor in numerous industrial processes, especially in wood saccharification and fermentation to biofuels. The ability to chemically differentiate and spatially locate lignins in wood cell structures provides an important contribution to the effort to improve these processes. The spatial distribution of the Syringyl (S) and guaiacyl (G) lignins, both over larger regions and within a single cell wall, on poplar (Populus trichocarpa) wood cross-sections was determined via time-of-flight secondary ion mass spectrometry (ToF-SIMS). This is the first time that direct chemically specific mass spectrometric mapping has been employed to elucidate the spatial distribution of S and G lignins. In agreement with results obtained by UV microscopy, ToF-SIMS images clearly show that the guaiacyl lignin is predominantly located in the vessel cell walls of poplar wood while Syringyl lignin is mainly located in the fiber cell walls. The G/S ratio in vessel ce...

  • improved wood properties through genetic manipulation engineering of Syringyl lignin in softwood species through xylem specific expression of hardwood Syringyl monolignol pathway genes
    2009
    Co-Authors: Chandrashekhar P Joshi, Vincent L Chiang
    Abstract:

    Project Objective: Our long-term goal is to genetically engineer higher value raw materials with desirable wood properties to promote energy efficiency, international competitiveness, and environmental responsiveness of the U.S. forest products industry. The immediate goal of this project was to produce the first higher value softwood raw materials engineered with a wide range of Syringyl lignin quantities. Summary: The most important wood property affecting directly the levels of energy, chemical and bleaching requirements for kraft pulp production is lignin. Softwoods contain almost exclusively chemically resistant guaiacyl (G) lignin, whereas hardwoods have more reactive or easily degradable lignins of the guaiacyl (G)-Syringyl (S) type. It is also well established that the reactive S lignin component is the key factor that permits much lower effective alkali and temperature, shorter pulping time and less bleaching stages for processing hardwoods than for softwoods. Furthermore, our pulping kinetic study explicitly demonstrated that every increase in one unit of the lignin S/G ratio would roughly double the rate of lignin removal. These are clear evidence that softwoods genetically engineered with S lignin are keys to revolutionizing the energy efficiency and enhancing the environmental performance of this industry. Softwoods and hardwoods share the same genetic mechanisms formore » the biosynthesis of G lignin. However, in hardwoods, three additional genes branch out from the G-lignin pathway and become specifically engaged in regulating S lignin biosynthesis. In this research, we simultaneously transferred aspen S-specific genes into a model softwood, black spruce, to engineer S lignin.« less

  • final report on regulation of guaiacyl and Syringyl monolignol biosynthesis
    2006
    Co-Authors: Vincent L Chiang
    Abstract:

    The focus of this research is to understand Syringyl monolignol biosynthesis that leads to the formation of Syringyl lignin, a type of lignin that can be easily removed during biomass conversion. We have achieved the three originally proposed goals for this project. (1) SAD and CAD genes (enzyme catalytic and kinetic properties) and their functional relevance to CAld5H/AldOMT pathway, (2) spatiotemporal expression patterns of Cald5H, AldOMT, SAD and CAD genes, and (3) functions of CAld5H, AldOMT, and SAD genes in vivo using transgenic aspen. Furthermore, we also found that microRNA might be involved in the upstream regulatory network of lignin biosynthesis and wood formation. The achievements are as below. (1) Based on biochemical and molecular studies, we discovered a novel Syringyl-specific alcohol dehydrogenase (SAD) involved in monolignol biosynthesis in angiosperm trees. Through CAld5H/OMT/SAD mediation, Syringyl monolignol biosynthesis branches out from guaiacyl pathway at coniferaldehyde; (2) The function of CAld5H gene in this Syringyl monolignol biosynthesis pathway also was confirmed in vivo in transgenic Populus; (3) The proposed major monolignol biosynthesis pathways were further supported by the involving biochemical functions of CCR based on a detailed kinetic study; (4) Gene promoter activity analysis also supported the cell-type specific expression of SADmore » and CAD genes in xylem tissue, consistent with the cell-specific locations of SAD and CAD proteins and with the proposed pathways; (5) We have developed a novel small interfering RNA (siRNA)-mediated stable gene-silencing system in transgenic plants; (6) Using the siRNA and P. trichocarpa transformation/regeneration systems we are currently producing transgenic P. trichocarpa to investigate the interactive functions of CAD and SAD in regulating guaiacyl and Syringyl lignin biosynthesis; (7) We have cloned for the first time from a tree species, P. trichocarpa, small regulatory RNAs termed microRNAs (miRNAs) with likely effector roles in regulating the expression of genes involved in lignin biosynthesis and wood formation networks.« less

  • genetic augmentation of Syringyl lignin in low lignin aspen trees final report
    2004
    Co-Authors: Chungjui Tsai, Mark F Davis, Vincent L Chiang
    Abstract:

    As a polysaccharide-encrusting component, lignin is critical to cell wall integrity and plant growth but also hinders recovery of cellulose fibers during the wood pulping process. To improve pulping efficiency, it is highly desirable to genetically modify lignin content and/or structure in pulpwood species to maximize pulp yields with minimal energy consumption and environmental impact. This project aimed to genetically augment the Syringyl-to-guaiacyl lignin ratio in low-lignin transgenic aspen in order to produce trees with reduced lignin content, more reactive lignin structures and increased cellulose content. Transgenic aspen trees with reduced lignin content have already been achieved, prior to the start of this project, by antisense downregulation of a 4-coumarate:coenzyme A ligase gene (Hu et al., 1999 Nature Biotechnol 17: 808- 812). The primary objective of this study was to genetically augment Syringyl lignin biosynthesis in these low-lignin trees in order to enhance lignin reactivity during chemical pulping. To accomplish this, both aspen and sweetgum genes encoding coniferaldehyde 5-hydroxylase (Osakabe et al., 1999 PNAS 96: 8955-8960) were targeted for over-expression in wildtype or low-lignin aspen under control of either a constitutive or a xylem-specific promoter. A second objective for this project was to develop reliable and cost-effective methods, such asmore » pyrolysis Molecular Beam Mass Spectrometry and NMR, for rapid evaluation of cell wall chemical components of transgenic wood samples. With these high-throughput techniques, we observed increased Syringyl-to-guaiacyl lignin ratios in the transgenic wood samples, regardless of the promoter used or gene origin. Our results confirmed that the coniferaldehyde 5-hydroxylase gene is key to Syringyl lignin biosynthesis. The outcomes of this research should be readily applicable to other pulpwood species, and promise to bring direct economic and environmental benefits to the pulp and paper industry.« less

  • the last step of Syringyl monolignol biosynthesis in angiosperms is regulated by a novel gene encoding sinapyl alcohol dehydrogenase
    The Plant Cell, 2001
    Co-Authors: Laigeng Li, Xiao Fei Cheng, Jacqueline Leshkevich, Toshiaki Umezawa, Scott A Harding, Vincent L Chiang
    Abstract:

    Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) has been thought to mediate the reduction of both coniferaldehyde and sinapaldehyde into guaiacyl and Syringyl monolignols in angiosperms. Here, we report the isolation of a novel aspen gene ( PtSAD ) encoding sinapyl alcohol dehydrogenase (SAD), which is phylogenetically distinct from aspen CAD (PtCAD). Liquid chromatography‐mass spectrometry-based enzyme functional analysis and substrate level‐controlled enzyme kinetics consistently demonstrated that PtSAD is sinapaldehyde specific and that PtCAD is coniferaldehyde specific. The enzymatic efficiency of PtSAD for sinapaldehyde was � 60 times greater than that of PtCAD. These data suggest that in addition to CAD, discrete SAD function is essential to the biosynthesis of Syringyl monolignol in angiosperms. In aspen stem primary tissues, PtCAD was immunolocalized exclusively to xylem elements in which only guaiacyl lignin was deposited, whereas PtSAD was abundant in Syringyl lignin‐enriched phloem fiber cells. In the developing secondary stem xylem, PtCAD was most conspicuous in guaiacyl lignin‐enriched vessels, but PtSAD was nearly absent from these elements and was conspicuous in fiber cells. In the context of additional protein immunolocalization and lignin histochemistry, these results suggest that the distinct CAD and SAD functions are linked spatiotemporally to the differential biosynthesis of guaiacyl and Syringyl lignins in different cell types. SAD is required for the biosynthesis of Syringyl lignin in angiosperms.

Kazuhiko Fukushima - One of the best experts on this subject based on the ideXlab platform.

  • On the Mechanism to Regulate the Ratio of Syringyl to Guaiacyl Moieties in Lignin
    Progress in Biotechnology, 2020
    Co-Authors: Kazuhiko Fukushima
    Abstract:

    ABSTRACT Now, lignin biosynthetic pathway is believed to form the metabolic grids. It is very important to elucidate the actual pathway that regulates the ratio of Syringyl to guaiacyl moieties in lignin. Here, possible regulating systems proposed on the basis of the enzymatic, genetic and feeding studies are introduced and discussed. In addition, our recent results are also introduced.

  • The regulation from guaiacyl to Syringyl lignin in the differentiating xylem of Robinia pseudoacacia.
    Comptes rendus biologies, 2020
    Co-Authors: Kazuchika Yamauchi, Kazuhiko Fukushima
    Abstract:

    13C- and deuterium (D)-labeled ferulic acid and sinapic acid ([8-(13)C, 3-OCD3]-ferulic acid and [8-(13)C, 3,5-OCD3]-sinapic acid) were administered to robinia (Robinia pseudoacacia L.) shoots. To estimate the distribution of the label from administrated ferulic or sinapic acid, continuous 50-microm-thick tangential sections cut from the cambium of robinia were subjected to lignin chemical analysis by the DFRC method. Labeled ferulic acid was incorporated into guaiacyl and Syringyl lignin. The incorporation of labeled ferulic acid into Syringyl units was observed only in the later stage of lignification. Labeled sinapic acid was incorporated into Syringyl lignin in the early stage and the later stage of lignification. In general, Syringyl lignin was deposited in the later stage of cell wall lignification. Thus, the incorporation of sinapic acid to Syringyl lignin in the early stage of lignification was abnormal. Taken together, the aromatic ring-modifying reactions (the conversion from guaiacyl to Syringyl moiety, including the hydroxylation and methylation) were more important for the regulation of the sinapyl alcohol biosynthesis than the reducing reactions (the reduction of acids to alcohols) in the differentiating xylem.

  • influence of Syringyl to guaiacyl ratio on the structure of natural and synthetic lignins
    Journal of Agricultural and Food Chemistry, 2010
    Co-Authors: Takao Kishimoto, Kazuhiko Fukushima, Wakako Chiba, Kaori Saito, Yasumitsu Uraki, Makoto Ubukata
    Abstract:

    Several kinds of natural woods and isolated lignins with various Syringyl to guaiacyl (S/G) ratios were subjected to thioacidolysis followed by Raney nickel desulfuration to elucidate the relationships between the S/G ratio and the interunit linkage types of lignin. Furthermore, enzymatic dehydrogenation polymers (DHP) were produced by the Zutropf (gradual monolignol addition) method from mixtures of various ratios of coniferyl alcohol and sinapyl alcohol. The analysis of DHPs and natural wood lignins exhibited basically a similar tendency. The existence of both Syringyl and guaiacyl units is effective for producing higher amounts of β-O-4 and 4-O-5 structures, but it lowers the total amount of cinnamyl alcohol and aldehyde end groups. The relative frequency of the β-β structure increased, whereas that of β-5 and 5-5 structures decreased with increasing Syringyl units.

  • phenolization of hardwood sulfuric acid lignin and comparison of the behavior of the Syringyl and guaiacyl units in lignin
    Journal of Wood Science, 2007
    Co-Authors: Yasuyuki Matsushita, Hitomi Sano, Masanori Imai, Takanori Imai, Kazuhiko Fukushima
    Abstract:

    To study the behavior of hardwood sulfuric acid lignin (SAL) during phenolization, we compared the product yield, average molecular weight, methoxy content, and reactions of simple model compounds with those of softwood SAL, focusing on the difference between Syringyl and guaiacyl units. The beech SAL reacted with phenol more readily than red pine SAL and yielded a larger soluble fraction of phenolized SAL. To investigate the difference in the phenolization activity of the Syringyl and guaiacyl units in beech lignin, we prepared Syringyl-nucleus-rich sulfuric acid lignin (S-rich-SAL) and guaiacyl-nucleus-rich sulfuric acid lignin (G-rich-SAL) from beech, which were subjected to phenolization. The results suggest that the Syringyl unit in SAL had greater phenolization activity and its phenolized products were more soluble in acidic aqueous medium and introduced less phenol than the guaiacyl unit. Using model compounds, the study also showed that the Syringyl unit had higher phenolization reactivity than the guaiacyl unit.

  • the regulation from guaiacyl to Syringyl lignin in the differentiating xylem of robinia pseudoacacia
    Comptes Rendus Biologies, 2004
    Co-Authors: Kazuchika Yamauchi, Kazuhiko Fukushima
    Abstract:

    Abstract 13 C- and deuterium (D)-labeled ferulic acid and sinapic acid ([8- 13 C, 3-OCD 3 ]-ferulic acid and [8- 13 C, 3,5-OCD 3 ]-sinapic acid) were administered to robinia ( Robinia pseudoacacia L.) shoots. To estimate the distribution of the label from administrated ferulic or sinapic acid, continuous 50-μm-thick tangential sections cut from the cambium of robinia were subjected to lignin chemical analysis by the DFRC method. Labeled ferulic acid was incorporated into guaiacyl and Syringyl lignin. The incorporation of labeled ferulic acid into Syringyl units was observed only in the later stage of lignification. Labeled sinapic acid was incorporated into Syringyl lignin in the early stage and the later stage of lignification. In general, Syringyl lignin was deposited in the later stage of cell wall lignification. Thus, the incorporation of sinapic acid to Syringyl lignin in the early stage of lignification was abnormal. Taken together, the aromatic ring-modifying reactions (the conversion from guaiacyl to Syringyl moiety, including the hydroxylation and methylation) were more important for the regulation of the sinapyl alcohol biosynthesis than the reducing reactions (the reduction of acids to alcohols) in the differentiating xylem. To cite this article: K. Yamauchi, K. Fukushima, C. R. Biologies 327 (2004).

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

  • in vitro enzymatic depolymerization of lignin with release of Syringyl guaiacyl and tricin units
    Applied and Environmental Microbiology, 2017
    Co-Authors: Daniel L Gall, John Ralph, Timothy J Donohue, Wayne S Kontur, Yanding Li, Daniel R Noguera
    Abstract:

    New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and Syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite, tricin, is a recently discovered and moderately abundant flavonoid in grasses. The most prevalent inter-unit linkage between guaiacyl, Syringyl, and tricin units is the β-ether linkage. Previous studies have shown that bacterial β-etherase pathway enzymes catalyze glutathione-dependent cleavage of β-ether bonds in dimeric β-ether lignin model compounds. To date, however, it remains unclear whether the known β-etherase enzymes are active on lignin polymers. Here, we report on enzymes that catalyze β-ether cleavage from bona fide lignin, under conditions that recycle the cosubstrates NAD + and glutathione. Guaiacyl, Syringyl and tricin derivatives were identified as reaction products when different model compounds or lignin fractions were used as substrates. These results demonstrate an in vitro enzymatic system that can recycle cosubstrates while releasing aromatic monomers from model compounds as well as natural and engineered lignin oligomers. These findings can improve the ability to produce valuable aromatic compounds from a renewable resource like lignin. IMPORTANCE Many bacteria are predicted to contain enzymes that could convert renewable carbon sources into substitutes for compounds that are derived from petroleum. The β-etherase pathway present in sphingomonad bacteria could cleave the abundant β–O–4-aryl ether bonds in plant lignin, releasing a bio-based source of aromatic compounds for the chemical industry. However, the activity of these enzymes on the complex aromatic oligomers found in plant lignin is unknown. Here, we demonstrate biodegradation of lignin polymers using a minimal set of β-etherase pathway enzymes, the ability to recycle needed cofactors (glutathione and NAD + ) in vitro , and the release of guaiacyl, Syringyl, and tricin, as depolymerized products from lignin. These observations provide critical evidence for the use and future optimization of these bacterial β-etherase pathway enzymes for industrial level biotechnological applications designed to derive high-value monomeric aromatic compounds from lignin.

  • Syringyl lignin production in conifers proof of concept in a pine tracheary element system
    Proceedings of the National Academy of Sciences of the United States of America, 2015
    Co-Authors: Armin Wagner, John Ralph, Yuki Tobimatsu, Lorelle Phillips, Heather Flint, Barbara Geddes, Fachuang Lu
    Abstract:

    Conifers (softwoods) naturally lack Syringyl units in their lignins, rendering lignocellulosic materials from such species more difficult to process than Syringyl-rich hardwood species. Using a transformable Pinus radiata tracheary element (TE) system as an experimental platform, we investigated whether metabolic engineering can be used to create Syringyl lignin in conifers. Pyrolysis-GC/MS and 2D-NMR analysis of P. radiata TE cultures transformed to express ferulate 5-hydroxylase (F5H) and caffeic acid O-methyltransferase (COMT) from Liquidambar styraciflua confirmed the production and incorporation of sinapyl alcohol into the lignin polymer. Transformation with F5H was sufficient for the production of Syringyl lignin in TEs, but cotransformation with COMT improved its formation. In addition, lower levels of the pathway intermediate 5-hydroxyconiferyl alcohol were evidenced in cotransformation experiments, indicating that the introduction of the COMT overcame the inefficiency of the native pine methyltransferases for supporting sinapyl alcohol production.Our results provide the proof of concept that it is possible to generate a lignin polymer that contains Syringyl units in softwood species such as P. radiata, suggesting that it might be possible to retain the outstanding fiber properties of softwoods while imbuing them with the lignin characteristics of hardwoods that are more favorable for industrial processing.

  • a group of sequence related sphingomonad enzymes catalyzes cleavage of β aryl ether linkages in lignin β guaiacyl and β Syringyl ether dimers
    Environmental Science & Technology, 2014
    Co-Authors: Daniel L Gall, John Ralph, Timothy J Donohue, Daniel R Noguera
    Abstract:

    Lignin biosynthesis occurs via radical coupling of guaiacyl and Syringyl hydroxycinnamyl alcohol monomers (i.e., “monolignols”) through chemical condensation with the growing lignin polymer. With each chain-extension step, monolignols invariably couple at their β-positions, generating chiral centers. Here, we report on activities of bacterial glutathione-S-transferase (GST) enzymes that cleave β-aryl ether bonds in lignin dimers that are composed of different monomeric units. Our data reveal that these sequence-related enzymes from Novosphingobium sp. strain PP1Y, Novosphingobium aromaticivorans strain DSM12444, and Sphingobium sp. strain SYK-6 have conserved functions as β-etherases, catalyzing cleavage of each of the four dimeric α-keto-β-aryl ether-linked substrates (i.e., guaiacyl-β-guaiacyl, guaiacyl-β-Syringyl, Syringyl-β-guaiacyl, and Syringyl-β-Syringyl). Although each β-etherase cleaves β-guaiacyl and β-Syringyl substrates, we have found that each is stereospecific for a given β-enantiomer in a r...

  • independent recruitment of an o methyltransferase for Syringyl lignin biosynthesis in selaginella moellendorffii
    The Plant Cell, 2011
    Co-Authors: Jingke Weng, John Ralph, Takuya Akiyama, Clint Chapple
    Abstract:

    Syringyl lignin, an important component of the secondary cell wall, has traditionally been considered to be a hallmark of angiosperms because ferns and gymnosperms in general lack lignin of this type. Interestingly, Syringyl lignin was also detected in Selaginella, a genus that represents an extant lineage of the most basal of the vascular plants, the lycophytes. In angiosperms, Syringyl lignin biosynthesis requires the activity of ferulate 5-hydroxylase (F5H), a cytochrome P450-dependent monooxygenase, and caffeic acid/5-hydroxyferulic acid O-methyltransferase (COMT). Together, these two enzymes divert metabolic flux from the biosynthesis of guaiacyl lignin, a lignin type common to all vascular plants, toward Syringyl lignin. Selaginella has independently evolved an alternative lignin biosynthetic pathway in which Syringyl subunits are directly derived from the precursors of p-hydroxyphenyl lignin, through the action of a dual specificity phenylpropanoid meta-hydroxylase, Sm F5H. Here, we report the characterization of an O-methyltransferase from Selaginella moellendorffii, COMT, the coding sequence of which is clustered together with F5H at the adjacent genomic locus. COMT is a bifunctional phenylpropanoid O-methyltransferase that can methylate phenylpropanoid meta-hydroxyls at both the 3- and 5-position and function in concert with F5H in Syringyl lignin biosynthesis in S. moellendorffii. Phylogenetic analysis reveals that Sm COMT, like F5H, evolved independently from its angiosperm counterparts.

  • convergent evolution of Syringyl lignin biosynthesis via distinct pathways in the lycophyte selaginella and flowering plants
    The Plant Cell, 2010
    Co-Authors: Jingke Weng, John Ralph, Takuya Akiyama, Xu Li, Nicholas D Bonawitz, Clint Chapple
    Abstract:

    Phenotypic convergence in unrelated lineages arises when different organisms adapt similarly under comparable selective pressures. In an apparent example of this process, Syringyl lignin, a fundamental building block of plant cell walls, occurs in two major plant lineages, lycophytes and angiosperms, which diverged from one another more than 400 million years ago. Here, we show that this convergence resulted from independent recruitment of lignin biosynthetic cytochrome P450-dependent monooxygenases that route cell wall monomers through related but distinct pathways in the two lineages. In contrast with angiosperms, in which Syringyl lignin biosynthesis requires two phenylpropanoid meta-hydroxylases C3′H and F5H, the lycophyte Selaginella employs one phenylpropanoid dual meta-hydroxylase to bypass several steps of the canonical lignin biosynthetic pathway. Transgenic expression of the Selaginella hydroxylase in Arabidopsis thaliana dramatically reroutes its endogenous lignin biosynthetic pathway, yielding a novel lignin composition not previously identified in nature. Our findings demonstrate a unique case of convergent evolution via distinct biochemical strategies and suggest a new way to genetically reconstruct lignin biosynthesis in higher plants.

Takuya Akiyama - One of the best experts on this subject based on the ideXlab platform.

  • chemical factors underlying the more rapid β o 4 bond cleavage of Syringyl than guaiacyl lignin under alkaline delignification conditions
    Journal of Wood Chemistry and Technology, 2017
    Co-Authors: Satoko Shimizu, Tomoya Yokoyama, Takuya Akiyama, Yuji Matsumoto
    Abstract:

    This study aimed to clarify why the β-O-4 bond cleavage of Syringyl lignin is more rapid than that of guaiacyl lignin under alkaline pulping conditions. We examined whether or not three chemical factors, acidity of the α-hydroxy group, nucleophilicity of the generated α-alkoxide, and leaving ability of the leaving phenoxide, are different between Syringyl and guaiacyl lignins and control the rate of the alkaline-induced β-O-4 bond cleavage, employing dimeric non-phenolic β-O-4-type lignin model compounds (LMCs) and novel methods for estimating these three factors. The results indicated that the α-hydroxy groups of Syringyl-type LMCs are relatively more acidic than those of guaiacyl-type and that Syringyl nucleus is a better leaving group than guaiacyl nucleus in the β-O-4 bond cleavage. These factors result in the β-O-4 bond of Syringyl lignin being more prone to the alkaline-induced cleavage than that of guaiacyl lignin.

  • reactivity of lignin with different composition of aromatic Syringyl guaiacyl structures and erythro threo side chain structures in β o 4 type during alkaline delignification as a basis for the different degradability of hardwood and softwood lignin
    Journal of Agricultural and Food Chemistry, 2012
    Co-Authors: Satoko Shimizu, Tomoya Yokoyama, Takuya Akiyama, Yuji Matsumoto
    Abstract:

    The reactivity of lignin during alkaline delignification was quantitatively investigated focusing on the effect of the structural differences between Syringyl and guaiacyl aromatic nuclei and between erythro and threo in the side chain of β-O-4 type lignin substructure on the β-O-4 bond cleavage rate. It was known that the ratio of this reaction rate of the erythro to threo isomers of the dimeric β-O-4 type lignin model compound with two guaiacyl aromatic nuclei was ca. 4. However, the presence of a Syringyl nucleus strongly influenced the rate, and the ratio of the Syringyl type analogue was in the range between 2.7 and 8.0 depending on the reaction temperature. The effect of Syringyl nucleus on the enhancement of the reaction rate appeared to be greater when the Syringyl nucleus consists of the cleaving ether bond rather than being a member of the carbon framework.

  • Reactivity of Lignin with Different Composition of Aromatic Syringyl/Guaiacyl Structures and Erythro/Threo Side Chain Structures in β-O-4 Type during Alkaline Delignification: As a Basis for the Different Degradability of Hardwood and Softwood Lignin
    Journal of Agricultural and Food Chemistry, 2012
    Co-Authors: Satoko Shimizu, Tomoya Yokoyama, Takuya Akiyama, Yuji Matsumoto
    Abstract:

    The reactivity of lignin during alkaline delignification was quantitatively investigated focusing on the effect of the structural differences between Syringyl and guaiacyl aromatic nuclei and between erythro and threo in the side chain of β-O-4 type lignin substructure on the β-O-4 bond cleavage rate. It was known that the ratio of this reaction rate of the erythro to threo isomers of the dimeric β-O-4 type lignin model compound with two guaiacyl aromatic nuclei was ca. 4. However, the presence of a Syringyl nucleus strongly influenced the rate, and the ratio of the Syringyl type analogue was in the range between 2.7 and 8.0 depending on the reaction temperature. The effect of Syringyl nucleus on the enhancement of the reaction rate appeared to be greater when the Syringyl nucleus consists of the cleaving ether bond rather than being a member of the carbon framework.

  • independent recruitment of an o methyltransferase for Syringyl lignin biosynthesis in selaginella moellendorffii
    The Plant Cell, 2011
    Co-Authors: Jingke Weng, John Ralph, Takuya Akiyama, Clint Chapple
    Abstract:

    Syringyl lignin, an important component of the secondary cell wall, has traditionally been considered to be a hallmark of angiosperms because ferns and gymnosperms in general lack lignin of this type. Interestingly, Syringyl lignin was also detected in Selaginella, a genus that represents an extant lineage of the most basal of the vascular plants, the lycophytes. In angiosperms, Syringyl lignin biosynthesis requires the activity of ferulate 5-hydroxylase (F5H), a cytochrome P450-dependent monooxygenase, and caffeic acid/5-hydroxyferulic acid O-methyltransferase (COMT). Together, these two enzymes divert metabolic flux from the biosynthesis of guaiacyl lignin, a lignin type common to all vascular plants, toward Syringyl lignin. Selaginella has independently evolved an alternative lignin biosynthetic pathway in which Syringyl subunits are directly derived from the precursors of p-hydroxyphenyl lignin, through the action of a dual specificity phenylpropanoid meta-hydroxylase, Sm F5H. Here, we report the characterization of an O-methyltransferase from Selaginella moellendorffii, COMT, the coding sequence of which is clustered together with F5H at the adjacent genomic locus. COMT is a bifunctional phenylpropanoid O-methyltransferase that can methylate phenylpropanoid meta-hydroxyls at both the 3- and 5-position and function in concert with F5H in Syringyl lignin biosynthesis in S. moellendorffii. Phylogenetic analysis reveals that Sm COMT, like F5H, evolved independently from its angiosperm counterparts.

  • convergent evolution of Syringyl lignin biosynthesis via distinct pathways in the lycophyte selaginella and flowering plants
    The Plant Cell, 2010
    Co-Authors: Jingke Weng, John Ralph, Takuya Akiyama, Xu Li, Nicholas D Bonawitz, Clint Chapple
    Abstract:

    Phenotypic convergence in unrelated lineages arises when different organisms adapt similarly under comparable selective pressures. In an apparent example of this process, Syringyl lignin, a fundamental building block of plant cell walls, occurs in two major plant lineages, lycophytes and angiosperms, which diverged from one another more than 400 million years ago. Here, we show that this convergence resulted from independent recruitment of lignin biosynthetic cytochrome P450-dependent monooxygenases that route cell wall monomers through related but distinct pathways in the two lineages. In contrast with angiosperms, in which Syringyl lignin biosynthesis requires two phenylpropanoid meta-hydroxylases C3′H and F5H, the lycophyte Selaginella employs one phenylpropanoid dual meta-hydroxylase to bypass several steps of the canonical lignin biosynthetic pathway. Transgenic expression of the Selaginella hydroxylase in Arabidopsis thaliana dramatically reroutes its endogenous lignin biosynthetic pathway, yielding a novel lignin composition not previously identified in nature. Our findings demonstrate a unique case of convergent evolution via distinct biochemical strategies and suggest a new way to genetically reconstruct lignin biosynthesis in higher plants.

Yuji Matsumoto - One of the best experts on this subject based on the ideXlab platform.

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