1
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Ye P, Su J, Lin J, Li Y, Wu H. Identification of a cinnamoyl-CoA reductase from Cinnamomum cassia involved in trans-cinnamaldehyde biosynthesis. PLANTA 2024; 259:138. [PMID: 38687380 DOI: 10.1007/s00425-024-04419-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 04/16/2024] [Indexed: 05/02/2024]
Abstract
MAIN CONCLUSION The identification of a functional cinnamoyl-CoA reductase enzyme from Cinnamomum cassia involved in trans-cinnamaldehyde biosynthesis offers the potential for enhancing trans-cinnamaldehyde production through genetic engineering. A significant accumulation of trans-cinnamaldehyde has been found in the bark tissues of C. cassia, used in traditional Chinese medicine. trans-Cinnamaldehyde exhibits various pharmacological properties such as anti-inflammatory, analgesic, and protection of the stomach and the digestive tract. However, further elucidation and characterization of the biosynthetic pathway for trans-cinnamaldehyde is required. In this study, we conducted an integrated analysis of trans-cinnamaldehyde accumulation profiles and transcriptomic data from five different C. cassia tissues to identify the genes involved in its biosynthesis. The transcriptome data we obtained included nearly all genes associated with the trans-cinnamaldehyde pathway, with the majority demonstrating high abundance in branch barks and trunk barks. We successfully cloned four C. cassia cinnamoyl-CoA reductases (CcCCRs), a key gene in trans-cinnamaldehyde biosynthesis. We found that the recombinant CcCCR1 protein was the only one that more efficiently converted cinnamoyl-CoA into trans-cinnamaldehyde. CcCCR1 exhibited approximately 14.7-fold higher catalytic efficiency (kcat/Km) compared to the Arabidopsis thaliana cinnamoyl-CoA reductase 1 (AtCCR1); therefore, it can be utilized for engineering higher trans-cinnamaldehyde production as previously reported. Molecular docking studies and mutagenesis experiments also validated the superior catalytic activity of CcCCR1 compared to AtCCR1. These findings provide valuable insights for the functional characterization of enzyme-coding genes and hold potential for future engineering of trans-cinnamaldehyde biosynthetic pathways.
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Affiliation(s)
- Peng Ye
- Center for Medicinal Plants Research, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Jianmu Su
- Center for Medicinal Plants Research, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Jianhao Lin
- Center for Medicinal Plants Research, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Yanqun Li
- Center for Medicinal Plants Research, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China.
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry, South China Agricultural University, Guangzhou, 510642, China.
| | - Hong Wu
- Center for Medicinal Plants Research, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China.
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry, South China Agricultural University, Guangzhou, 510642, China.
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2
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Wang Q, Ma L, Wang Z, Chen Q, Wang Q, Qi Q. Construction and yield optimization of a cinnamylamine biosynthesis route in Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:100. [PMID: 36175923 PMCID: PMC9524069 DOI: 10.1186/s13068-022-02199-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 09/22/2022] [Indexed: 11/10/2022]
Abstract
Background With the development of metabolic engineering and synthetic biology, the biosynthesis of aromatic compounds has attracted much attention. Cinnamylamine is an aromatic compound derived from l-phenylalanine, which is used in the synthesis of biologically active molecules, including drugs, and energetic materials. Cinnamylamine has been mainly synthesized by chemical methods to date, and few reports have focused on the biosynthesis of cinnamylamine. Therefore, it is desirable to establish an efficient biosynthesis method for cinnamylamine. Results The ω-aminotransferase Cv-ωTA from Chromobacterium violaceum has been demonstrated to have high enzyme activity in the conversion of cinnamaldehyde to cinnamylamine. To prevent the preferable conversion of cinnamaldehyde to cinnamyl alcohol in wild-type Escherichia coli, the E. coli MG1655 strain with reduced aromatic aldehyde reduction (RARE) in which six aldehyde ketone reductase and alcohol dehydrogenase genes have been knocked out was employed. Then, the carboxylic acid reductase from Neurospora crassa (NcCAR) and phosphopantetheinyl transferase (PPTase) from E. coli were screened for a high conversion rate of cinnamic acid to cinnamaldehyde. To shift the equilibrium of the reaction toward cinnamylamine, saturation mutagenesis of Cv-ωTA at key amino acid residues was performed, and Cv-ωTA Y168G had the highest conversion rate with 88.56 mg/L cinnamylamine obtained after 4 h of fermentation. Finally, by optimizing the substrates and the supply of the cofactors, PLP and NADPH, in the fermentation, the yield of cinnamylamine in engineered E. coli reached 523.15 mg/L. Conclusion We achieved the first biosynthesis of cinnamylamine using cinnamic acid as the precursor in E. coli using a combinatorial metabolic engineering strategy. This study provides a reference for the biosynthesis of other amine compounds and lays a foundation for the de novo synthesis of cinnamylamine. Supplementary Information The online version contains supplementary material available at 10.1186/s13068-022-02199-7.
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3
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Characterization, Expression Profiling, and Biochemical Analyses of the Cinnamoyl-CoA Reductase Gene Family for Lignin Synthesis in Alfalfa Plants. Int J Mol Sci 2022; 23:ijms23147762. [PMID: 35887111 PMCID: PMC9316543 DOI: 10.3390/ijms23147762] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/09/2022] [Accepted: 07/12/2022] [Indexed: 02/01/2023] Open
Abstract
Cinnamoyl-CoA reductase (CCR) is a pivotal enzyme in plant lignin synthesis, which has a role in plant secondary cell wall development and environmental stress defense. Alfalfa is a predominant legume forage with excellent quality, but the lignin content negatively affects fodder digestibility. Currently, there is limited information on CCR characteristics, gene expression, and its role in lignin metabolism in alfalfa. In this study, we identified 30 members in the CCR gene family of Medicago sativa. In addition, gene structure, conserved motif, and evolution analysis suggested MsCCR1–7 presumably functioned as CCR, while the 23 MsCCR-likes fell into three categories. The expression patterns of MsCCRs/MsCCR-likes suggested their role in plant development, response to environmental stresses, and phytohormone treatment. These results were consistent with the cis-elements in their promoters. Histochemical staining showed that lignin accumulation gradually deepened with the development, which was consistent with gene expression results. Furthermore, recombinant MsCCR1 and MsCCR-like1 were purified and the kinetic parameters were tested under four substrates. In addition, three-dimensional structure models of MsCCR1 and MsCCR-like1 proteins showed the difference in the substrate-binding motif H212(X)2K215R263. These results will be useful for further application for legume forage quality modification and biofuels industry engineering in the future.
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4
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de Vries L, Brouckaert M, Chanoca A, Kim H, Regner MR, Timokhin VI, Sun Y, De Meester B, Van Doorsselaere J, Goeminne G, Chiang VL, Wang JP, Ralph J, Morreel K, Vanholme R, Boerjan W. CRISPR-Cas9 editing of CAFFEOYL SHIKIMATE ESTERASE 1 and 2 shows their importance and partial redundancy in lignification in Populus tremula × P. alba. PLANT BIOTECHNOLOGY JOURNAL 2021; 19:2221-2234. [PMID: 34160888 PMCID: PMC8541784 DOI: 10.1111/pbi.13651] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/10/2021] [Accepted: 06/18/2021] [Indexed: 05/06/2023]
Abstract
Lignins are cell wall-located aromatic polymers that provide strength and hydrophobicity to woody tissues. Lignin monomers are synthesized via the phenylpropanoid pathway, wherein CAFFEOYL SHIKIMATE ESTERASE (CSE) converts caffeoyl shikimate into caffeic acid. Here, we explored the role of the two CSE homologs in poplar (Populus tremula × P. alba). Reporter lines showed that the expression conferred by both CSE1 and CSE2 promoters is similar. CRISPR-Cas9-generated cse1 and cse2 single mutants had a wild-type lignin level. Nevertheless, CSE1 and CSE2 are not completely redundant, as both single mutants accumulated caffeoyl shikimate. In contrast, the cse1 cse2 double mutants had a 35% reduction in lignin and associated growth penalty. The reduced-lignin content translated into a fourfold increase in cellulose-to-glucose conversion upon limited saccharification. Phenolic profiling of the double mutants revealed large metabolic shifts, including an accumulation of p-coumaroyl, 5-hydroxyferuloyl, feruloyl and sinapoyl shikimate, in addition to caffeoyl shikimate. This indicates that the CSEs have a broad substrate specificity, which was confirmed by in vitro enzyme kinetics. Taken together, our results suggest an alternative path within the phenylpropanoid pathway at the level of the hydroxycinnamoyl-shikimates, and show that CSE is a promising target to improve plants for the biorefinery.
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Affiliation(s)
- Lisanne de Vries
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
| | - Marlies Brouckaert
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
| | - Alexandra Chanoca
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
| | - Hoon Kim
- Department of Biochemistry, and U.S. Department of Energy Great Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Matthew R. Regner
- Department of Biochemistry, and U.S. Department of Energy Great Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Vitaliy I. Timokhin
- Department of Biochemistry, and U.S. Department of Energy Great Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Yi Sun
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbinChina
| | - Barbara De Meester
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
| | | | - Geert Goeminne
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
- VIB Metabolomics CoreGhentBelgium
| | - Vincent L. Chiang
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbinChina
- Forest Biotechnology GroupDepartment of Forestry and Environmental ResourcesNorth Carolina State UniversityRaleighNCUSA
- Department of Forest BiomaterialsNorth Carolina State UniversityRaleighNCUSA
| | - Jack P. Wang
- State Key Laboratory of Tree Genetics and BreedingNortheast Forestry UniversityHarbinChina
- Forest Biotechnology GroupDepartment of Forestry and Environmental ResourcesNorth Carolina State UniversityRaleighNCUSA
| | - John Ralph
- Department of Biochemistry, and U.S. Department of Energy Great Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Kris Morreel
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
| | - Ruben Vanholme
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
| | - Wout Boerjan
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
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5
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Martínez-Cortés T, Pomar F, Novo-Uzal E. Evolutionary Implications of a Peroxidase with High Affinity for Cinnamyl Alcohols from Physcomitrium patens, a Non-Vascular Plant. PLANTS 2021; 10:plants10071476. [PMID: 34371679 PMCID: PMC8309402 DOI: 10.3390/plants10071476] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 07/15/2021] [Accepted: 07/15/2021] [Indexed: 01/15/2023]
Abstract
Physcomitrium (Physcomitrella) patens is a bryophyte highly tolerant to different stresses, allowing survival when water supply is a limiting factor. This moss lacks a true vascular system, but it has evolved a primitive water-conducting system that contains lignin-like polyphenols. By means of a three-step protocol, including ammonium sulfate precipitation, adsorption chromatography on phenyl Sepharose and cationic exchange chromatography on SP Sepharose, we were able to purify and further characterize a novel class III peroxidase, PpaPrx19, upregulated upon salt and H2O2 treatments. This peroxidase, of a strongly basic nature, shows surprising homology to angiosperm peroxidases related to lignification, despite the lack of true lignins in P. patens cell walls. Moreover, PpaPrx19 shows catalytic and kinetic properties typical of angiosperm peroxidases involved in oxidation of monolignols, being able to efficiently use hydroxycinnamyl alcohols as substrates. Our results pinpoint the presence in P. patens of peroxidases that fulfill the requirements to be involved in the last step of lignin biosynthesis, predating the appearance of true lignin.
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Affiliation(s)
- Teresa Martínez-Cortés
- Grupo de Investigación en Biología Evolutiva, Centro de Investigaciones Científicas Avanzadas, Universidade da Coruña, 15071 A Coruña, Spain; (T.M.-C.); (F.P.)
| | - Federico Pomar
- Grupo de Investigación en Biología Evolutiva, Centro de Investigaciones Científicas Avanzadas, Universidade da Coruña, 15071 A Coruña, Spain; (T.M.-C.); (F.P.)
| | - Esther Novo-Uzal
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
- Correspondence:
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6
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Prototyping of microbial chassis for the biomanufacturing of high-value chemical targets. Biochem Soc Trans 2021; 49:1055-1063. [PMID: 34100907 DOI: 10.1042/bst20200017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/06/2021] [Accepted: 05/10/2021] [Indexed: 12/19/2022]
Abstract
Metabolic engineering technologies have been employed with increasing success over the last three decades for the engineering and optimization of industrial host strains to competitively produce high-value chemical targets. To this end, continued reductions in the time taken from concept, to development, to scale-up are essential. Design-Build-Test-Learn pipelines that are able to rapidly deliver diverse chemical targets through iterative optimization of microbial production strains have been established. Biofoundries are employing in silico tools for the design of genetic parts, alongside combinatorial design of experiments approaches to optimize selection from within the potential design space of biological circuits based on multi-criteria objectives. These genetic constructs can then be built and tested through automated laboratory workflows, with performance data analysed in the learn phase to inform further design. Successful examples of rapid prototyping processes for microbially produced compounds reveal the potential role of biofoundries in leading the sustainable production of next-generation bio-based chemicals.
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7
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Genome-wide analysis of general phenylpropanoid and monolignol-specific metabolism genes in sugarcane. Funct Integr Genomics 2021; 21:73-99. [PMID: 33404914 DOI: 10.1007/s10142-020-00762-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 11/23/2020] [Accepted: 11/27/2020] [Indexed: 10/22/2022]
Abstract
Lignin is the main component of secondary cell walls and is essential for plant development and defense. However, lignin is recognized as a major recalcitrant factor for efficiency of industrial biomass processing. Genes involved in general phenylpropanoid and monolignol-specific metabolism in sugarcane have been previously analyzed at the transcriptomic level. Nevertheless, the number of genes identified in this species is still very low. The recently released sugarcane genome sequence has allowed the genome-wide characterization of the 11 gene families involved in the monolignol biosynthesis branch of the phenylpropanoid pathway. After an exhaustive analysis of sugarcane genomes, 438 haplotypes derived from 175 candidate genes from Saccharum spontaneum and 144 from Saccharum hybrid R570 were identified as associated with this biosynthetic route. The phylogenetic analyses, combined with the search for protein conserved residues involved in the catalytic activity of the encoded enzymes, were employed to identify the family members potentially involved in developmental lignification. Accordingly, 15 candidates were identified as bona fide lignin biosynthesis genes: PTAL1, PAL2, C4H4, 4CL1, HCT1, HCT2, C3'H1, C3'H2, CCoAOMT1, COMT1, F5H1, CCR1, CCR2, CAD2, and CAD7. For this core set of lignin biosynthetic genes, we searched for the chromosomal location, the gene expression pattern, the promoter cis-acting elements, and microRNA targets. Altogether, our results present a comprehensive characterization of sugarcane general phenylpropanoid and monolignol-specific genes, providing the basis for further functional studies focusing on lignin biosynthesis manipulation and biotechnological strategies to improve sugarcane biomass utilization.
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8
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Jardim-Messeder D, da Franca Silva T, Fonseca JP, Junior JN, Barzilai L, Felix-Cordeiro T, Pereira JC, Rodrigues-Ferreira C, Bastos I, da Silva TC, de Abreu Waldow V, Cassol D, Pereira W, Flausino B, Carniel A, Faria J, Moraes T, Cruz FP, Loh R, Van Montagu M, Loureiro ME, de Souza SR, Mangeon A, Sachetto-Martins G. Identification of genes from the general phenylpropanoid and monolignol-specific metabolism in two sugarcane lignin-contrasting genotypes. Mol Genet Genomics 2020; 295:717-739. [PMID: 32124034 DOI: 10.1007/s00438-020-01653-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/12/2020] [Indexed: 11/29/2022]
Abstract
The phenylpropanoid pathway is an important route of secondary metabolism involved in the synthesis of different phenolic compounds such as phenylpropenes, anthocyanins, stilbenoids, flavonoids, and monolignols. The flux toward monolignol biosynthesis through the phenylpropanoid pathway is controlled by specific genes from at least ten families. Lignin polymer is one of the major components of the plant cell wall and is mainly responsible for recalcitrance to saccharification in ethanol production from lignocellulosic biomass. Here, we identified and characterized sugarcane candidate genes from the general phenylpropanoid and monolignol-specific metabolism through a search of the sugarcane EST databases, phylogenetic analysis, a search for conserved amino acid residues important for enzymatic function, and analysis of expression patterns during culm development in two lignin-contrasting genotypes. Of these genes, 15 were cloned and, when available, their loci were identified using the recently released sugarcane genomes from Saccharum hybrid R570 and Saccharum spontaneum cultivars. Our analysis points out that ShPAL1, ShPAL2, ShC4H4, Sh4CL1, ShHCT1, ShC3H1, ShC3H2, ShCCoAOMT1, ShCOMT1, ShF5H1, ShCCR1, ShCAD2, and ShCAD7 are strong candidates to be bona fide lignin biosynthesis genes. Together, the results provide information about the candidate genes involved in monolignol biosynthesis in sugarcane and may provide useful information for further molecular genetic studies in sugarcane.
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Affiliation(s)
- Douglas Jardim-Messeder
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Tatiane da Franca Silva
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, Lorena, São Paulo, Brazil
| | - Jose Pedro Fonseca
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - José Nicomedes Junior
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Centro de Pesquisa e Desenvolvimento Leopoldo Américo Miguez de Mello, Gerência de Biotecnologia, CENPES, Petrobras, Rio de Janeiro, Brazil
| | - Lucia Barzilai
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Thais Felix-Cordeiro
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Joyce Carvalho Pereira
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Clara Rodrigues-Ferreira
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Isabela Bastos
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Tereza Cristina da Silva
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Vinicius de Abreu Waldow
- Centro de Pesquisa e Desenvolvimento Leopoldo Américo Miguez de Mello, Gerência de Biotecnologia, CENPES, Petrobras, Rio de Janeiro, Brazil
| | - Daniela Cassol
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Willian Pereira
- Departamento de Química, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, Brazil
| | - Bruno Flausino
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Adriano Carniel
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Centro de Pesquisa e Desenvolvimento Leopoldo Américo Miguez de Mello, Gerência de Biotecnologia, CENPES, Petrobras, Rio de Janeiro, Brazil
| | - Jessica Faria
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Thamirys Moraes
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fernanda P Cruz
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Roberta Loh
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marc Van Montagu
- Institute of Plant Biotechnology Outreach, Gent University, Technologiepark 3, Zwijnaarde, 9052, Gent, Belgium
| | - Marcelo Ehlers Loureiro
- Laboratório de Fisiologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Sonia Regina de Souza
- Departamento de Química, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, Brazil
| | - Amanda Mangeon
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Gilberto Sachetto-Martins
- Laboratório de Genômica Funcional e Transdução de Sinal, Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
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9
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Yang J, Liang J, Shao L, Liu L, Gao K, Zhang JL, Sun Z, Xu W, Lin P, Yu R, Zi J. Green production of silybin and isosilybin by merging metabolic engineering approaches and enzymatic catalysis. Metab Eng 2020; 59:44-52. [PMID: 32004707 DOI: 10.1016/j.ymben.2020.01.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/23/2020] [Accepted: 01/23/2020] [Indexed: 01/30/2023]
Abstract
Silymarin extracted from milk thistle seeds, is used for treating hepatic diseases. Silybin and isosilybin are its main components, and synthesized from coupling of taxifolin and coniferyl alcohol. Here, the biosynthetic pathways of taxifolin and coniferyl alcohol were reconstructed in Saccharomyces cerevisiae for the first time. To alleviate substantial burden caused by a great deal of genetic manipulation, expression of the enzymes (e.g. ZWF1, TYR1 and ARO8) playing multiple roles in the relevant biosynthetic pathways was selectively optimized. The strain YT1035 overexpressing seven heterologous enzymes and five native enzymes and the strain YC1053 overexpressing seven heterologous enzymes and four native enzymes, respectively produce 336.8 mg/L taxifolin and 201.1 mg/L coniferyl alcohol. Silybin and isosilybin are synthesized from taxifolin and coniferyl alcohol under catalysis of APX1t (the truncated milk thistle peroxidase), with a yield of 62.5%. This study demonstrates an approach for producing silybin and isosilybin from glucose for the first time.
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Affiliation(s)
- Jiazeng Yang
- Biotechnological Institute of Chinese Materia Medic, Jinan University, Guangzhou, 510632, China
| | - Jincai Liang
- Biotechnological Institute of Chinese Materia Medic, Jinan University, Guangzhou, 510632, China
| | - Lei Shao
- Microbial Pharmacology Laboratory, Shanghai University of Medicine and Health Sciences, Shanghai, 201318, China
| | - Lihong Liu
- Biotechnological Institute of Chinese Materia Medic, Jinan University, Guangzhou, 510632, China
| | - Ke Gao
- Biotechnological Institute of Chinese Materia Medic, Jinan University, Guangzhou, 510632, China
| | - Jun-Liang Zhang
- State Key Laboratory of New Drug and Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, Shanghai, 200040, China
| | - Zhenjiao Sun
- Guangdong Qingyunshan Pharmaceutical Co., Ltd., Shaoguan, 512600, China
| | - Wendong Xu
- National Engineering Research Center for Modernization of Extraction and Separation Process of TCM/Guangzhou Hanfang Pharmaceutical Co., Ltd., Guangzhou, 510240, China
| | - Pengcheng Lin
- College of Pharmacy, Qinghai Nationalities University, Xining, 810007, China
| | - Rongmin Yu
- Biotechnological Institute of Chinese Materia Medic, Jinan University, Guangzhou, 510632, China
| | - Jiachen Zi
- Biotechnological Institute of Chinese Materia Medic, Jinan University, Guangzhou, 510632, China.
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10
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Chao N, Jiang WT, Wang XC, Jiang XN, Gai Y. Novel motif is capable of determining CCR and CCR-like proteins based on the divergence of CCRs in plants. TREE PHYSIOLOGY 2019; 39:2019-2026. [PMID: 31748812 DOI: 10.1093/treephys/tpz098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/23/2019] [Accepted: 09/09/2019] [Indexed: 05/22/2023]
Abstract
Cinnamoyl-coenzyme A reductases (CCRs) have been reported as key enzymes involved in monolignol biosynthesis. In this study, a motif-aware workflow based on a new signature motif effectively distinguished CCRs from CCR-like proteins. The divergence of CCRs and CCR-like sequences in Populus tomentosa Carr, Panicum virgatum L, Oryza sativa L and Selaginella moellendorffii Hieron suggests that NWYCY is not efficient for CCR recognition. The novel motif H202(X)2K205 (CCR-SBM or CCR substrate binding motif) was introduced to distinguish between CCRs and CCR-like proteins. The site-directed mutant R205K in Os(I)CCR-like and H202 in PtoCCR7 resulted in the rescue and loss of activity, respectively, further validating the fact that CCR-SBM is critical for maintaining CCR activity. The molecular docking using feruloyl-cinnamoyl-coenzyme A (CoA) as the ligand and binary PhCCR-NADP structures as receptors indicated an interaction between H202 and K205 with CoA moiety. The genuine CCRs and CCR-like proteins from several angiosperms and gymnosperms were screened using a motif-aware workflow and were validated using a biochemical assay. Our results suggest that the motif-aware workflow is efficient and effective for the identification of CCRs and CCR-like proteins in land plants and can be used as a more accurate way of identifying genuine CCRs among land plants.
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Affiliation(s)
- Nan Chao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No 35, Qinghua East Road, Haidian District, Beijing 100083, People's Republic of China
- School of Biotechnology, Jiangsu University of Science and Technology, ZhenJiang, Jiangsu 212003, People's Republic of China
| | - Wen-Ting Jiang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No 35, Qinghua East Road, Haidian District, Beijing 100083, People's Republic of China
| | - Xue-Chun Wang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No 35, Qinghua East Road, Haidian District, Beijing 100083, People's Republic of China
| | - Xiang-Ning Jiang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No 35, Qinghua East Road, Haidian District, Beijing 100083, People's Republic of China
- National Engineering Laboratory for Tree Breeding, the Tree and Ornamental Plant Breeding and Biotechnology Laboratory of Chinese Forestry Administration, Beijing 100083, People's Republic of China
| | - Ying Gai
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No 35, Qinghua East Road, Haidian District, Beijing 100083, People's Republic of China
- National Engineering Laboratory for Tree Breeding, the Tree and Ornamental Plant Breeding and Biotechnology Laboratory of Chinese Forestry Administration, Beijing 100083, People's Republic of China
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11
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Wang P, Guo L, Jaini R, Klempien A, McCoy RM, Morgan JA, Dudareva N, Chapple C. A 13C isotope labeling method for the measurement of lignin metabolic flux in Arabidopsis stems. PLANT METHODS 2018; 14:51. [PMID: 29977324 PMCID: PMC6015466 DOI: 10.1186/s13007-018-0318-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 06/16/2018] [Indexed: 05/07/2023]
Abstract
BACKGROUND Metabolic fluxes represent the functional phenotypes of biochemical pathways and are essential to reveal the distribution of precursors among metabolic networks. Although analysis of metabolic fluxes, facilitated by stable isotope labeling and mass spectrometry detection, has been applied in the studies of plant metabolism, we lack experimental measurements for carbon flux towards lignin, one of the most abundant polymers in nature. RESULTS We developed a feeding strategy of excised Arabidopsis stems with 13C labeled phenylalanine (Phe) for the analysis of lignin biosynthetic flux. We optimized the feeding methods and found the stems continued to grow and lignify. Consistent with lignification profiles along the stems, higher levels of phenylpropanoids and activities of lignin biosynthetic enzymes were detected in the base of the stem. In the feeding experiments, 13C labeled Phe was quickly accumulated and used for the synthesis of phenylpropanoid intermediates and lignin. The intermediates displayed two different patterns of labeling kinetics during the feeding period. Analysis of lignin showed rapid incorporation of label into all three subunits in the polymers. CONCLUSIONS Our feeding results demonstrate the effectiveness of the stem feeding system and suggest a potential application for the investigations of other aspects in plant metabolism. The supply of exogenous Phe leading to a higher lignin deposition rate indicates the availability of Phe is a determining factor for lignification rates.
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Affiliation(s)
- Peng Wang
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
| | - Longyun Guo
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
| | - Rohit Jaini
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907 USA
| | - Antje Klempien
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
| | - Rachel M. McCoy
- Department of Horticulture and Landscape, Purdue University, West Lafayette, IN 47907 USA
| | - John A. Morgan
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907 USA
| | - Natalia Dudareva
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907 USA
| | - Clint Chapple
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907 USA
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12
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Jaini R, Wang P, Dudareva N, Chapple C, Morgan JA. Targeted Metabolomics of the Phenylpropanoid Pathway in Arabidopsis thaliana using Reversed Phase Liquid Chromatography Coupled with Tandem Mass Spectrometry. PHYTOCHEMICAL ANALYSIS : PCA 2017; 28:267-276. [PMID: 28146307 DOI: 10.1002/pca.2672] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 10/19/2016] [Accepted: 12/05/2016] [Indexed: 05/07/2023]
Abstract
INTRODUCTION The phenylpropanoid pathway is a source of a diverse group of compounds derived from phenylalanine, many of which are involved in lignin biosynthesis and serve as precursors for the production of valuable compounds, such as coumarins, flavonoids, and lignans. Consequently, recent efforts have been invested in mechanistically understanding monolignol biosynthesis, making the quantification of these metabolites vital. OBJECTIVE To develop an improved and comprehensive analytical method for (i) extensively profiling, and (ii) accurately quantifiying intermediates of the monolignol biosynthetic network, using Arabidopsis thaliana as a model system. METHOD A liquid chromatography-tandem mass spectrometry with electrospray ionization was developed to quantify phenylpropanoid metabolites in Arabidopsis wildtype and cinnamoyl CoA reductase1 (CCR1) deficient lines (ccr1). RESULTS Vortexing at high temperatures (65°C) enhanced release of phenylpropanoids, specifically the more hydrophobic compounds. A pH of 5.3 and ammonium acetate buffer concentration of 2.5 mM resulted in an optimal analyte response across standards. Ion suppression was estimated using standard spike recovery studies for accurate quantitation. The optimized method was used to profile Arabidopsis wildtype and ccr1 stems. An increase in hydroxycinnamic acid derivatives and a decrease in the hydroxycinnamyl aldehydes and alcohols in ccr1 lines, supports a shift of flux from lignin synthesis to other secondary metabolites and phenylpropanoid derivatives. CONCLUSIONS Compared to existing targeted profiling techniques, our method is capable of quantifying a wider range of intermediates (15 out of 22 in WT Arabidopsis stems) at low in vivo concentrations (~50 pmol/g-FW for certain compounds), while requiring minimal sample preparation. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Rohit Jaini
- School of Chemical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Peng Wang
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Natalia Dudareva
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
- Department of Horticulture & Landscape Architecture, West Lafayette, IN, 47907, USA
| | - Clint Chapple
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - John A Morgan
- School of Chemical Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
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Chao N, Li S, Li N, Qi Q, Jiang WT, Jiang XN, Gai Y. Two distinct cinnamoyl-CoA reductases in Selaginella moellendorffii offer insight into the divergence of CCRs in plants. PLANTA 2017; 246:33-43. [PMID: 28321576 DOI: 10.1007/s00425-017-2678-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 03/10/2017] [Indexed: 06/06/2023]
Abstract
Two distinct cinnamoyl-coenzyme A reductases (CCRs) from Selaginella moellendorffii were evaluated, and of these, SmCCR2-1, which has both distinct sequence motifs and catalytic properties, was clustered into a new CCR subgroup. Cinnamoyl-coenzyme A reductases (CCRs) have been reported in many land plants to have critical functions in monolignol biosynthesis. In this study, we performed a genome-wide screen and obtained two distinct SmCCRs from S. moellendorffii. Phylogenetic analysis indicated that SmCCR2 (both SmCCR2-1 and 2-2) and SmCCR3 together with PpaCCR belong to a distinct subgroup of genuine CCRs with variations in the NAD(P)H-binding motif. Enzymatic assays showed detectable activity by both SmCCR1 and SmCCR2-1 toward four hydroxycinnamoyl-CoA esters. SmCCR1, which clustered with reported CCRs from angiosperms and gymnosperms, exhibited specificity toward feruloyl-CoA, while SmCCR2-1 showed a preference for sinapoyl-CoA. Interestingly, the reaction temperature profiles for SmCCR1 and SmCCR2-1 are complementary. Homology models and molecular simulations suggest that the variations in NADPH-binding motifs, especially R(X)6K instead of R(X)5K, affect the NADP+ conformation. Notably, the signature motif NWYCY was replaced with NGYCL in SmCCR1 and with EWYCL in SmCCR2-1, while the signature residues H202 and R253, reported in a previous study, were conserved in SmCCR1 and SmCCR2-1 but varied in SmCCR-like genes. It is likely that NWYCY is not a reliable signature for CCRs in plants. The detectable activity of site-direct mutant S123T of SmCCR1 suggested that S123 which consists of catalytic triad is changeable. Possible evolution process for the emergence of two subgroups of genuine CCRs was also revealed. Altogether, these findings revise our understanding of CCRs with regard to divergence and active sites.
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Affiliation(s)
- Nan Chao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China
| | - Shuang Li
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China
| | - Ning Li
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China
| | - Qi Qi
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China
| | - Wen-Ting Jiang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China
| | - Xiang-Ning Jiang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of Chinese Forestry Administration, National Engineering Laboratory for Tree Breeding, Beijing, 100083, China
| | - Ying Gai
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China.
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of Chinese Forestry Administration, National Engineering Laboratory for Tree Breeding, Beijing, 100083, China.
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Park HL, Bhoo SH, Kwon M, Lee SW, Cho MH. Biochemical and Expression Analyses of the Rice Cinnamoyl-CoA Reductase Gene Family. FRONTIERS IN PLANT SCIENCE 2017; 8:2099. [PMID: 29312373 PMCID: PMC5732984 DOI: 10.3389/fpls.2017.02099] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 11/24/2017] [Indexed: 05/06/2023]
Abstract
Cinnamoyl-CoA reductase (CCR) is the first committed enzyme in the monolignol pathway for lignin biosynthesis and catalyzes the conversion of hydroxycinnamoyl-CoAs into hydroxycinnamaldehydes. In the rice genome, 33 genes are annotated as CCR and CCR-like genes, collectively called OsCCRs. To elucidate the functions of OsCCRs, their phylogenetic relationships, expression patterns at the transcription levels and biochemical characteristics were thoroughly analyzed. Of the 33 OsCCRs, 24 of them encoded polypeptides of lengths similar to those of previously identified plant CCRs. The other nine OsCCRs had much shorter peptide lengths. Phylogenetic tree and sequence similarities suggested OsCCR4, 5, 17, 18, 19, 20, and 21 as likely candidates for functional CCRs in rice. To elucidate biochemical functions, OsCCR1, 5, 17, 19, 20, 21, and 26 were heterologously expressed in Escherichia coli and the resulting recombinant OsCCRs were purified to apparent homogeneity. Activity assays of the recombinant OsCCRs with hydroxycinnamoyl-CoAs revealed that OsCCR17, 19, 20, and 21 were biochemically active CCRs, in which the NAD(P)-binding and NADP-specificity motifs as well as the CCR signature motif were fully conserved. The kinetic parameters of enzyme reactions revealed that feruloyl-CoA, a precursor for the guaiacyl (G)-unit of lignin, is the most preferred substrate of OsCCR20 and 21. This result is consistent with a high content (about 70%) of G-units in rice lignins. Phylogenetic analysis revealed that OsCCR19 and 20 were grouped with other plant CCRs involved in developmental lignification, whereas OsCCR17 and 21 were closely related to stress-responsible CCRs identified from other plant species. In agreement with the phylogenetic analysis, expression analysis demonstrated that OsCCR20 was constitutively expressed throughout the developmental stages of rice, showing particularly high expression levels in actively lignifying tissues, such as roots and stems. These results suggest that OsCCR20 is primarily involved in developmental deposition of lignins in secondary cell walls. As expected, the expressions of OsCCR17 and 21 were induced in response to biotic and abiotic stresses, such as Magnaporthe grisea and Xanthomonas oryzae pv. oryzae (Xoo) infections, UV-irradiation and high salinity, suggesting that these genes play a role in defense-related processes in rice.
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Affiliation(s)
- Hye Lin Park
- Graduate School of Biotechnology and College of Life Sciences, Kyung Hee University, Yongin, South Korea
| | - Seong Hee Bhoo
- Graduate School of Biotechnology and College of Life Sciences, Kyung Hee University, Yongin, South Korea
| | - Mi Kwon
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Sang-Won Lee
- Graduate School of Biotechnology and College of Life Sciences, Kyung Hee University, Yongin, South Korea
- *Correspondence: Sang-Won Lee
| | - Man-Ho Cho
- Graduate School of Biotechnology and College of Life Sciences, Kyung Hee University, Yongin, South Korea
- Man-Ho Cho
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15
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Chao N, Li N, Qi Q, Li S, Lv T, Jiang XN, Gai Y. Characterization of the cinnamoyl-CoA reductase (CCR) gene family in Populus tomentosa reveals the enzymatic active sites and evolution of CCR. PLANTA 2017; 245:61-75. [PMID: 27580618 DOI: 10.1007/s00425-016-2591-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 08/23/2016] [Indexed: 05/18/2023]
Abstract
Two distinct cinnamoyl-coenzyme A reductases (CCRs) from Populus tomentosa were cloned and studied and active sites in CCRs were further identified based on sequence divergence, molecular simulation, and site-directed mutants. Cinnamoyl-coenzyme A (CoA) reductase (CCR) is the first committed gene in the lignin-specific pathway and plays a role in the lignin biosynthesis pathway. In this study, we cloned 11 genes encoding CCR or CCR-like proteins in Populus tomentosa. An enzymatic assay of the purified recombinant P. tomentosa (Pto) CCR and PtoCCR-like proteins indicated that only PtoCCR1 and PtoCCR7 had detectable activities toward hydroxycinnamoyl-CoA esters. PtoCCR1 exhibited specificity for feruloyl-CoA, with no detectable activity for any other hydroxycinnamoyl-CoA esters. However, PtoCCR7 catalyzed p-coumaroyl-CoA, caffeoyl-CoA, feruloyl-CoA, and sinapoyl-CoA with a preference for feruloyl-CoA. Site-directed mutations of selected amino acids divergent between PtoCCR1 and 7, combined with modeling and docking, showed that A132 in CCR7 combined with the catalytic triad might comprise the catalytic center. In CCR7, L192, F155, and H208 were identified as the substrate-binding sites, and site-directed mutations of these amino acids showed obvious changes in catalytic efficiency with respect to both feruloyl-CoA and sinapoyl-CoA. Mutant F155Y exhibited greater catalytic efficiency for sinapoyl-CoA compared with that of wild-type PtoCCR7. Finally, recent genome duplication events provided the foundation for CCR divergence. This study further identified the active sites in CCRs and the evolutionary process of CCRs in terrestrial plants.
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Affiliation(s)
- Nan Chao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Ning Li
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Qi Qi
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Shuang Li
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Tong Lv
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Xiang-Ning Jiang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of Chinese Forestry Administration, Beijing, 100083, China
| | - Ying Gai
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China.
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of Chinese Forestry Administration, Beijing, 100083, China.
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16
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Metabolic engineering of Escherichia coli for the production of cinnamaldehyde. Microb Cell Fact 2016; 15:16. [PMID: 26785776 PMCID: PMC4719340 DOI: 10.1186/s12934-016-0415-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/07/2016] [Indexed: 11/16/2022] Open
Abstract
Background Plant parasitic nematodes are harmful to agricultural crops and plants, and may cause severe yield losses. Cinnamaldehyde, a volatile, yellow liquid commonly used as a flavoring or food additive, is increasingly becoming a popular natural nematicide because of its high nematicidal activity and, there is a high demand for the development of a biological platform to produce cinnamaldehyde. Results We engineered Escherichia coli as an eco-friendly biological platform for the production of cinnamaldehyde. In E. coli, cinnamaldehyde can be synthesized from intracellular l-phenylalanine, which requires the activities of three enzymes: phenylalanine-ammonia lyase (PAL), 4-coumarate:CoA ligase (4CL), and cinnamoyl-CoA reductase (CCR). For the efficient production of cinnamaldehyde in E. coli, we first examined the activities of enzymes from different sources and a gene expression system for the selected enzymes was constructed. Next, the metabolic pathway for l-phenylalanine biosynthesis was engineered to increase the intracellular pool of l-phenylalanine, which is a main precursor of cinnamaldehyde. Finally, we tried to produce cinnamaldehyde with the engineered E. coli. According to this result, cinnamaldehyde production as high as 75 mg/L could be achieved, which was about 35-fold higher compared with that in the parental E. coli W3110 harboring a plasmid for cinnamaldehyde biosynthesis. We also confirmed that cinnamaldehyde produced by our engineered E. coli had a nematicidal activity similar to the activity of commercial cinnamaldehyde by nematicidal assays against Bursaphelenchus xylophilus. Conclusion As a potential natural pesticide, cinnamaldehyde was successfully produced in E. coli by construction of the biosynthesis pathway and, its production titer was also significantly increased by engineering the metabolic pathway of l-phenylalanine. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0415-9) contains supplementary material, which is available to authorized users.
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17
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Labeeuw L, Martone PT, Boucher Y, Case RJ. Ancient origin of the biosynthesis of lignin precursors. Biol Direct 2015; 10:23. [PMID: 25994183 PMCID: PMC4455696 DOI: 10.1186/s13062-015-0052-y] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 03/31/2015] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Lignin plays an important role in plant structural support and water transport, and is considered one of the hallmarks of land plants. The recent discovery of lignin or its precursors in various algae has raised questions on the evolution of its biosynthetic pathway, which could be much more ancient than previously thought. To determine the taxonomic distribution of the lignin biosynthesis genes, we screened all publicly available genomes of algae and their closest non-photosynthetic relatives, as well as representative land plants. We also performed phylogenetic analysis of these genes to decipher the evolution and origin(s) of lignin biosynthesis. RESULTS Enzymes involved in making p-coumaryl alcohol, the simplest lignin monomer, are found in a variety of photosynthetic eukaryotes, including diatoms, dinoflagellates, haptophytes, cryptophytes as well as green and red algae. Phylogenetic analysis of these enzymes suggests that they are ancient and spread to some secondarily photosynthetic lineages when they acquired red and/or green algal endosymbionts. In some cases, one or more of these enzymes was likely acquired through lateral gene transfer (LGT) from bacteria. CONCLUSIONS Genes associated with p-coumaryl alcohol biosynthesis are likely to have evolved long before the transition of photosynthetic eukaryotes to land. The original function of this lignin precursor is therefore unlikely to have been related to water transport. We suggest that it participates in the biological defense of some unicellular and multicellular algae.
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Affiliation(s)
- Leen Labeeuw
- Department of Biological Sciences, University of Alberta, Edmonton, AB, , T6G 2E9, , Canada.
| | - Patrick T Martone
- Department of Botany and Biodiversity Research Centre, University of British, Columbia, BC, , V6T 1Z4, , Canada.
| | - Yan Boucher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, , T6G 2E9, , Canada.
| | - Rebecca J Case
- Department of Biological Sciences, University of Alberta, Edmonton, AB, , T6G 2E9, , Canada.
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18
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Muhlemann JK, Woodworth BD, Morgan JA, Dudareva N. The monolignol pathway contributes to the biosynthesis of volatile phenylpropenes in flowers. THE NEW PHYTOLOGIST 2014; 204:661-670. [PMID: 24985707 DOI: 10.1111/nph.12913] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/31/2014] [Indexed: 05/06/2023]
Abstract
Volatile phenylpropenes play important roles in the mediation of interactions between plants and their biotic environments. Their biosynthesis involves the elimination of the oxygen functionality at the side-chain of monolignols and competes with lignin formation for monolignol utilization. We hypothesized that biochemical steps before the monolignol branch point are shared between phenylpropene and lignin biosynthesis; however, genetic evidence for this shared pathway has been missing until now. Our hypothesis was tested by RNAi suppression of the petunia (Petunia hybrida) cinnamoyl-CoA reductase 1 (PhCCR1), which catalyzes the first committed step in monolignol biosynthesis. Detailed metabolic profiling and isotopic labeling experiments were performed in petunia transgenic lines. Downregulation of PhCCR1 resulted in reduced amounts of total lignin and decreased flux towards phenylpropenes, whereas internal and emitted pools of phenylpropenes remained unaffected. Surprisingly, PhCCR1 silencing increased fluxes through the general phenylpropanoid pathway by upregulating the expression of cinnamate-4-hydroxylase (C4H), which catalyzes the second reaction in the phenylpropanoid pathway. In conclusion, our results show that PhCCR1 is involved in both the biosynthesis of phenylpropenes and lignin production. However, PhCCR1 does not perform a rate-limiting step in the biosynthesis of phenylpropenes, suggesting that scent biosynthesis is prioritized over lignin formation in petals.
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Affiliation(s)
- Joëlle K Muhlemann
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907-2063, USA
| | - Benjamin D Woodworth
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907-2063, USA
| | - John A Morgan
- School of Chemical Engineering, Purdue University, West Lafayette, IN, 47907-2100, USA
| | - Natalia Dudareva
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907-2063, USA
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19
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Pan H, Zhou R, Louie GV, Mühlemann JK, Bomati EK, Bowman ME, Dudareva N, Dixon RA, Noel JP, Wang X. Structural studies of cinnamoyl-CoA reductase and cinnamyl-alcohol dehydrogenase, key enzymes of monolignol biosynthesis. THE PLANT CELL 2014; 26:3709-27. [PMID: 25217505 PMCID: PMC4213152 DOI: 10.1105/tpc.114.127399] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 07/27/2014] [Accepted: 08/08/2014] [Indexed: 05/18/2023]
Abstract
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.
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Affiliation(s)
- Haiyun Pan
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Rui Zhou
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Gordon V Louie
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Joëlle K Mühlemann
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Erin K Bomati
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037 Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92037
| | - Marianne E Bowman
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Natalia Dudareva
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Richard A Dixon
- Department of Biological Sciences, University of North Texas, Denton, Texas 76203-5017
| | - Joseph P Noel
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037 Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92037
| | - Xiaoqiang Wang
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
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20
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Sonawane PD, Khan BM, Gaikwad SM. Conformational transitions of cinnamoyl CoA reductase 1 from Leucaena leucocephala. Int J Biol Macromol 2014; 64:30-5. [DOI: 10.1016/j.ijbiomac.2013.11.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 11/22/2013] [Accepted: 11/25/2013] [Indexed: 10/26/2022]
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Steady state fluorescence studies of wild type recombinant cinnamoyl CoA reductase (Ll-CCRH1) and its active site mutants. J Fluoresc 2013; 24:665-73. [PMID: 24322526 DOI: 10.1007/s10895-013-1343-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 12/02/2013] [Indexed: 10/25/2022]
Abstract
Fluorescence quenching and time resolved fluorescence studies of wild type recombinant cinnamoyl CoA reductase (Ll-CCRH1), a multitryptophan protein from Leucaena leucocephala and 10 different active site mutants were carried out to investigate tryptophan environment. The enzyme showed highest affinity for feruloyl CoA (K(a) = 3.72 × 10(5) M(-1)) over other CoA esters and cinnamaldehydes, as determined by fluorescence spectroscopy. Quenching of the fluorescence by acrylamide for wild type and active site mutants was collisional with almost 100% of the tryptophan fluorescence accessible under native condition and remained same after denaturation of protein with 6 M GdnHCl. In wild type Ll-CCRH1, the extent of quenching achieved with iodide (f(a) = 1.0) was significantly higher than cesium ions (f(a) = 0.33) suggesting more density of positive charge around surface of trp conformers under native conditions. Denaturation of wild type protein with 6 M GdnHCl led to significant increase in the quenching with cesium (f(a) = 0.54), whereas quenching with iodide ion was decreased (f(a) = 0.78), indicating reorientation of charge density around trp from positive to negative and heterogeneity in trp environment. The Stern-Volmer plots for wild type and mutants Ll-CCRH1 under native and denatured conditions, with cesium ion yielded biphasic quenching profiles. The extent of quenching for cesium and iodide ions under native and denatured conditions observed in active site mutants was significantly different from wild type Ll-CCRH1 under the same conditions. Thus, single substitution type mutations of active site residues showed heterogeneity in tryptophan microenvironment and differential degree of conformation of protein under native or denatured conditions.
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Sonawane P, Patel K, Vishwakarma RK, Srivastava S, Singh S, Gaikwad S, Khan BM. Probing the active site of cinnamoyl CoA reductase 1 (Ll-CCRH1) from Leucaena leucocephala. Int J Biol Macromol 2013; 60:33-8. [PMID: 23688416 DOI: 10.1016/j.ijbiomac.2013.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 05/09/2013] [Accepted: 05/09/2013] [Indexed: 10/26/2022]
Abstract
Lack of three dimensional crystal structure of cinnamoyl CoA reductase (CCR) limits its detailed active site characterization studies. Putative active site residues involved in the substrate/NADPH binding and catalysis for Leucaena leucocephala CCR (Ll-CCRH1; GenBank: DQ986907) were identified by amino acid sequence alignment and homology modeling. Putative active site residues and proximal H215 were subjected for site directed mutagenesis, and mutated enzymes were expressed, purified and assayed to confirm their functional roles. Mutagenesis of S136, Y170 and K174 showed complete loss of activity, indicating their pivotal roles in catalysis. Mutant S212G exhibited the catalytic efficiencies less than 10% of wild type, showing its indirect involvement in substrate binding or catalysis. R51G, D77G, F30V and I31N double mutants showed significant changes in Km values, specifying their roles in substrate binding. Finally, chemical modification and substrate protection studies corroborated the presence Ser, Tyr, Lys, Arg and carboxylate group at the active site of Ll-CCRH1.
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Affiliation(s)
- Prashant Sonawane
- Plant Tissue Culture Division, CSIR-National Chemical Laboratory, Pune-411008, India
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Sonawane P, Vishwakarma RK, Khan BM. Biochemical characterization of recombinant cinnamoyl CoA reductase 1 (Ll-CCRH1) from Leucaena leucocephala. Int J Biol Macromol 2013; 58:154-9. [PMID: 23541561 DOI: 10.1016/j.ijbiomac.2013.03.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 11/15/2022]
Abstract
Recombinant cinnamoyl CoA reductase 1 (Ll-CCRH1) protein from Leucaena leucocephala was overexpressed in Escherichia coli BL21 (DE3) strain and purified to apparent homogeneity. Optimum pH for forward and reverse reaction was found to be 6.5 and 7.8 respectively. The enzyme was most stable around pH 6.5 at 25°C for 90 min. The enzyme showed Kcat/Km for feruloyl, caffeoyl, sinapoyl, coumaroyl CoA, coniferaldehyde and sinapaldehyde as 4.6, 2.4, 2.3, 1.7, 1.9 and 1.2 (×10(6) M(-1) s(-1)), respectively, indicating affinity of enzyme for feruloyl CoA over other substrates and preference of reduction reaction over oxidation. Activation energy, Ea for various substrates was found to be in the range of 20-50 kJ/mol. Involvement of probable carboxylate ion, histidine, lysine or tyrosine at the active site of enzyme was predicted by pH activity profile. SAXS studies of protein showed radius 3.04 nm and volume 49.25 nm(3) with oblate ellipsoid shape. Finally, metal ion inhibition studies revealed that Ll-CCRH1 is a metal independent enzyme.
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Affiliation(s)
- Prashant Sonawane
- Plant Tissue Culture Division, CSIR-National Chemical Laboratory, Pune 411008, India
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Fraser CM, Chapple C. The phenylpropanoid pathway in Arabidopsis. THE ARABIDOPSIS BOOK 2011; 9:e0152. [PMID: 22303276 PMCID: PMC3268504 DOI: 10.1199/tab.0152] [Citation(s) in RCA: 371] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The phenylpropanoid pathway serves as a rich source of metabolites in plants, being required for the biosynthesis of lignin, and serving as a starting point for the production of many other important compounds, such as the flavonoids, coumarins, and lignans. In spite of the fact that the phenylpropanoids and their derivatives are sometimes classified as secondary metabolites, their relevance to plant survival has been made clear via the study of Arabidopsis and other plant species. As a model system, Arabidopsis has helped to elucidate many details of the phenylpropanoid pathway, its enzymes and intermediates, and the interconnectedness of the pathway with plant metabolism as a whole. These advances in our understanding have been made possible in large part by the relative ease with which mutations can be generated, identified, and studied in Arabidopsis. Herein, we provide an overview of the research progress that has been made in recent years, emphasizing both the genes (and gene families) associated with the phenylpropanoid pathway in Arabidopsis, and the end products that have contributed to the identification of many mutants deficient in the phenylpropanoid metabolism: the sinapate esters.
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Affiliation(s)
- Christopher M. Fraser
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Bioanalytical Computing, LLC, www.bioanalyticalcomputing.com
| | - Clint Chapple
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Address correspondence to
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Prasad NK, Vindal V, Kumar V, Kabra A, Phogat N, Kumar M. Structural and docking studies of Leucaena leucocephala Cinnamoyl CoA reductase. J Mol Model 2010; 17:533-41. [DOI: 10.1007/s00894-010-0744-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 05/04/2010] [Indexed: 11/29/2022]
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Weng JK, Akiyama T, Bonawitz ND, Li X, Ralph J, Chapple C. Convergent evolution of syringyl lignin biosynthesis via distinct pathways in the lycophyte Selaginella and flowering plants. THE PLANT CELL 2010; 22:1033-45. [PMID: 20371642 PMCID: PMC2879749 DOI: 10.1105/tpc.109.073528] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/08/2010] [Accepted: 03/22/2010] [Indexed: 05/18/2023]
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.
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Affiliation(s)
- Jing-Ke Weng
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Takuya Akiyama
- U.S. Dairy Forage Research Center, U.S. Department of Agriculture–Agricultural Research Service, Madison, Wisconsin 53706
| | | | - Xu Li
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - John Ralph
- U.S. Dairy Forage Research Center, U.S. Department of Agriculture–Agricultural Research Service, Madison, Wisconsin 53706
- Department of Biochemistry (Enzyme Institute) and Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin 53726
| | - Clint Chapple
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
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Ralph J, Kim H, Lu F, Grabber JH, Leplé JC, Berrio-Sierra J, Derikvand MM, Jouanin L, Boerjan W, Lapierre C. Identification of the structure and origin of a thioacidolysis marker compound for ferulic acid incorporation into angiosperm lignins (and an indicator for cinnamoyl CoA reductase deficiency). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 53:368-79. [PMID: 18184422 DOI: 10.1111/j.1365-313x.2007.03345.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
A molecular marker compound, derived from lignin by the thioacidolysis degradative method, for structures produced when ferulic acid is incorporated into lignin in angiosperms (poplar, Arabidopsis, tobacco), has been structurally identified as 1,2,2-trithioethyl ethylguaiacol [1-(4-hydroxy-3-methoxyphenyl)-1,2,2-tris(ethylthio)ethane]. Its truncated side chain and distinctive oxidation state suggest that it derives from ferulic acid that has undergone bis-8-O-4 (cross) coupling during lignification, as validated by model studies. A diagnostic contour for such structures is found in two-dimensional (13)C-(1)H correlated (HSQC) NMR spectra of lignins isolated from cinnamoyl CoA reductase (CCR)-deficient poplar. As low levels of the marker are also released from normal (i.e. non-transgenic) plants in which ferulic acid may be present during lignification, notably in grasses, the marker is only an indicator for CCR deficiency in general, but is a reliable marker in woody angiosperms such as poplar. Its derivation, together with evidence for 4-O-etherified ferulic acid, strongly implies that ferulic acid is incorporated into angiosperm lignins. Its endwise radical coupling reactions suggest that ferulic acid should be considered an authentic lignin precursor. Moreover, ferulic acid incorporation provides a new mechanism for producing branch points in the polymer. The findings sharply contradict those reported in a recent study on CCR-deficient Arabidopsis.
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Affiliation(s)
- John Ralph
- US Dairy Forage Research Center, USDA-Agricultural Research Service, Madison, WI 53706, USA.
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