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  • 1
    Language: English
    In: The Plant cell, 2010-05-01, Vol.22 (5), p.1549-1563
    Description: The process of dark-induced senescence in plants is relatively poorly understood, but a functional electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) complex, which supports respiration during carbon starvation, has recently been identified. Here, we studied the responses of Arabidopsis thaliana mutants deficient in the expression of isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase to extended darkness and other environmental stresses. Evaluations of the mutant phenotypes following carbon starvation induced by extended darkness identify similarities to those exhibited by mutants of the ETF/ETFQO complex. Metabolic profiling and isotope tracer experimentation revealed that isovaleryl-CoA dehydrogenase is involved in degradation of the branched-chain amino acids, phytol, and Lys, while 2-hydroxyglutarate dehydrogenase is involved exclusively in Lys degradation. These results suggest that isovaleryl-CoA dehydrogenase is the more critical for alternative respiration and that a series of enzymes, including 2-hydroxyglutarate dehydrogenase, plays a role in Lys degradation. Both physiological and metabolic phenotypes of the isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase mutants were not as severe as those observed for mutants of the ETF/ETFQO complex, indicating some functional redundancy of the enzymes within the process. Our results aid in the elucidation of the pathway of plant Lys catabolism and demonstrate that both isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase act as electron donors to the ubiquinol pool via an ETF/ETFQO-mediated route.
    Subject(s): Acyl Coenzyme A - metabolism ; Alcohol Oxidoreductases - metabolism ; Amino acid metabolism ; Amino acids ; Arabidopsis - enzymology ; Arabidopsis thaliana ; Carbohydrate Metabolism ; Catabolism ; Chlorophylls ; Darkness ; Dehydrogenases ; DNA, Bacterial - genetics ; Electron Transport ; Electrons ; Enzymes ; Gas Chromatography-Mass Spectrometry ; Genetic aspects ; Glutamine ; Growth ; Isotope Labeling ; Isovaleryl-CoA Dehydrogenase - metabolism ; Leaves ; Leucine - metabolism ; Lysine - metabolism ; Metabolome ; Mitochondria - enzymology ; Models, Biological ; Mutagenesis, Insertional - genetics ; Mutation - genetics ; Observations ; Phenotype ; Phenotypes ; Phytol - metabolism ; Plant cells ; Plant Leaves - metabolism ; Plant mitochondria ; Plants ; Properties ; s
    ISSN: 1040-4651
    E-ISSN: 1532-298X
    Source: American Society of Plant Biologists
    Source: JSTOR Life Sciences
    Source: JSTOR Ecology & Botany II
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: PubMed Central
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  • 2
    Language: English
    In: The Plant cell, 2011-02-01, Vol.23 (2), p.583-599
    Description: Arabidopsis thaliana COMATOSE (CTS) encodes an ABC transporter involved in peroxisomal import of substrates for β-oxidation. Various cts alleles and mutants disrupted in steps of peroxisomal β-oxidation have previously been reported to exhibit a severe block on seed germination. Oxylipin analysis on cts, acyl CoA oxidase1 acyl CoA oxidase2 (acx1 acx2), and keto acyl thiolase2 dry seeds revealed that they contain elevated levels of 12-oxo-phytodienoic acid (OPDA), jasmonic acid (JA), and JA-lle. Oxylipin and transcriptomic analysis showed that accumulation of these oxylipins occurs during late seed maturation in cts. Analysis of double mutants generated by crossing cts with mutants in the JA biosynthesis pathway indicate that OPDA, rather than JA or JA-lle, contributes to the block on germination in cts seeds. We found that OPDA was more effective at inhibiting wild-type germination than was JA and that this effect was independent of CORONATINE INSENSITIVE1 but was synergistic with abscisic acid (ABA). Consistent with this, OPDA treatment increased ABA INSENSITIVE5 protein abundance in a manner that parallels the inhibitory effect of OPDA and OPDA+ABA on seed germination. These results demonstrate that OPDA acts along with ABA to regulate seed germination in Arabidopsis.
    Subject(s): Abscisic Acid - metabolism ; Analysis ; Arabidopsis - drug effects ; Arabidopsis - genetics ; Arabidopsis - growth & development ; Arabidopsis thaliana ; Baker, Alison ; Biosynthesis ; Cyclopentanes - metabolism ; Endosperm ; Fatty acids ; Fatty Acids, Unsaturated - pharmacology ; Gene expression regulation ; Gene Expression Regulation, Developmental ; Gene Expression Regulation, Plant ; Genes ; Germination ; Germination - drug effects ; Mutation ; Oxylipins - metabolism ; Phenotypes ; Plant cells ; Seed germination ; Seeds ; Seeds - drug effects ; Seeds - growth & development
    ISSN: 1040-4651
    E-ISSN: 1532-298X
    Source: American Society of Plant Biologists
    Source: JSTOR Life Sciences
    Source: JSTOR Ecology & Botany II
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: PubMed Central
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  • 3
    Language: English
    In: Science (American Association for the Advancement of Science), 2015-07-17, Vol.349 (6245), p.309-312
    Description: Morphinan alkaloids from the opium poppy are used for pain relief. The direction of metabolites to morphinan biosynthesis requires isomerization of (S)- to (R)-reticuline. Characterization of high-reticuline poppy mutants revealed a genetic locus, designated STORR [(S)- to (R)-reticuline] that encodes both cytochrome P450 and oxidoreductase modules, the latter belonging to the aldo-keto reductase family. Metabolite analysis of mutant alleles and heterologous expression demonstrate that the P450 module is responsible for the conversion of (S)-reticuline to 1,2-dehydroreticuline, whereas the oxidoreductase module converts 1,2-dehydroreticuline to (R)-reticuline rather than functioning as a P450 redox partner. Proteomic analysis confirmed that these two modules are contained on a single polypeptide in vivo. This modular assembly implies a selection pressure favoring substrate channeling. The fusion protein STORR may enable microbial-based morphinan production.
    Subject(s): REPORTS
    ISSN: 0036-8075
    E-ISSN: 1095-9203
    Source: JSTOR Life Sciences
    Source: Single Journals
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
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  • 4
    Language: English
    In: The Plant cell, 2005-09-01, Vol.17 (9), p.2587-2600
    Description: In mammals, electron-transfer flavoprotein:ubiquinone oxidoreductase (ETFQO) and electron-transfer flavoprotein (ETF) are functionally associated, and ETF accepts electrons from at least nine mitochondrial matrix flavoprotein dehydrogenases and transfers them to ubiquinone in the inner mitochondrial membrane. In addition, the mammalian ETF/ETFQO system plays a key role in β-oxidation of fatty acids and catabolism of amino acids and choline. By contrast, nothing is known of the function of ETF and ETFQO in plants. Sequence analysis of the unique Arabidopsis thaliana homologue of ETFQO revealed high similarity to the mammalian ETFQO protein. Moreover, green fluorescent protein cellular localization experiments suggested a mitochondrial location for this protein. RNA gel blot analysis revealed that Arabidopsis ETFQO transcripts accumulated in long-term dark-treated leaves. Analysis of three independent insertional mutants of Arabidopsis ETFQO revealed a dramatic reduction in their ability to withstand extended darkness, resulting in senescence and death within 10 d after transfer, whereas wild-type plants remained viable for at least 15 d. Metabolite profiling of dark-treated leaves of the wild type and mutants revealed a dramatic decline in sugar levels. In contrast with the wild type, the mutants demonstrated a significant accumulation of several amino acids, an intermediate of Leu catabolism, and, strikingly, high-level accumulation of phytanoyl-CoA. These data demonstrate the involvement of a mitochondrial protein, ETFQO, in the catabolism of Leu and potentially of other amino acids in higher plants and also imply a novel role for this protein in the chlorophyll degradation pathway activated during dark-induced senescence and sugar starvation.
    Subject(s): Acyl Coenzyme A - metabolism ; Amino acids ; Animals ; Arabidopsis ; Arabidopsis - enzymology ; Arabidopsis Proteins - genetics ; Arabidopsis Proteins - metabolism ; Catabolism ; Cell Survival ; Chlorophylls ; Darkness ; Dehydrogenases ; DNA, Bacterial - metabolism ; Electron Transport - physiology ; Electron-Transferring Flavoproteins - genetics ; Electron-Transferring Flavoproteins - metabolism ; Fatty acids ; Humans ; Iron-Sulfur Proteins - genetics ; Iron-Sulfur Proteins - metabolism ; Leucine - metabolism ; Mammals ; Mitochondria ; Mitochondria - enzymology ; Molecular Sequence Data ; Mutation ; Oxidoreductases ; Oxidoreductases Acting on CH-NH Group Donors - genetics ; Oxidoreductases Acting on CH-NH Group Donors - metabolism ; Phenotype ; Phytol - metabolism ; Plant cells ; Plants ; Protein Isoforms - genetics ; Protein Isoforms - metabolism ; Proteins ; Recombinant Fusion Proteins - genetics ; Recombinant Fusion Proteins - metabolism ; Research ; Starvation ; Sucrose - metabolism
    ISSN: 1040-4651
    E-ISSN: 1532-298X
    Source: American Society of Plant Biologists
    Source: JSTOR Life Sciences
    Source: JSTOR Ecology & Botany II
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: PubMed Central
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  • 5
    Language: English
    In: Analytical chemistry (Washington), 2012-01-03, Vol.84 (1), p.283-289
    Description: Liquid chromatography coupled to mass spectrometry is routinely used for metabolomics experiments. In contrast to the fairly routine and automated data acquisition steps, subsequent compound annotation and identification require extensive manual analysis and thus form a major bottleneck in data interpretation. Here we present CAMERA, a Bioconductor package integrating algorithms to extract compound spectra, annotate isotope and adduct peaks, and propose the accurate compound mass even in highly complex data. To evaluate the algorithms, we compared the annotation of CAMERA against a manually defined annotation for a mixture of known compounds spiked into a complex matrix at different concentrations. CAMERA successfully extracted accurate masses for 89.7% and 90.3% of the annotatable compounds in positive and negative ion modes, respectively. Furthermore, we present a novel annotation approach that combines spectral information of data acquired in opposite ion modes to further improve the annotation rate. We demonstrate the utility of CAMERA in two different, easily adoptable plant metabolomics experiments, where the application of CAMERA drastically reduced the amount of manual analysis.
    Subject(s): Algorithms ; Analytical chemistry ; Chemistry ; Chromatographic methods and physical methods associated with chromatography ; Chromatography, Liquid - methods ; Exact sciences and technology ; Extraction (Chemistry) ; Liquid chromatography ; Mass spectrometry ; Metabolomics ; Methods ; Other chromatographic methods ; Plants - chemistry ; Research ; Spectrometric and optical methods ; Spectrometry, Mass, Electrospray Ionization - methods ; Usage
    ISSN: 0003-2700
    E-ISSN: 1520-6882
    Source: Hellenic Academic Libraries Link
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  • 6
    Language: English
    In: The New phytologist, 2013-11-01, Vol.200 (3), p.641-649
    Description: Fatty acid β-oxidation is an essential process in many aspects of plant development, and storage oil in the form of triacylglycerol (TAG) is an important food source for humans and animals, for biofuel and for industrial feedstocks. In this study we characterize the effects of a small molecule, diphenyl methylphosphonate, on oil mobilization in . Confocal laser scanning microscopy, transmission electron microscopy and quantitative lipid profiling were used to examine the effects of diphenyl methylphosphonate treatment on seedlings. Diphenyl methylphosphonate causes peroxisome clustering around oil bodies but does not affect morphology of other cellular organelles. We show that this molecule blocks the breakdown of pre-existing oil bodies resulting in retention of TAG and accumulation of acyl CoAs. The biochemical and phenotypic effects are consistent with a block in the early part of the b-oxidation pathway. Diphenyl methylphosphonate appears to be a fairly specific inhibitor of TAG mobilization in plants and whilst further work is required to identify the molecular target of the compound it should prove a useful tool to interrogate and manipulate these pathways in a controlled and reproducible manner.
    Subject(s): Acyl Coenzyme A - metabolism ; Arabidiopsis ; Arabidopsis - metabolism ; Arabidopsis Proteins - metabolism ; Arabidopsis thaliana ; Biomass energy ; Fatty acids ; Fatty Acids - metabolism ; Hypocotyls ; Indoles ; inhibitor ; Lipid bodies ; lipid metabolism ; Lipids ; oil body ; Organophosphorus Compounds - metabolism ; Oxidation-Reduction ; peroxisome ; Peroxisomes ; Peroxisomes - metabolism ; Phosphonic acids ; Plant cells ; Plant Oils - metabolism ; Plants ; Rapid reports ; Seedlings ; triacylglycerol ; Triglycerides ; Triglycerides - metabolism ; β‐oxidation
    ISSN: 0028-646X
    E-ISSN: 1469-8137
    Source: JSTOR Life Sciences
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 7
    Language: English
    In: Planta, 2012-03-01, Vol.235 (3), p.629-639
    Description: Acy1-acy1 carrier protein (ACP) thioesterases are enzymes that control the termination of intraplastidial fatty acid synthesis by hydrolyzing the acy1-ACP complexes. Among the different thioesterase gene families found in plants, the FatA-type fulfills a fundamental role in the export of the C18 fatty acid moieties that will be used to synthesize most plant glycerolipids. A reverse genomic approach has been used to study the FatA thioesterase in seed oil accumulation by screening different mutant collections of Arabidopsis thaliana for FatA knockouts. Two mutants were identified with T-DNA insertions in the promoter region of each of the two copies of FatA present in the Arabidopsis genome, from which a double FatA Arabidopsis mutant was made. The expression of both forms of FatA thioesterases was reduced in this double mutant (fata1 fata2), as was FatA activity. This decrease did not cause any evident morphological changes in the mutant plants, although the partial reduction of this activity affected the oil content and fatty acid composition of the Arabidopsis seeds. Thus, dry mutant seeds had less triacylglycerol content, while other neutral lipids like diacylglycerols were not affected. Furthermore, the metabolic flow of the different glycerolipid species into seed oil in the developing seeds was reduced at different stages of seed formation in the fata1 fata2 line. This diminished metabolic flow induced increases in the proportion of linolenic and erucic fatty acids in the seed oil, in a similar way as previously reported for the wril Arabidopsis mutant that accumulates oil poorly. The similarities between these two mutants and the origin of their phenotype are discussed in function of the results.
    Subject(s): Acyl–acyl carrier protein thioesterase ; Agriculture ; Arabidopsis ; Arabidopsis - genetics ; Arabidopsis - metabolism ; Arabidopsis Proteins - genetics ; Arabidopsis Proteins - metabolism ; Arabidopsis thaliana ; Biological and medical sciences ; Carrier proteins ; Cotyledons ; Deficient mutant ; Ecology ; Enzymes ; FatA ; Fatty acids ; Fatty Acids - genetics ; Fatty Acids - metabolism ; Forestry ; Fundamental and applied biological sciences. Psychology ; Gene expression regulation ; Genetic research ; Life Sciences ; Lipid metabolism ; Lipids ; Metabolic flux ; Oil content ; Plant Oils - metabolism ; Plant Sciences ; Plants ; Plants, Genetically Modified - genetics ; Plants, Genetically Modified - metabolism ; Seeds ; Seeds - genetics ; Seeds - metabolism ; Synthesis ; Thiolester Hydrolases - genetics ; Thiolester Hydrolases - metabolism ; Triacylglycerols ; Triglycerides
    ISSN: 0032-0935
    E-ISSN: 1432-2048
    Source: JSTOR Ecology & Botany II
    Source: Alma/SFX Local Collection
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  • 8
    Language: English
    In: Planta, 2014-03-01, Vol.239 (3), p.667-677
    Description: The substrate specificity of the acyl-acyl carrier protein (ACP) thioesterases significantly determines the type of fatty acids that are exported from plastids. Thus, designing acyl-ACP thioesterases with different substrate specificities or kinetic properties would be of interest for plant lipid biotechnology to produce oils enriched in specialty fatty acids. In the present work, the FatA thioesterase from Helianthus annuus was used to test the impact of changes in the amino acids present in the binding pocket on substrate specificity and catalytic efficiency. Amongst all the mutated enzymes studied, Q215W was especially interesting as it had higher specificity towards saturated acyl-ACP substrates and higher catalytic efficiency compared to wild-type H. annuus FatA. Null, wild type and high-efficiency alleles were transiently expressed in tobacco leaves to check their effect on lipid biosynthesis. Expression of active FatA thioesterases altered the composition of leaf triacylglycerols but did not alter total lipid content. However, the expression of the wild type and the high-efficiency alíeles in Arabidopsis thaliana transgenic seeds resulted in a strong reduction in oil content and an increase in total saturated fatty acid content. The role and influence of acyl-ACP thioesterases in plant metabolism and their possible applications in lipid biotechnology are discussed.
    Subject(s): Acyl-ACP thioesterase ; Agriculture ; Alleles ; Amino acids ; Arabidopsis ; Arabidopsis - enzymology ; Arabidopsis thaliana ; Carrier proteins ; Ecology ; Enzymes ; Escherichia coli ; Fatty acids ; Forestry ; Genetic engineering ; Helianthus - enzymology ; Helianthus - genetics ; Helianthus annuus ; Leaves ; Life Sciences ; Lipid Metabolism ; Lipids ; Mutagenesis, Site-Directed ; Physiological aspects ; Plant Sciences ; Plants ; Plants, Genetically Modified - enzymology ; Seeds ; Seeds - enzymology ; Sink tissues ; Substrate specificity ; Thiolester Hydrolases - metabolism ; Tobacco ; Tobacco - enzymology ; Transient expression ; Triacylglycerols ; Triglycerides
    ISSN: 0032-0935
    E-ISSN: 1432-2048
    Source: JSTOR Ecology & Botany II
    Source: Alma/SFX Local Collection
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  • 9
    Language: English
    In: Proceedings of the National Academy of Sciences - PNAS, 2016-12-27, Vol.113 (52), p.15150-15155
    Description: Artemisinin, a sesquiterpene lactone produced by glandular secretory trichomes, is the active ingredient in the most effective treatment for malaria currently available. We identified a mutation that disrupts the amorpha-4,11-diene C-12 oxidase (CYP71AV1) enzyme, responsible for a series of oxidation reactions in the artemisinin biosynthetic pathway. Detailed metabolic studies of revealed that the consequence of blocking the artemisinin biosynthetic pathway is the redirection of sesquiterpene metabolism to a sesquiterpene epoxide, which we designate arteannuin X. This sesquiterpene approaches half the concentration observed for artemisinin in wild-type plants, demonstrating high-flux plasticity in glandular trichomes and their potential as factories for the production of novel alternate sesquiterpenes at commercially viable levels. Detailed metabolite profiling of leaf maturation time-series and precursor-feeding experiments revealed that nonenzymatic conversion steps are central to both artemisinin and arteannuin X biosynthesis. In particular, feeding studies using C-labeled dihydroartemisinic acid (DHAA) provided strong evidence that the final steps in the synthesis of artemisinin are nonenzymatic in vivo. Our findings also suggest that the specialized subapical cavity of glandular secretory trichomes functions as a location for both the chemical conversion and the storage of phytotoxic compounds, including artemisinin. We conclude that metabolic engineering to produce high yields of novel secondary compounds such as sesquiterpenes is feasible in complex glandular trichomes. Such systems offer advantages over single-cell microbial hosts for production of toxic natural products.
    Subject(s): Antimalarials - metabolism ; Artemisia ; Artemisia annua ; Artemisia annua - genetics ; Artemisia annua - metabolism ; artemisinin ; Artemisinins - metabolism ; Biological Sciences ; Biosynthetic Pathways - genetics ; Crosses, Genetic ; DNA, Plant - genetics ; Gene Dosage ; Gene mutations ; Genetic aspects ; Genotype ; Mutagenesis ; Mutation ; Observations ; p450 oxidase ; Plant Leaves - metabolism ; Plant Proteins - genetics ; Polymorphism, Single Nucleotide ; sesquiterpene ; Sesquiterpenes - metabolism ; Terpenes - metabolism ; terpenoid ; Trichomes
    ISSN: 0027-8424
    E-ISSN: 1091-6490
    Source: JSTOR Life Sciences
    Source: HighWire Press (Free Journals)
    Source: Hellenic Academic Libraries Link
    Source: PubMed Central
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  • 10
    Language: English
    In: Science (American Association for the Advancement of Science), 2012-06-29, Vol.336 (6089), p.1704-1708
    Description: Noscapine is an antitumor alkaloid from opium poppy that binds tubulin, arrests metaphase, and induces apoptosis in dividing human cells. Elucidation of the biosynthetic pathway will enable improvement in the commercial production of noscapine and related bioactive molecules. Transcriptomic analysis revealed the exclusive expression of 10 genes encoding five distinct enzyme classes in a high noscapine-producing poppy variety, HN1. Analysis of an F₂ mapping population indicated that these genes are tightly linked in HN1, and bacterial artificial chromosome sequencing confirmed that they exist as a complex gene cluster for plant alkaloids. Virus-induced gene silencing resulted in accumulation of pathway intermediates, allowing gene function to be linked to noscapine synthesis and a novel biosynthetic pathway to be proposed.
    Subject(s): Alkaloids ; Antineoplastic Agents, Phytogenic - biosynthesis ; Biological and medical sciences ; Biosynthesis ; Capsules ; Classical genetics, quantitative genetics, hybrids ; Enzymes ; Fundamental and applied biological sciences. Psychology ; Gene silencing ; Genes ; Genes, Plant ; Genetic aspects ; Genetics of eukaryotes. Biological and molecular evolution ; Genomes ; Latex ; Libraries ; Molecular Sequence Data ; Morphinans ; Multigene Family ; Noscapine - metabolism ; Open reading frames ; Papaver - enzymology ; Papaver - genetics ; Papaver - metabolism ; Physiological aspects ; Pteridophyta, spermatophyta ; REPORTS ; Research ; Vegetals
    ISSN: 0036-8075
    E-ISSN: 1095-9203
    Source: JSTOR Life Sciences
    Source: Single Journals
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
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