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Abstract
Phosphatidic acid phosphatase (PAP; EC 3.1.3.4) catalyzes the dephosphorylation of phosphatidic acid (PA) to produce diacylglycerol (DAG) and inorganic phosphate. In seed plants, PA plays pivotal roles both as a precursor to membrane lipids and as a signaling molecule. As more information on the roles of PAP in plants becomes available and the importance of PAP is revealed, protocols for assaying plant PAP activity are of interest to an increasing audience. This chapter describes procedures to assay plant PAP activity that are based on recent publications.
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Affiliation(s)
- Yuki Nakamura
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, ROC
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52
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Nakamura Y. Phosphate starvation and membrane lipid remodeling in seed plants. Prog Lipid Res 2012; 52:43-50. [PMID: 22954597 DOI: 10.1016/j.plipres.2012.07.002] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 06/25/2012] [Accepted: 07/02/2012] [Indexed: 01/07/2023]
Abstract
Phosphate is an essential, yet scarce, nutrient that seed plants need to maintain viability. Phosphate-starved plants utilize their membrane phospholipids as a major source for internal phosphate supply by replacing phospholipids in their membranes with the non-phosphorus galactolipid, digalactosyldiacylglycerol. This membrane lipid remodeling has drawn much attention as a model of metabolic switching from phospholipids to the galactolipid. In the past decade, a considerable effort has been devoted to unraveling the molecular biology of this phenomenon. This review thus aims to summarize recent achievements with a focus on metabolic pathways during lipid remodeling.
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Affiliation(s)
- Yuki Nakamura
- Institute of Plant and Microbial Biology, Academia Sinica, 128 Sec. 2 Academia Rd., Nankang, Taipei 11529, Taiwan.
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53
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Nakagawa N, Kato M, Takahashi Y, Shimazaki KI, Tamura K, Tokuji Y, Kihara A, Imai H. Degradation of long-chain base 1-phosphate (LCBP) in Arabidopsis: functional characterization of LCBP phosphatase involved in the dehydration stress response. JOURNAL OF PLANT RESEARCH 2012; 125:439-49. [PMID: 21910031 DOI: 10.1007/s10265-011-0451-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 08/06/2011] [Indexed: 05/08/2023]
Abstract
Sphingolipid metabolites, long-chain base 1-phosphates (LCBPs), are involved in ABA signaling pathways. The LCBPs synthesized by long-chain base kinase are dephosphorylated by LCBP phosphatase or degraded by LCBP lyase. Here we show that the At3g58490 gene encodes AtSPP1, a functional LCBP phosphatase. Transient expression of green fluorescent protein fusion in suspension-cultured Arabidopsis cells showed that AtSPP1 is localized in the endoplasmic reticulum. The level of dihydrosphingosine 1-phosphate was increased in loss-of-function mutants (spp1) compared with wild-type (WT) plants, suggesting a role of AtSPP1 in regulating LCBP levels. The rate of decrease in fresh weight of detached aerial parts was significantly slower in spp1 mutants than in WT plants. A stomatal closure bioassay showed that the stomata of spp1 mutants were more sensitive than the WT to ABA, suggesting that AtSPP1 is involved in guard cell signaling. However, spp1 mutants showed decreased sensitivity to ABA with respect to primary root growth but not to seed germination. The response to fumonisin B(1) did not differ between the WT and spp1 mutant. A significant decrease in AtDPL1 (LCBP lyase) transcripts in spp1 mutants was observed. We conclude that AtSPP1 is a functional LCBP phosphatase that may play a role in stomatal responses through LCBP-mediated ABA signaling.
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Affiliation(s)
- Noriko Nakagawa
- Department of Biology, Graduate School of Natural Science, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
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54
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Pleskot R, Pejchar P, Bezvoda R, Lichtscheidl IK, Wolters-Arts M, Marc J, Žárský V, Potocký M. Turnover of Phosphatidic Acid through Distinct Signaling Pathways Affects Multiple Aspects of Pollen Tube Growth in Tobacco. FRONTIERS IN PLANT SCIENCE 2012; 3:54. [PMID: 22639652 PMCID: PMC3355619 DOI: 10.3389/fpls.2012.00054] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 02/29/2012] [Indexed: 05/20/2023]
Abstract
Phosphatidic acid (PA) is an important intermediate in membrane lipid metabolism that acts as a key component of signaling networks, regulating the spatio-temporal dynamics of the endomembrane system and the cytoskeleton. Using tobacco pollen tubes as a model, we addressed the signaling effects of PA by probing the functions of three most relevant enzymes that regulate the production and degradation of PA, namely, phospholipases D (PLD), diacylglycerol kinases (DGKs), and lipid phosphate phosphatases (LPPs). Phylogenetic analysis indicated a highly dynamic evolution of all three lipid-modifying enzymes in land plants, with many clade-specific duplications or losses and massive diversification of the C2-PLD family. In silico transcriptomic survey revealed increased levels of expression of all three PA-regulatory genes in pollen development (particularly the DGKs). Using specific inhibitors we were able to distinguish the contributions of PLDs, DGKs, and LPPs into PA-regulated processes. Thus, suppressing PA production by inhibiting either PLD or DGK activity compromised membrane trafficking except early endocytosis, disrupted tip-localized deposition of cell wall material, especially pectins, and inhibited pollen tube growth. Conversely, suppressing PA degradation by inhibiting LPP activity using any of three different inhibitors significantly stimulated pollen tube growth, and similar effect was achieved by suppressing the expression of tobacco pollen LPP4 using antisense knock-down. Interestingly, inhibiting specifically DGK changed vacuolar dynamics and the morphology of pollen tubes, whereas inhibiting specifically PLD disrupted the actin cytoskeleton. Overall, our results demonstrate the critical importance of all three types of enzymes involved in PA production and degradation, with strikingly different roles of PA produced by the PLD and DGK pathways, in pollen tube growth.
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Affiliation(s)
- Roman Pleskot
- Institute of Experimental Botany, v. v. i., Academy of Sciences of the Czech RepublicPrague, Czech Republic
| | - Přemysl Pejchar
- Institute of Experimental Botany, v. v. i., Academy of Sciences of the Czech RepublicPrague, Czech Republic
| | - Radek Bezvoda
- Department of Experimental Plant Biology, Faculty of Science, Charles University in PraguePrague, Czech Republic
| | - Irene K. Lichtscheidl
- Core Facility of Cell Imaging and Ultrastructure Research, University of ViennaVienna, Austria
| | - Mieke Wolters-Arts
- Department of Molecular Plant Physiology, Institute for Wetland and Water Research, Radboud University NijmegenNijmegen, Netherlands
| | - Jan Marc
- School of Biological Sciences, University of SydneySydney, NSW, Australia
| | - Viktor Žárský
- Institute of Experimental Botany, v. v. i., Academy of Sciences of the Czech RepublicPrague, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University in PraguePrague, Czech Republic
| | - Martin Potocký
- Institute of Experimental Botany, v. v. i., Academy of Sciences of the Czech RepublicPrague, Czech Republic
- *Correspondence: Martin Potocký, Laboratory of Cell Biology, Institute of Experimental Botany AS CR, v.v.i., Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Lysolaje, Czech Republic. e-mail:
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55
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Merchant SS, Kropat J, Liu B, Shaw J, Warakanont J. TAG, you're it! Chlamydomonas as a reference organism for understanding algal triacylglycerol accumulation. Curr Opin Biotechnol 2011; 23:352-63. [PMID: 22209109 DOI: 10.1016/j.copbio.2011.12.001] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Revised: 12/04/2011] [Accepted: 12/07/2011] [Indexed: 10/14/2022]
Abstract
Photosynthetic organisms are responsible for converting sunlight into organic matter, and they are therefore seen as a resource for the renewable fuel industry. Ethanol and esterified fatty acids (biodiesel) are the most common fuel products derived from these photosynthetic organisms. The potential of algae as producers of biodiesel precursor (or triacylglycerols (TAGs)) has yet to be realized because of the limited knowledge of the underlying biochemistry, cell biology and genetics. Well-characterized pathways from fungi and land plants have been used to identify algal homologs of key enzymes in TAG synthesis, including diacylglcyerol acyltransferases, phospholipid diacylglycerol acyltransferase and phosphatidate phosphatases. Many laboratories have adopted Chlamydomonas reinhardtii as a reference organism for discovery of algal-specific adaptations of TAG metabolism. Stressed Chlamydomonas cells, grown either photoautotrophically or photoheterotrophically, accumulate TAG in plastid and cytoplasmic lipid bodies, reaching 46-65% of dry weight in starch accumulation (sta) mutants. State of the art genomic technologies including expression profiling and proteomics have identified new proteins, including key components of lipid droplets, candidate regulators and lipid/TAG degrading activities. By analogy with crop plants, it is expected that advances in algal breeding and genome engineering may facilitate realizing the potential in algae.
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Affiliation(s)
- Sabeeha S Merchant
- Institute for Genomics and Proteomics and Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, United States.
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56
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Cagliari A, Margis R, Dos Santos Maraschin F, Turchetto-Zolet AC, Loss G, Margis-Pinheiro M. Biosynthesis of Triacylglycerols (TAGs) in plants and algae. INTERNATIONAL JOURNAL OF PLANT BIOLOGY 2011. [DOI: 10.4081/pb.2011.e10] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Triacylglycerols (TAGs), which consist of three fatty acids bound to a glycerol backbone, are major storage lipids that accumulate in developing seeds, flower petals, pollen grains, and fruits of innumerous plant species. These storage lipids are of great nutritional and nutraceutical value and, thus, are a common source of edible oils for human consumption and industrial purposes. Two metabolic pathways for the production of TAGs have been clarified: an acyl¬ CoA-dependent pathway and an acyl-CoA-independent pathway. Lipid metabolism, specially the pathways to fatty acids and TAG biosynthesis, is relatively well understood in plants, but poorly known in algae. It is generally accepted that the basic pathways of fatty acid and TAG biosynthesis in algae are analogous to those of higher plants. However, unlike higher plants where individual classes of lipids may be synthesized and localized in a specific cell, tissue or organ, the complete pathway, from carbon dioxide fixation to TAG synthesis and sequestration, takes place within a single algal cell. Another distinguishing feature of some algae is the large amounts of very long-chain polyunsaturated fatty acids (VLC- PUFAs) as major fatty acid components. Nowadays, the focus of attention in biotechnology is the isolation of novel fatty acid metabolizing genes, especially elongases and desaturases that are responsible for PUFAs synthesis, from different species of algae, and its transfer to plants. The aim is to boost the seed oil content and to generate desirable fatty acids in oilseed crops through genetic engineering approaches. This paper presents the current knowledge of the neutral storage lipids in plants and algae from fatty acid biosynthesis to TAG accumulation.
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57
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Botté CY, Deligny M, Roccia A, Bonneau AL, Saïdani N, Hardré H, Aci S, Yamaryo-Botté Y, Jouhet J, Dubots E, Loizeau K, Bastien O, Bréhélin L, Joyard J, Cintrat JC, Falconet D, Block MA, Rousseau B, Lopez R, Maréchal E. Chemical inhibitors of monogalactosyldiacylglycerol synthases in Arabidopsis thaliana. Nat Chem Biol 2011; 7:834-42. [DOI: 10.1038/nchembio.658] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 07/19/2011] [Indexed: 12/25/2022]
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58
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Bourgis F, Kilaru A, Cao X, Ngando-Ebongue GF, Drira N, Ohlrogge JB, Arondel V. Comparative transcriptome and metabolite analysis of oil palm and date palm mesocarp that differ dramatically in carbon partitioning. Proc Natl Acad Sci U S A 2011; 108:12527-32. [PMID: 21709233 PMCID: PMC3145713 DOI: 10.1073/pnas.1106502108] [Citation(s) in RCA: 232] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Oil palm can accumulate up to 90% oil in its mesocarp, the highest level observed in the plant kingdom. In contrast, the closely related date palm accumulates almost exclusively sugars. To gain insight into the mechanisms that lead to such an extreme difference in carbon partitioning, the transcriptome and metabolite content of oil palm and date palm were compared during mesocarp development. Compared with date palm, the high oil content in oil palm was associated with much higher transcript levels for all fatty acid synthesis enzymes, specific plastid transporters, and key enzymes of plastidial carbon metabolism, including phosphofructokinase, pyruvate kinase, and pyruvate dehydrogenase. Transcripts representing an ortholog of the WRI1 transcription factor were 57-fold higher in oil palm relative to date palm and displayed a temporal pattern similar to its target genes. Unexpectedly, despite more than a 100-fold difference in flux to lipids, most enzymes of triacylglycerol assembly were expressed at similar levels in oil palm and date palm. Similarly, transcript levels for all but one cytosolic enzyme of glycolysis were comparable in both species. Together, these data point to synthesis of fatty acids and supply of pyruvate in the plastid, rather than acyl assembly into triacylglycerol, as a major control over the storage of oil in the mesocarp of oil palm. In addition to greatly increasing molecular resources devoted to oil palm and date palm, the combination of temporal and comparative studies illustrates how deep sequencing can provide insights into gene expression patterns of two species that lack genome sequence information.
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Affiliation(s)
- Fabienne Bourgis
- Université de Bordeaux Ségalen, Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200, F-33000 Bordeaux, France
- Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200, F-33000 Bordeaux, France
| | - Aruna Kilaru
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824
| | - Xia Cao
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824
| | - Georges-Frank Ngando-Ebongue
- Centre de Recherches sur le Palmier à Huile de la Dibamba, Institut de Recherche Agricole pour le Développement, BP243 Douala, Cameroon; and
| | - Noureddine Drira
- Laboratoire de Biotechnologie Végétale, Faculté des Sciences de Sfax, Sfax 3038, Tunisia
| | - John B. Ohlrogge
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824
| | - Vincent Arondel
- Université de Bordeaux Ségalen, Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200, F-33000 Bordeaux, France
- Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, Unité Mixte de Recherche 5200, F-33000 Bordeaux, France
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59
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Role of phosphatidic acid in plant galactolipid synthesis. Biochimie 2011; 94:86-93. [PMID: 21501653 DOI: 10.1016/j.biochi.2011.03.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 03/31/2011] [Indexed: 01/19/2023]
Abstract
Phosphatidic acid (PA) is a precursor metabolite for phosphoglycerolipids and also for galactoglycerolipids, which are essential lipids for formation of plant membranes. PA has in addition a main regulatory role in a number of developmental processes notably in the response of the plant to environmental stresses. We review here the different pools of PA dispatched at different locations in the plant cell and how these pools are modified in different growth conditions, particularly during plastid membrane biogenesis and when the plant is exposed to phosphate deprivation. We analyze how these modifications can affect galactolipid synthesis by tuning the activity of MGD1 enzyme allowing a coupling of phospho- and galactolipid metabolisms. Some mechanisms are considered to explain how physicochemical properties of PA allow this lipid to act as a central internal sensor in plant physiology.
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60
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Paradis S, Villasuso AL, Aguayo SS, Maldiney R, Habricot Y, Zalejski C, Machado E, Sotta B, Miginiac E, Jeannette E. Arabidopsis thaliana lipid phosphate phosphatase 2 is involved in abscisic acid signalling in leaves. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:357-362. [PMID: 21277215 DOI: 10.1016/j.plaphy.2011.01.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 12/21/2010] [Accepted: 01/04/2011] [Indexed: 05/30/2023]
Abstract
Lipid phosphate phosphatases (LPPs, E.C. 3.1.3.4) catalyse the dephosphorylation of diacylglycerol pyrophosphate (DGPP) and phosphatidic acid (PA), which are secondary messengers in abscisic acid (ABA) signalling. In this study, we investigated the effect of ABA on the expression of AtLPP genes as they encode putative ABA-signalling partners. We observed that AtLPP2 expression was down-regulated by ABA and we performed experiments on Atlpp2-2, an AtLPP2 knockout mutant, to determine whether AtLPP2 was involved in ABA signalling. We observed that Atlpp2-2 plantlets contained about twice as much PA as the wild-type Col-0 and exhibited higher PA kinase (PAK) activity than Col-0 plants. In addition, we showed that ABA stimulated diacylglycerol kinase (DGK) activity independently of AtLPP2 activity but that the ABA-stimulation of PAK activity recorded in Col-0 was dependent on AtLPP2. In order to evaluate the involvement of AtLPP2 activity in guard cell function, we measured the ABA sensitivity of Atlpp2-2 stomata. The inhibition of stomatal opening was less sensitive to ABA in Atlpp2-2 than in Col-0. Watered and water-stressed plants of the two genotypes accumulated ABA to the same extent, thus leading us to consider Atlpp2-2 an ABA-signalling mutant. Taken together our observations show that AtLPP2 is a part of ABA signalling and participate to the regulation of stomatal movements.
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Affiliation(s)
- Sophie Paradis
- Université Pierre et Marie Curie, Laboratoire de Physiologie Cellulaire et Moléculaire des Plantes, Unité de Recherche 5-Equipe d'Accueil 7180/CNRS, 4 place Jussieu, Paris Cedex 05, France
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61
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Mietkiewska E, Siloto RMP, Dewald J, Shah S, Brindley DN, Weselake RJ. Lipins from plants are phosphatidate phosphatases that restore lipid synthesis in a pah1Δ mutant strain of Saccharomyces cerevisiae. FEBS J 2011; 278:764-75. [PMID: 21205207 DOI: 10.1111/j.1742-4658.2010.07995.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The identification of the yeast phosphatidate phosphohydrolase (PAH1) gene encoding an enzyme with phosphatidate phosphatase (PAP; 3-sn-phosphatidate phosphohydrolase, EC 3.1.3.4) activity led to the discovery of mammalian Lipins and subsequently to homologous genes from plants. In the present study, we describe the functional characterization of Arabidopsis and Brassica napus homologs of PAH1. Recombinant expression studies confirmed that homologous PAHs from plants can rescue different phenotypes exhibited by the yeast pah1Δ strain, such as temperature growth sensitivity and atypical neutral lipid composition. Using this expression system, we examined the role of the putative catalytic motif DXDXT and other conserved residues by mutational analysis. Mutants within the carboxy-terminal lipin domain displayed significantly decreased PAP activity, which was reflected by their limited ability to complement different phenotypes of pah1Δ. Subcellular localization studies using a green fluorescent protein fusion protein showed that Arabidopsis PAH1 is mostly present in the cytoplasm of yeast cells. However, upon oleic acid stimulation, green fluorescent protein fluorescence was predominantly found in the nucleus, suggesting that plant PAH1 might be involved in the transcriptional regulation of gene expression. In addition, we demonstrate that mutation of conserved residues that are essential for the PAP activity of the Arabidopsis PAH1 enzyme did not impair its nuclear localization in response to oleic acid. In conclusion, the present study provides evidence that Arabidopsis and B. napus PAHs restore lipid synthesis in yeast and that DXDXT is a functional enzymic motif within plant PAHs.
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Affiliation(s)
- Elzbieta Mietkiewska
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada
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62
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Cagliari A, Margis-Pinheiro M, Loss G, Mastroberti AA, de Araujo Mariath JE, Margis R. Identification and expression analysis of castor bean (Ricinus communis) genes encoding enzymes from the triacylglycerol biosynthesis pathway. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2010; 179:499-509. [PMID: 21802608 DOI: 10.1016/j.plantsci.2010.07.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 07/18/2010] [Accepted: 07/24/2010] [Indexed: 05/12/2023]
Abstract
Castor bean (Ricinus communis) oil contains ricinoleic acid-rich triacylglycerols (TAGs). As a result of its physical and chemical properties, castor oil and its derivatives are used for numerous bio-based products. In this study, we survey the Castor Bean Genome Database to report the identification of TAG biosynthesis genes. A set of 26 genes encoding six distinct classes of enzymes involved in TAGs biosynthesis were identified. In silico characterization and sequence analysis allowed the identification of plastidic isoforms of glycerol-3-phosphate acyltransferase and lysophosphatidate acyltransferase enzyme families, involved in the prokaryotic lipid biosynthesis pathway, that form a cluster apart from the cytoplasmic isoforms, involved in the eukaryotic pathway. In addition, two distinct membrane bound diacylglycerol acyltransferase enzymes were identified. Quantitative expression pattern analyses demonstrated variations in gene expressions during castor seed development. A tendency of maximum expression level at the middle of seed development was observed. Our results represent snapshots of global transcriptional activities of genes encompassing six enzyme families involved in castor bean TAG biosynthesis that are present during seed development. These genes represent potential targets for biotechnological approaches to produce nutritionally and industrially desirable oils.
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Affiliation(s)
- Alexandro Cagliari
- Departamento de Genética, Universidade Federal do Rio Grande do Sul, Brazil.
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63
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Eastmond PJ, Quettier AL, Kroon JTM, Craddock C, Adams N, Slabas AR. Phosphatidic acid phosphohydrolase 1 and 2 regulate phospholipid synthesis at the endoplasmic reticulum in Arabidopsis. THE PLANT CELL 2010; 22:2796-811. [PMID: 20699392 PMCID: PMC2947160 DOI: 10.1105/tpc.109.071423] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 06/22/2010] [Accepted: 07/21/2010] [Indexed: 05/17/2023]
Abstract
Phospholipid biosynthesis is essential for the construction of most eukaryotic cell membranes, but how this process is regulated in plants remains poorly understood. Here, we show that in Arabidopsis thaliana, two Mg(2+)-dependent phosphatidic acid phosphohydrolases called PAH1 and PAH2 act redundantly to repress phospholipid biosynthesis at the endoplasmic reticulum (ER). Leaves from pah1 pah2 double mutants contain ~1.8-fold more phospholipid than the wild type and exhibit gross changes in ER morphology, which are consistent with massive membrane overexpansion. The net rate of incorporation of [methyl-(14)C]choline into phosphatidylcholine (PC) is ~1.8-fold greater in the double mutant, and the transcript abundance of several key genes that encode enzymes involved in phospholipid synthesis is increased. In particular, we show that PHOSPHORYLETHANOLAMINE N-METHYLTRANSFERASE1 (PEAMT1) is upregulated at the level of transcription in pah1 pah2 leaves. PEAMT catalyzes the first committed step of choline synthesis in Arabidopsis and defines a variant pathway for PC synthesis not found in yeasts or mammals. Our data suggest that PAH1/2 play a regulatory role in phospholipid synthesis that is analogous to that described in Saccharomyces cerevisiae. However, the target enzymes differ, and key components of the signal transduction pathway do not appear to be conserved.
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Affiliation(s)
- Peter J Eastmond
- Warwick HRI, University of Warwick, Wellesbourne, Warwickshire CV35 9EF, United Kingdom.
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64
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Li-Beisson Y, Shorrosh B, Beisson F, Andersson MX, Arondel V, Bates PD, Baud S, Bird D, DeBono A, Durrett TP, Franke RB, Graham IA, Katayama K, Kelly AA, Larson T, Markham JE, Miquel M, Molina I, Nishida I, Rowland O, Samuels L, Schmid KM, Wada H, Welti R, Xu C, Zallot R, Ohlrogge J. Acyl-lipid metabolism. THE ARABIDOPSIS BOOK 2010; 8:e0133. [PMID: 22303259 PMCID: PMC3244904 DOI: 10.1199/tab.0133] [Citation(s) in RCA: 236] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables.
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65
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Joyard J, Ferro M, Masselon C, Seigneurin-Berny D, Salvi D, Garin J, Rolland N. Chloroplast proteomics highlights the subcellular compartmentation of lipid metabolism. Prog Lipid Res 2010; 49:128-58. [DOI: 10.1016/j.plipres.2009.10.003] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 10/22/2009] [Accepted: 10/23/2009] [Indexed: 01/14/2023]
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66
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Abstract
Chloroplasts are the defining organelle of photoautotrophic plant cells. Photosynthetic light reactions and electron transport are the functions of an elaborate thylakoid membrane system inside chloroplasts. The lipid composition of photosynthetic membranes is characterized by a substantial fraction of nonphosphorous galactoglycerolipids reflecting the need of sessile plants to conserve phosphorus. Lipid transport and assembly of glycerolipids play an essential role in the biogenesis of the photosynthetic apparatus in developing chloroplasts. During chloroplast biogenesis, fatty acids are synthesized in the plastid and are exported to the endoplasmic reticulum, where they are incorporated into membrane lipids. Alternatively, lipids can also be assembled de novo at the inner envelope membrane of plastids in many plants. A rich repertoire of lipid exchange mechanisms involving the thylakoid membranes, the chloroplast inner and outer envelope membranes, and the endoplasmic reticulum is emerging. Studies of thylakoid biogenesis provide new insights into the general mechanisms of intermembrane lipid transfer.
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Affiliation(s)
- Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA.
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67
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Nakamura Y, Shimojima M, Ohta H, Shimojima K. Chapter 13 Biosynthesis and Function of Monogalactosyldiacylglycerol (MGDG), the Signature Lipid of Chloroplasts. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/978-90-481-8531-3_13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
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Dubots E, Audry M, Yamaryo Y, Bastien O, Ohta H, Breton C, Maréchal E, Block MA. Activation of the chloroplast monogalactosyldiacylglycerol synthase MGD1 by phosphatidic acid and phosphatidylglycerol. J Biol Chem 2009; 285:6003-11. [PMID: 20023301 DOI: 10.1074/jbc.m109.071928] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One of the major characteristics of chloroplast membranes is their enrichment in galactoglycerolipids, monogalactosyldiacylglycerol (MGDG), and digalactosyldiacylglycerol (DGDG), whereas phospholipids are poorly represented, mainly as phosphatidylglycerol (PG). All these lipids are synthesized in the chloroplast envelope, but galactolipid synthesis is also partially dependent on phospholipid synthesis localized in non-plastidial membranes. MGDG synthesis was previously shown essential for chloroplast development. In this report, we analyze the regulation of MGDG synthesis by phosphatidic acid (PA), which is a general precursor in the synthesis of all glycerolipids and is also a signaling molecule in plants. We demonstrate that under physiological conditions, MGDG synthesis is not active when the MGDG synthase enzyme is supplied with its substrates only, i.e. diacylglycerol and UDP-gal. In contrast, PA activates the enzyme when supplied. This is shown in leaf homogenates, in the chloroplast envelope, as well as on the recombinant MGDG synthase, MGD1. PG can also activate the enzyme, but comparison of PA and PG effects on MGD1 activity indicates that PA and PG proceed through different mechanisms, which are further differentiated by enzymatic analysis of point-mutated recombinant MGD1s. Activation of MGD1 by PA and PG is proposed as an important mechanism coupling phospholipid and galactolipid syntheses in plants.
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Affiliation(s)
- Emmanuelle Dubots
- Laboratoire de Physiologie Cellulaire Végétale, CNRS/CEA/INRA/Université Joseph Fourier, CEA-Grenoble, F-38054 Grenoble, France
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69
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Arabidopsis lipins mediate eukaryotic pathway of lipid metabolism and cope critically with phosphate starvation. Proc Natl Acad Sci U S A 2009; 106:20978-83. [PMID: 19923426 DOI: 10.1073/pnas.0907173106] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Phosphate is an essential nutrient for plant viability. It is well-established that phosphate starvation triggers membrane lipid remodeling, a process that converts significant portion of phospholipids to non-phosphorus-containing galactolipids. This remodeling is mediated by either phospholipase C (PLC) or phospholipase D (PLD) in combination with phosphatidate phosphatase (PAP). Two PLC genes, NPC4 and NPC5, and PLD genes, PLDzeta1 and PLDzeta2, are shown to be involved in the remodeling. However, gene knockout studies show that none of them plays decisive roles in the remodeling. Thus, although this phenomenon is widely observed among plants, the key enzyme(s) responsible for the lipid remodeling in a whole plant body is unknown; therefore, the physiological significance of this conversion process has remained to be elucidated. We herein focused on PAP as a key enzyme for this adaptation, and identified Arabidopsis lipin homologs, AtPAH1 and AtPAH2, that encode the PAPs involved in galactolipid biosynthesis. Double mutant pah1pah2 plants had decreased phosphatidic acid hydrolysis, thus affecting the eukaryotic pathway of galactolipid synthesis. Upon phosphate starvation, pah1pah2 plants were severely impaired in growth and membrane lipid remodeling. These results indicate that PAH1 and PAH2 are the PAP responsible for the eukaryotic pathway of galactolipid synthesis, and the membrane lipid remodeling mediated by these two enzymes is an essential adaptation mechanism to cope with phosphate starvation.
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Moellering ER, Miller R, Benning C. Molecular Genetics of Lipid Metabolism in the Model Green Alga Chlamydomonas reinhardtii. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/978-90-481-2863-1_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
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73
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Andersson MX, Dörmann P. Chloroplast Membrane Lipid Biosynthesis and Transport. PLANT CELL MONOGRAPHS 2008. [DOI: 10.1007/978-3-540-68696-5_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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75
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França MGC, Matos AR, D'arcy-Lameta A, Passaquet C, Lichtlé C, Zuily-Fodil Y, Pham-Thi AT. Cloning and characterization of drought-stimulated phosphatidic acid phosphatase genes from Vigna unguiculata. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:1093-100. [PMID: 18755595 DOI: 10.1016/j.plaphy.2008.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 06/14/2008] [Accepted: 07/09/2008] [Indexed: 05/22/2023]
Abstract
Under environmental stresses, several lipolytic enzymes are known to be activated and to contribute to membrane lipid turnover and generation of second messengers. In animal cells, phosphatidic acid phosphatase (PAP, EC 3.1.3.4), which dephosphorylates phosphatidic acid generating diacylglycerol, is long known as an enzyme involved in lipid synthesis and cell signalling. However, knowledge on PAP in plants remains very limited. The aim of this work was to isolate and characterize PAP genes in the tropical legume Vigna unguiculata (cowpea), and to study their expression under different stress conditions. Two cDNAs designated as VuPAPalpha and VuPAPbeta were cloned from the leaves of cowpea. Both proteins share sequence homology to animal type 2 PAP, namely, the six transmembrane regions and the consensus sequences corresponding to the catalytic domain of the phosphatase family, like the recently described Arabidopsis LPP (Lipid Phosphate Phosphatase) proteins. The recombinant protein VuPAPalpha expressed in Escherichia coli cells was able to convert phosphatidic acid into diacylglycerol. Unlike VuPAPbeta, VuPAPalpha has an N-terminal transit peptide and was addressed to chloroplast in vitro. Both genes are expressed in several cowpea organs and their transcripts accumulate in leaves in response to water deficit, including progressive dehydration of whole plants and rapid desiccation of detached leaves. No changes in expression of both genes were observed after wounding or by treatment with jasmonic acid. Furthermore, the in silico analysis of VuPAPalpha promoter allowed the identification of several putative drought-related regulatory elements. The possible physiological role of the two cloned PAPs is discussed.
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Affiliation(s)
- Marcel Giovanni Costa França
- Departamento de Botânica, Universidade Federal de Minas Gerais, ICB, Av. Antônio Carlos 6627, Pampulha, 31270-901 Belo Horizonte, MG, Brazil
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76
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Racagni G, Villasuso AL, Pasquaré SJ, Giusto NM, Machado E. Diacylglycerol pyrophosphate inhibits the alpha-amylase secretion stimulated by gibberellic acid in barley aleurone. PHYSIOLOGIA PLANTARUM 2008; 134:381-93. [PMID: 18573189 DOI: 10.1111/j.1399-3054.2008.01148.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
ABA plays an important regulatory role in seed germination because it inhibits the response to GA in aleurone, a secretory tissue surrounding the endosperm. Phosphatidic acid (PA) is a well-known intermediary in ABA signaling, but the role of diacylglycerol pyrophosphate (DGPP) in germination processes is not clearly established. In this study, we show that PA produced by phospholipase D (E.C. 3.1.4.4) during the antagonist effect of ABA in GA signaling is rapidly phosphorylated by phosphatidate kinase (PAK) to DGPP. This is a crucial fact for aleurone function because exogenously added dioleoyl-DGPP inhibits secretion of alpha-amylase (E.C. 3.2.1.1). Aleurone treatment with ABA and 1-butanol results in normal secretory activity, and this effect is reversed by addition of dioleoyl-DGPP. We also found that ABA decreased the activity of an Mg2+-independent, N-ethylmaleimide-insensitive form of phosphatidate phosphohydrolase (PAP2) (E.C. 3.1.3.4), leading to reduction of PA dephosphorylation and increased PAK activity. Sequence analysis using Arabidopsis thaliana lipid phosphate phosphatase (LPP) sequences as queries identified two putative molecular homologues, termed HvLPP1 and HvLPP2, encoding putative Lpps with the presence of well-conserved structural Lpp domains. Our results are consistent with a role of DGPP as a regulator of ABA antagonist effect in GA signaling and provide evidence about regulation of PA level by a PAP2 during ABA response in aleurone.
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Affiliation(s)
- Graciela Racagni
- Química Biológica, FCEFQN, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto, Córdoba, Argentina
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Xu C, Fan J, Cornish AJ, Benning C. Lipid trafficking between the endoplasmic reticulum and the plastid in Arabidopsis requires the extraplastidic TGD4 protein. THE PLANT CELL 2008; 20:2190-204. [PMID: 18689504 PMCID: PMC2553622 DOI: 10.1105/tpc.108.061176] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 07/19/2008] [Accepted: 07/27/2008] [Indexed: 05/18/2023]
Abstract
The development of chloroplasts in Arabidopsis thaliana requires extensive lipid trafficking between the endoplasmic reticulum (ER) and the plastid. The biosynthetic enzymes for the final steps of chloroplast lipid assembly are associated with the plastid envelope membranes. For example, during biosynthesis of the galactoglycerolipids predominant in photosynthetic membranes, galactosyltransferases associated with these membranes transfer galactosyl residues from UDP-Gal to diacylglycerol. In Arabidopsis, diacylglycerol can be derived from the ER or the plastid. Here, we describe a mutant of Arabidopsis, trigalactosyldiacylglycerol4 (tgd4), in which ER-derived diacylglycerol is not available for galactoglycerolipid biosynthesis. This mutant accumulates diagnostic oligogalactoglycerolipids, hence its name, and triacylglycerol in its tissues. The TGD4 gene encodes a protein that appears to be associated with the ER membranes. Mutant ER microsomes show a decreased transfer of lipids to isolated plastids consistent with in vivo labeling data, indicating a disruption of ER-to-plastid lipid transfer. The complex lipid phenotype of the mutant is similar to that of the tgd1,2,3 mutants disrupted in components of a lipid transporter of the inner plastid envelope membrane. However, unlike the TGD1,2,3 complex, which is proposed to transfer phosphatidic acid through the inner envelope membrane, TGD4 appears to be part of the machinery mediating lipid transfer between the ER and the outer plastid envelope membrane. The extent of direct ER-to-plastid envelope contact sites is not altered in the tgd4 mutant. However, this does not preclude a possible function of TGD4 in those contact sites as a conduit for lipid transfer between the ER and the plastid.
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Affiliation(s)
- Changcheng Xu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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79
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Andersson MX, Dörmann P. Chloroplast Membrane Lipid Biosynthesis and Transport. PLANT CELL MONOGRAPHS 2008. [DOI: 10.1007/7089_2008_18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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80
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Nakamura Y, Ohta H. The diacylglycerol forming pathways differ among floral organs ofPetunia hybrida. FEBS Lett 2007; 581:5475-9. [DOI: 10.1016/j.febslet.2007.10.053] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 10/26/2007] [Accepted: 10/26/2007] [Indexed: 11/25/2022]
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