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Lynch JH. Revisiting the dual pathway hypothesis of Chorismate production in plants. HORTICULTURE RESEARCH 2022; 9:uhac052. [PMID: 35350169 PMCID: PMC8945279 DOI: 10.1093/hr/uhac052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/19/2022] [Indexed: 06/14/2023]
Abstract
The shikimate pathway, the seven enzymatic steps that synthesize chorismate from phosphoenolpyruvate and erythrose 4-phosphate, produces the last common precursor of the three aromatic amino acids. It is firmly established that all seven enzymes are present in plastids, and it is generally accepted that this organelle is likely the sole location for production of chorismate in plants. However, recently a growing body of evidence has provided support for a previous proposal that at least portions of the pathway are duplicated in the cytosol, referred to as the Dual Pathway Hypothesis. Here I revisit this obscure hypothesis by reviewing the findings that provided the original basis for its formulation as well as more recent results that provide fresh support for a possible extra-plastidial shikimate pathway duplication. Similarities between this possible intercompartmental metabolic redundancy and that of terpenoid metabolism are used to discuss potential advantages of pathway duplication, and the translational implications of the Dual Pathway Hypothesis for metabolic engineering are noted.
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Qian Y, Lynch JH, Guo L, Rhodes D, Morgan JA, Dudareva N. Completion of the cytosolic post-chorismate phenylalanine biosynthetic pathway in plants. Nat Commun 2019. [PMID: 30604768 DOI: 10.1038/s41467-018-07969-7962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
In addition to being a vital component of proteins, phenylalanine is also a precursor of numerous aromatic primary and secondary metabolites with broad physiological functions. In plants phenylalanine is synthesized predominantly via the arogenate pathway in plastids. Here, we describe the structure, molecular players and subcellular localization of a microbial-like phenylpyruvate pathway for phenylalanine biosynthesis in plants. Using a reverse genetic approach and metabolic flux analysis, we provide evidence that the cytosolic chorismate mutase is responsible for directing carbon flux towards cytosolic phenylalanine production via the phenylpyruvate pathway. We also show that an alternative transcription start site of a known plastidial enzyme produces a functional cytosolic prephenate dehydratase that catalyzes the conversion of prephenate to phenylpyruvate, the intermediate step between chorismate mutase and phenylpyruvate aminotransferase. Thus, our results complete elucidation of phenylalanine biosynthesis via phenylpyruvate in plants, showing that this pathway splits from the known plastidial arogenate pathway at chorismate, instead of prephenate as previously thought, and the complete pathway is localized in the cytosol.
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Affiliation(s)
- Yichun Qian
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN, 47907-2010, USA
| | - Joseph H Lynch
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - Longyun Guo
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - David Rhodes
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN, 47907-2010, USA
| | - John A Morgan
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
- Davidson School of Chemical Engineering, Purdue University, 480 Stadium Mall Dr., West Lafayette, IN, 47907-2100, USA
| | - Natalia Dudareva
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN, 47907-2010, USA.
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA.
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA.
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Qian Y, Lynch JH, Guo L, Rhodes D, Morgan JA, Dudareva N. Completion of the cytosolic post-chorismate phenylalanine biosynthetic pathway in plants. Nat Commun 2019; 10:15. [PMID: 30604768 PMCID: PMC6318282 DOI: 10.1038/s41467-018-07969-2] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 12/05/2018] [Indexed: 01/10/2023] Open
Abstract
In addition to being a vital component of proteins, phenylalanine is also a precursor of numerous aromatic primary and secondary metabolites with broad physiological functions. In plants phenylalanine is synthesized predominantly via the arogenate pathway in plastids. Here, we describe the structure, molecular players and subcellular localization of a microbial-like phenylpyruvate pathway for phenylalanine biosynthesis in plants. Using a reverse genetic approach and metabolic flux analysis, we provide evidence that the cytosolic chorismate mutase is responsible for directing carbon flux towards cytosolic phenylalanine production via the phenylpyruvate pathway. We also show that an alternative transcription start site of a known plastidial enzyme produces a functional cytosolic prephenate dehydratase that catalyzes the conversion of prephenate to phenylpyruvate, the intermediate step between chorismate mutase and phenylpyruvate aminotransferase. Thus, our results complete elucidation of phenylalanine biosynthesis via phenylpyruvate in plants, showing that this pathway splits from the known plastidial arogenate pathway at chorismate, instead of prephenate as previously thought, and the complete pathway is localized in the cytosol.
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Affiliation(s)
- Yichun Qian
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN, 47907-2010, USA
| | - Joseph H Lynch
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - Longyun Guo
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - David Rhodes
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN, 47907-2010, USA
| | - John A Morgan
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA.,Davidson School of Chemical Engineering, Purdue University, 480 Stadium Mall Dr., West Lafayette, IN, 47907-2100, USA
| | - Natalia Dudareva
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN, 47907-2010, USA. .,Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA. .,Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA.
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Maeda H, Dudareva N. The shikimate pathway and aromatic amino Acid biosynthesis in plants. ANNUAL REVIEW OF PLANT BIOLOGY 2012; 63:73-105. [PMID: 22554242 DOI: 10.1146/annurev-arplant-042811-105439] [Citation(s) in RCA: 736] [Impact Index Per Article: 61.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
L-tryptophan, L-phenylalanine, and L-tyrosine are aromatic amino acids (AAAs) that are used for the synthesis of proteins and that in plants also serve as precursors of numerous natural products, such as pigments, alkaloids, hormones, and cell wall components. All three AAAs are derived from the shikimate pathway, to which ≥30% of photosynthetically fixed carbon is directed in vascular plants. Because their biosynthetic pathways have been lost in animal lineages, the AAAs are essential components of the diets of humans, and the enzymes required for their synthesis have been targeted for the development of herbicides. This review highlights recent molecular identification of enzymes of the pathway and summarizes the pathway organization and the transcriptional/posttranscriptional regulation of the AAA biosynthetic network. It also identifies the current limited knowledge of the subcellular compartmentalization and the metabolite transport involved in the plant AAA pathways and discusses metabolic engineering efforts aimed at improving production of the AAA-derived plant natural products.
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Affiliation(s)
- Hiroshi Maeda
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907-2010, USA.
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Hertel SC, Hieke M, Gröuger D. Purification and characterization of chorismate mutase isoenzymes from ruta graveolens l. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/abio.370110113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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6
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Effect of cold storage on proteinase and chorismate mutase activities inSolanum tuberosum L. Genotypes differing in blackspot susceptibility. ACTA ACUST UNITED AC 1996. [DOI: 10.1007/bf02855961] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Romero R, Roberts M, Phillipson J. Chorismate mutase in microorganisms and plants. PHYTOCHEMISTRY 1995; 40:1015-1025. [PMID: 0 DOI: 10.1016/0031-9422(95)00408-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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Graf R, Dubaquié Y, Braus GH. Modulation of the allosteric equilibrium of yeast chorismate mutase by variation of a single amino acid residue. J Bacteriol 1995; 177:1645-8. [PMID: 7883726 PMCID: PMC176788 DOI: 10.1128/jb.177.6.1645-1648.1995] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Chorismate mutase (EC 5.4.99.5) from the yeast Saccharomyces cerevisiae is an allosteric enzyme which can be locked in its active R (relaxed) state by a single threonine-to-isoleucine exchange at position 226. Seven new replacements of residue 226 reveal that this position is able to direct the enzyme's allosteric equilibrium, without interfering with the catalytic constant or the affinity for the activator.
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Affiliation(s)
- R Graf
- Institut für Mikrobiologie, Biochemie & Genetik, Friedrich-Alexander Universität, Erlangen-Nürnberg, Germany
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Muday GK, Herrmann KM. Wounding Induces One of Two Isoenzymes of 3-Deoxy-d-arabino-Heptulosonate 7-Phosphate Synthase in Solanum tuberosum L. PLANT PHYSIOLOGY 1992; 98:496-500. [PMID: 16668667 PMCID: PMC1080216 DOI: 10.1104/pp.98.2.496] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Potato (Solanum tuberosum L.) tubers contain two isoenzymes of 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (EC 4.1.2.15), the enzyme that catalyzes the first step of aromatic amino acid biosynthesis. One of the isoenzymes is specifically activated by Mn(2+), and the other requires Co(2+), Mg(2+), or another divalent cation for activity. Monospecific polyclonal antibodies against the Mn(2+)-activated isoenzyme do not cross-react with the other isoenzyme. Wounding of potato tubers induces the Mn(2+)-activated form but not the other. We conclude that two different genes encode two different isoenzymes that catalyze the first step in the shikimate pathway.
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Affiliation(s)
- G K Muday
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47906
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Schmidt CL, Danneel HJ, Schultz G, Buchanan BB. Shikimate kinase from spinach chloroplasts : purification, characterization, and regulatory function in aromatic amino Acid biosynthesis. PLANT PHYSIOLOGY 1990; 93:758-66. [PMID: 16667533 PMCID: PMC1062580 DOI: 10.1104/pp.93.2.758] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Shikimate kinase was purified to near homogenity from spinach Spinacia oleracea L. chloroplasts and found to consist of a single 31 kilodalton polypeptide. The purified enzyme was unstable, but could be stabilized by a variety of added proteins, including oxidized and reduced thioredoxins. Whereas the isolated enzyme was stimulated by mono- and dithiol reagents, the enzyme in intact chloroplasts was unaffected by added thiols and showed only minor response to dark/light transitions. These results indicate that the previously reported stimulation of shikimate kinase activity by reduced thioredoxins is due to enzyme stabilization rather than to activation. In the current study, the purified enzyme was inhibited by added ADP and showed a strong response to energy charge. When intact chloroplasts were incubated in the dark in presence of shikimate, phosphoenolpyruvate and a source of ATP (dihydroxyacetone phosphate or ATP itself under appropriate conditions), aromatic amino acids were formed: phenylalanine and tyrosine. The data indicate that energy charge plays a role in regulating shikimate kinase, thereby controlling the shikimate pathway. An unidentified enzyme of the latter part of the pathway, leading from shikimate-3-phosphate to phenylalanine, appears to be activated by light.
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Affiliation(s)
- C L Schmidt
- Botanisches Institut der Tierärztlichen Hochschule Hannover, Bünteweg 17 D, D-3000 Hannover 71, Federal Republic of Germany
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Belknap WR, Rickey TM, Rockhold DR. Blackspot bruise dependent changes in enzyme activity and gene expression in Lemhi russet potato. ACTA ACUST UNITED AC 1990. [DOI: 10.1007/bf02987268] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Affiliation(s)
- R Bentley
- Department of Chemistry, University of Sheffield, U.K
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Kuroki GW, Conn EE. Differential Activities of Chorismate Mutase Isozymes in Tubers and Leaves of Solanum tuberosum L. PLANT PHYSIOLOGY 1989; 89:472-6. [PMID: 16666567 PMCID: PMC1055865 DOI: 10.1104/pp.89.2.472] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Chromatography on DEAE cellulose equilibrated with Pipes buffer resolved three forms of chorismate mutase (CM) from tubers and leaves of Solanum tuberosum: CM-1A and CM-1B were activated by tryptophan and inhibited by phenylalanine and tyrosine; CM-2 was unaffected by these aromatic amino acids. When compared to freshly excised discs, 3 day old tuber discs demonstrated a 4.5-fold increase in CM-1 activity following wounding. By contrast, CM-2 activity levels were not affected by this treatment. In aged tuber discs the CM-1:CM-2 activity ratio was 9:1. However, in green leaves the CM-1:CM-2 activity ratio was 1:4 suggesting organ specific regulation for the expression of these isozymes. The CM-1 isozymes isolated from both tubers and leaves shared similar native molecular weight values of 55,000, K(m) values of 40 to 56 micromolar, and inhibition by phenylalanine (110-145 micromolar concentrations required for 50% inhibition) and tyrosine (50-70 micromolar concentrations required for 50% inhibition). The resolution of CM-1 into two forms occurred only in the presence of Pipes buffer. When this buffer was replaced with Aces, Bes, imidazole or Tris, only a single peak of CM-1 activity was observed. In these buffers CM-2 eluted as a shoulder on the CM-1 peak. Analytical isoelectric focusing of the CM-1 fraction followed by assay of the gel yielded only one form of CM-1 with an isoelectric point of 5.0. Gel filtration studies with Pipes buffer yielded molecular weights of 60,000 for both CM-1A and CM-1B indicating these forms are not the result of aggregation. The two forms of CM-1 may be artifacts generated by Pipes buffer.
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Affiliation(s)
- G W Kuroki
- Department of Biochemistry and Biophysics, University of California, Davis, California 95616
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Morris PF, Doong RL, Jensen RA. Evidence from Solanum tuberosum in Support of the Dual-Pathway Hypothesis of Aromatic Biosynthesis. PLANT PHYSIOLOGY 1989; 89:10-4. [PMID: 16666497 PMCID: PMC1055790 DOI: 10.1104/pp.89.1.10] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Key branchpoint enzymes of aromatic amino acid biosynthesis, 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DS) and chorismate mutase (CM), have previously been shown to exist as separate compartmentalized isozymes in the chloroplasts and cytosol of tobacco, sorghum and spinach. Although additional examples of plants containing these isozyme pairs are accumulating, some studies in the literature report the presence of only the single plastidic DS or CM enzyme. Such apparent exceptions contradict the universality of pathway organization existing in higher plants that is implied by the dual-pathway hypothesis of aromatic biosynthesis. Since potato (Solanum tuberosum) exemplifies a case where only a single species of both DS and CM have been reported, we selected this system for further analysis. The DS-Mn and DS-Co isozyme pair, exhibiting all of the differential properties described in Nicotiana silvestris, have now been identified in S. tuberosum. Likewise, partial purification via DEAE-cellulose chromatography revealed two isozymes of CM in disks excised from tubers of S. tuberosum. The differential regulatory properties of these isozymes were comparable to the CM-1 and CM-2 isozymes of N. silvestris.
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Affiliation(s)
- P F Morris
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, 32611
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Kuroki G, Conn EE. Increased Chorismate Mutase Levels as a Response to Wounding in Solanum tuberosum L. Tubers. PLANT PHYSIOLOGY 1988; 86:895-8. [PMID: 16666004 PMCID: PMC1054590 DOI: 10.1104/pp.86.3.895] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Discs excised from Solanum tuberosum L. cv White Rose tubers demonstrated a 4.5-fold increase in chorismate mutase activity 48 hours after excision. Incubation in the presence of cycloheximide (25 micromolar) or actinomycin D (100 micromolar) completely inhibited the wound response suggesting de novo synthesis of chorismate mutase. Ratios of activity in the presence of the activator tryptophan to that in the absence of tryptophan remained relatively constant during the induction period. This indicated either a constant ratio of tryptophan sensitive to tryptophan insensitive isozymes, or that only one form of chorismate mutase was present. Chromatography of crude extracts on three different columns yielded only one peak of chorismate mutase activity, activated by tryptophan in each case. Incubation under white light had no effect on chorismate mutase activity when compared to dark controls.
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Affiliation(s)
- G Kuroki
- Department of Biochemistry and Biophysics, University of California, Davis, California 95616
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Kuroki GW, Conn EE. Purification and characterization of an inducible aromatic amino acid-sensitive form of chorismate mutase from Solanum tuberosum L. tubers. Arch Biochem Biophys 1988; 260:616-21. [PMID: 3341760 DOI: 10.1016/0003-9861(88)90489-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
An amino acid-sensitive form of chorismate mutase (CM) has been purified over 1000-fold from disks excised from tubers of Solanum tuberosum L. cv White Rose. Purification was accomplished by chromatography on Matrix Blue A followed by affinity chromatography with tryptophan as ligand. CM assays performed in the absence of tryptophan yielded pH-dependent sigmoidal kinetics. At pH 8.0, sigmoidal kinetics were observed with a Hill coefficient of 1.66 (S0.5 = 188 microM). However, a shift from sigmoidal to hyperbolic kinetics was observed when assays were performed at pH 8.5. Addition of 9 microM tryptophan to the assay resulted in maximum activation of the enzyme with a Ka of 1.2 microM. When assayed in the presence of tryptophan, hyperbolic kinetics were observed over the pH range 6.0-8.0. Addition of tryptophan also decreased the Km for chorismate from 185 to 45 microM. Tryptophan (0.1 mM) completely protected CM from inhibition by phenylalanine (1.8 mM) and tyrosine (1.8 mM). However, in the absence of the activator, phenylalanine and tyrosine exhibited 50% inhibition at 0.80 and 0.68 mM concentrations, respectively. Both phenylalanine and tyrosine competitively inhibited CM activity with Ki values of 550 and 440 mM, respectively. Arogenate (1.0 mM) had no effect on CM activity in either the presence or absence of tryptophan. Analytical isoelectric focusing yielded an isoelectric point of 4.73.
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Affiliation(s)
- G W Kuroki
- Department of Biochemistry and Biophysics, University of California, Davis 95616
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