The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Emily J Parker - One of the best experts on this subject based on the ideXlab platform.
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a pseudoisostructural type ii dah7ps enzyme from pseudomonas aeruginosa alternative evolutionary strategies to control Shikimate Pathway flux
Biochemistry, 2018Co-Authors: Oliver W Sterritt, Sarah A Kessans, Geoffrey B Jameson, Emily J ParkerAbstract:The Shikimate Pathway is responsible for the biosynthesis of key aromatic metabolites in microorganisms and plants. The enzyme 3-deoxy-d- arabino-heptulosonate 7-phosphate synthase (DAH7PS) catalyzes the first step of the Pathway and DAH7PSs are classified as either type I or type II. The DAH7PSs from Pseudomonas aeruginosa are of particular interest as open reading frames encoding four putative DAH7PS isoenzymes, two classified as type Iα and two classified as type II, have been identified. Here, the structure of a type II DAH7PS enzyme from P. aeruginosa (PAO1) has been determined at 1.54 A resolution, in complex with its allosteric inhibitor tryptophan. Structural differences in the extra-barrel elements, when compared to other type II DAH7PS enzymes, directly relate to the formation of a distinct quaternary conformation with consequences for allosteric function and the control of flux to branching Pathways. In contrast to the well-characterized Mycobacterium tuberculosis type II DAH7PS, which binds multiple allosteric inhibitors, this PaeDAH7PSPA2843 is observed to be modestly allosterically inhibited by a single aromatic amino acid, tryptophan. In addition, structures in complex with tyrosine or with no allosteric ligand bound were determined. These structures provide new insights into the linkages between the active and allosteric sites. With four putative DAH7PS enzymes, P. aeruginosa appears to have evolved control of Shikimate Pathway flux at the genetic level, rather than control by multiple allosteric effectors to a single type II DAH7PS, as in M. tuberculosis. Type II DAH7PSs, thus, appear to have a more varied evolutionary trajectory than previously indicated.
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A Pseudoisostructural Type II DAH7PS Enzyme from Pseudomonas aeruginosa: Alternative Evolutionary Strategies to Control Shikimate Pathway Flux
2018Co-Authors: Oliver W Sterritt, Sarah A Kessans, Geoffrey B Jameson, Emily J ParkerAbstract:The Shikimate Pathway is responsible for the biosynthesis of key aromatic metabolites in microorganisms and plants. The enzyme 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAH7PS) catalyzes the first step of the Pathway and DAH7PSs are classified as either type I or type II. The DAH7PSs from Pseudomonas aeruginosa are of particular interest as open reading frames encoding four putative DAH7PS isoenzymes, two classified as type Iα and two classified as type II, have been identified. Here, the structure of a type II DAH7PS enzyme from P. aeruginosa (PAO1) has been determined at 1.54 Å resolution, in complex with its allosteric inhibitor tryptophan. Structural differences in the extra-barrel elements, when compared to other type II DAH7PS enzymes, directly relate to the formation of a distinct quaternary conformation with consequences for allosteric function and the control of flux to branching Pathways. In contrast to the well-characterized Mycobacterium tuberculosis type II DAH7PS, which binds multiple allosteric inhibitors, this PaeDAH7PSPA2843 is observed to be modestly allosterically inhibited by a single aromatic amino acid, tryptophan. In addition, structures in complex with tyrosine or with no allosteric ligand bound were determined. These structures provide new insights into the linkages between the active and allosteric sites. With four putative DAH7PS enzymes, P. aeruginosa appears to have evolved control of Shikimate Pathway flux at the genetic level, rather than control by multiple allosteric effectors to a single type II DAH7PS, as in M. tuberculosis. Type II DAH7PSs, thus, appear to have a more varied evolutionary trajectory than previously indicated
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investigating the role of the hydroxyl groups of substrate erythrose 4 phosphate in the reaction catalysed by the first enzyme of the Shikimate Pathway
Bioorganic & Medicinal Chemistry Letters, 2011Co-Authors: David Tran, Geoffrey B Jameson, Amy L Pietersma, Linley R Schofield, Matthias Rost, Emily J ParkerAbstract:3-Deoxy-D-arabino-heptulosonate 7-phosphate (DAH7P) synthase catalyses the first step of the Shikimate Pathway, which is responsible for the biosynthesis of aromatic amino acids in microorganisms and plants. This enzyme catalyses an aldol reaction between phosphoenolpyruvate and D-erythrose 4-phosphate to generate DAH7P. Both 2-deoxyerythrose 4-phosphate and 3-deoxyerythrose 4-phosphate were synthesised and tested as alternative substrates for the enzyme. Both compounds were found to be substrates for the DAH7P synthases from Escherichia coli, Pyrococcus furiosus and Mycobacterium tuberculosis, consistent with an acyclic mechanism for the enzyme for which neither C2 nor C3 hydroxyl groups are required for catalysis. The enzymes all showed greater tolerance for the loss of the C2 hydroxyl group than the C3 hydroxyl group.
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potent inhibitors of a Shikimate Pathway enzyme from mycobacterium tuberculosis combining mechanism and modeling based design
Journal of Biological Chemistry, 2011Co-Authors: Sebastian Reichau, Wanting Jiao, Scott Walker, Richard D Hutton, Edward N Baker, Emily J ParkerAbstract:Tuberculosis remains a serious global health threat, with the emergence of multidrug-resistant strains highlighting the urgent need for novel antituberculosis drugs. The enzyme 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAH7PS) catalyzes the first step of the Shikimate Pathway for the biosynthesis of aromatic compounds. This Pathway has been shown to be essential in Mycobacterium tuberculosis, the pathogen responsible for tuberculosis. DAH7PS catalyzes a condensation reaction between P-enolpyruvate and erythrose 4-phosphate to give 3-deoxy-D-arabino-heptulosonate 7-phosphate. The enzyme reaction mechanism is proposed to include a tetrahedral intermediate, which is formed by attack of an active site water on the central carbon of P-enolpyruvate during the course of the reaction. Molecular modeling of this intermediate into the active site reported in this study shows a configurational preference consistent with water attack from the re face of P-enolpyruvate. Based on this model, we designed and synthesized an inhibitor of DAH7PS that mimics this reaction intermediate. Both enantiomers of this intermediate mimic were potent inhibitors of M. tuberculosis DAH7PS, with inhibitory constants in the nanomolar range. The crystal structure of the DAH7PS-inhibitor complex was solved to 2.35 A. Both the position of the inhibitor and the conformational changes of active site residues observed in this structure correspond closely to the predictions from the intermediate modeling. This structure also identifies a water molecule that is located in the appropriate position to attack the re face of P-enolpyruvate during the course of the reaction, allowing the catalytic mechanism for this enzyme to be clearly defined.
Gad Galili - One of the best experts on this subject based on the ideXlab platform.
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altered levels of aroma and volatiles by metabolic engineering of Shikimate Pathway genes in tomato fruits
Bioengineering 2015 Vol. 2 Pages 75-92, 2015Co-Authors: Vered Tzin, Asaph Aharoni, Michal Moyal Ben Zvi, Ilana Rogachev, Sagit Meir, Tania Masci, Alexander Vainstein, Gad GaliliAbstract:The tomato ( Solanum lycopersicum ) fruit is an excellent source of antioxidants, dietary fibers, minerals and vitamins and therefore has been referred to as a “functional food”. Ripe tomato fruits produce a large number of specialized metabolites including volatile organic compounds. These volatiles serve as key components of the tomato fruit flavor, participate in plant pathogen and herbivore defense, and are used to attract seed dispersers. A major class of specialized metabolites is derived from the Shikimate Pathway followed by aromatic amino acid biosynthesis of phenylalanine, tyrosine and tryptophan. We attempted to modify tomato fruit flavor by overexpressing key regulatory genes in the Shikimate Pathway. Bacterial genes encoding feedback-insensitive variants of 3-Deoxy-D-Arabino-Heptulosonate 7-Phosphate Synthase (DAHPS; AroG 209-9 ) and bi-functional Chorismate Mutase/Prephenate Dehydratase (CM/PDT; PheA 12 ) were expressed under the control of a fruit-specific promoter. We crossed these transgenes to generate tomato plants expressing both the AroG 209 and PheA 12 genes. Overexpression of the AroG 209-9 gene had a dramatic effect on the overall metabolic profile of the fruit, including enhanced levels of multiple volatile and non-volatile metabolites. In contrast, the PheA 12 overexpression line exhibited minor metabolic effects compared to the wild type fruit. Co-expression of both the AroG 209-9 and PheA 12 genes in tomato resulted overall in a similar metabolic effect to that of expressing only the AroG 209-9 gene. However, the aroma ranking attributes of the tomato fruits from PheA 12 //AroG 209-9 were unique and different from those of the lines expressing a single gene, suggesting a contribution of the PheA 12 gene to the overall metabolic profile. We suggest that expression of bacterial genes encoding feedback-insensitive enzymes of the Shikimate Pathway in tomato fruits provides a useful metabolic engineering tool for the modification of fruits aroma and the generation of new combinations of tomato flavors.
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tomato fruits expressing a bacterial feedback insensitive 3 deoxy d arabino heptulosonate 7 phosphate synthase of the Shikimate Pathway possess enhanced levels of multiple specialized metabolites and upgraded aroma
Journal of Experimental Botany, 2013Co-Authors: Vered Tzin, Asaph Aharoni, Michal Moyal Ben Zvi, Ilana Rogachev, Sagit Meir, Tania Masci, Alexander Vainstein, Gad GaliliAbstract:Tomato (Solanum lycopersicum) fruit contains significant amounts of bioactive compounds, particularly multiple classes of specialized metabolites. Enhancing the synthesis and accumulation of these substances, specifically in fruits, are central for improving tomato fruit quality (e.g. flavour and aroma) and could aid in elucidate Pathways of specialized metabolism. To promote the production of specialized metabolites in tomato fruit, this work expressed under a fruit ripening-specific promoter, E8, a bacterial AroG gene encoding a 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS), which is feedback-insensitive to phenylalanine inhibition. DAHPS, the first enzyme of the Shikimate Pathway, links between the primary and specialized metabolism derived from aromatic amino acids. AroG expression influenced the levels of number of primary metabolites, such as shikimic acid and aromatic amino acids, as well as multiple volatile and non-volatile phenylpropanoids specialized metabolites and carotenoids. An organoleptic test, performed by trained panellists, suggested that the ripe AroG-expressing tomato fruits had a preferred floral aroma compare with fruits of the wild-type line. These results imply that fruit-specific manipulation of the conversion of primary to specialized metabolism is an attractive approach for improving fruit aroma and flavour qualities as well as discovering novel fruit-specialized metabolites.
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Shikimate Pathway and aromatic amino acid biosynthesis
eLS, 2012Co-Authors: Vered Tzin, Gad Galili, Asaph AharoniAbstract:The Shikimate Pathway consists of seven enzymatic reactions whose end product chorismate is the precursor for the synthesis of the aromatic amino acids Phe, Tyr and Trp. In fungi and plants, chorismate is a precursor for many specialised metabolites (i.e. secondary metabolites) that play an important role in the plant's interaction with its environment. The Shikimate Pathway and aromatic amino acid biosynthesis have been extensively studied in a variety of microorganisms, fungi and plants. Furthermore, the dual involvement of the Shikimate and aromatic amino acid biosynthesis Pathways in central and specialised metabolism still raises major questions regarding the genes and enzymes involved, and their control, their evolutionary origins and coordinated regulation with genes of associated Pathways in response to altered environmental conditions and diverse developmental programs. Key Concepts: The Shikimate Pathway is the only known Pathway for biosynthesis of chorismate and the aromatic amino acids Phe, Tyr and Trp. The Shikimate Pathway is a bridge between central metabolism and specialised metabolism. The Shikimate Pathway occurs in various groups of microorganisms, plants and parasites, whereas it does not occur in animals. The Pathway enzymes are being targeted for antimicrobial drug and herbicide design. Shikimic acid is an essential metabolite that may balance the metabolic status of the Pathway. Chorismate is a branch point metabolite for aromatic amino acids and phenolic compounds. This is an ancient eukaryotic Pathway which has been subject to diverse evolutionary processes. Several enzymes from these Pathways are allosterically regulated by their end products: Phe, Tyr or Trp. The Shikimate Pathway and aromatic amino acids, and the specialised metabolites derived from them, simultaneously respond to rhythmic changes. Keywords: Shikimate; chorismate; phenylalanine; tyrosine; tryptophan; central metabolism; specialised metabolites; secondary metabolites
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expression of a bacterial feedback insensitive 3 deoxy d arabino heptulosonate 7 phosphate synthase of the Shikimate Pathway in arabidopsis elucidates potential metabolic bottlenecks between primary and secondary metabolism
New Phytologist, 2012Co-Authors: Vered Tzin, Asaph Aharoni, Sergey Malitsky, Michal Moyal Ben Zvi, Mohamed Bedair, Lloyd W Sumner, Gad GaliliAbstract:Summary •The Shikimate Pathway of plants mediates the conversion of primary carbon metabolites via chorismate into the three aromatic amino acids and to numerous secondary metabolites derived from them. However, the regulation of the Shikimate Pathway is still far from being understood. We hypothesized that 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS) is a key enzyme regulating flux through the Shikimate Pathway. •To test this hypothesis, we expressed a mutant bacterial AroG gene encoding a feedback-insensitive DAHPS in transgenic Arabidopsis plants. The plants were subjected to detailed analysis of primary metabolism, using GC-MS, as well as secondary metabolism, using LC-MS. •Our results exposed a major effect of bacterial AroG expression on the levels of Shikimate intermediate metabolites, phenylalanine, tryptophan and broad classes of secondary metabolite, such as phenylpropanoids, glucosinolates, auxin and other hormone conjugates. •We propose that DAHPS is a key regulatory enzyme of the Shikimate Pathway. Moreover, our results shed light on additional potential metabolic bottlenecks bridging plant primary and secondary metabolism.
John R. Coggins - One of the best experts on this subject based on the ideXlab platform.
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a complete Shikimate Pathway in toxoplasma gondii an ancient eukaryotic innovation
International Journal for Parasitology, 2004Co-Authors: Samantha A Campbell, John R. Coggins, Thomas A Richards, Ernest Mui, Benjamin U Samuel, R Mcleod, Craig W. RobertsAbstract:The Shikimate Pathway is essential for survival of the apicomplexan parasites Plasmodium falciparum, Toxoplasma gondii and Cryptosporidium parvum. As it is absent in mammals it is a promising therapeutic target. Herein, we describe the genes encoding the Shikimate Pathway enzymes in T. gondii. The molecular arrangement and phylogeny of the proteins suggests homology with the eukaryotic fungal enzymes, including a pentafunctional AROM. Current rooting of the eukaryotic evolutionary tree infers that the fungi and apicomplexan lineages diverged deeply, suggesting that the arom is an ancient supergene present in early eukaryotes and subsequently lost or replaced in a number of lineages.
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experiences with the Shikimate Pathway enzymes as targets for rational drug design
Biochemical Society Transactions, 2003Co-Authors: John R. Coggins, Chris Abell, L B Evans, M Frederickson, David A Robinson, Aleksander W Roszak, A P LapthornAbstract:The background and current context of work on the Shikimate-Pathway enzymes as potential targets for anti-bacterial, anti-fungal and anti-parasitic drugs is reviewed. Recent work on the third enzyme of the Pathway, dehydroquinase, which occurs in two structurally and mechanistically distinct forms, is used to illustrate the present state of studies into rational drug design.
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twists and turns a tale of two Shikimate Pathway enzymes
Biochemical Society Transactions, 2003Co-Authors: Katherine A Brown, John R. Coggins, Alastair R Hawkins, Elisabeth P Carpenter, Kimberly A Watson, M H J Koch, Dmitri I SvergunAbstract:We are studying two enzymes from the Shikimate Pathway, dehydroquinate synthase (DHQS) and 5-enolpyruvylShikimate-3-phosphate synthase (EPSPS). Both enzymes have been the subject of numerous studies to elucidate their reaction mechanisms. Crystal structures of DHQS and EPSPS in the presence and absence of substrates, cofactors and/or inhibitors are now available. These structures reveal movements of domains, rearrangements of loops and changes in side-chain positions necessary for the formation of a catalytically competent active site. The potential for using complementary small-angle X-ray scattering (SAXS) studies to confirm the presence of these structural differences in solution has also been explored. Comparative analysis of crystal structures, in the presence and absence of ligands, has revealed structural features critical for substrate-binding and catalysis. We have also analysed these structures by generating GRID energy maps to detect favourable binding sites. The combination of X-ray crystallography, SAXS and computational techniques provides an enhanced analysis of structural features important for the function of these complex enzymes.
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The Shikimate Pathway and Its Branches in Apicomplexan Parasites
The Journal of Infectious Diseases, 2002Co-Authors: Craig w. Roberts, Fiona Roberts, John R. Coggins, Russell e. Lyons, Michael j. Kirisits, Ernest j Mui, John Finnerty, Jennifer j. Johnson, David j. p. Ferguson, Tino KrellAbstract:The Shikimate Pathway is essential for production of a plethora of aromatic compounds in plants, bacteria, and fungi. Seven enzymes of the Shikimate Pathway catalyze sequential conversion of erythrose 4-phosphate and phosphoenol pyruvate to chorismate. Chorismate is then used as a substrate for other Pathways that culminate in production of folates, ubiquinone, napthoquinones, and the aromatic amino acids tryptophan, phenylalanine, and tyrosine. The Shikimate Pathway is absent from animals and present in the apicomplexan parasites Toxoplasma gondii, Plasmodium falciparum, and Cryptosporidium parvum. Inhibition of the Pathway by glyphosate is effective in controlling growth of these parasites. These findings emphasize the potential benefits of developing additional effective inhibitors of the Shikimate Pathway. Such inhibitors may function as broad-spectrum antimicrobial agents that are effective against bacterial and fungal pathogens and apicomplexan parasites
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Evidence for the Shikimate Pathway in apicomplexan parasites
Nature, 1998Co-Authors: Fiona Roberts, Craig W. Roberts, Jennifer J. Johnson, Dennis E. Kyle, Tino Krell, John R. Coggins, Graham H. Coombs, Wilbur K. Milhous, Saul Tzipori, David J. P. FergusonAbstract:Parasites of the phylum Apicomplexa cause substantial morbidity, mortality and economic losses, and new medicines to treat them are needed urgently. The Shikimate Pathway is an attractive target for herbicides and antimicrobial agents because it is essential in algae, higher plants, bacteria and fungi, but absent from mammals. Here we present biochemical, genetic and chemotherapeutic evidence for the presence of enzymes of the Shikimate Pathway in apicomplexan parasites. In vitro growth of Toxoplasma gondii, Plasmodium falciparum (malaria) and Cryptosporidium parvum was inhibited by the herbicide glyphosate, a well-characterized inhibitor of the Shikimate Pathway enzyme 5-enolpyruvyl Shikimate 3-phosphate synthase. This effect on T. gondii and P. falciparum was reversed by treatment with p-aminobenzoate, which suggests that the Shikimate Pathway supplies folate precursors for their growth. Glyphosate in combination with pyrimethamine limited T. gondii infection in mice. Four Shikimate Pathway enzymes were detected in extracts of T. gondii and glyphosate inhibited 5-enolpyruvyl Shikimate 3-phosphate synthase activity. Genes encoding chorismate synthase, the final Shikimate Pathway enzyme, were cloned from T. gondii and P. falciparum. This discovery of a functional Shikimate Pathway in apicomplexan parasites provides several targets for the development of new antiparasite agents.
Vered Tzin - One of the best experts on this subject based on the ideXlab platform.
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altered levels of aroma and volatiles by metabolic engineering of Shikimate Pathway genes in tomato fruits
Bioengineering 2015 Vol. 2 Pages 75-92, 2015Co-Authors: Vered Tzin, Asaph Aharoni, Michal Moyal Ben Zvi, Ilana Rogachev, Sagit Meir, Tania Masci, Alexander Vainstein, Gad GaliliAbstract:The tomato ( Solanum lycopersicum ) fruit is an excellent source of antioxidants, dietary fibers, minerals and vitamins and therefore has been referred to as a “functional food”. Ripe tomato fruits produce a large number of specialized metabolites including volatile organic compounds. These volatiles serve as key components of the tomato fruit flavor, participate in plant pathogen and herbivore defense, and are used to attract seed dispersers. A major class of specialized metabolites is derived from the Shikimate Pathway followed by aromatic amino acid biosynthesis of phenylalanine, tyrosine and tryptophan. We attempted to modify tomato fruit flavor by overexpressing key regulatory genes in the Shikimate Pathway. Bacterial genes encoding feedback-insensitive variants of 3-Deoxy-D-Arabino-Heptulosonate 7-Phosphate Synthase (DAHPS; AroG 209-9 ) and bi-functional Chorismate Mutase/Prephenate Dehydratase (CM/PDT; PheA 12 ) were expressed under the control of a fruit-specific promoter. We crossed these transgenes to generate tomato plants expressing both the AroG 209 and PheA 12 genes. Overexpression of the AroG 209-9 gene had a dramatic effect on the overall metabolic profile of the fruit, including enhanced levels of multiple volatile and non-volatile metabolites. In contrast, the PheA 12 overexpression line exhibited minor metabolic effects compared to the wild type fruit. Co-expression of both the AroG 209-9 and PheA 12 genes in tomato resulted overall in a similar metabolic effect to that of expressing only the AroG 209-9 gene. However, the aroma ranking attributes of the tomato fruits from PheA 12 //AroG 209-9 were unique and different from those of the lines expressing a single gene, suggesting a contribution of the PheA 12 gene to the overall metabolic profile. We suggest that expression of bacterial genes encoding feedback-insensitive enzymes of the Shikimate Pathway in tomato fruits provides a useful metabolic engineering tool for the modification of fruits aroma and the generation of new combinations of tomato flavors.
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tomato fruits expressing a bacterial feedback insensitive 3 deoxy d arabino heptulosonate 7 phosphate synthase of the Shikimate Pathway possess enhanced levels of multiple specialized metabolites and upgraded aroma
Journal of Experimental Botany, 2013Co-Authors: Vered Tzin, Asaph Aharoni, Michal Moyal Ben Zvi, Ilana Rogachev, Sagit Meir, Tania Masci, Alexander Vainstein, Gad GaliliAbstract:Tomato (Solanum lycopersicum) fruit contains significant amounts of bioactive compounds, particularly multiple classes of specialized metabolites. Enhancing the synthesis and accumulation of these substances, specifically in fruits, are central for improving tomato fruit quality (e.g. flavour and aroma) and could aid in elucidate Pathways of specialized metabolism. To promote the production of specialized metabolites in tomato fruit, this work expressed under a fruit ripening-specific promoter, E8, a bacterial AroG gene encoding a 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS), which is feedback-insensitive to phenylalanine inhibition. DAHPS, the first enzyme of the Shikimate Pathway, links between the primary and specialized metabolism derived from aromatic amino acids. AroG expression influenced the levels of number of primary metabolites, such as shikimic acid and aromatic amino acids, as well as multiple volatile and non-volatile phenylpropanoids specialized metabolites and carotenoids. An organoleptic test, performed by trained panellists, suggested that the ripe AroG-expressing tomato fruits had a preferred floral aroma compare with fruits of the wild-type line. These results imply that fruit-specific manipulation of the conversion of primary to specialized metabolism is an attractive approach for improving fruit aroma and flavour qualities as well as discovering novel fruit-specialized metabolites.
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Shikimate Pathway and aromatic amino acid biosynthesis
eLS, 2012Co-Authors: Vered Tzin, Gad Galili, Asaph AharoniAbstract:The Shikimate Pathway consists of seven enzymatic reactions whose end product chorismate is the precursor for the synthesis of the aromatic amino acids Phe, Tyr and Trp. In fungi and plants, chorismate is a precursor for many specialised metabolites (i.e. secondary metabolites) that play an important role in the plant's interaction with its environment. The Shikimate Pathway and aromatic amino acid biosynthesis have been extensively studied in a variety of microorganisms, fungi and plants. Furthermore, the dual involvement of the Shikimate and aromatic amino acid biosynthesis Pathways in central and specialised metabolism still raises major questions regarding the genes and enzymes involved, and their control, their evolutionary origins and coordinated regulation with genes of associated Pathways in response to altered environmental conditions and diverse developmental programs. Key Concepts: The Shikimate Pathway is the only known Pathway for biosynthesis of chorismate and the aromatic amino acids Phe, Tyr and Trp. The Shikimate Pathway is a bridge between central metabolism and specialised metabolism. The Shikimate Pathway occurs in various groups of microorganisms, plants and parasites, whereas it does not occur in animals. The Pathway enzymes are being targeted for antimicrobial drug and herbicide design. Shikimic acid is an essential metabolite that may balance the metabolic status of the Pathway. Chorismate is a branch point metabolite for aromatic amino acids and phenolic compounds. This is an ancient eukaryotic Pathway which has been subject to diverse evolutionary processes. Several enzymes from these Pathways are allosterically regulated by their end products: Phe, Tyr or Trp. The Shikimate Pathway and aromatic amino acids, and the specialised metabolites derived from them, simultaneously respond to rhythmic changes. Keywords: Shikimate; chorismate; phenylalanine; tyrosine; tryptophan; central metabolism; specialised metabolites; secondary metabolites
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expression of a bacterial feedback insensitive 3 deoxy d arabino heptulosonate 7 phosphate synthase of the Shikimate Pathway in arabidopsis elucidates potential metabolic bottlenecks between primary and secondary metabolism
New Phytologist, 2012Co-Authors: Vered Tzin, Asaph Aharoni, Sergey Malitsky, Michal Moyal Ben Zvi, Mohamed Bedair, Lloyd W Sumner, Gad GaliliAbstract:Summary •The Shikimate Pathway of plants mediates the conversion of primary carbon metabolites via chorismate into the three aromatic amino acids and to numerous secondary metabolites derived from them. However, the regulation of the Shikimate Pathway is still far from being understood. We hypothesized that 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS) is a key enzyme regulating flux through the Shikimate Pathway. •To test this hypothesis, we expressed a mutant bacterial AroG gene encoding a feedback-insensitive DAHPS in transgenic Arabidopsis plants. The plants were subjected to detailed analysis of primary metabolism, using GC-MS, as well as secondary metabolism, using LC-MS. •Our results exposed a major effect of bacterial AroG expression on the levels of Shikimate intermediate metabolites, phenylalanine, tryptophan and broad classes of secondary metabolite, such as phenylpropanoids, glucosinolates, auxin and other hormone conjugates. •We propose that DAHPS is a key regulatory enzyme of the Shikimate Pathway. Moreover, our results shed light on additional potential metabolic bottlenecks bridging plant primary and secondary metabolism.
Geoffrey B Jameson - One of the best experts on this subject based on the ideXlab platform.
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a pseudoisostructural type ii dah7ps enzyme from pseudomonas aeruginosa alternative evolutionary strategies to control Shikimate Pathway flux
Biochemistry, 2018Co-Authors: Oliver W Sterritt, Sarah A Kessans, Geoffrey B Jameson, Emily J ParkerAbstract:The Shikimate Pathway is responsible for the biosynthesis of key aromatic metabolites in microorganisms and plants. The enzyme 3-deoxy-d- arabino-heptulosonate 7-phosphate synthase (DAH7PS) catalyzes the first step of the Pathway and DAH7PSs are classified as either type I or type II. The DAH7PSs from Pseudomonas aeruginosa are of particular interest as open reading frames encoding four putative DAH7PS isoenzymes, two classified as type Iα and two classified as type II, have been identified. Here, the structure of a type II DAH7PS enzyme from P. aeruginosa (PAO1) has been determined at 1.54 A resolution, in complex with its allosteric inhibitor tryptophan. Structural differences in the extra-barrel elements, when compared to other type II DAH7PS enzymes, directly relate to the formation of a distinct quaternary conformation with consequences for allosteric function and the control of flux to branching Pathways. In contrast to the well-characterized Mycobacterium tuberculosis type II DAH7PS, which binds multiple allosteric inhibitors, this PaeDAH7PSPA2843 is observed to be modestly allosterically inhibited by a single aromatic amino acid, tryptophan. In addition, structures in complex with tyrosine or with no allosteric ligand bound were determined. These structures provide new insights into the linkages between the active and allosteric sites. With four putative DAH7PS enzymes, P. aeruginosa appears to have evolved control of Shikimate Pathway flux at the genetic level, rather than control by multiple allosteric effectors to a single type II DAH7PS, as in M. tuberculosis. Type II DAH7PSs, thus, appear to have a more varied evolutionary trajectory than previously indicated.
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A Pseudoisostructural Type II DAH7PS Enzyme from Pseudomonas aeruginosa: Alternative Evolutionary Strategies to Control Shikimate Pathway Flux
2018Co-Authors: Oliver W Sterritt, Sarah A Kessans, Geoffrey B Jameson, Emily J ParkerAbstract:The Shikimate Pathway is responsible for the biosynthesis of key aromatic metabolites in microorganisms and plants. The enzyme 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAH7PS) catalyzes the first step of the Pathway and DAH7PSs are classified as either type I or type II. The DAH7PSs from Pseudomonas aeruginosa are of particular interest as open reading frames encoding four putative DAH7PS isoenzymes, two classified as type Iα and two classified as type II, have been identified. Here, the structure of a type II DAH7PS enzyme from P. aeruginosa (PAO1) has been determined at 1.54 Å resolution, in complex with its allosteric inhibitor tryptophan. Structural differences in the extra-barrel elements, when compared to other type II DAH7PS enzymes, directly relate to the formation of a distinct quaternary conformation with consequences for allosteric function and the control of flux to branching Pathways. In contrast to the well-characterized Mycobacterium tuberculosis type II DAH7PS, which binds multiple allosteric inhibitors, this PaeDAH7PSPA2843 is observed to be modestly allosterically inhibited by a single aromatic amino acid, tryptophan. In addition, structures in complex with tyrosine or with no allosteric ligand bound were determined. These structures provide new insights into the linkages between the active and allosteric sites. With four putative DAH7PS enzymes, P. aeruginosa appears to have evolved control of Shikimate Pathway flux at the genetic level, rather than control by multiple allosteric effectors to a single type II DAH7PS, as in M. tuberculosis. Type II DAH7PSs, thus, appear to have a more varied evolutionary trajectory than previously indicated
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investigating the role of the hydroxyl groups of substrate erythrose 4 phosphate in the reaction catalysed by the first enzyme of the Shikimate Pathway
Bioorganic & Medicinal Chemistry Letters, 2011Co-Authors: David Tran, Geoffrey B Jameson, Amy L Pietersma, Linley R Schofield, Matthias Rost, Emily J ParkerAbstract:3-Deoxy-D-arabino-heptulosonate 7-phosphate (DAH7P) synthase catalyses the first step of the Shikimate Pathway, which is responsible for the biosynthesis of aromatic amino acids in microorganisms and plants. This enzyme catalyses an aldol reaction between phosphoenolpyruvate and D-erythrose 4-phosphate to generate DAH7P. Both 2-deoxyerythrose 4-phosphate and 3-deoxyerythrose 4-phosphate were synthesised and tested as alternative substrates for the enzyme. Both compounds were found to be substrates for the DAH7P synthases from Escherichia coli, Pyrococcus furiosus and Mycobacterium tuberculosis, consistent with an acyclic mechanism for the enzyme for which neither C2 nor C3 hydroxyl groups are required for catalysis. The enzymes all showed greater tolerance for the loss of the C2 hydroxyl group than the C3 hydroxyl group.