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Buddy Ullman - One of the best experts on this subject based on the ideXlab platform.
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a role for adenine nucleotides in the sensing mechanism to purine starvation in leishmania donovani
Molecular Microbiology, 2016Co-Authors: Jessica L Martin, Phillip A Yates, Buddy Ullman, Jan M. Boitz, Dennis R Koop, Audrey L Fulwiler, Maria Belen Cassera, Nicola S. CarterAbstract:Purine salvage by Leishmania is an obligatory nutritional process that impacts both cell viability and growth. Previously, we have demonstrated that the removal of Purines in culture provokes significant metabolic changes that enable Leishmania to survive prolonged periods of purine starvation. In order to understand how Leishmania sense and respond to changes in their purine environment, we have exploited several purine pathway mutants, some in which adenine and guanine nucleotide metabolism is uncoupled. While wild type parasites grow in any one of a variety of naturally occurring Purines, the proliferation of these purine pathway mutants requires specific types or combinations of exogenous Purines. By culturing purine pathway mutants in high levels of extracellular Purines that are either permissive or non-permissive for growth and monitoring for previously defined markers of the adaptive response to purine starvation, we determined that adaptation arises from a surveillance of intracellular purine nucleotide pools rather than from a direct sensing of the extracellular purine content of the environment. Specifically, our data suggest that perturbation of intracellular adenine-containing nucleotide pools provides a crucial signal for inducing the metabolic changes necessary for the long-term survival of Leishmania in a purine-scarce environment.
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a role for adenine nucleotides in the sensing mechanism to purine starvation in leishmania donovani
Molecular Microbiology, 2016Co-Authors: Jessica L Martin, Phillip A Yates, Buddy Ullman, Jan M. Boitz, Dennis R Koop, Audrey L Fulwiler, Maria Belen Cassera, Nicola S. CarterAbstract:Summary Purine salvage by Leishmania is an obligatory nutritional process that impacts both cell viability and growth. Previously, we have demonstrated that the removal of Purines in culture provokes significant metabolic changes that enable Leishmania to survive prolonged periods of purine starvation. In order to understand how Leishmania sense and respond to changes in their purine environment, we have exploited several purine pathway mutants, some in which adenine and guanine nucleotide metabolism is uncoupled. While wild type parasites grow in any one of a variety of naturally occurring Purines, the proliferation of these purine pathway mutants requires specific types or combinations of exogenous Purines. By culturing purine pathway mutants in high levels of extracellular Purines that are either permissive or non-permissive for growth and monitoring for previously defined markers of the adaptive response to purine starvation, we determined that adaptation arises from a surveillance of intracellular purine nucleotide pools rather than from a direct sensing of the extracellular purine content of the environment. Specifically, our data suggest that perturbation of intracellular adenine-containing nucleotide pools provides a crucial signal for inducing the metabolic changes necessary for the long-term survival of Leishmania in a purine-scarce environment. This article is protected by copyright. All rights reserved.
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sequence and biochemical characterization of equilibrative nucleoside transporters from crithidia fasciculata seeking ligand binding residues
The FASEB Journal, 2010Co-Authors: Cassandra S. Arendt, Stephen M Beverley, Buddy UllmanAbstract:Eukaryotic cells acquire Purines via de novo synthesis or salvage mechanisms. Unlike human cells, protozoan parasites from the Apicomplexan and Trypanosomatid lineages such as Plasmodium, Toxoplasma, Leishmania, Trypanosoma and Crithidia species lack de novo purine synthesis enzymes, and therefore rely on salvage of pre-formed purine bases for growth and proliferation, making purine salvage an attractive drug target in these organisms. A key step in purine salvage is transport of purine nucleobases and nucleosides into the cell, and each species encodes a unique repertoire of transporter proteins from the equilibrative nucleoside transporter (ENT) family, each with its own ligand preference. ENT proteins have 11 transmembrane domains (TMs; see the figure), and residues that affect ligand specificity in a number of different ENTs have been identified in TMs 1, 2, 4 and 5 (see [1]).
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Purine and pyrimidine metabolism in Leishmania.
Advances in Experimental Medicine and Biology, 2008Co-Authors: Nicola S. Carter, Phillip A Yates, Jan M. Boitz, Cassandra S. Arendt, Buddy UllmanAbstract:Purines and pyrimidines are indispensable to all life, performing many vital functions for cells: ATP serves as the universal currency of cellular energy, cAMP and cGMP are key second messenger molecules, purine and pyrimidine nucleotides are precursors for activated forms of both carbohydrates and lipids, nucleotide derivatives of vitamins are essential cofactors in metabolic processes, and nucleoside triphosphates are the immediate precursors for DNA and RNA synthesis. Unlike their mammalian and insect hosts, Leishmania lack the metabolic machinery to make purine nudeotides de novo and must rely on their host for preformed Purines. The obligatory nature of purine salvage offers, therefore, a plethora of potential targets for drug targeting, and the pathway has consequently been the focus of considerable scientific investigation. In contrast, Leishmania are prototrophic for pyrimidines and also express a small complement of pyrimidine salvage enzymes. Because the pyrimidine nucleotide biosynthetic pathways of Leishmania and humans are similar, pyrimidine metabolism in Leishmania has generally been considered less amenable to therapeutic manipulation than the purine salvage pathway. However, evidence garnered from a variety of parasitic protozoa suggests that the selective inhibition of pyrimidine biosynthetic enzymes offers a rational therapeutic paradigm. In this chapter, we present an overview of the purine and pyrimidine pathways in Leishmania, make comparisons to the equivalent pathways in their mammalian host, and explore how these pathways might be amenable to selective therapeutic targeting.
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a conditional mutant deficient in hypoxanthine guanine phosphoribosyltransferase and xanthine phosphoribosyltransferase validates the purine salvage pathway of leishmania donovani
Journal of Biological Chemistry, 2006Co-Authors: Jan M. Boitz, Buddy UllmanAbstract:Leishmania donovani cannot synthesize Purines de novo and express a multiplicity of enzymes that enable them to salvage Purines from their hosts. Previous efforts to generate an L. donovani strain deficient in both hypoxanthine-guanine phosphoribosyl-transferase (HGPRT) and xanthine phosphoribosyltransferase (XPRT) using gene replacement approaches were not successful, lending indirect support to the hypothesis that either HGPRT or XPRT is crucial for purine salvage by the parasite. We now report the genetic confirmation of this hypothesis through the construction of a conditional delta hgprt/delta xprt mutant strain that exhibits an absolute requirement for 2'-deoxycoformycin, an inhibitor of the leishmanial adenine aminohydrolase enzyme, and either adenine or adenosine as a source of purine. Unlike wild type parasites, the delta hgprt/delta xprt strain cannot proliferate indefinitely without 2'-deoxycoformycin or with hypoxanthine, guanine, xanthine, guanosine, inosine, or xanthosine as the sole purine nutrient. The delta hgprt/delta xprt mutant infects murine bone marrow-derived macrophages <5% as effectively as wild type parasites and cannot sustain an infection. These data establish genetically that either HGPRT or XPRT is absolutely essential for purine acquisition, parasite viability, and parasite infectivity of mouse macrophages, that all exogenous Purines are funneled to hypoxanthine and/or xanthine by L. donovani, and that the purine sources within the macrophage to which the parasites have access are HGPRT or XPRT substrates.
Jan M. Boitz - One of the best experts on this subject based on the ideXlab platform.
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a role for adenine nucleotides in the sensing mechanism to purine starvation in leishmania donovani
Molecular Microbiology, 2016Co-Authors: Jessica L Martin, Phillip A Yates, Buddy Ullman, Jan M. Boitz, Dennis R Koop, Audrey L Fulwiler, Maria Belen Cassera, Nicola S. CarterAbstract:Purine salvage by Leishmania is an obligatory nutritional process that impacts both cell viability and growth. Previously, we have demonstrated that the removal of Purines in culture provokes significant metabolic changes that enable Leishmania to survive prolonged periods of purine starvation. In order to understand how Leishmania sense and respond to changes in their purine environment, we have exploited several purine pathway mutants, some in which adenine and guanine nucleotide metabolism is uncoupled. While wild type parasites grow in any one of a variety of naturally occurring Purines, the proliferation of these purine pathway mutants requires specific types or combinations of exogenous Purines. By culturing purine pathway mutants in high levels of extracellular Purines that are either permissive or non-permissive for growth and monitoring for previously defined markers of the adaptive response to purine starvation, we determined that adaptation arises from a surveillance of intracellular purine nucleotide pools rather than from a direct sensing of the extracellular purine content of the environment. Specifically, our data suggest that perturbation of intracellular adenine-containing nucleotide pools provides a crucial signal for inducing the metabolic changes necessary for the long-term survival of Leishmania in a purine-scarce environment.
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a role for adenine nucleotides in the sensing mechanism to purine starvation in leishmania donovani
Molecular Microbiology, 2016Co-Authors: Jessica L Martin, Phillip A Yates, Buddy Ullman, Jan M. Boitz, Dennis R Koop, Audrey L Fulwiler, Maria Belen Cassera, Nicola S. CarterAbstract:Summary Purine salvage by Leishmania is an obligatory nutritional process that impacts both cell viability and growth. Previously, we have demonstrated that the removal of Purines in culture provokes significant metabolic changes that enable Leishmania to survive prolonged periods of purine starvation. In order to understand how Leishmania sense and respond to changes in their purine environment, we have exploited several purine pathway mutants, some in which adenine and guanine nucleotide metabolism is uncoupled. While wild type parasites grow in any one of a variety of naturally occurring Purines, the proliferation of these purine pathway mutants requires specific types or combinations of exogenous Purines. By culturing purine pathway mutants in high levels of extracellular Purines that are either permissive or non-permissive for growth and monitoring for previously defined markers of the adaptive response to purine starvation, we determined that adaptation arises from a surveillance of intracellular purine nucleotide pools rather than from a direct sensing of the extracellular purine content of the environment. Specifically, our data suggest that perturbation of intracellular adenine-containing nucleotide pools provides a crucial signal for inducing the metabolic changes necessary for the long-term survival of Leishmania in a purine-scarce environment. This article is protected by copyright. All rights reserved.
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Purine and pyrimidine metabolism in Leishmania.
Advances in Experimental Medicine and Biology, 2008Co-Authors: Nicola S. Carter, Phillip A Yates, Jan M. Boitz, Cassandra S. Arendt, Buddy UllmanAbstract:Purines and pyrimidines are indispensable to all life, performing many vital functions for cells: ATP serves as the universal currency of cellular energy, cAMP and cGMP are key second messenger molecules, purine and pyrimidine nucleotides are precursors for activated forms of both carbohydrates and lipids, nucleotide derivatives of vitamins are essential cofactors in metabolic processes, and nucleoside triphosphates are the immediate precursors for DNA and RNA synthesis. Unlike their mammalian and insect hosts, Leishmania lack the metabolic machinery to make purine nudeotides de novo and must rely on their host for preformed Purines. The obligatory nature of purine salvage offers, therefore, a plethora of potential targets for drug targeting, and the pathway has consequently been the focus of considerable scientific investigation. In contrast, Leishmania are prototrophic for pyrimidines and also express a small complement of pyrimidine salvage enzymes. Because the pyrimidine nucleotide biosynthetic pathways of Leishmania and humans are similar, pyrimidine metabolism in Leishmania has generally been considered less amenable to therapeutic manipulation than the purine salvage pathway. However, evidence garnered from a variety of parasitic protozoa suggests that the selective inhibition of pyrimidine biosynthetic enzymes offers a rational therapeutic paradigm. In this chapter, we present an overview of the purine and pyrimidine pathways in Leishmania, make comparisons to the equivalent pathways in their mammalian host, and explore how these pathways might be amenable to selective therapeutic targeting.
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a conditional mutant deficient in hypoxanthine guanine phosphoribosyltransferase and xanthine phosphoribosyltransferase validates the purine salvage pathway of leishmania donovani
Journal of Biological Chemistry, 2006Co-Authors: Jan M. Boitz, Buddy UllmanAbstract:Leishmania donovani cannot synthesize Purines de novo and express a multiplicity of enzymes that enable them to salvage Purines from their hosts. Previous efforts to generate an L. donovani strain deficient in both hypoxanthine-guanine phosphoribosyl-transferase (HGPRT) and xanthine phosphoribosyltransferase (XPRT) using gene replacement approaches were not successful, lending indirect support to the hypothesis that either HGPRT or XPRT is crucial for purine salvage by the parasite. We now report the genetic confirmation of this hypothesis through the construction of a conditional delta hgprt/delta xprt mutant strain that exhibits an absolute requirement for 2'-deoxycoformycin, an inhibitor of the leishmanial adenine aminohydrolase enzyme, and either adenine or adenosine as a source of purine. Unlike wild type parasites, the delta hgprt/delta xprt strain cannot proliferate indefinitely without 2'-deoxycoformycin or with hypoxanthine, guanine, xanthine, guanosine, inosine, or xanthosine as the sole purine nutrient. The delta hgprt/delta xprt mutant infects murine bone marrow-derived macrophages <5% as effectively as wild type parasites and cannot sustain an infection. These data establish genetically that either HGPRT or XPRT is absolutely essential for purine acquisition, parasite viability, and parasite infectivity of mouse macrophages, that all exogenous Purines are funneled to hypoxanthine and/or xanthine by L. donovani, and that the purine sources within the macrophage to which the parasites have access are HGPRT or XPRT substrates.
Michal Hocek - One of the best experts on this subject based on the ideXlab platform.
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direct c h sulfenylation of Purines and deazaPurines
ChemInform, 2013Co-Authors: Michal Hocek, Radek Pohl, Martin Klecka, Jan CejkaAbstract:In Purines (VI), the title reaction proceeds selectively in position 8, in 7-deazaPurines (I) in position 7, and in 9-deazaPurines (IV) in position 9, leading to novel arylsulfanyl derivatives of purine or deazapurine bases.
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direct c h sulfenylation of Purines and deazaPurines
Organic and Biomolecular Chemistry, 2013Co-Authors: Michal Hocek, Radek Pohl, Martin Klecka, Jan CejkaAbstract:A general method for Cu-catalyzed C–H sulfenylation of Purines, 7-deaza- and 9-deazaPurines with aryl- or alkyldisulfides has been developed. In Purines, the reaction occurs at position 8, in 7-deazaPurines at position 7 and in 9-deazaPurines at position 9, leading to new interesting arylsulfanyl derivatives of purine or deazapurine bases. The resulting 8-arylsulfanylPurines undergo Liebesking–Srogl coupling with arylstannanes or boronic acids, whereas the (arylsulfanyl)deazaPurines are not reactive under these conditions.
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SYNTHESIS OF (PURIN-6-YL)ACETATES AND THEIR TRANSFORMATIONS TO 6-(2-HYDROXYETHYL)- AND 6-(CARBAMOYLMETHYL)Purines
2009Co-Authors: Zbyněk Hasník, Radek Pohl, Blanka Klepetářová, Michal HocekAbstract:Dedicated to Dr. Alfred Bader for his generous support of chemical research and education. A novel approach to the synthesis of (purin-6-yl)acetates was developed based on Pd-catalyzed cross-coupling reactions of 6-chloroPurines with a Reformatsky reagent. Their reduction with NaBH4 and treatment with MnO2 gave 6-(2-hydroxyethyl)Purines, while re-actions with amines in presence of NaCN afforded 6-(carbamoylmethyl)Purines. Mesylation of the 6-(2-hydroxyethyl)Purines followed by nucleophilic substitutions gave rise to several 6-(2-substituted ethyl)Purines. This methodology was successfully applied to the synthesis of substituted purine bases and nucleosides for cytostatic and antiviral activity screening. None of the compounds exerted significant activity
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synthesis of 2 substituted 6 hydroxymethyl purine bases and nucleosides
Collection of Czechoslovak Chemical Communications, 2005Co-Authors: Peter Silhar, Ivan Votruba, Radek Pohl, Michal HocekAbstract:A facile and efficient methodology of the synthesis of 6-(hydroxymethyl)purine derivatives (bases and nucleosides) was developed based on Pd-catalyzed cross-coupling reactions of 6-haloPurines or N -protected 2-amino-6-haloPurines with (benzoyloxymethyl)zinc iodide followed by deprotection. Regioselective hydroxymethylations of 2,6-dihaloPurines were also studied and used for the synthesis of 2-chloro-6-(hydroxymethyl)- or 2,6-bis(hydroxymethyl)Purines. The 6-(hydroxymethyl)purine ribonucleoside 5f exerted high cytostatic effect and moderate inhibition of adenosine deaminase, while all the other derivatives were much less effective or entirely inactive.
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regioselectivity in cross coupling reactions of 2 6 8 trichloro 9 tetrahydropyran 2 yl purine synthesis of 2 6 8 trisubstituted purine bases
Synthesis, 2004Co-Authors: Michal Hocek, Radek PohlAbstract:The regioselectivity of cross-coupling reactions (Pd-catalyzed Suzuki-Miyaura reactions with phenylboronic acid and Fe-catalyzed reactions with methylmagnesium chloride) of 2,6,8-trichloro-9-(tetrahydropyran-2-yl)purine with varying amounts of the organometallic reagent was studied. In general, the regioselectivity of these reactions was quite low giving mixtures of isomers of mono-, di- and trisubstituted products. Nevertheless, 2,6-dichloro8-methyl-9-THP-purine (laab), 2-chloro-6,8-dimethyl-9-THP-purine (labb) and 2,8-dichloro-6-phenyl-9-THP-purine (laca) were isolated in acceptable yields and used as intermediates for further cross-coupling reactions giving a series of 2,6,8-trisubstituted 9-THP-Purines that were deprotected to the corresponding purine bases. Characteristic 1 3 C NMR shifts cf CH 3 or ipso-Ph carbons in different positions of the purine ring have been observed enabling rapid and facile identification of the particular isomer.
Nicola S. Carter - One of the best experts on this subject based on the ideXlab platform.
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a role for adenine nucleotides in the sensing mechanism to purine starvation in leishmania donovani
Molecular Microbiology, 2016Co-Authors: Jessica L Martin, Phillip A Yates, Buddy Ullman, Jan M. Boitz, Dennis R Koop, Audrey L Fulwiler, Maria Belen Cassera, Nicola S. CarterAbstract:Purine salvage by Leishmania is an obligatory nutritional process that impacts both cell viability and growth. Previously, we have demonstrated that the removal of Purines in culture provokes significant metabolic changes that enable Leishmania to survive prolonged periods of purine starvation. In order to understand how Leishmania sense and respond to changes in their purine environment, we have exploited several purine pathway mutants, some in which adenine and guanine nucleotide metabolism is uncoupled. While wild type parasites grow in any one of a variety of naturally occurring Purines, the proliferation of these purine pathway mutants requires specific types or combinations of exogenous Purines. By culturing purine pathway mutants in high levels of extracellular Purines that are either permissive or non-permissive for growth and monitoring for previously defined markers of the adaptive response to purine starvation, we determined that adaptation arises from a surveillance of intracellular purine nucleotide pools rather than from a direct sensing of the extracellular purine content of the environment. Specifically, our data suggest that perturbation of intracellular adenine-containing nucleotide pools provides a crucial signal for inducing the metabolic changes necessary for the long-term survival of Leishmania in a purine-scarce environment.
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a role for adenine nucleotides in the sensing mechanism to purine starvation in leishmania donovani
Molecular Microbiology, 2016Co-Authors: Jessica L Martin, Phillip A Yates, Buddy Ullman, Jan M. Boitz, Dennis R Koop, Audrey L Fulwiler, Maria Belen Cassera, Nicola S. CarterAbstract:Summary Purine salvage by Leishmania is an obligatory nutritional process that impacts both cell viability and growth. Previously, we have demonstrated that the removal of Purines in culture provokes significant metabolic changes that enable Leishmania to survive prolonged periods of purine starvation. In order to understand how Leishmania sense and respond to changes in their purine environment, we have exploited several purine pathway mutants, some in which adenine and guanine nucleotide metabolism is uncoupled. While wild type parasites grow in any one of a variety of naturally occurring Purines, the proliferation of these purine pathway mutants requires specific types or combinations of exogenous Purines. By culturing purine pathway mutants in high levels of extracellular Purines that are either permissive or non-permissive for growth and monitoring for previously defined markers of the adaptive response to purine starvation, we determined that adaptation arises from a surveillance of intracellular purine nucleotide pools rather than from a direct sensing of the extracellular purine content of the environment. Specifically, our data suggest that perturbation of intracellular adenine-containing nucleotide pools provides a crucial signal for inducing the metabolic changes necessary for the long-term survival of Leishmania in a purine-scarce environment. This article is protected by copyright. All rights reserved.
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Purine and pyrimidine metabolism in Leishmania.
Advances in Experimental Medicine and Biology, 2008Co-Authors: Nicola S. Carter, Phillip A Yates, Jan M. Boitz, Cassandra S. Arendt, Buddy UllmanAbstract:Purines and pyrimidines are indispensable to all life, performing many vital functions for cells: ATP serves as the universal currency of cellular energy, cAMP and cGMP are key second messenger molecules, purine and pyrimidine nucleotides are precursors for activated forms of both carbohydrates and lipids, nucleotide derivatives of vitamins are essential cofactors in metabolic processes, and nucleoside triphosphates are the immediate precursors for DNA and RNA synthesis. Unlike their mammalian and insect hosts, Leishmania lack the metabolic machinery to make purine nudeotides de novo and must rely on their host for preformed Purines. The obligatory nature of purine salvage offers, therefore, a plethora of potential targets for drug targeting, and the pathway has consequently been the focus of considerable scientific investigation. In contrast, Leishmania are prototrophic for pyrimidines and also express a small complement of pyrimidine salvage enzymes. Because the pyrimidine nucleotide biosynthetic pathways of Leishmania and humans are similar, pyrimidine metabolism in Leishmania has generally been considered less amenable to therapeutic manipulation than the purine salvage pathway. However, evidence garnered from a variety of parasitic protozoa suggests that the selective inhibition of pyrimidine biosynthetic enzymes offers a rational therapeutic paradigm. In this chapter, we present an overview of the purine and pyrimidine pathways in Leishmania, make comparisons to the equivalent pathways in their mammalian host, and explore how these pathways might be amenable to selective therapeutic targeting.
Stephen J. Benkovic - One of the best experts on this subject based on the ideXlab platform.
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mapping post translational modifications of de novo purine biosynthetic enzymes implications for pathway regulation
Journal of Proteome Research, 2019Co-Authors: Giselle M Knudsen, Anthony M Pedley, Jingxuan He, Jared L Johnson, Tomer M Yaron, Lewis C Cantley, Stephen J. BenkovicAbstract:Purines represent a class of essential metabolites produced by the cell to maintain cellular homeostasis and facilitate cell proliferation. In times of high purine demand, the de novo purine biosynthetic pathway is activated; however, the mechanisms that facilitate this process are largely unknown. One plausible mechanism is through intracellular signaling, which results in enzymes within the pathway becoming post-translationally modified to enhance their individual enzyme activities and the overall pathway metabolic flux. Here, we employ a proteomic strategy to investigate the extent to which de novo purine biosynthetic pathway enzymes are post-translationally modified in 293T cells. We identified 7 post-translational modifications on 135 residues across the 6 human pathway enzymes. We further asked whether there were differences in the post-translational modification state of each pathway enzyme isolated from cells cultured in the presence or absence of Purines. Of the 174 assigned modifications, 67% of them were only detected in one experimental growth condition in which a significant number of serine and threonine phosphorylations were noted. A survey of the most-probable kinases responsible for these phosphorylation events uncovered a likely AKT phosphorylation site at residue Thr397 of PPAT, which was only detected in cells under purine-supplemented growth conditions. These data suggest that this modification might alter enzyme activity or modulate its interaction(s) with downstream pathway enzymes. Together, these findings propose a role for post-translational modifications in pathway regulation and activation to meet intracellular purine demand.
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Mapping Post-Translational Modifications of de Novo Purine Biosynthetic Enzymes: Implications for Pathway Regulation
2019Co-Authors: Chunliang Liu, Giselle M Knudsen, Anthony M Pedley, Jared L Johnson, Tomer M Yaron, Lewis C Cantley, Stephen J. BenkovicAbstract:Purines represent a class of essential metabolites produced by the cell to maintain cellular homeostasis and facilitate cell proliferation. In times of high purine demand, the de novo purine biosynthetic pathway is activated; however, the mechanisms that facilitate this process are largely unknown. One plausible mechanism is through intracellular signaling, which results in enzymes within the pathway becoming post-translationally modified to enhance their individual enzyme activities and the overall pathway metabolic flux. Here, we employ a proteomic strategy to investigate the extent to which de novo purine biosynthetic pathway enzymes are post-translationally modified in 293T cells. We identified 7 post-translational modifications on 135 residues across the 6 human pathway enzymes. We further asked whether there were differences in the post-translational modification state of each pathway enzyme isolated from cells cultured in the presence or absence of Purines. Of the 174 assigned modifications, 67% of them were only detected in one experimental growth condition in which a significant number of serine and threonine phosphorylations were noted. A survey of the most-probable kinases responsible for these phosphorylation events uncovered a likely AKT phosphorylation site at residue Thr397 of PPAT, which was only detected in cells under purine-supplemented growth conditions. These data suggest that this modification might alter enzyme activity or modulate its interaction(s) with downstream pathway enzymes. Together, these findings propose a role for post-translational modifications in pathway regulation and activation to meet intracellular purine demand
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the purinosome a multi protein complex involved in the de novo biosynthesis of Purines in humans
ChemInform, 2013Co-Authors: Hong Zhao, Jarrod B French, Ye Fang, Stephen J. BenkovicAbstract:Purine nucleotides are ubiquitous molecules that play vital roles in all kingdoms of life, not only as components of nucleic acids, but also participating in signaling and energy storage. Cellular pools of Purines are maintained by the tight control of several complementary and sometimes competing processes including de novo biosynthesis, salvage and catabolism of nucleotides. While great strides have been made over the past sixty years in understanding the biosynthesis of Purines, we are experiencing a renaissance in this field. In this feature article we discuss the most recent discoveries relating to purine biosynthesis, with particular emphasis upon the dynamic multi-protein complex called the purinosome. In particular we highlight advances made towards understanding the assembly, control and function of this protein complex and the attempts made to exploit this knowledge for drug discovery.
