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Guy Herve - One of the best experts on this subject based on the ideXlab platform.
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Catabolism of Pyrimidine Nucleotides in the Deep-sea Tube WormRiftia pachyptila
The Journal of biological chemistry, 2001Co-Authors: Zoran Minic, Francoise Gaill, Styliani Pastra-landis, Guy HerveAbstract:The present study describes the distribution and properties of enzymes of the catabolic pathway of Pyrimidine Nucleotides in Riftia pachyptila, a tubeworm living around deep-sea hydrothermal vents and known to be involved in a highly specialized symbiotic association with a bacterium. The catabolic enzymes, 5'-nucleotidase, uridine phosphorylase, and uracil reductase, are present in all tissues of the worm, whereas none of these enzymatic activities were found in the symbiotic bacteria. The 5'-nucleotidase activity was particularly high in the trophosome, the symbiont-harboring tissue. These results suggest that the production of nucleosides in the trophosome may represent an alternative source of carbon and nitrogen for R. pachyptila, because these nucleosides can be delivered to other parts of the worm. This process would complement the source of carbon and nitrogen from organic metabolites provided by the bacterial assimilatory pathways. The localization of the enzymes participating in catabolism, 5'-nucleotidase and uridine phosphorylase, and of the enzymes involved in the biosynthesis of Pyrimidine Nucleotides, aspartate transcarbamylase and dihydroorotase, shows a non-homogeneous distribution of these enzymes in the trophosome. The catabolic enzymes 5'-nucleotidase and uridine phosphorylase activities increase from the center of the trophosome to its periphery. In contrast, the anabolic enzymes aspartate transcarbamylase and dihydroorotase activities decrease from the center toward the periphery of the trophosome. We propose a general scheme of anatomical and physiological organization of the metabolic pathways of the Pyrimidine Nucleotides in R. pachyptila and its bacterial endosymbiont.
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contribution of the bacterial endosymbiont to the biosynthesis of Pyrimidine Nucleotides in the deep sea tube worm riftia pachyptila
Journal of Biological Chemistry, 2001Co-Authors: Zoran Minic, Valerie Simon, Bernadette Penverne, Francoise Gaill, Guy HerveAbstract:Abstract The deep-sea tube worm Riftia pachyptila (Vestimentifera) from hydrothermal vents lives in an intimate symbiosis with a sulfur-oxidizing bacterium. That involves specific interactions and obligatory metabolic exchanges between the two organisms. In this work, we analyzed the contribution of the two partners to the biosynthesis of Pyrimidine Nucleotides through both the “de novo” and “salvage” pathways. The first three enzymes of the de novo pathway, carbamyl-phosphate synthetase, aspartate transcarbamylase, and dihydroorotase, were present only in the trophosome, the symbiont-containing tissue. The study of these enzymes in terms of their catalytic and regulatory properties in both the trophosome and the isolated symbiotic bacteria provided a clear indication of the microbial origin of these enzymes. In contrast, the succeeding enzymes of this de novo pathway, dihydroorotate dehydrogenase and orotate phosphoribosyltransferase, were present in all body parts of the worm. This finding indicates that the animal is fully dependent on the symbiont for the de novo biosynthesis of Pyrimidines. In addition, it suggests that the synthesis of Pyrimidines in other tissues is possible from the intermediary metabolites provided by the trophosomal tissue and from nucleic acid degradation products since the enzymes of the salvage pathway appear to be present in all tissues of the worm. Analysis of these salvage pathway enzymes in the trophosome strongly suggested that these enzymes belong to the worm. In accordance with this conclusion, none of these enzyme activities was found in the isolated bacteria. The enzymes involved in the production of the precursors of carbamyl phosphate and nitrogen assimilation, glutamine synthetase and nitrate reductase, were also investigated, and it appears that these two enzymes are present in the bacteria.
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the enzymes involved in synthesis and utilization of carbamylphosphate in the deep sea tube worm riftia pachyptila
Marine Biology, 2000Co-Authors: Valerie Simon, Francoise Gaill, Cristina Purcarea, K Sun, J Joseph, Ghislaine Frebourg, Jeanpierre Lechaire, Guy HerveAbstract:The obligate symbiosis of the deep-sea tube worm Riftia pachyptila with a sulphur-oxidizing bacterium raises important questions concerning its metabolism and metabolic exchanges. In this study, the presence and properties of the enzymes synthesizing and utilizing carbamylphosphate in the arginine and Pyrimidine nucleotide pathways were investigated in this worm. The results show that the ammonium-dependent carbamylphosphate synthetase and ornithine transcarbamylase, enzymes involved in the arginine pathway, are present in all body parts of the worm. In contrast, the glutamine-dependent carbamylphosphate synthetase and aspartate transcarbamylase, enzymes involved in the de novo pathway for Pyrimidine Nucleotides biosynthesis, are present only in the trophosome, the symbiont-harbouring tissue. Although the bacterial nature of these enzymes is not unambigously established, these results strongly suggest that the de novo biosynthesis of Pyrimidine Nucleotides is limited to the trophosome, the organ where the production of metabolic energy takes place, while the other parts of the worm's body rely on the salvage pathway for the production of the Pyrimidine triphosphate Nucleotides.
Roland Seifert - One of the best experts on this subject based on the ideXlab platform.
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Analysis of substrate specificity and kinetics of cyclic nucleotide phosphodiesterases with N'-methylanthraniloyl-substituted purine and Pyrimidine 3',5'-cyclic Nucleotides by fluorescence spectrometry.
PLOS ONE, 2013Co-Authors: Daniel Reinecke, Frank Schwede, Hans-gottfried Genieser, Roland SeifertAbstract:As second messengers, the cyclic purine Nucleotides adenosine 3′,5′-cyclic monophosphate (cAMP) and guanosine 3′,5′-cyclic monophosphate (cGMP) play an essential role in intracellular signaling. Recent data suggest that the cyclic Pyrimidine Nucleotides cytidine 3′,5′-cyclic monophosphate (cCMP) and uridine 3′,5′-cyclic monophosphate (cUMP) also act as second messengers. Hydrolysis by phosphodiesterases (PDEs) is the most important degradation mechanism for cAMP and cGMP. Elimination of cUMP and cCMP is not completely understood, though. We have shown that human PDEs hydrolyze not only cAMP and cGMP but also cyclic Pyrimidine Nucleotides, indicating that these enzymes may be important for termination of cCMP- and cUMP effects as well. However, these findings were acquired using a rather expensive HPLC/mass spectrometry assay, the technical requirements of which are available only to few laboratories. N’-Methylanthraniloyl-(MANT-)labeled Nucleotides are endogenously fluorescent and suitable tools to study diverse protein/nucleotide interactions. In the present study, we report the synthesis of new MANT-substituted cyclic purine- and Pyrimidine Nucleotides that are appropriate to analyze substrate specificity and kinetics of PDEs with more moderate technical requirements. MANT-labeled nucleoside 3′,5′-cyclic monophosphates (MANT-cNMPs) are shown to be substrates of various human PDEs and to undergo a significant change in fluorescence upon cleavage, thus allowing direct, quantitative and continuous determination of hydrolysis via fluorescence detection. As substrates of several PDEs, MANT-cNMPs show similar kinetics to native Nucleotides, with some exceptions. Finally, they are shown to be also appropriate tools for PDE inhibitor studies.
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differential activation of camp and cgmp dependent protein kinases by cyclic purine and Pyrimidine Nucleotides
Biochemical and Biophysical Research Communications, 2011Co-Authors: Sabine Wolter, Marina Golombek, Roland SeifertAbstract:Abstract The cyclic purine Nucleotides cAMP and cGMP are well-characterized second messengers and activators of PKA and PKG, respectively. In contrast, the functions of the cyclic Pyrimidine Nucleotides cCMP and cUMP are poorly understood. cCMP induces relaxation of smooth muscle via PKGI, and phosphodiesterases differentially hydrolyze cNMPs. Here, we report that cNMPs differentially activate PKA isoforms and PKGIα. The combination of cCMP with cAMP reduced the EC 50 of cAMP for PKA. PKGIα exhibited higher specificity for the cognate cNMP than PKA. Our data support a role of cCMP and cUMP as second messengers.
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interaction of the diguanylate cyclase ydeh of escherichia coli with 2 3 substituted purine and Pyrimidine Nucleotides
Journal of Pharmacology and Experimental Therapeutics, 2011Co-Authors: Christian Spangler, Volkhard Kaever, Roland SeifertAbstract:Di-guanylate cyclases (DGCs) synthesize the bacterial second messenger cyclic di-guanosine monophosphate (c-di-GMP) which is degraded by specific phosphodiesterases (PDEs). c-di-GMP levels control the transition of bacteria from a motile to a biofilm-forming lifestyle. These bacterial communities are highly resistant to antibiotic treatment and represent the predominant lifestyle in most chronic infections. Hence, DGCs serve as starting-point for the development of novel therapeutics interfering with the second messenger signaling network in bacteria. In previous studies we showed that 29,39-O-(N-methylanthraniloyl) (MANT)- and 29,39-O-(2,4,6-trinitrophenyl) (TNP)-substituted Nucleotides are potent adenylyl and guanylyl cyclase inhibitors. The catalytic domain of DGCs is homologous to the mammalian adenylyl cyclase catalytic domain. Therefore, we investigated the interaction of various MANT purine and Pyrimidine Nucleotides with the model DGC YdeH from Escherichia coli. We observed strong fluorescence resonance energy transfer (FRET) between tryptophan and tyrosine residues of YdeH and the MANT-group of MANT-NTPs (MANT-ATP, -CTP, -GTP, -ITP, -UTP, and -XTP) and an enhanced direct MANT fluorescence upon interaction with YdeH. We assessed the affinity of MANT-NTPs to YdeH by performing competition assays with NTPs. We conducted an amino acid alignment of YdeH with the earlier crystallized Caulobacter crescentus DGC pleD and found high similarities in the nucleotide binding site of pleD. In vitro mass-spectrometric activity assays with YdeH resulted in the identification of new MANT/TNP nucleotide-based inhibitors of DGC activity. Collectively, the analysis of interactions between MANT/TNP Nucleotides and YdeH provided a new basis for the identification and development of DGC inhibitors and allows insights into nucleotide-protein interactions
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interaction of the diguanylate cyclase ydeh of escherichia coli with 2 3 substituted purine and Pyrimidine Nucleotides
Journal of Pharmacology and Experimental Therapeutics, 2011Co-Authors: Christian Spangler, Volkhard Kaever, Roland SeifertAbstract:Diguanylate cyclases (DGCs) synthesize the bacterial second messenger cyclic 3',5'-diguanosine monophosphate (c-di-GMP), which is degraded by specific phosphodiesterases. c-di-GMP levels control the transition of bacteria from a motile to a biofilm-forming lifestyle. These bacterial communities are highly resistant to antibiotic treatment and represent the predominant lifestyle in most chronic infections. Hence, DGCs serve as starting point for the development of novel therapeutics interfering with the second messenger-signaling network in bacteria. In previous studies, we showed that 2'(3')-O-(N-methylanthraniloyl) (MANT)- and 2',3'-O-(2,4,6-trinitrophenyl) (TNP)-substituted Nucleotides are potent adenylyl and guanylyl cyclase inhibitors. The catalytic domain of DGCs is homologous to the mammalian adenylyl cyclase catalytic domain. Therefore, we investigated the interaction of various MANT purine and Pyrimidine Nucleotides with the model DGC YdeH from Escherichia coli. We observed strong fluorescence resonance energy transfer between tryptophan and tyrosine residues of YdeH and the MANT group of MANT-NTPs (MANT-ATP, -CTP, -GTP, -ITP, -UTP, and -XTP) and an enhanced direct MANT fluorescence upon interaction with YdeH. We assessed the affinity of MANT-NTPs to YdeH by performing competition assays with NTPs. We conducted an amino acid alignment of YdeH with the earlier crystallized Caulobacter crescentus DGC PleD and found high similarities in the nucleotide-binding site of PleD. In vitro mass-spectrometric activity assays with YdeH resulted in the identification of new MANT/TNP nucleotide-based inhibitors of DGC activity. Together, the analysis of interactions between MANT/TNP Nucleotides and YdeH provides a new basis for the identification and development of DGC inhibitors and allows insights into nucleotide-protein interactions.
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differential inhibition of adenylyl cyclase isoforms and soluble guanylyl cyclase by purine and Pyrimidine Nucleotides
Journal of Biological Chemistry, 2004Co-Authors: Andreas Gille, Gerald H Lushington, Michael B Doughty, Roger A Johnson, Roland SeifertAbstract:Abstract Mammals express nine membranous adenylyl cyclase isoforms (ACs 1–9), a structurally related soluble guanylyl cyclase (sGC) and a soluble AC (sAC). Moreover, Bacillus anthracis and Bacillus pertussis produce the AC toxins, edema factor (EF), and adenylyl cyclase toxin (ACT), respectively. 2′(3′)-O-(N-methylanthraniloyl)-guanosine 5′-[γ-thio]triphosphate is a potent competitive inhibitor of AC in S49 lymphoma cell membranes. These data prompted us to study systematically the effects of 24 Nucleotides on AC in S49 and Sf9 insect cell membranes, ACs 1, 2, 5, and 6, expressed in Sf9 membranes and purified catalytic subunits of membranous ACs (C1 of AC5 and C2 of AC2), sAC, sGC, EF, and ACT in the presence of MnCl2. N-Methylanthraniloyl (MANT)-GTP inhibited C1·C2 with a Ki of 4.2 nm. Phe-889 and Ile-940 of C2 mediate hydrophobic interactions with the MANT group. MANT-inosine 5′-[γ-thio]triphosphate potently inhibited C1·C2 and ACs 1, 5, and 6 but exhibited only low affinity for sGC, EF, ACT, and G-proteins. Inosine 5′-[γ-thio]triphosphate and uridine 5′-[γ-thio]triphosphate were mixed G-protein activators and AC inhibitors. AC5 was up to 15-fold more sensitive to inhibitors than AC2. EF and ACT exhibited unique inhibitor profiles. At sAC, 2′,5′-dideoxyadenosine 3′-triphosphate was the most potent compound (IC50, 690 nm). Several MANT-adenine and MANT-guanine Nucleotides inhibited sGC with Ki values in the 200–400 nm range. UTP and ATP exhibited similar affinities for sGC as GTP and were mixed sGC substrates and inhibitors. The exchange of MnCl2 against MgCl2 reduced inhibitor potencies at ACs and sGC 1.5–250-fold, depending on the nucleotide and cyclase studied. The omission of the NTP-regenerating system from cyclase reactions strongly reduced the potencies of MANT-ADP, indicative for phosphorylation to MANT-ATP by pyruvate kinase. Collectively, AC isoforms and sGC are differentially inhibited by purine and Pyrimidine Nucleotides.
Francoise Gaill - One of the best experts on this subject based on the ideXlab platform.
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Catabolism of Pyrimidine Nucleotides in the Deep-sea Tube WormRiftia pachyptila
The Journal of biological chemistry, 2001Co-Authors: Zoran Minic, Francoise Gaill, Styliani Pastra-landis, Guy HerveAbstract:The present study describes the distribution and properties of enzymes of the catabolic pathway of Pyrimidine Nucleotides in Riftia pachyptila, a tubeworm living around deep-sea hydrothermal vents and known to be involved in a highly specialized symbiotic association with a bacterium. The catabolic enzymes, 5'-nucleotidase, uridine phosphorylase, and uracil reductase, are present in all tissues of the worm, whereas none of these enzymatic activities were found in the symbiotic bacteria. The 5'-nucleotidase activity was particularly high in the trophosome, the symbiont-harboring tissue. These results suggest that the production of nucleosides in the trophosome may represent an alternative source of carbon and nitrogen for R. pachyptila, because these nucleosides can be delivered to other parts of the worm. This process would complement the source of carbon and nitrogen from organic metabolites provided by the bacterial assimilatory pathways. The localization of the enzymes participating in catabolism, 5'-nucleotidase and uridine phosphorylase, and of the enzymes involved in the biosynthesis of Pyrimidine Nucleotides, aspartate transcarbamylase and dihydroorotase, shows a non-homogeneous distribution of these enzymes in the trophosome. The catabolic enzymes 5'-nucleotidase and uridine phosphorylase activities increase from the center of the trophosome to its periphery. In contrast, the anabolic enzymes aspartate transcarbamylase and dihydroorotase activities decrease from the center toward the periphery of the trophosome. We propose a general scheme of anatomical and physiological organization of the metabolic pathways of the Pyrimidine Nucleotides in R. pachyptila and its bacterial endosymbiont.
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contribution of the bacterial endosymbiont to the biosynthesis of Pyrimidine Nucleotides in the deep sea tube worm riftia pachyptila
Journal of Biological Chemistry, 2001Co-Authors: Zoran Minic, Valerie Simon, Bernadette Penverne, Francoise Gaill, Guy HerveAbstract:Abstract The deep-sea tube worm Riftia pachyptila (Vestimentifera) from hydrothermal vents lives in an intimate symbiosis with a sulfur-oxidizing bacterium. That involves specific interactions and obligatory metabolic exchanges between the two organisms. In this work, we analyzed the contribution of the two partners to the biosynthesis of Pyrimidine Nucleotides through both the “de novo” and “salvage” pathways. The first three enzymes of the de novo pathway, carbamyl-phosphate synthetase, aspartate transcarbamylase, and dihydroorotase, were present only in the trophosome, the symbiont-containing tissue. The study of these enzymes in terms of their catalytic and regulatory properties in both the trophosome and the isolated symbiotic bacteria provided a clear indication of the microbial origin of these enzymes. In contrast, the succeeding enzymes of this de novo pathway, dihydroorotate dehydrogenase and orotate phosphoribosyltransferase, were present in all body parts of the worm. This finding indicates that the animal is fully dependent on the symbiont for the de novo biosynthesis of Pyrimidines. In addition, it suggests that the synthesis of Pyrimidines in other tissues is possible from the intermediary metabolites provided by the trophosomal tissue and from nucleic acid degradation products since the enzymes of the salvage pathway appear to be present in all tissues of the worm. Analysis of these salvage pathway enzymes in the trophosome strongly suggested that these enzymes belong to the worm. In accordance with this conclusion, none of these enzyme activities was found in the isolated bacteria. The enzymes involved in the production of the precursors of carbamyl phosphate and nitrogen assimilation, glutamine synthetase and nitrate reductase, were also investigated, and it appears that these two enzymes are present in the bacteria.
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the enzymes involved in synthesis and utilization of carbamylphosphate in the deep sea tube worm riftia pachyptila
Marine Biology, 2000Co-Authors: Valerie Simon, Francoise Gaill, Cristina Purcarea, K Sun, J Joseph, Ghislaine Frebourg, Jeanpierre Lechaire, Guy HerveAbstract:The obligate symbiosis of the deep-sea tube worm Riftia pachyptila with a sulphur-oxidizing bacterium raises important questions concerning its metabolism and metabolic exchanges. In this study, the presence and properties of the enzymes synthesizing and utilizing carbamylphosphate in the arginine and Pyrimidine nucleotide pathways were investigated in this worm. The results show that the ammonium-dependent carbamylphosphate synthetase and ornithine transcarbamylase, enzymes involved in the arginine pathway, are present in all body parts of the worm. In contrast, the glutamine-dependent carbamylphosphate synthetase and aspartate transcarbamylase, enzymes involved in the de novo pathway for Pyrimidine Nucleotides biosynthesis, are present only in the trophosome, the symbiont-harbouring tissue. Although the bacterial nature of these enzymes is not unambigously established, these results strongly suggest that the de novo biosynthesis of Pyrimidine Nucleotides is limited to the trophosome, the organ where the production of metabolic energy takes place, while the other parts of the worm's body rely on the salvage pathway for the production of the Pyrimidine triphosphate Nucleotides.
Anna Junker - One of the best experts on this subject based on the ideXlab platform.
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structure activity relationship of purine and Pyrimidine Nucleotides as ecto 5 nucleotidase cd73 inhibitors
Journal of Medicinal Chemistry, 2019Co-Authors: Shanu Jain, Anna Junker, Christian Renn, Clemens Dobelmann, Vigneshwaran Namasivayam, Karolina Losenkova, Heikki Irjala, Sierra DucaAbstract:Cluster of differentiation 73 (CD73) converts adenosine 5′-monophosphate to immunosuppressive adenosine, and its inhibition was proposed as a new strategy for cancer treatment. We synthesized 5′-O-[(phosphonomethyl)phosphonic acid] derivatives of purine and Pyrimidine nucleosides, which represent nucleoside diphosphate analogues, and compared their CD73 inhibitory potencies. In the adenine series, most ribose modifications and 1-deaza and 3-deaza were detrimental, but 7-deaza was tolerated. Uracil substitution with N3-methyl, but not larger groups, or 2-thio, was tolerated. 1,2-Diphosphono-ethyl modifications were not tolerated. N4-(Aryl)alkyloxy-cytosine derivatives, especially with bulky benzyloxy substituents, showed increased potency. Among the most potent inhibitors were the 5′-O-[(phosphonomethyl)phosphonic acid] derivatives of 5-fluorouridine (4l), N4-benzoyl-cytidine (7f), N4-[O-(4-benzyloxy)]-cytidine (9h), and N4-[O-(4-naphth-2-ylmethyloxy)]-cytidine (9e) (Ki values 5–10 nM at human CD73). Selec...
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Structure–Activity Relationship of Purine and Pyrimidine Nucleotides as Ecto-5′-Nucleotidase (CD73) Inhibitors
2019Co-Authors: Anna Junker, Shanu Jain, Ramachandran Balasubramanian, Christian Renn, Clemens Dobelmann, Vigneshwaran Namasivayam, Karolina Losenkova, Heikki Irjala, Sierra Duca, Saibal ChakrabortyAbstract:Cluster of differentiation 73 (CD73) converts adenosine 5′-monophosphate to immunosuppressive adenosine, and its inhibition was proposed as a new strategy for cancer treatment. We synthesized 5′-O-[(phosphonomethyl)phosphonic acid] derivatives of purine and Pyrimidine nucleosides, which represent nucleoside diphosphate analogues, and compared their CD73 inhibitory potencies. In the adenine series, most ribose modifications and 1-deaza and 3-deaza were detrimental, but 7-deaza was tolerated. Uracil substitution with N3-methyl, but not larger groups, or 2-thio, was tolerated. 1,2-Diphosphono-ethyl modifications were not tolerated. N4-(Aryl)alkyloxy-cytosine derivatives, especially with bulky benzyloxy substituents, showed increased potency. Among the most potent inhibitors were the 5′-O-[(phosphonomethyl)phosphonic acid] derivatives of 5-fluorouridine (4l), N4-benzoyl-cytidine (7f), N4-[O-(4-benzyloxy)]-cytidine (9h), and N4-[O-(4-naphth-2-ylmethyloxy)]-cytidine (9e) (Ki values 5–10 nM at human CD73). Selected compounds tested at the two uridine diphosphate-activated P2Y receptor subtypes showed high CD73 selectivity, especially those with large nucleobase substituents. These nucleotide analogues are among the most potent CD73 inhibitors reported and may be considered for development as parenteral drugs
Zoran Minic - One of the best experts on this subject based on the ideXlab platform.
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Catabolism of Pyrimidine Nucleotides in the Deep-sea Tube WormRiftia pachyptila
The Journal of biological chemistry, 2001Co-Authors: Zoran Minic, Francoise Gaill, Styliani Pastra-landis, Guy HerveAbstract:The present study describes the distribution and properties of enzymes of the catabolic pathway of Pyrimidine Nucleotides in Riftia pachyptila, a tubeworm living around deep-sea hydrothermal vents and known to be involved in a highly specialized symbiotic association with a bacterium. The catabolic enzymes, 5'-nucleotidase, uridine phosphorylase, and uracil reductase, are present in all tissues of the worm, whereas none of these enzymatic activities were found in the symbiotic bacteria. The 5'-nucleotidase activity was particularly high in the trophosome, the symbiont-harboring tissue. These results suggest that the production of nucleosides in the trophosome may represent an alternative source of carbon and nitrogen for R. pachyptila, because these nucleosides can be delivered to other parts of the worm. This process would complement the source of carbon and nitrogen from organic metabolites provided by the bacterial assimilatory pathways. The localization of the enzymes participating in catabolism, 5'-nucleotidase and uridine phosphorylase, and of the enzymes involved in the biosynthesis of Pyrimidine Nucleotides, aspartate transcarbamylase and dihydroorotase, shows a non-homogeneous distribution of these enzymes in the trophosome. The catabolic enzymes 5'-nucleotidase and uridine phosphorylase activities increase from the center of the trophosome to its periphery. In contrast, the anabolic enzymes aspartate transcarbamylase and dihydroorotase activities decrease from the center toward the periphery of the trophosome. We propose a general scheme of anatomical and physiological organization of the metabolic pathways of the Pyrimidine Nucleotides in R. pachyptila and its bacterial endosymbiont.
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contribution of the bacterial endosymbiont to the biosynthesis of Pyrimidine Nucleotides in the deep sea tube worm riftia pachyptila
Journal of Biological Chemistry, 2001Co-Authors: Zoran Minic, Valerie Simon, Bernadette Penverne, Francoise Gaill, Guy HerveAbstract:Abstract The deep-sea tube worm Riftia pachyptila (Vestimentifera) from hydrothermal vents lives in an intimate symbiosis with a sulfur-oxidizing bacterium. That involves specific interactions and obligatory metabolic exchanges between the two organisms. In this work, we analyzed the contribution of the two partners to the biosynthesis of Pyrimidine Nucleotides through both the “de novo” and “salvage” pathways. The first three enzymes of the de novo pathway, carbamyl-phosphate synthetase, aspartate transcarbamylase, and dihydroorotase, were present only in the trophosome, the symbiont-containing tissue. The study of these enzymes in terms of their catalytic and regulatory properties in both the trophosome and the isolated symbiotic bacteria provided a clear indication of the microbial origin of these enzymes. In contrast, the succeeding enzymes of this de novo pathway, dihydroorotate dehydrogenase and orotate phosphoribosyltransferase, were present in all body parts of the worm. This finding indicates that the animal is fully dependent on the symbiont for the de novo biosynthesis of Pyrimidines. In addition, it suggests that the synthesis of Pyrimidines in other tissues is possible from the intermediary metabolites provided by the trophosomal tissue and from nucleic acid degradation products since the enzymes of the salvage pathway appear to be present in all tissues of the worm. Analysis of these salvage pathway enzymes in the trophosome strongly suggested that these enzymes belong to the worm. In accordance with this conclusion, none of these enzyme activities was found in the isolated bacteria. The enzymes involved in the production of the precursors of carbamyl phosphate and nitrogen assimilation, glutamine synthetase and nitrate reductase, were also investigated, and it appears that these two enzymes are present in the bacteria.
