scholarly journals INFLUENCE OF X-RAY AND MICROWAVE RADIATION ON DEAMINATION OF PURINE NUCLEOTIDES IN YEAST CELLS CANDIDA GUILLIERMONDII NP-4

2019 ◽  
Vol 62 (2) ◽  
pp. 48-52
Author(s):  
Seda V. Marutyan ◽  
Gayane H. Petrosyan ◽  
Syuzan A. Marutyan ◽  
Liparit A. Navasardyan ◽  
Armen H. Trchounian
Keyword(s):  
Electromagnetic Waves ◽  
De Novo ◽  
Candida Guilliermondii ◽  
Nucleotide Metabolism ◽  
Yeast Cells ◽  
X Rays ◽  
Purine Nucleotides ◽  
Nucleotide Synthesis ◽  
X Ray ◽  
Salvage Pathways

In metabolism of living cells a key role play purine nucleotides which cells can be supplied either by de novo synthesis from lower molecular weight precursors, or by alternate ways of nucleotide synthesis or so-called "nucleotide salvage pathways", which allow reusing of intermediate products of nucleotide metabolism in nucleotide synthesis. This way is important in the post-stress repair period, saving energy and substrates in the repairing cells. Purine nucleotides are allosteric inhibitors of enzymes of nucleotide salvage pathways, therefore the increase in their catabolism leads to a decrease of their amount in the cells, which contributes to the intensive work of the nucleotide salvage pathways and provides substrates for DNA synthesis. Investigation of deamination of purine nucleotides in yeasts Candida guilliermondii NP-4 irradiated with X-rays, millimeter and decimeter electromagnetic waves, as well as after post-radiation incubation of cells has been realized. It has been shown that under the influence of X-ray and microwave irradiation in yeasts, the intensity of deamination of purine nucleotide-polyphosphates - ADP, ATP, GDF and GTP, has changed, which in all probability is an adaptive mechanism in the repair of yeasts after irradiation, provides the work of nucleotide salvage pathways, and can be associated with the metabolism of these compounds.

scholarly journals Nucleotide Biosynthesis Links Glutathione Metabolism to Ferroptosis Sensitivity

2021 ◽  
Author(s):  
Amy Tarangelo ◽  
Joon Tae Kim ◽  
Jonathan Z Long ◽  
Scott J Dixon
Keyword(s):  
Cell Death ◽  
De Novo ◽  
Apoptotic Cell ◽  
Lipid Peroxides ◽  
Nucleotide Metabolism ◽  
Apoptotic Cell Death ◽  
Death Process ◽  
Glutathione Metabolism ◽  
Dependent Manner ◽  
Nucleotide Synthesis

Nucleotide synthesis is a metabolically demanding process essential for cell division. Several anti-cancer drugs that inhibit nucleotide metabolism induce apoptosis. How inhibition of nucleotide metabolism impacts non-apoptotic cell death is less clear. Here, we report that inhibition of nucleotide metabolism by the p53 pathway is sufficient to suppress the non-apoptotic cell death process of ferroptosis. Mechanistically, stabilization of wild-type p53 and induction of the p53 target gene CDKN1A (p21) leads to decreased expression of the ribonucleotide reductase (RNR) subunits RRM1 and RRM2. RNR is the rate-limiting enzyme of de novo nucleotide synthesis that reduces ribonucleotides to deoxyribonucleotides in a glutathione-dependent manner. Direct inhibition of RNR conserves glutathione which can then be used to limit the accumulation of toxic lipid peroxides, preventing the onset of ferroptosis. These results support a mechanism linking p53-dependent regulation of nucleotide metabolism to non-apoptotic cell death.

Regulation of purine nucleotide biosynthesis: in yeast and beyond

2006 ◽  
Vol 34 (5) ◽  
pp. 786-790 ◽  
Author(s):  
R.J. Rolfes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
De Novo ◽  
Purine Nucleotide ◽  
De Novo Synthesis ◽  
Normal Functioning ◽  
Purine Nucleotides ◽  
Yeast Saccharomyces Cerevisiae ◽  
Nucleotide Biosynthesis ◽  
Salvage Pathways ◽  
Pool Sizes

Purine nucleotides are critically important for the normal functioning of cells due to their myriad of activities. It is important for cells to maintain a balance in the pool sizes of the adenine-containing and guanine-containing nucleotides, which occurs by a combination of de novo synthesis and salvage pathways that interconvert the purine nucleotides. This review describes the mechanism for regulation of the biosynthetic genes in the yeast Saccharomyces cerevisiae and compares this mechanism with that described in several microbial species.

scholarly journals Multi-crystal native SAD analysis at 6 keV

2014 ◽  
Vol 70 (10) ◽  
pp. 2544-2557 ◽  
Author(s):  
Qun Liu ◽  
Youzhong Guo ◽  
Yanqi Chang ◽  
Zheng Cai ◽  
Zahra Assur ◽  
...  
Keyword(s):  
De Novo ◽  
Real Life ◽  
Kinase Domain ◽  
X Rays ◽  
Protein Kinase Domain ◽  
Anomalous Diffraction ◽  
X Ray ◽  
Tyrosine Protein Kinase ◽  
Sad Phasing ◽  
Feasibility Test

Anomalous diffraction signals from typical native macromolecules are very weak, frustrating their use inde novostructure determination. Here, native SAD procedures are described to enhance signal to noise in anomalous diffraction by using multiple crystals in combination with synchrotron X-rays at 6 keV. Increased anomalous signals were obtained at 6 keV compared with 7 keV X-ray energy, which was used for previous native SAD analyses. A feasibility test of multi-crystal-based native SAD phasing was performed at 3.2 Å resolution for a known tyrosine protein kinase domain, and real-life applications were made to two novel membrane proteins at about 3.0 Å resolution. The three applications collectively serve to validate the robust feasibility of native SAD phasing at lower energy.

scholarly journals Metabolism of xanthine and hypoxanthine in the tea plant (Thea sinensis L.)

1975 ◽  
Vol 146 (1) ◽  
pp. 79-85 ◽  
Author(s):  
T Suzuki ◽  
E Takahashi
Keyword(s):  
De Novo ◽  
Tea Plant ◽  
Shoot Tips ◽  
Purine Nucleotides ◽  
Purine Salvage ◽  
Nucleotide Synthesis ◽  
Caffeine Biosynthesis ◽  
Tea Shoot ◽  
Tea Plants ◽  
Almost All

1. The metabolism of xanthine and hypoxanthine in excised shoot tips of tea was studied with micromolar amounts of [2(-14)C]xanthine or [8(-14)C]hypoxanthine. Almost all of the radioactive compounds supplied were utilized by tea shoot tips by 30 h after their uptake. 2. The main products of [2(-14)C]xanthine and [8(-14)C]hypoxanthine metabolism in tea shoots were urea, allantoin and allantoic acid. There was also incorporation of the label into theobromine, caffeine and RNA purine nucleotides. 3. The results indicate that tea plants can catabolize purine bases by the same pathways as animals. It is also suggested that tea plants have the ability to snythesize purine nucleotides from glycine by the pathways of purine biosynthesis de novo and from hypoxanthine and xanthine by the pathway of purine salvage. 4. The results of incorporation of more radioactivity from [8(-14)C]hypoxanthine than from [2(-14)C]xanthine into RNA purine nucleotides and caffeine suggest that hypoxanthine is a more effective precursor of caffeine biosynthesis than xanthine. The formation of caffeine from hypoxanthine is a result of nucleotide synthesis via the pathway of purine salvage.

scholarly journals Purine salvage networks in Giardia lamblia.

1983 ◽  
Vol 158 (5) ◽  
pp. 1703-1712 ◽  
Author(s):  
C C Wang ◽  
S Aldritt
Keyword(s):  
Giardia Lamblia ◽  
De Novo ◽  
Adenine Nucleotides ◽  
Guanine Nucleotides ◽  
Rational Approach ◽  
Purine Nucleotides ◽  
Purine Salvage ◽  
Nucleotide Synthesis ◽  
Guanine Base

Purine metabolism in Giardia lamblia was investigated by monitoring incorporation of radiolabeled precursors into purine nucleotides in the log-phase trophozoites cultivated in vitro in axenic media and incubated in buffered saline glucose. The lack of incorporation of formate, glycine, hypoxanthine, inosine, and xanthine into the nucleotide pool suggests the absence of de novo purine nucleotide synthesis and the inability to form IMP as the precursor of AMP and GMP in G. lamblia. Only adenine, adenosine, guanine, and guanosine were incorporated. Further analysis of the labeled nucleotides by HPLC indicated that adenine and adenosine are converted only to adenine nucleotides whereas guanine and guanosine are only incorporated into guanine nucleotides. There is no competition of incorporation between adenine/adenosine and guanine/guanosine, and there is no interconversion between adenine and guanine nucleotides. Results from analyzing [5'-3H]guanosine incorporation indicate that the ribose moiety is not incorporated with the guanine base. Assays of purine salvage enzymic activities in the crude extracts of G. lamblia revealed the presence of only four major enzymes; adenosine and guanosine hydrolases and adenine and guanine phosphoribosyl transferases. Apparently, G. lamblia has an exceedingly simple purine salvage system; it converts adenosine and guanosine to corresponding purine bases and then forms AMP and GMP by the actions of corresponding purine phosphoribosyl transferases. The guanine phosphoribosyl transferase in G. lamblia is interesting because it does not recognize either hypoxanthine or xanthine as substrate. It thus must have a unique substrate specificity and may be regarded as a potential target to attack as a rational approach to chemotherapeutic control of giardiasis.

scholarly journals Renal hypertrophy in experimental diabetes. The activity of the ‘de novo’ and salvage pathways of purine [corrected] synthesis

1988 ◽  
Vol 249 (3) ◽  
pp. 911-914 ◽  
Author(s):  
S Kunjara ◽  
S J Beardsley ◽  
A L Greenbaum
Keyword(s):  
Nucleic Acids ◽  
De Novo ◽  
Experimental Diabetes ◽  
Salvage Pathway ◽  
Phosphoribosyl Pyrophosphate ◽  
Renal Hypertrophy ◽  
Early Diabetes ◽  
Nucleotide Synthesis ◽  
Main Route ◽  
Salvage Pathways

Measurements were made of the activity of phosphoribosyl pyrophosphate amidotransferase (PPRibP-At, EC 2.4.2.14) and of adenine (APRT, EC 2.4.2.7) and hypoxanthine (HPRT, EC 2.4.2.8) phosphoribosyltransferases, representing the ‘de novo’ and salvage pathways respectively. PPRibP-At activity increased within 3 days of diabetes, whereas APRT and HPRT increased later. Incorporation of [14C]formate and of [8-14C]adenine into the nucleic acids of kidney slices showed that formate was incorporated earlier, and to a greater extent, than was adenine. These results indicate that, although the ‘de novo’ pathway for nucleotide synthesis is the main route in early diabetes, the salvage pathway assumes greater importance at later stages.

Effects of Chinese Herbal Medicines on DNA-Synthesizing Enzyme Activities in Mammary Tumors of Mice

1994 ◽  
Vol 22 (01) ◽  
pp. 43-50 ◽  
Author(s):  
Shinobu Sakamoto ◽  
Ryuta Furuichi ◽  
Manabu Matsuda ◽  
Hideki Kudo ◽  
Satoe Suzuki ◽  
...  
Keyword(s):  
Prolactin Level ◽  
De Novo ◽  
Herbal Medicines ◽  
Mammary Tumors ◽  
Serum Prolactin ◽  
Serum Prolactin Level ◽  
Nucleotide Synthesis ◽  
Chinese Herbal ◽  
Pyrimidine Nucleotide ◽  
Salvage Pathways

Sho-saiko-to (SST) and Juzen-taiho-to (JTT), Japanese modified Chinese herbal prescriptions, suppressed the activities of thymidylate synthetase and thymidine kinase involved in de novo and salvage pathways for pyrimidine nucleotide synthesis, respectively, in mammary tumors of SHN mice with the reduction of serum prolactin level. These results indicate that SST and JTT may have the anti-tumor effects on mammary tumors.

scholarly journals Pyrimidine nucleotide metabolism in rat hepatocytes: evidence for compartmentation of nucleotide pools

1993 ◽  
Vol 293 (1) ◽  
pp. 207-213 ◽  
Author(s):  
W R Pels Rijcken ◽  
B Overdijk ◽  
D H van den Eijnden ◽  
W Ferwerda
Keyword(s):  
Orotic Acid ◽  
De Novo ◽  
Rat Hepatocytes ◽  
Nucleotide Metabolism ◽  
Double Labelling ◽  
Pyrimidine Nucleotides ◽  
Nucleotide Biosynthesis ◽  
Pyrimidine Nucleotide ◽  
Salvage Pathways ◽  
Lower Ratio

Pyrimidine nucleotide metabolism in rat hepatocytes was studied by measurement of the labelling kinetics of the various intermediates after double labelling with [14C]orotic acid and [3H]cytidine, the precursors for the de novo and the salvage pathways respectively. For the uridine nucleotides, differences were found for the 14C/3H ratios in the UDP-sugars, in UMP (of RNA) and in their precursor UTP, suggesting the existence of separated flows of the radioactive precursors through the de novo and the salvage pathways. Higher ratios in the UDP-sugars, which are synthesized in the cytoplasm, and a lower ratio in UMP (of RNA) relative to the 14C/3H ratio in UTP indicated that UTP derived from orotic acid is preferentially used for the cytoplasmic biosynthesis of the UDP-sugars. Uridine, derived from cytidine, is preferentially used for the nuclear-localized synthesis of RNA. In contrast to these findings, the 14C/3H ratios in the cytidine derivatives CMP-NeuAc and CMP (of RNA), and in the liponucleotides CDP-choline and CDP-ethanolamine, were all lower than that in the precursor CTP. This indicates a preferential utilization of the salvage-derived CTP for the synthesis of the liponucleotides as well as for RNA and CMP-NeuAc. Similar conclusions could be drawn from experiments in which the intracellular amounts of several uridine- and cytidine-nucleotide-containing derivatives were increased by preincubating the hepatocytes with unlabelled pyrimidine nucleotides or ethanolamine. Based on these data, we propose a refined model for the intracellular compartmentation of pyrimidine nucleotide biosynthesis in which three pools of UTP are distinguished: a pool of de novo-derived molecules and a pool of salvage-derived molecules, both of which are channelled to the site of utilization; in addition an ‘overflow’ pool exists, consisting of molecules having escaped from channelling. An overflow pool could also be distinguished for CTP, but no discrimination between de novo and salvage-derived molecules could be made.

Characterization of the novelTrypanosoma bruceiinosine 5′-monophosphate dehydrogenase

Parasitology ◽  
2013 ◽  
Vol 140 (6) ◽  
pp. 735-745 ◽  
Author(s):  
TOMOAKI BESSHO ◽  
SHOKO MORII ◽  
TOSHIHIDE KUSUMOTO ◽  
TAKAHIRO SHINOHARA ◽  
MASANORI NODA ◽  
...  
Keyword(s):  
Analytical Ultracentrifugation ◽  
De Novo ◽  
Binding Mode ◽  
Nucleotide Metabolism ◽  
Sub Saharan Africa ◽  
Size Exclusion ◽  
Purine Nucleotides ◽  
Exclusion Chromatography ◽  
Sub Saharan ◽  
Monophosphate Dehydrogenase

SUMMARYThere is an alarming rate of human African trypanosomiasis recrudescence in many parts of sub-Saharan Africa. Yet, the disease has no successful chemotherapy.Trypanosomalacks the enzymatic machinery for thede novosynthesis of purine nucleotides, and is critically dependent on salvage mechanisms. Inosine 5′-monophosphate dehydrogenase (IMPDH) is responsible for the rate-limiting step in guanine nucleotide metabolism. Here, we characterize recombinantTrypanosoma bruceiIMPDH (TbIMPDH) to investigate the enzymatic differences between TbIMPDH and host IMPDH. Size-exclusion chromatography and analytical ultracentrifugation sedimentation velocity experiments reveal that TbIMPDH forms a heptamer, different from type 1 and 2 mammalian tetrameric IMPDHs. Kinetic analysis reveals calculatedKmvalues of 30 and 1300 μmfor IMP and NAD, respectively. The obtainedKmvalue of TbIMPDH for NAD is approximately 20–200-fold higher than that of mammalian enzymes and indicative of a different NAD binding mode between trypanosomal and mammalian IMPDHs. Inhibition studies showKivalues of 3·2 μm, 21 nM and 3·3 nM for ribavirin 5′-monophosphate, mycophenolic acid and mizoribine 5′-monophosphate, respectively. Our results show that TbIMPDH is different from its mammalian counterpart and thus may be a good target for further studies on anti-trypanosomal drugs.

scholarly journals DDRE-29. DE NOVO PYRIMIDINE SYNTHESIS IS A TARGETABLE VULNERABILITY IN IDH-MUTANT GLIOMA

2020 ◽  
Vol 3 (Supplement_1) ◽  
pp. i12-i13
Author(s):  
Diana D Shi ◽  
Adam C Wang ◽  
Michael M Levitt ◽  
Jennifer E Endress ◽  
Min Xu ◽  
...  
Keyword(s):  
Cell Lines ◽  
De Novo ◽  
Synthetic Lethality ◽  
Nucleotide Metabolism ◽  
Metabolic Inhibitor ◽  
Lower Grade ◽  
Nucleotide Synthesis ◽  
Pyrimidine Synthesis ◽  
Pyrimidine Nucleotide ◽  
Idh1 Mutations

Abstract 70–90% of lower-grade gliomas and secondary glioblastomas harbor gain-of-function mutations in isocitrate dehydrogenase 1 (IDH1), causing overproduction of the oncometabolite (R)-2-hydroxyglutarate [(R)-2HG]. Although inhibitors of mutant IDH enzymes are effective in other cancers, including leukemia, they have shown guarded efficacy in preclinical and clinical brain tumor studies, thus underscoring the need to identify additional therapeutic targets in IDH mutant glioma. We sought to identify tumor-specific metabolic vulnerabilities induced by IDH1 mutations that could be exploited therapeutically. To uncover such vulnerabilities, we conducted a chemical synthetic lethality screen using isogenic IDH1 mutant and IDH1 wild-type (WT) glioma cell lines and a novel metabolic inhibitor screening platform. We discovered that IDH1 mutant cells are hypersensitive to drugs targeting enzymes in the de novo pyrimidine nucleotide synthesis pathway, including dihydroorotate dehydrogenase (DHODH). This vulnerability is specific because inhibitors of purine nucleotide metabolism did not score in our screen. We validated that the cytotoxicity of pyrimidine synthesis inhibitors is on-target and showed that IDH1 mutant patient-derived glioma stem-like cell lines are also hyperdependent on de novo pyrimidine nucleotide synthesis compared to IDH1 WT lines. To test pyrimidine synthesis dependence of IDH1 mutant gliomas in vivo, we used a brain-penetrent DHODH inhibitor currently undergoing evaluation in leukemia patients, BAY 2402234. We found that BAY 2402234 displays monotherapy activity against gliomas in an orthotopic xenograft model of IDH1 mutant glioma, with an effect size that compared favorably with radiotherapy. We also developed novel genetically engineered and allograft mouse models of mutant IDH1-driven anaplastic astrocytoma and showed that BAY 2402234 blocked growth of orthotopic astrocytoma allografts. Our findings bolster rationale to target DHODH in glioma, highlight BAY 2402234 as a clinical-stage drug that can be used to inhibit DHODH in brain tumors, and establish IDH1 mutations as predictive biomarkers of DHODH inhibitor efficacy.

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