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Academic literature on the topic 'Enzyme-DNA precursor synthesis'
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Journal articles on the topic "Enzyme-DNA precursor synthesis"
1
Conrad-Webb, H., and R. A. Butow. "A polymerase switch in the synthesis of rRNA in Saccharomyces cerevisiae." Molecular and Cellular Biology 15, no. 5 (May 1995): 2420–28. http://dx.doi.org/10.1128/mcb.15.5.2420.
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Transcription of ribosomal DNA by RNA polymerase I is believed to be the sole source of the 25S, 18S, and 5.8S rRNAs in wild-type cells of Saccharomyces cerevisiae. Here we present evidence for a switch from RNA polymerase I to RNA polymerase II in the synthesis of a substantial fraction of those rRNAs in respiratory-deficient (petite) cells. The templates for the RNA polymerase II transcripts are largely, if not exclusively, episomal copies of ribosomal DNA arising from homologous recombination events within the ribosomal DNA repeat on chromosome XII. Ribosomal DNA contains a cryptic RNA polymerase II promoter that is activated in petites; it overlaps the RNA polymerase I promoter and produces a transcript equivalent to the 35S precursor rRNA made by RNA polymerase I. Yeast cells that lack RNA polymerase I activity, because of a disruption of the RPA135 gene that encodes subunit II of the enzyme, can survive by using the RNA polymerase II promoter in ribosomal DNA to direct the synthesis of the 35S rRNA precursor. This polymerase switch could provide cells with a mechanism to synthesize rRNA independent of the controls of RNA polymerase I transcription.
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Klein, Beate, and Hartmut Follmann. "Deoxyribonucleotide Biosynthesis in Green Algae. S Phase-Specific Thymidylate Kinase and Unspecific Nucleoside Diphosphate Kinase in Scenedesmus obliquus." Zeitschrift für Naturforschung C 43, no. 5-6 (June 1, 1988): 377–85. http://dx.doi.org/10.1515/znc-1988-5-610.
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NDP kinase and thymidylate kinase are essential for DNA precursor formation in that they phosphorylate the products of de novo deoxyribonucleotide biosynthesis, deoxyribonucleoside 5′-diphosphates and thymidine 5′-monophosphate to the corresponding triphosphates which then serve as DNA polymerase substrates. The two enzymes have been measured in synchronous cultures of the green algae, S. obliquus. Thymidylate kinase exhibits an activity peak at the 11 -12th hour of the 24-hour cell cycle, coinciding with DNA synthesis. Enzyme activity is markedly stimulated in presence of fluorodeoxyuridine in the culture medium. This behaviour of dTMP kinase is very similar to that of three other S phase-specific peak enzymes previously analyzed in synchronous algae, viz. ribonucleotide reductase, thymidylate synthase, and dihydrofolate reductase. In contrast, NDP kinase exhibits high and constant activity through the entire cell cycle. The two kinases have been isolated from cell-free extracts, and separated from each other by chromatography on Blue Sepharose. The peak enzyme, dTMP kinase, has been purified to near homogeneity and its catalytic properties are described; the molecular weight is 56,000. NDP kinase activity is separable into two enzyme fractions, both of molecular weight 100,000 (or higher), which are unspecific with respect to ribonucleotide and deoxyribonucleotide substrates. Characterization and purification of the whole series of deoxyribonucleotide-synthesizing enzymes from one organism provides a basis for in vitro experiments towards reconstitution of an S phase-specific DNA precursor/DNA replication multienzyme aggregate.
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Woolford, C. A., L. B. Daniels, F. J. Park, E. W. Jones, J. N. Van Arsdell, and M. A. Innis. "The PEP4 gene encodes an aspartyl protease implicated in the posttranslational regulation of Saccharomyces cerevisiae vacuolar hydrolases." Molecular and Cellular Biology 6, no. 7 (July 1986): 2500–2510. http://dx.doi.org/10.1128/mcb.6.7.2500.
Full textAbstract:
pep4 mutants of Saccharomyces cerevisiae accumulate inactive precursors of vacuolar hydrolases. The PEP4 gene was isolated from a genomic DNA library by complementation of the pep4-3 mutation. Deletion analysis localized the complementing activity to a 1.5-kilobase pair EcoRI-XhoI restriction enzyme fragment. This fragment was used to identify an 1,800-nucleotide mRNA capable of directing the synthesis of a 44,000-dalton polypeptide. Southern blot analysis of yeast genomic DNA showed that the PEP4 gene is unique; however, several related sequences exist in yeasts. Tetrad analysis and mitotic recombination experiments localized the PEP4 gene proximal to GAL4 on chromosome XVI. Analysis of the DNA sequence indicated that PEP4 encodes a polypeptide with extensive homology to the aspartyl protease family. A comparison of the PEP4 predicted amino acid sequence with the yeast protease A protein sequence revealed that the two genes are, in fact, identical (see also Ammerer et al., Mol. Cell. Biol. 6:2490-2499, 1986). Based on our observations, we propose a model whereby inactive precursor molecules produced from the PEP4 gene self-activate within the yeast vacuole and subsequently activate other vacuolar hydrolases.
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Woolford, C. A., L. B. Daniels, F. J. Park, E. W. Jones, J. N. Van Arsdell, and M. A. Innis. "The PEP4 gene encodes an aspartyl protease implicated in the posttranslational regulation of Saccharomyces cerevisiae vacuolar hydrolases." Molecular and Cellular Biology 6, no. 7 (July 1986): 2500–2510. http://dx.doi.org/10.1128/mcb.6.7.2500-2510.1986.
Full textAbstract:
pep4 mutants of Saccharomyces cerevisiae accumulate inactive precursors of vacuolar hydrolases. The PEP4 gene was isolated from a genomic DNA library by complementation of the pep4-3 mutation. Deletion analysis localized the complementing activity to a 1.5-kilobase pair EcoRI-XhoI restriction enzyme fragment. This fragment was used to identify an 1,800-nucleotide mRNA capable of directing the synthesis of a 44,000-dalton polypeptide. Southern blot analysis of yeast genomic DNA showed that the PEP4 gene is unique; however, several related sequences exist in yeasts. Tetrad analysis and mitotic recombination experiments localized the PEP4 gene proximal to GAL4 on chromosome XVI. Analysis of the DNA sequence indicated that PEP4 encodes a polypeptide with extensive homology to the aspartyl protease family. A comparison of the PEP4 predicted amino acid sequence with the yeast protease A protein sequence revealed that the two genes are, in fact, identical (see also Ammerer et al., Mol. Cell. Biol. 6:2490-2499, 1986). Based on our observations, we propose a model whereby inactive precursor molecules produced from the PEP4 gene self-activate within the yeast vacuole and subsequently activate other vacuolar hydrolases.
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Tiganos, E., and M. B. Herrington. "Kasugamycin inhibition of nonsense suppression by thymine-requiring strains of Escherichia coli K12." Canadian Journal of Microbiology 39, no. 4 (April 1, 1993): 448–50. http://dx.doi.org/10.1139/m93-065.
Full textAbstract:
Thymine-requiring strains of Escherichia coli suppress nonsense and frame-shift mutations. This appears to occur during translation, suggesting that the lack of activity of an enzyme thymidylate synthase, required for the synthesis of a DNA precursor, alters the fidelity of translation. The aminoglycoside antibiotic kasugamycin, which enhances translational accuracy in vitro, prevents thymine-requiring cells from suppressing. The inhibition of suppression by kasugamycin is not prevented by the introduction of two different kasugamycin-resistance mutations, although the dose required for inhibition increases. These observations support the conclusion that suppression occurs during translation.Key words: suppression, kasugamycin, translation, thymine-requiring.
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Cortes, P., F. Dumler, and N. W. Levin. "Glomerular uracil nucleotide synthesis." American Journal of Physiology-Renal Physiology 255, no. 4 (October 1, 1988): F635—F646. http://dx.doi.org/10.1152/ajprenal.1988.255.4.f635.
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The biosynthesis of basement membrane material requires the sugar derivatives of uridine 5'-triphosphate (UTP) for protein glycosylation. Uridine and orotate utilization for the biosynthesis of uracil ribonucleotides was studied in isolated rat glomeruli incubated in vitro. At a 1 microM concentration total orotate utilization was 9.6 +/- 1.8 pmol.min-1.mg DNA-1 (1 mg DNA approximately 0.175 X 10(6) glomeruli), 51% of the total amount metabolized was used in ribonucleotide formation, and there was a significant UTP accretion. Except at a high initial concentration (50 microM), exogenous uridine failed to increase the UTP pool due to rapid uridine breakdown by a cytosolic phosphorylase. Inhibition of this enzyme with benzylacyclouridine resulted in increased biosynthesis and accretion of UTP, and in a 17-fold higher concentration of uridine, primarily produced from performed sources of nucleosides. Continuous addition of exogenous uridine to maintain its concentration at 1 microM resulted in a total uridine utilization of 550 +/- 30 pmol.min-1.mg DNA-1. Uridine salvage for ribonucleotide biosynthesis was only 3% of the total metabolized. In contrast to uridine, and presumably due to UTP pool compartmentation, orotate incorporation into uridine 5'-diphosphosugars was prominent. The metabolism of exogenous orotate was not decreased by the presence of large amounts of uridine and by an expanded UTP pool. It is concluded that when exogenous orotate is present, it is an important precursor for glomerular uracil ribonucleotide biosynthesis. Due to its rapid rate of catabolism, uridine cannot maintain ribonucleotide biosynthesis at a rate sufficient to result in UTP accretion unless it is provided continuously in substantial quantities.
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Lai, Lilin, Hongmei Liu, Xiaoyun Wu, and John C. Kappes. "Moloney Murine Leukemia Virus Integrase Protein Augments Viral DNA Synthesis in Infected Cells." Journal of Virology 75, no. 23 (December 1, 2001): 11365–72. http://dx.doi.org/10.1128/jvi.75.23.11365-11372.2001.
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ABSTRACT Mutations in the IN domain of retroviral DNA may affect multiple steps of the virus life cycle, suggesting that the IN protein may have other functions in addition to its integration function. We previously reported that the human immunodeficiency virus type 1 IN protein is required for efficient viral DNA synthesis and that this function requires specific interaction with other viral components but not enzyme (integration) activity. In this report, we characterized the structure and function of the Moloney murine leukemia virus (MLV) IN protein in viral DNA synthesis. Using an MLV vector containing green fluorescent protein as a sensitive reporter for virus infection, we found that mutations in either the catalytic triad (D184A) or the HHCC motif (H61A) reduced infectivity by approximately 1,000-fold. Mutations that deleted the entire IN (ΔIN) or 34 C-terminal amino acid residues (Δ34) were more severely defective, with infectivity levels consistently reduced by 10,000-fold. Immunoblot analysis indicated that these mutants were similar to wild-type MLV with respect to virion production and proteolytic processing of the Gag and Pol precursor proteins. Using semiquantitative PCR to analyze viral cDNA synthesis in infected cells, we found the Δ34 and ΔIN mutants to be markedly impaired while the D184A and H61A mutants synthesized cDNA at levels similar to the wild type. The DNA synthesis defect was rescued by complementing the Δ34 and ΔIN mutants intrans with either wild-type IN or the D184A mutant IN, provided as a Gag-IN fusion protein. However, the DNA synthesis defect of ΔIN mutant virions could not be complemented with the Δ34 IN mutant. Taken together, these analyses strongly suggested that the MLV IN protein itself is required for efficient viral DNA synthesis and that this function may be conserved among other retroviruses.
8
Fang, Feng, Jason Hoskins, and J. Scott Butler. "5-Fluorouracil Enhances Exosome-Dependent Accumulation of Polyadenylated rRNAs." Molecular and Cellular Biology 24, no. 24 (December 15, 2004): 10766–76. http://dx.doi.org/10.1128/mcb.24.24.10766-10776.2004.
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ABSTRACT The antimetabolite 5-fluorouracil (5FU) is a widely used chemotherapeutic for the treatment of solid tumors. Although 5FU slows DNA synthesis by inhibiting the ability of thymidylate synthetase to produce dTMP, the drug also has significant effects on RNA metabolism. Recent genome-wide assays for 5FU-induced haploinsufficiency in Saccharomyces cerevisiae identified genes encoding components of the RNA processing exosome as potential targets of the drug. In this report, we used DNA microarrays to analyze the effect of 5FU on the yeast transcriptome and found that the drug causes the accumulation of polyadenylated fragments of the 27S rRNA precursor and that defects in the nuclear exoribonuclease Rrp6p enhance this effect. The size distribution of these RNAs and their sensitivity to Rrp6p suggest that they are normally degraded by the nuclear exosome and a 5′-3′ exoribonuclease. Consistent with this hypothesis, 5FU inhibits the growth of RRP6 mutants with defects in the degradation function of the enzyme and it interferes with the degradation of an rRNA precursor. The detection of poly(A)+ pre-RNAs in strains defective in various steps in ribosome biogenesis suggests that the production of poly(A)+ pre-rRNAs may be a general result of defects in rRNA processing. These findings suggest that 5FU inhibits an exosome-dependent surveillance pathway that degrades polyadenylated precursor rRNAs.
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Olsen, W. A., E. Perchellet, and R. L. Malinowski. "Intestinal mucosa in diabetes: synthesis of total proteins and sucrase-isomaltase." American Journal of Physiology-Gastrointestinal and Liver Physiology 250, no. 6 (June 1, 1986): G788—G793. http://dx.doi.org/10.1152/ajpgi.1986.250.6.g788.
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The effects of insulin deficiency on nitrogen metabolism in muscle and liver have been extensively studied with recent in vivo demonstration of impaired protein synthesis in rats with streptozotocin-induced diabetes. Despite the significant contribution of small intestinal mucosa to overall protein metabolism, the effects of insulin deficiency on intestinal protein synthesis have not been completely defined. We studied the effects of streptozotocin-induced diabetes on total protein synthesis by small intestinal mucosa and on synthesis of a single enzyme protein of the enterocyte brush-border membrane sucrase-isomaltase. We used the flooding-dose technique of McNurlan, Tomkins, and Garlick (Biochem. J. 178: 373–379, 1979) to minimize the difficulties of measuring specific radioactivity of precursor phenylalanine and determined incorporation into mucosal proteins and sucrase-isomaltase 20 min after injection of the labeled amino acid. Diabetes did not alter mucosal mass as determined by weight and content of protein and DNA during the 5 days after injection of streptozotocin. Increased rates of sucrase-isomaltase synthesis developed beginning on day 3, and those of total protein developed on day 5. Thus intestinal mucosal protein synthesis is not an insulin-sensitive process.
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Chen, Yuzhi, Wenyun Liu, Donna L. McPhie, Linda Hassinger, and Rachael L. Neve. "APP-BP1 mediates APP-induced apoptosis and DNA synthesis and is increased in Alzheimer's disease brain." Journal of Cell Biology 163, no. 1 (October 13, 2003): 27–33. http://dx.doi.org/10.1083/jcb.200304003.
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APP-BP1, first identified as an amyloid precursor protein (APP) binding protein, is the regulatory subunit of the activating enzyme for the small ubiquitin-like protein NEDD8. We have shown that APP-BP1 drives the S- to M-phase transition in dividing cells, and causes apoptosis in neurons (Chen, Y., D.L. McPhie, J. Hirschberg, and R.L. Neve. 2000. J. Biol. Chem. 275:8929–8935). We now demonstrate that APP-BP1 binds to the COOH-terminal 31 amino acids of APP (C31) and colocalizes with APP in a lipid-enriched fraction called lipid rafts. We show that coexpression of a peptide representing the domain of APP-BP1 that binds to APP, abolishes the ability of overexpressed APP or the V642I mutant of APP to cause neuronal apoptosis and DNA synthesis. A dominant negative mutant of the NEDD8 conjugating enzyme hUbc12, which participates in the ubiquitin-like pathway initiated by APP-BP1, blocks neuronal apoptosis caused by APP, APP(V642I), C31, or overexpression of APP-BP1. Neurons overexpressing APP or APP(V642I) show increased APP-BP1 protein levels in lipid rafts. A similar increase in APP-BP1 in lipid rafts is observed in the Alzheimer's disease brain hippocampus, but not in less-affected areas of Alzheimer's disease brain. This translocation of APP-BP1 to lipid rafts is accompanied by a change in the subcellular localization of the ubiquitin-like protein NEDD8, which is activated by APP-BP1.
Dissertations / Theses on the topic "Enzyme-DNA precursor synthesis"
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Harvey, G. "Multi-enzyme complexes of DNA precursor pathways in uninfected mammalian cells and cells infected by Herpes simplex virus type-1." Thesis, University of Aberdeen, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377617.
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This study was carried out to investigate the existence of a functioning multi-enzyme complex, providing DNA precursors, in a mammalian cell system. Both uninfected BHK-21/C13 cells and cells infected with HSV-1 were investigated. Sucrose gradient centrifugation of uninfected BHK cell lysates showed co-sedimentation of a number of DNA precursor pathway enzymes, indicative of a multi-enzyme complex, including DNA polymerase, thymidine kinase, NDP kinase, dihydrofolate reductase and ribonucleotide reductase. This complex association was seen to be cell-cycle dependent and sensitive to ionic conditions. The enzymes involved were not non-specifically bound to either RNA or DNA, but did have template DNA associated at times of DNA replication. Sedimentation analysis of virus-induced enzymes synthesised in HSV-1 infected cells showed the enzymes not to form such a complete complex, although thymidine kinase and ribonucleotide reductase did sediment together. Again, this association was sensitive to ionic conditions. Optimally permeabilized cell systems were characterised and implemented to carry out kinetic analysis. No evidence for substrate channeling, in either uninfected or HSV-1 infected BHK-21/C13 cells, was obtained using such permeabilized cell systems.
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Stevenson, David. "An investigation of potential multi-enzyme complexes of DNA precursor synthesis and DNA replication in eukaryotic cells." Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277287.
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1. Efforts to display a 'replitase' complex in two disparate lower eukaryotes, Saccharomyces cerevisiae and Physarum polycephalum whether employing physical or kinetic techniques have yielded no evidence to support its existence at this level of biological complexity. 2. Some indication of potential interaction of the folate-metabolising enzymes, dihydrofolate reductase and thymidylate synthase, were attained from affinity chromatography and non-denaturing gel electrophoresis studies of S. cerevisiae lysates. 3. Experiments on lysates prepared from S. cerevisiae spheroplasts imply a cytoplasmic location for the enzymes NDP kinase, dihydrofolate reductase, thymidylate kinase and thymidylate synthase while DNA polymerase, by virtue of its much reduced activity in such extracts, appears to be non-cytoplasmic. 4. Lysates of S-phase P. polycephalum macroplasmodia and exponentially-growing microplasmodia have different DNA polymerase elution profiles when subjected to Sepharose 6B gel filtration chromatography implying the existence of an S-phase-specific activity. 5. Fractions from the trailing section of the S-phase-specific peak of P. polycephalum DNA polymerase following gel filtration chromatography are capable of utilising [3H]dTMP but not [3H]TdR as substrate. The substrates of dTMP synthetase (dUMP plus co-factors) are not capable of substituting for dTTP in the DNA polymerase assay in these fractions. 6. Thymidylate synthase does not seem to be physically linked with the DNA polymerase from S-phase BHK-21/C13 cells.