Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plagemann, Peter G. W. (Western Reserve University, Cleveland, Ohio), and H. Earle Swim. Replication of mengovirus. II. General properties of the viral-induced ribonucleic acid polymerase. J. Bacteriol. 91:2327-2332. 1966.-Mengovirus induces the appearance of a ribonucleic acid (RNA) polymerase activity in Novikoff hepatoma cells which is readily distinguished from the deoxyribonucleic acid (DNA)-dependent RNA polymerase since it is not inhibited by actinomycin D or deoxyribonuclease, but is inhibited by ammonium sulfate, and is stable at -17 C. The incorporation of uridine into RNA by infected cells in the presence of actinomycin D does not reflect the viral polymerase activity as measured in cell-free preparations. The viral-induced RNA polymerase is produced in a biphasic fashion. Puromycin inhibits the production of viral polymerase, and in its presence the enzyme appears to be unstable between 4 and 6 hr. Puromycin also prevents the secondary rise in polymerase which begins at the end of replicative cycle. Under these conditions, however, the polymerase appears to be stable. The overall data indicated that some unspecified process is responsible for the apparent instability of viral-induced RNA polymerase between 4 and 6 hr and that it becomes inoperative toward the end of the replicative cycle.
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PMID:Replication of mengovirus. II. General properties of the viral-induced ribonucleic acid polymerase. 428 86

The presence of adenosine triphosphate, guanosine triphosphate, cytosine triphosphate, or uridine triphosphate reduced the rate of inactivation of vaccinia when heated at 50 C. The virus-associated nucleoside triphosphate phosphohydrolases (adenosine triphosphatase, guanosine triphosphatase, cytosine triphosphatase, and uridine triphosphatase) and ribonucleic acid polymerase were also protected from heat inactivation by these compounds. These obervations are best explained by postulating that ribonucleoside triphosphates bind to enzymes in the virus particle, and that these enzyme-substrate complexes are more resistant to thermal denaturation than are the enzymes without their substrates. The kinetics of heat inactivation of the vaccinia ATP phosphohydrolase activity is biphasic, suggesting that there are two proteins in the vaccinia particle that have this enzyme activity but they have different kinetics of heat inactivation. Any of the vaccinia-associated nucleotide phosphohydrolase activities are protected from heat inactivation by the presence of any one of the respective nucleoside triphosphates. This observation suggests that there is a single enzymatic site in vaccinia that is able to react with any ribonucleoside triphosphate.
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PMID:Protection of vaccinia from heat inactivation by nucleotide triphosphates. 431 59

A ribonucleic acid (RNA)-dependent RNA polymerase was induced in chick embryo fibroblast cells after infection with Sendai virus (parainfluenza 1 virus). The enzyme was associated with the microsomal fraction of infected cells and reached maximum detectable activity at 18 hr after virus infection. The activity of the enzyme in vitro was dependent on the presence of added magnesium ions and all four nucleoside triphosphates and was not inhibited by actinomycin D. The RNA synthesized by the enzyme in vitro was sensitive to ribonuclease and consisted of a complex mixture of RNA species including 34S, 24S, and 18S components. Similar RNA components were detected in the microsomal fraction of Sendai virus-infected cells by labeling with (3)H-uridine from 17 to 18 hr postinfection in the presence of actinomycin D. Of the RNA synthesized by Sendai virus-induced RNA polymerase in vitro, 98% became insensitive to ribonuclease after annealing with RNA extracted from purified Sendai virus particles.
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PMID:Ribonucleic acid polymerase induced in cells infected with Sendai virus. 431 10

Cytoplasmic extracts of chicken embryo fibroblast cells infected with Semliki Forest virus were subjected to isopycnic centrifugation in discontinuous sucrose gradients. Seven distinct bands were usually formed. The four upper bands contained predominantly smooth membranes and the lowest band was enriched in rough endoplasmic reticulum. One fraction (fraction 5), banding at a density of 1.16 g/cm(3), was found to be heavily enriched in pulse-labeled ribonucleic acid (RNA), viral RNA polymerase, and viral RNA forms associated with RNA replication. Thus, fraction 5 evidently contained a membrane-associated viral replication complex of a type previously defined in picornavirus infections. Fraction 5 was also consistently enriched with unique membranous structures previously observed in intact cells as type 1 cytopathic vacuoles (CPV-1). When the CPV-1 in fraction 5 were isolated from cells briefly incubated with (3)H-uridine and (3)H-adenosine prior to cell disruption, a large proportion was found to be labeled by high-resolution autoradiography. Thus, ultrastructural, biochemical, and biological evidence were all consistent with the interpretation that the CPV-1 membranes represent a significant element of the viral replication complex.
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PMID:Membrane-associated replication complex in arbovirus infection. 434 56

Transcriptase activity was dissociated from vesicular stomatitis virions by highionic-strength buffer containing Triton X-100. Considerable enzyme activity could be restored by recombining inactive sedimentable and nonsedimentable virion fractions. Reconstituted transcriptase activity was dependent on the presence of all four nucleoside triphosphates and the concentration of heat-labile molecules in both supernatant and pellet fractions. Lower NaCl concentrations removed approximately 46% of virion protein, but did not release transcriptase activity from the pellet fraction, nor could incorporation of (3)H-uridine-5'-triphosphate by complete virions be increased by adding soluble transcriptase. Evidence that the virion nucleocapsid is the transcription template was provided by finding that the pellet contained predominantly virion core nucleoprotein, ribonucleic acid, and homogeneous nucleocapsid coils when viewed by electron microscopy. Removal of envelope G and M proteins by Triton and low-salt buffer without decreasing nucleocapsid polymerase activity indicates that neither G nor M protein is necessary for transcription. Additional data are required to determine whether the minor nucleocapsid proteins L or NSl, or both, which are at least partially solubilized in high-salt buffer, are the transcriptase. Preliminary data suggest that the major N nucleoprotein, which was not solubilized by high-salt buffer, is also required for transcription. Defective T virions contained at least as much transcriptase per weight as did B virions, as determined by restoration with T supernatant fluids of transcription function to B nucleocapsid template. However, the T nucleocapsid would not serve as template for B or T transcriptase, a finding which is interpreted as evidence of T template defectiveness. The presence of defective T nucleocapsids did not interfere with B or T transcriptase function reconstituted with B template.
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PMID:Dissociation and reconstitution of the transcriptase and template activities of vesicular stomatitis B and T virions. 434 47

At a concentration of 10 mum, camptothecin inhibited vaccinia deoxyribonucleic acid (DNA) synthesis in HeLa cells. Inhibition of viral DNA synthesis was observed when the drug was added before infection or at 1 or 2 hr after infection. Inhibitory effects of camptothecin on vaccinia DNA synthesis could be reversed, even after exposure to the alkaloid for 2 hr. Viral DNA, isolated from vaccinia-infected, camptothecin-treated cells, displayed an altered sedimentation constant after alkaline sucrose density gradient centrifugation. Incorporation of uridine into vaccinia messenger ribonucleic acid was inhibited by camptothecin, but the activity of ribonucleic acid polymerase, as tested in isolated vaccinia cores, was not affected by the drug. Camptothecin had essentially no effect on replication of poliovirus in HeLa cells.
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PMID:Antiviral action of camptothecin. 436 89

Chromatin template activity of mouse parotid glands increases after a single injection of isoproterenol (IPR), a procedure that causes, after a lag period of 20 hr, a marked stimulation of DNA synthesis and cell division in salivary glands of rodents. The increase in chromatin template activity occurs as early as 1 hr and peaks between 6 and 10 hr after IPR, paralleling previously reported changes in the incorporation of uridine-(3)H into total cellular RNA of mouse parotids. Template activity was measured in vitro in a system in which parotid gland chromatin was incubated with an exogenous RNA polymerase isolated from Escherichia coli. Similar results were obtained when template activity of parotid gland chromatin was assayed using an homologous RNA polymerase from mouse liver. Chromatin template activity in mouse parotids was also studied after the administration of drugs capable of inducing in salivary glands both DNA synthesis and secretion or secretion alone. The results indicate that the increased chromatin template activity occurring 6 hr after IPR is related to the subsequent onset of DNA synthesis. Furthermore, the increased chromatin template activity caused by IPR is inhibited by the previous administration of puromycin, an inhibitor of IPR-stimulated DNA synthesis.
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PMID:Changes in chromatin template activity and their relationship to DNA synthesis in mouse parotid glands stimulated by isoproterenol. 457 Dec 29

The restitution of RNA synthesis in cultures progressing from metaphase into interphase (G(1)) has been investigated in synchronized HeLa S(3) cells by using inhibitors of macro-molecular synthesis and the technique of electron microscope autoradiography. The rate of incorporation of radioactive uridine into RNA approached interphase levels in the absence of renewed protein synthesis. In contrast, maintenance of this rate in G(1) was dependent upon renewed protein synthesis. Restoration of synthesis of heterogeneous nuclear RNA occurred under conditions that inhibited production of ribosomal precursor RNA. In autoradiographs of individual cells exposed to radioactive uridine, silver grains were first detected after nuclear envelope reformation at the periphery of the chromosome mass but before chromosomal decondensation. These data are consistent with the following interpretation. Multiple RNA polymerase activities persist through mitosis and are involved in the initiation of RNA synthesis in early telophase at sites on the nuclear envelope.
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PMID:Nuclear envelope-associated resumption of RNA synthesis in late mitosis of HeLa cells. 475 3

Ribonucleic acid (RNA) polymerases of Histoplasma capsulatum (yeast phase) were fractionated by phosphocellulose chromatography and partially characterized. Three distinct, active fractions were seen. The major RNA polymerase species was inhibited strongly by alpha-amanitin, whereas the other two were resistant. When either slightly purified (HSE) extract or the major active component was assayed at 37 C, the incorporation of tritiated uridine monophosphate into RNA stopped after 10 to 15 min. In contrast, the synthesis continued for at least 1 h at 23 C. The other two RNA polymerase species exhibited higher rates of incorporation when tested at 37 C, and continued to synthesize RNA even after 60 min. However, by that time the levels of incorporation at 23 C were higher than at 37 C for all three enzymes. The temperature sensitivity was not affected by changing substrate concentration or employing either native or denatured calf thymus deoxyribonucleic acid as a template. These results are compared with the data obtained with RNA polymerases from different fungi and other organisms. A possible involvement of RNA polymerase(s) in morphological differentiation of H. capsulatum is discussed.
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PMID:Ribonucleic acid polymerases of the yeast phase of Histoplasma capsulatum. 482 8

DNA from Mycoplasma sp. Kid which was enriched for tRNA genes (containing about 10% tDNA) was transcribed by E. coli RNA polymerase. The RNA transcription product labeled with [(14)C]uridine was formed in good yield (70-fold net synthesis). After incubation of this [(14)C]uridine-labeled RNA with E. coli extracts, nucleotide analyses revealed that [(14)C]pseudouridine was formed. The experiments support the idea that the conversion of uridine to pseudouridine takes place at the macromolecular level. Furthermore, the conversion was shown to be specific for a uridine residue in tRNA-like material since neither [(14)C]polyuridylic acid nor the [(14)C]uridine-labeled RNA transcribed from lambda DNA served as substrate for the pseudouridine-forming enzyme(s).
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PMID:In vitro biosynthesis of pseudouridine at the polynucleotide level by an enzyme extract from Escherichia coli. 494 84


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