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)

Ten ribonucleic acid (RNA) tumor viruses grown in five different host cell species and three non-oncogenic viruses from three different virus groups have been examined for ribonuclease H content. Three different substrates were used to assay ribonuclease H: calf thymus [(3)H]RNA-deoxyribonucleic acid (DNA) hybrid prepared with denatured calf thymus DNA and Escherichia coli DNA-directed RNA polymerase, (3)H-polydenylic acid [(3)H-poly(A)] complexed to polydeoxythymidylic acid [poly(dT)], and (3)H-polyuridylic acid [(3)H-poly(U)] complexed to polydeoxyadenylic acid [poly(dA)]. All ten RNA tumor viruses contained ribonuclease H activity which degraded the RNA of both the calf thymus hybrid and poly(A)-poly(dT), whereas only the ribonuclease H in the Moloney strain of murine sarcoma-leukemia virus and in RD-feline leukemia virus hydrolyzed the RNA strand of poly(U)-poly(dA). No appreciable ribonuclease H activity was detected in influenza, Sendai, or vesicular stomatitis virus. The ribonuclease H and RNA-directed DNA polymerase activities in Moloney murine sarcoma-leukemia virus were inseparable by phosphocellulose chromatography or glycerol gradient centrifugation, but appeared to be partially separated by diethylaminoethyl-cellulose chromatography.
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PMID:Ribonuclease H: a ubiquitous activity in virions of ribonucleic acid tumor viruses. 411 67

A polycytidylate-dependent RNA polymerase of encephalomyocarditis virus was isolated from infected BHK 21 cells. The enzyme was associated with a smooth-membrane fraction, from which it was extracted by a mixture of sodium dodecyl sulfate, Triton X-100, and dithiothreitol, and further purified by chromatography on a Dowex-1 column and by glycerol gradient sedimentation. Analysis of a 6S glycerol gradient peak of RNA polymerase activity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of five polypeptides, of molecular weights 72,000, 65,000, 57,000, 45,000, and 35,000. The molecular weights of four of the polypeptides (72,000, 65,000, 45,000, and 35,000) are almost identical to the reported molecular weights of the four subunits of Qbeta replicase.
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PMID:Isolation and subunit structure of polycytidylate-dependent RNA polymerase of encephalomyocarditis virus. 434 9

The endogenous transcriptase present in purified vesicular stomatitis (VS) virions was solubilized with a Triton X-100 high-salt solution. The polymerase activity was purified on glycerol gradients and by phosphocellulose column chromatography; the viral proteins present in the active enzyme fractions were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It was demonstrated that L protein, but not NS protein, was required for in vitro RNA synthesis on the VS viral nucleocapsid template. Solubilized L protein rebinds to the ribonucleoprotein template when the transcription complex is reconstituted, and the RNA synthesized in vitro by purified L protein hybridizes to virion RNA. Cyanogen bromide peptide fingerprints indicate that the large L protein is a unique polypeptide chain. It is concluded that the L protein functions as the transcriptase, and the nucleocapsid NS protein is not essential for in vitro RNA synthesis.
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PMID:L protein requirement for in vitro RNA synthesis by vesicular stomatitis virus. 435 10

RNA polymerase has been purified from vegetative cells of Bacillus brevis and resolved into "core" enzyme and sigma factor. The purified enzyme is rapidly inactivated by incubation at low temperatures in the presence of 1-2 mM ATP, dATP, or NAD(+), while other nucleotides at this concentration have little or no effect. Inactivation is not accompanied by the incorporation of an adenylyl or phosphoryl moiety into RNA polymerase; nevertheless, it is essentially irreversible. DNA, high concentrations of glycerol, as well as low concentrations (1 mM) of orthophosphate protect RNA polymerase from the nucleotide-dependent inactivation.A similar inactivation of RNA polymerase in the presence of ATP is observed with crude preparations from Bacillus subtilis and Bacillus polymyxa. This phenomenon may represent a novel mode of regulation of transcription that does not involve a covalent modification of RNA polymerase or its interaction with other protein factors, but rather is due to a structural transition to an inactive form induced by small molecules.
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PMID:Nucleotide-dependent inactivation of RNA polymerase from Bacillus brevis. 440 27

The RNA nucleotidyltransferase (RNA polymerase) of the plant-tumorigenic bacterium Agrobacterium tumefaciens was purified. The method involves the disruption of the bacterial cells with glass beads in a Waring Blendor, treatment with DEAE-cellulose, fractionation with (NH(4))(2)SO(4), protamine sulphate precipitation, DEAE-cellulose column chromatography and either glycerol-gradient centrifugation or phosphocellulose chromatography. The subunit structure of the highly purified enzyme is similar to, although not identical with, the RNA nucleotidyltransferase of Escherichia coli. It can be described as beta', beta, chi(1) and alpha (mol.wts. 160000, 150000, 98000, and 41000+/-10% respectively). chi(1) is the temporary designation for a protein subunit, which might have the same functions as the sigma subunit in E. coli. The enzyme of A. tumefaciens is rifampicin-sensitive, has a temperature optimum in vitro of 41+/-1 degrees C and a pH optimum of 8.2+/-0.1. Mg(2+) and Mn(2+) are activators. The enzyme transcribes with different efficiencies artificial, viral, bacterial, plant and animal templates.
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PMID:The nucleoside triphosphate-ribonucleic acid nucleotidyltransferase (EC 2.7.7.6) of Agrobacterium tumefaciens (Smith and Townsend) Conn. Purification and properties of the enzyme from the tumorigenic strain B6806. 446 37

A rapid procedure involving DNA-cellulose chromatography followed either by sedimentation in a high-salt glycerol gradient or by gel filtration is described for the complete purification of Escherichia coli DNA-dependent RNA polymerase.
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PMID:A procedure for the rapid purification of Escherichia coli deoxyribonucleic acid-dependent ribonucleic acid polymerase. 457 61

1. The perturbing effect of glycerol on the direct spectrum of Escherichia coli DNA-dependent RNA polymerase has been studied. 2. By comparison with model compounds and with the unfolded polymerase in 3.8m-urea it was possible to determine the ratio of tyrosine and tryptophan residues present. On reduction of the urea-treated enzyme with 2-mercaptoethanol, no further change in the difference spectrum occurred. 3. The amino acid composition of the enzyme is given. 4. In the intact protein approx. 30% of the tryptophan and 54% of the tyrosine residues were exposed. In conjunction with the extinction value and molecular weight this corresponded to 7 tryptophan residues and 57 tyrosine residues on the surface and 16 tryptophan residues and 48 tyrosine residues ;buried'. 5. The optical rotatory dispersion of the enzyme was unaffected by 20% glycerol. 6. The helix content calculated from Moffit plots over 560-300nm was 13%, and from the 233nm trough 13%.
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PMID:Location of aromatic amino acids and belix content in Escherichia coli ribonucleic acid polymerase. 494 33

A DNA-dependent RNA polymerase has been solubilized and partially purified from washed chloroplasts prepared from maize seedlings. The purified enzyme was completely dependent on added DNA after purification by phospho- or DEAE-cellulose chromatography. On glycerol density gradients, the enzyme ran ahead of a marker with a sedimentation constant of 18 S, indicating a molecular weight of 500,000 or more. The instability of the highly purified enzyme made intensive study difficult, but the properties of the enzyme purified by phosphocellulose chromatography are reported. Template specificity varied during purification but the activity was always higher with denatured than with native DNA and the preference for maize DNA over calf-thymus DNA increased during purification. The enzyme required magnesium for optimal activity, was inhibited by salt concentrations in excess of 0.1 M, and had a temperature optimum of 48 degrees C. The chloroplast enzyme differed from similar activities so far reported from maize or other sources, particularly in the high salt concentrations needed to elute it from phosphocellulose. The soluble, DNA-dependent enzyme was not inhibited by either alpha-amanitin or by rifamycin-SV under the assay conditions used.
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PMID:RNA polymerases of maize: partial purification and properties of the chloroplast enzyme. 500 19

A procedure is described for isolation in a soluble form of a ribonucleic acid polymerase from rat testes. Evidence is presented that this enzyme catalyzes three distinct reactions: (a) deoxyribonucleic acid-directed synthesis of RNA in the presence of all four major ribonucleoside triphosphates; (b) DNA-primed formation of polyadenylic acid and other ribohomopolymers in the presence of single ribonucleoside triphosphate substrates; (c) synthesis of complementary polyribonucleotides in the presence of various ribohomopolymer primers. The properties of these reactions are discussed with respect to metal ion requirements, affinities for ribonucleoside triphosphates and primer polynucleotides, heat denaturation of DNA primers, and the effects of ionic strength, beta-mercaptoethanol, polyamines, temperature, and inhibitors on the rates and extent of the reactions. The testicular ribonucleic acid polymerase is a very unstable enzyme that can be stabilized by high concentrations of glycerol.
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PMID:Isolation and properties of a testicular ribonucleic acid polymerase. 531 60

The Bacteroides fragilis bacteriocin which inhibits ribonucleic acid (RNA) polymerase activity had a narrow activity spectrum in vivo and only inhibited the growth of certain B. fragilis strains. In vitro the bacteriocin was not specific and inhibited RNA polymerases from widely diverse bacterial genera. RNA polymerases from rifampin-resistant strains of Bacteroides thetaiotaomicron and Clostridium acetobutylicum were resistant to the bacteriocin in vitro. Purified bacteriocin bound to partially purified RNA polymerase, and both proteins were cosedimented in a glycerol gradient. In the RNA polymerase reaction, the bacteriocin acted as a competitive inhibitor for adenosine, cytidine, and uridine 5'-triphosphates and as a noncompetitive inhibitor for guanosine 5'-triphosphate. The bacteriocin did not inhibit RNA polymerase from chicken embryos.
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PMID:Inhibition of ribonucleic acid polymerase by a bacteriocin from Bacteroides fragilis. 617 80


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