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)

The interaction of pyridoxal, pyridoxal-5'-mono-, di- and triphosphate with certain enzymes of polynucleotide synthesis (DNA-dependent RNA polymerase, DNA-dependent DNA polymerase I and polynucleotide phosphorylase from Escherichia coli and terminal deoxyribonucleotide transferase from calf thymus) was studied. All compounds tested was found to be reversible and competitive inhibitors of these enzymes. The reduction of the enzyme-inhibitor complex with NaBH4 gives rise to the complete irreversible inhibition of the enzymes under study. The comparison of the inhibition constants for pyridoxal and its phosphorylated derivatives with those for mono-, di- and triphosphates of nucleosides was carried out for the enzymes. The results obtained suggest that the modified epsilon-amino-group of lysine residue should be localized at the catalytic site in the vicinity of the pyrophosphate binding area of an enzyme.
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PMID:[Interaction of oligophosphates of pyridoxal with certain enzymes of polynucleotide synthesis]. 38 98

Minicells segregated from Escherichia coli chi925 carrying a drug-resistance plasmid were separated from nucleated cells by differential centrifugation and purified by rate-zonal centrifugation in sucrose gradients. Minicells purified in this way were capable of donating the plasmid to nucleated cells. They also incorporated thymidine, uridine and methionine into macromolecules. Methods are described for purification of plasmid-containing minicells on a scale large enough to allow isolation of DNA, DNA polymerase and RNA polymerase in sufficient quantities for studies of enzymes involved in replication and transcription of plasmid DNA.
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PMID:Isolation by differential and zonal centrifugation of minicells segregated by Escherichia coli. 38 90

A modified in vitro replication system has been characterized and used to catalogue the host proteins required for the replication of plasmid RSF1030. These extracts differ from systems described previously in that endogenous DNA is removed. Replication in vitro therefore requires an exogenouos RSF1030. Synthesis in the in vitro system faithfully mimics in vivo replication with respect to the products synthesized, effects of specific inhibitors, and requirements for RNA polymerase and DNA polymerase I. In addition, we find that proteins encoded by dnaB, dnaC, dnaG, dnaI, dnaP and polC (DNA polymerase III), are required for in vitro plasmid synthesis. The product of dnaA is not required. Extracts prepared from E. coli mutants deficient in in vitro replication can be complemented by addition of purified proteins or of extracts carrying the wild type protein.
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PMID:Characterization of an improved in vitro DNA replication system for Escherichia coli plasmids. 38 67

Synthesis of DNA complementary to the transferred strand of an IncI alpha plasmid has been shown previously to require DNA polymerase III. The possible involvement of the two defined priming proteins of Escherichia coli K12, RNA polymerase and primase, in initiating this conjugal DNA synthesis had been examined. Primase was inactivated using temperature-sensitive dnaG3 mutants and RNA polymerase was inhibited using rifampicin. When these two proteins were simultaneously inactivated in both parental strains, the average recipient synthesised at least one single-stranded equivalent of R144drd-3 before the rifampicin-treated donors lost the ability to transmit DNA. It is proposed that the product of a plasmid transfer gene is responsible for initiating this DNA synthesis in recipients. The results imply that this protein is supplied by the donors.
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PMID:A novel priming system for conjugal synthesis of an IncI alpha plasmid in recipients. 39 29

Activities of DNA polymerases and RNA polymerases were studied by autoradiographic methods in growing and differentiating root cortex cells of Zea mays - a species in which endomitosis occurs - and Tulipa kaufmanniana - in which this process does not occur. In Tulipa kaufmanniana, the highest activity of DNA polymerase appears in the nuclei of meristematic zone during the S phase of the cell cycle. In Zea mays, endomitotic replication of DNA occurs in all growth and differentiation zones and the activity of DNA polymerase in the nuclei is similar to that in the meristematic zone. In both species, nuclear RNA synthesis, measured with 3H uridine incorporation, is highest in the meristematic zone and declines steadily with development. Activity of nuclear RNA polymerase is present in all developmental zones in both species and is similar to that in the meristematic zone. 3H uridine incorporation into nucleoli decreases markedly in both species, whereas the activity of nucleolar RNA polymerase remains at a high level in all root segments in Zea mays and decreases slightly in Tulipa kaufmanniana. It is argued that the differences between the incorporation of 3H uridine and that or 3H UMP may be caused by a reduction of the pool of endogenous ribonucleoside triphosphates. Marked activities of DNA polymerase and RNA polymerase in cytoplasm are possibly related to the growth and division of plastids and mitochondria.
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PMID:Activities of DNA polymerases and RNA polymerases detected in situ in growing and differentiating cells of root cortex. 42 7

The quassinoids bruceantin, brucein D, brucein E, bruceoside A, and brusatol significantly inhibited P-388 lymphocytic leukemic cell RNA and protein synthesis in tissue culture. However, DNA synthesis inhibition seemed to correlate more directly with the anti-neoplastic activity of these compounds in the in vivo P-338 survival system. In vitro, brusatol and bruceoside A marginally inhibited 10-day P-388 lymphocytic leukemia DNA polymerase, RNA polymerase, thymidylate synthetase, dihydrofolate reductase, phosphoribosyl pyrophosphate aminotransferase, and cathepsin protease activities. In vivo studies demonstrated similar inhibition and elevated cyclic AMP levels, correlating positively with the antineoplastic activity of individual compounds. Purine synthesis was inhibited drastically by brusatol in vivo, and one key inhibition site in purine synthesis was at phosphoribosyl pyrophosphate aminotransferase, the regulatory enzyme. Histone phosphorylation and ribonucleotide reductase activity also were inhibited marginally by brusatol.
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PMID:Antitumor agents. XXXIV: Mechanism of action of bruceoside A and brusatol on nucleic acid metabolism of P-388 lymphocytic leukemia cells. 45 10

RNA polymerase B and DNA polymerase alpha were highly enriched simultaneously from calf thymus. It was shown that the preparation exhibits RNA-synthesizing activity, which is able to stimulate in vitro DNA synthesis by DNA polymerase alpha by its preceding RNA synthesis. A part of the DNA was found to be covalently attached to RNA in Cs2SO4 equilibrium gradients after denaturation by formamide.
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PMID:RNA-primed DNA synthesis by an enzyme preparation of calf thymus containing highly enriched RNA polymerase B and DNA polymerase. 54 71

We report the first measurement of the magnetic circular dichroism (MCD) of the basic polypeptide antibiotic netropsin (Nt). The MCD shows that the longest wavelength absorption band of Nt is the sum of more than one component and permits a radically new interpretation of the circular dichroism of the complex which Nt forms with DNA. We conclude that Nt has no major effect on the CD and thus the helical structure of the bases of the DNA to which it is bound. Thus the ability of Nt to inhibit the function of DNA polymerase, RNA polymerase, and the photoreactivating enzyme must be mediated by factors other than a distortion of the helical structure of the bases.
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PMID:Magnetic circular dichroism of netropsin and natural circular dichroism of the netropsin-DNA complex. 56 96

The rational design of antitumor and antiviral agents must ultimately take advantage of biochemical differences between normal host cells and transformed cells. The initial experiments must be performed with subcellular or cellular model systems. For the studies with arabinosyl nucleosides we have chosen those enzyme systems, synthesizing DNA and RNA; being precursor analogues, the different arabinosyl nucleosides have been added in the triphosphate state to the different DNA- and RNA polymerase assays. 1-beta-D-Arabinofuranosylcytosine-5'-triphosphate has been found to inhibit the RNA-dependent DNA polymerases (isolated from oncogenic RNA viruses) 200-fold more sensitively than viral and cellular DNA-dependent DNA polymerases. Recent results, showing that RNA-leukemia-virus-related sequences are present in DNA of some human leukemia patients might support the assumption that the efficacy of this antimetabolite in the treatment of acute leukemia is due to its, at least relative selective inhibitory activity on reverse transcriptase. 9-beta-D-Arabinofuranosyladenine-5'-triphosphate is a strong inhibitor of cellular DNA polymerases with the cytological consequence of an inhibition of cell proliferation. The clinical benefit of the compound in treatment of tumors is dependent on their levels of adenosine deaminase. The triphosphate of this compound is a 100-fold more sensitive inhibitor of the herpesvirus DNA polymerase compared to the cellular replicative DNA polymerase. In addition the analogue, incorporated into herpesvirus DNA, acts as chain terminator. These effects are the biochemical basis for the highly selective antiherpesvirus activity of this antimetabolite. The anomer 9-alpha-D-arabinofuranosyladenine-5'-triphosphate only inhibits cellular replicative DNA polymerase and has no effect on herpesvirus DNA polymerase. Consequently this agent acts only cytostatically and not antivirally. Concerning 1-beta-D-arabinofuranosyluracil and 1-beta-D-arabinofuranosylthymine no pronounced antitumor or antiviral effect is known.
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PMID:Rational design of arabinosyl nucleosides as antitumor and antiviral agents. 61 2

A non-enzymic protein factor that increases the in vitro rate of synthesis by HeLa DNA polymerase alpha 15- to 30-fold with denatured DNA as template has been partially purified from the cytoplasmic fraction of HeLa cells. The stimulatory effect is highly specific for HeLa DNA polymerase alpha and for DNA templates that contain extensive regions of single-strandedness. Synthesis with denatured DNA as template presumably proceeds from 3'-hydroxyl termini formed at loop-back regions since the synthesized DNA product and template are covalently linked. The stimulatory protein factor chromatographs as a basic protein, has an approximate molecular weight of 30,000 daltons and binds with moderate affinity to denatured DNA cellulose, being eluted by o.4M NaCl. The purified factor lacks detectable DNA polymerase, exo- and endodeoxyribonuclease and RNA polymerase activities. It also does not promote helix-coil transitions with poly[d(A-T)] and Clostridium perfringens DNA.
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PMID:HeLa DNA polymerase alpha activity in vitro: specific stimulation by a non-enzymic protein factor. 64 10


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