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)

Analysis of RNA transcription from isolated mouse liver chromatin has been undertaken by means of RNA-excess hybridizations with small amounts of radioactive DNA. This analysis indicates that mouse liver chromatin is a restricted template for the in vitro synthesis of RNA complements to repetitive DNA, but more RNA species are synthesized than are found in the RNA isolated from mouse liver nuclei. Extraction with 0.5 M NaC1 destroys the template restriction of isolated chromatin. RNA synthesized in vitro from DNA or chromatin templates by Escherichia coli RNA polymerase, as well as in vivo mouse liver nuclear RNA, were each hybridized to 125I-labeled DNA of high, intermediate, or low reiteration frequency. Chromatin-primed and nuclear RNA saturate a smaller portion of each DNA fraction than does DNA-primed RNA. However, chromatin-primed RNA saturates more high and low reiteration frequency DNA than does nuclear RNA. Simultaneous hybridization of nuclear-and chromatin-primed RNA with 125I-labeled DNA indicates that chromatin-primed RNA contains all of the sequences present in nuclear RNA. Extraction of chromatin with 0.5 MNaC1 leads to removal of histone F1, as well as a wide variety of non-histone proteins. When used as a template for in vitro RNA synthesis, such salt-extracted chromatin produced RNAs that hybridize as large a portion of each DNA fraction as does DNA-primed RNA.
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PMID:Transcription of isolated mouse liver chromatin. 95 55

Amal, an alpha-amanitin-resistant mutant of the Chinese hamster ovary cell line, contains an RNA polymerase activity which elutes from DEAE-Sephadex at a salt concentration characteristic of an RNA polymerase II, but which is not sensitive to alpha-amanitin at levels where the polymerase II of wild-type cells is strongly inhibited. This result suggests that Amal owes its amanitin-resistant phenotype to a mutation affecting one of its genes for RNA polymerase II. To test this hypothesis, we purified the enzyme from Amal and then compared its properties with those of the wild-type enzyme. The mutant enzyme is indeed a polymerase II, and is over 600 times less sensitive to alpha-amanitin and more thermolabile than the wild-type enzyme.
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PMID:The RNA polymerase II of an alpha-amanitin-resistant Chinese hamster ovary cell line. 95 93

Dormant embryos at the gastrula stage of Artemia salina contain three DNA-dependent RNA polymerases: I, II, and III. The enzymes are solubilized from whole embryos and they are separated by chromatography on DEAE Sephadex. The ratio of activities with native and denatured DNA at the optimal salt concentrations is 3.5 for RNA polymerase I, 0.1 for RNA polymerase II and 1.0 for RNA polymerase III.Mn(i2+) is more efficient than Mg(2+) for the three enzymes. RNA polymerase II is 50% inhibited by 5 ng/ml of alpha-amanitin while RNA polymerases I and III are 10% and 30% inhibited by 1 mg/ml. During the embryonic development there is am independent variation of the levels of the RNA polymerases. RNA polymerase I increases its specific activity 4-5-fold, RNA polymerase III increases 2-fold, and RNA polymerase II less than 2-fold. The increase in RNA polymerase activity may represent a mechanism to control the rate of synthesis of RNA during the embryogenesis of A. salina.
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PMID:Characterization and levels of the RNA polymerases during the embryogenesis of Artemia salina. 97 89

Part of the nucleotide sequence of a restriction fragment covering the origin of phiX174 DNA replication 1 has been determined. The fragment A7c was obtained by digestion of phiX174 RF DNA by the restriction enzyme from Arthrobacter luteus, Alu 1. It was further cleaved into two fragments, one large and one small, by the action of the restriction enzyme from Haemophilus aegyptius, Hae 111. The nucleotide sequence of the small fragment has been determined by analysis of the transcription products obtained by the action of Escherichia coli DNA-dependent RNA polymerase on denaturated template under conditions of low salt. Transcripts longer than the template were found. The whole sequence of 71 nucleotide pairs could be derived from complementary oligonucleotides, obtained after digestion of the transcripts with T1 or pancreatic RNAase. The sequence suggests that at least 4 of the 5 amber mutants 2 that have been mapped on this fragment are identical. On account of this and other evidence a reading frame is proposed.
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PMID:The nucleotide sequence of a DNA fragment, 71 base pairs in length, near the origin of DNA replication of bacteriophage 0X174. 99 52

Differences noted in enzyme II directed RNA synthesis under varying salt conditions in nuclei isolated from uninfected and Friend virus (FV)-infected spleen cells, have been attributed to chromosomal modifications (Babcock and Rich 1973). This investigation was undertaken to determine if compositional changes occur in the chromatin of FV-infected spleens, which correlate with an altered rate of synthesis by enzyme II. A quantitative study of the chromatin constituents at various times after infection indicated that they vary in the same temporal manner as the rate of RNA synthesis in isolated nuclei. Relative to DNA, RNA, histone, and nonhistone protein reached a maximum at 14 days postinfection. This was followed by a gradual decrease during the remainder of the infection. Chromatin endogenous DNA-dependent RNA polymerase activity varied in the same manner, suggesting that RNA synthesis directed by enzyme II is modulated by chromosomal proteins.
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PMID:Temporal changes in chromatin isolated from Friend virus-infected mouse spleens. 101 37

The DNA-directed in vitro synthesis of beta-galactosidase has been investigated in a system dependent on Escherichia coli ribosomes, a salt wash of the ribosomes, and a supernatant fraction. Fractionation of the supernatant has made it possible to obtain dependencies on RNA polymerase and another protein factor for beta-galactosidase synthesis. The other factor (called L factor) cannot be replaced by a variety of proteins known to be required for transcription and translation. It has been purified to homogeneity and has a molecular weight of approximately 65,000. Although it is required for the in vitro synthesis of beta-galactosidase, it has no effect on total DNA-dependent amino acid incorporation under the conditions of the incubation. However, total RNA synthesis is depressed by the addition of L factor in a manner similar to what is observed with rho factor could not replace L factor in beta-galactosidase synthesis.
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PMID:Purification and properties of a soluble factor required for the deoxyribonucleic acid-directed in vitro synthesis of beta-galactosidase. 108 61

The transcription of Azotobacter phage A21 DNA by Escherichia coli or Azotobacter vinelandii RNA polymerase differs from that of some other DNAs in its inhibition by moderate concentrations of KCl. This characteristic results in an apparent low template activity for this DNA as compared with T4 DNA under standard assay conditions. From an analysis of the dependence of the various steps in initiation on KCl it is concluded that the effect is exerted on an equilibrium between an inactive polymerase-DNA complex and an active preintitiation complex. This salt-sensitive equilibrium favors the inactive complex at a lower KCl concentration than with other templates. It can be approached from other low or high salt concentrations at a measurably slow rate.
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PMID:Transcription of Azotobacter phage deoxyribonucleic acid. Salt-dependent equilibrium between steps in initiation. 109 43

The reality of the nonrandom distribution of histones along the chromatin strand was investigated in several ways. It does not appear to derive from histone exchange during shearing and is evident in chromatin fixed with formaldehyde prior to shearing. Endogenous or Escherichia coli polymerase are preferentially associated with regions of chromatin with a low protein/DNAratio. Although RNA polymerase and histones are fixed to chromatin after formaldehyde treatment with high efficiency, only a minor fraction of non-histone protein is fixed under similar conditions. Even after washing in high salt to minimize adventitious association, most remaining non-histone protein fails to be fixed. The utility of this approach for defining chromosomal proteins is discussed.
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PMID:The nature of protein association with chromatin. 109 33

Isolated rat liver nuclei demonstrate an increased ability to synthesize RNA in the presence of either spermine or spermidine. Spermidine has more effect on the low-salt alpha-amanitin-insensitive reaction, and spermine has more effect on the high-salt alpha-amanitin-sensitive reaction. Spermine is effective at concentrations of 0.1 mM and 1 muM, showing a biphasic effect. The RNA polymerase activity associated with nuclear chromatin is increased in the presence of spermine only at a concentration of 0.1 mM. Aso the transcription of deproteinized liver DNA by liver form-B polymerase or Escherichia coli enzyme is more efficient in the presence of 0.1 mM-spermine. Only when liver chromatin is transcribed by its homologous enzyme (and not by E. coli enzyme) is spermine active at both 0.1mM and 1 muM as in purified nuclei. The lower concentration of spermine (1 muM) is able to affect chromatin transcription by increasing the affinity of chromatin for the enzyme. Our findings suggest a regulatory role of spermine at the level of genome transcription.
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PMID:The effect of spermine on transcription of mammalian chromatin by mammalian deoxyribonucleic acid-dependent ribonucleic acid polymerase. 109 73

The influence of temperature and KCl concentration on the formation of rifampicin-resistant preinitiation complexes by holo RNA polymerase has been compared for T4 DNA and Azotobacter phage A21 DNA. The sharp transition with respect to temperature between an inactive complex of polymerase and DNA and a preinitiation complex reflects an equilibrium between the two complexes, the position of which depends on the temperature and the salt concentration. The transition is shifted to higher temperatures by increasing the KCl concentration. The position of this transition is characteristically different for T4 and A21 DNA. The midpoint for A21 DNA is about 15 degrees C above that for T4 at 0.006 M KCl. At 0.15 M KCl the transition for A21 DNA cannot be observed below 37 degrees C. This difference is responsible for the apparent inhibition of a21 dna transcription by KCl and for the low template activity of A21 DNA under the conditions of the standard assay. Both holo and core RNA polymerases are able to form complexes with A21 DNA that are resistant to attack by rifampicin. The second-order rate constant for the inactivation of the complex with the core enxyme is three times greater than that for the complex with the holoenzyme.
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PMID:Temperature and salt effects on the formation of preinitiation complexes between RNA polymerase and phage DNA. 110 Jan 15


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