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)

Sucrose density gradient centrifugation in the presence or absence of Na-EDTA and at different ionic strengths allows one to obtain well-defined nucleosome subpopulations the DNA of which, examined by gas chromatography-mass spectrometry, is in all cases hypermethylated as compared to spacer regions, but to a different extent for the different subpopulations. The various nucleosomes differ also in their content of histones and of high-mobility-group proteins, as well as in the levels of RNA polymerase activity associated with them. Such data suggest that these nucleosome subpopulations originate from chromatin fractions differently involved in gene expression.
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PMID:5-Methylcytosine levels in nucleosome subpopulations differently involved in gene expression. 374 73

A gene-specific transcription factor, called USF, has been partially purified from HeLa cell nuclear extracts. Addition of USF results in a 10 to 20 fold increase in transcription from the adenovirus major late promoter in an in vitro system reconstituted with transcription factors TFIIB, TFIID, TFIIE, and RNA polymerase II. Binding of USF to the promoter inhibits DNAase I cleavages over a 20 base pair region just upstream of the -45 to +35 region shown previously to interact with TFIID. More discriminating footprint analyses using methidiumpropyl-EDTA-Fe(II) as the cleaving agent indicate that USF interacts primarily with the small palindromic DNA sequence GGCCACGTGACC located between positions -63 and -52 of the major late promoter, while TFIID interacts primarily with a 10 base pair DNA region centered on the consensus TATA sequence. Dissociation rate measurements indicate a cooperative interaction between USF and TFIID when simultaneously bound to the promoter DNA.
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PMID:Interaction of a gene-specific transcription factor with the adenovirus major late promoter upstream of the TATA box region. 407 92

1. Additional evidence was obtained that the nuclear oestradiol-17beta receptor is an acidic protein. Partial purification of the receptor protein was obtained by chromatography on hydroxyapatite and it contains protein-bound phosphate. 2. The nuclear ;5s' and cytoplasmic ;9.5s' and ;5s' receptors from uterus, dimethylbenzanthracene-induced mammary adenocarcinoma and kidney are precipitated together with bound oestradiol-17beta by protamine sulphate. This common property suggests that the nuclear and cytoplasmic receptors are related to each other. 3. The properties of two acidic protein fractions from both liver and dimethylbenzanthracene-induced mammary adenocarcinoma are described. Fraction 1 contains two major components and fraction 2 contains one component, as judged from polyacrylamide-gel electrophoresis. Fraction 2 contains RNA and both fractions contain protein-bound phosphate. 4. These fractions form insoluble complexes with calf thymus histone, protamine sulphate and poly-l-lysine. The formation of these complexes is markedly affected by ionic strength and pH. Ionization of both the in-amino group of lysine and carboxyl group are involved. RNA and DNA do not appear to be involved. The interaction is not affected by EDTA or 1mm-Na(+), -K(+), -Ca(2+), -Mg(2+) or -Mn(2+). Per unit weight, whole histone has 4-5 times as many binding sites for the acidic proteins as the latter have for the former. 5. No convincing evidence was obtained for DNA-acidic protein interaction, but, as judged from precipitation experiments, there was competition between DNA and acidic protein for histone. 6. Relatively large amounts of acidic protein partly relieved the histone inhibition of the template activity of DNA for Escherichia coli RNA polymerase (EC 2.7.7.6).
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PMID:The properties of a nuclear acidic protein fraction that binds [6,7-3H]oestradiol-17beta. 489 41

1. The effects of various ions on the Mg(2+)- and Mn(2+)/ammonium sulphate-activated RNA polymerase activities of isolated liver nuclei were studied. 2. The Mg(2+)-activated RNA polymerase reaction was inhibited by more than 60% by Cd(2+), SeO(3) (2-), Be(2+), Cu(2+), Co(2+), Ca(2+) and La(3+), all at 1mm concentrations. 3. The Mn(2+)/ammonium sulphate-activated RNA polymerase reaction was strongly inhibited by Hg(2+), Cd(2+), Cu(2+) and Ag(+). The effect of Hg(2+), Cd(2+) and Ag(+) was relieved by cysteine or mercaptoethanol. 4. Inhibition by Cu(2+) was not affected by addition of DNA, and was relieved only partially by EDTA or histidine. 5. No changes of RNA polymerase activities were observed in nuclei isolated from the liver of rats treated with copper albuminate.
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PMID:The effects of copper and other ions on the ribonucleic acid polymerase activity of isolated rat liver nuclei. 497 30

The characteristics of human rotavirus-associated RNA polymerase activity have been examined in relation to the effects of ribonucleoside triphosphate analogs and S-adenosylmethionine. These effects were analyzed by testing two forms of activated virus particles: EDTA- and heat-treated virions. The former lack outer shell proteins, and activation by means of heat treatment does not introduce any apparent modification in virion structure. Virus-associated RNA polymerase shows similar properties in both preparations, suggesting that outer proteins are not directly involved in RNA synthesis. Transcription in this virus is specifically dependent on a hydrolyzable form of ATP. Such a requirement is not overcome by preincubation or by the addition of S-adenosylmethionine, suggesting a hypothetical mechanism that couples transcription to ATP hydrolysis. The addition of S-adenosylmethionine stimulated transcription and diminished the Km value not only for ATP but also for the other three ribonucleoside triphosphates. Analysis of methylated RNA products suggested that methyl groups were incorporated into all of the RNA species synthesized by virion-associated polymerase. Further analysis of those RNA molecules showed that they contained cap structures at the 5' end. The results suggest that the cap structure at the end of RNA molecules may enable RNA polymerase to elongate transcripts more efficiently, in a reaction in which the hydrolysis of ATP is involved.
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PMID:Effect of S-adenosylmethionine on human rotavirus RNA synthesis. 609 Jun 96

Mesenchymal cells isolated from the papilla of embryonic tooth germs of the mouse were cultured in a complex medium for five to six days. Liquid nitrogen lysates, prepared from these cells, incorporated nucleoside monophosphates into a cold acid-insoluble product. The product was sensitive to RNase and no product was formed if the lysate was pretreated with DNase. The reaction was sensitive to EDTA and, in its presence, optimum activity was obtained with 2 mM MgCl2. On sucrose gradients, the reaction product was distributed between two broad peaks; one centered about 18S and the other above 28S. The RNA polymerase inhibitor alpha-amanitin inhibited approximately 50% of the activity at a concentration of 10 microgram/ml.
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PMID:Transcriptional activity in lysates of cultured mesenchymal cells from embryonic tooth germs. 615 75

A subcellular system from mouse L-cells has been used to study RNA synthesis and processing in vitro. The nuclei in this system incorporate nucleoside triphosphates into RNA with high yield for more than 120 min. The capacity for RNA synthesis is stable for extended periods at 4 degrees C. All three RNA polymerases contribute to the overall synthetic activity as shown by differential inhibition with alpha-amanitin. The in vitro labeled RNA contains about 15% of polyadenylated RNA. The non-polyadenylated RNA shows molecules in the range of larger than 20 S down to 4-5 S. The polyadenylated RNA exhibits mainly transcripts around 18 S and below 8 S. Methylation of nucleoside bases and the ribose 2'-OH group including 5'-caps is performed in vitro as well. Base methylation and 5'-cap methylation are partially sensitive to alpha-amanitin. 28% of the methyl groups are found in polyadenylated RNA being distributed throughout molecules of all sizes. The methylated non-polyadenylated RNA shows peaks at 45 S, around 28 S and 18 S, and a very prominent low-molecular weight RNA peak. Addition of the poly(A) tract to RNA molecules in vitro is revealed by the presence of [3H]-uridine-labeled polyadenylated RNA. The poly(A) tract was isolated and analyzed on polyacrylamide gels. Its maximum length coincides with an in vivo poly(A) marker indicating the addition of about 150-200 nucleotides. Poly(A) addition is possible on pre-existing RNA chains, preferably on 3'-oligo(A) tracts. This process is insensitive to alpha-amanitin. In addition, the specificity of polyadenylation may be relaxed since incorporation of [3H]UTP into polyadenylated RNA is only reduced to about 50% under conditions (1 microgram alpha-amanitin/ml) where RNA polymerase II is inhibited. A small fraction of the in vitro labeled RNA binds to polysomes which can be recovered from the cytoplasm adhering to the nuclei. This RNA contains poly(A) and is enriched in base methylations and 5' end caps. It can be dissociated from the polysomes by EDTA. It is likely to be in vitro labeled and maturated mRNA.
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PMID:RNA synthesis and processing reactions in a subcellular system from mouse L cells. 617 4

Classical electron-microscopic techniques (enzymic digestion, EDTA regressive staining) allied with autoradiographic studies after [3H]uridine incorporation or after RNA synthesis initiated by an exogeneous RNA polymerase in the presence of tritiated GTP, enabled us to describe the fine structure and activity of the nucleolus in an established Drosophila cell line. This nucleolus is composed of a large central multilobed core containing proteins, RNA molecules and a DNA-containing component. This core is surrounded by and connected to large clumps of dense fibrillar nucleolus-associated chromatin, which are intermingled with fibrillogranular ramifications extending from the core towards the nuclear envelope. These ramifications are covered by granules of ribosomal ribonucleoprotein. As shown by EDTA regressive staining the nucleolar core contains a ribonucleoprotein network, which unravels and ramifies within a fibrous matrix. RNA synthesis takes place at the level of this network in the internal part of the core. The molecules synthesized are associated with proteins and are exported out of the core in the form of granules. Although it is composed of the same constituents as other nucleoli, the nucleolus of Drosophila cells seems to be less organized, in that it never displays fibrillar centres, which have been referred to as the nucleolar counterparts of the nucleolus-organizers in a wide variety of organisms.
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PMID:Nucleolar organizer structure and activity in a nucleolus without fibrillar centres: the nucleolus in an established Drosophila cell line. 618 16

Rotavirus particles are unique in their configuration. They have a double-shelled protein capsid, inside which are the viral RNA fragments and a viral polymerase. The outer shell is involved in the infectivity of the virus particle; without it the particle is not infective. At the cellular level during the infection process, this outer shell is made permeable by an unknown mechanism. This makes the RNA polymerase within the particle accessible to precursors of new RNA. Transcription begins, and progeny virus RNA and protein soon accumulate in the cell. In vitro studies show that chelators such as EDTA and EGTA may be used to make the virion permeable, allowing the measurement of viral RNA polymerase activity. These chelators remove divalent cations such as Ca++ from the virus particle, thereby altering the outer shell of the virus [2]. We were interested in measuring the effect on rotavirus of chelators that have been used to treat diarrheal disease, such as clioquinol, an 8-hydroxyquinoline derivative and the principal ingredient of Entero-Vioform (Ciba Pharmaceutical Co, Summit, NJ). Seven of 10 three-day-old Icr white mice simultaneously inoculated with EDIM and administered a single dose of clioquinol developed diarrhea 48 hr after inoculation, although none had displayed diarrhea at 24 hr. These mice, therefore, developed diarrhea 24 hr later than six of eight untreated animals (P = 0.004 at 24 hr by Fisher's exact test). Moreover, no animals receiving doses of clioquinol every 12 hr had developed diarrhea by 48 hr after inoculation (P = 0.006 at 24 hr and P = 0.0001 at 48 hr, compared to untreated mice).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of clioquinol, an 8-hydroxyquinoline derivative, on rotavirus infection in mice. 622 9

We have studied the specificity and kinetics of release of nascent RNA from ternary transcription complexes by Escherichia coli transcription termination factor rho in vitro. Stable ternary complexes, initiated at the lambda PR promoter, were prepared either by quenching the elongation reaction with EDTA or by preventing further elongation by incorporating 3'-O-methyl nucleotides at the 3' end of the nascent RNA chains. We find that rho protein can only release lambda PR-initiated transcripts from ternary complexes in which transcription has proceeded beyond 288 base pairs from PR; shorter chains are not released. Substitution of inosine for guanosine in the nascent RNA permits the rho-dependent release process to operate on complexes located as close as 108-116 base pairs downstream from PR. The regions of the template from which rho can release transcripts correspond, for both guanosine- and inosine-containing RNA, to those within which rho-dependent termination has also been shown to occur (Morgan, W. D., Bear, D. G., and von Hippel, P. H. (1983) J. Biol. Chem. 258, 9553-9564, 9565-9574). The half-time for the major part of the release process is less than 10 s. These results are in good accord with the hypothesis that the specificity of rho-dependent termination is jointly determined by two separable processes: (i) the specificity of rho binding to the nascent RNA chain and (ii) the location and strength of RNA polymerase-pausing sites.
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PMID:Specificity of release by Escherichia coli transcription termination factor rho of nascent mRNA transcripts initiated at the lambda PR. 633 Jan 19


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