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)

DNA alpha-polymerase has been partially purified from nuclei of cultured chic, fibroblasts and separated on phosphocellulose columns into two distinct activities designated DNA polymerases alpha(a) and alpha(b), respectively. The enzyme preparations were devoid of activities of DNA beta,gamma-polymerases terminal deoxyribonucleoside transferase, DNase, DNA-dependent RNA polymerase, and phosphatase. DNA polymerases alpha(a) and alpha(b) both having molecular weights of 160 000, constitute 35-50 and 65-50%, respectively, of the activity of alpha-polymerase in the nucleus. These enzymes differ in their requirements for maximal activity, their relative ability to copy oligo(dG)-poly(dC), their response to ribonucleoside triphosphates, and their kinetics of heat inactivation. When the properties of alpha polymerases derived from early or late passage cultures have been compared, no difference could be detected as a function of cell age in the specific activities of the polymerases in crude cell extracts, their chromatographic behavior on diethylaminoethylcellulose and phosphocellulose columns, and their relative abilities to utilize single deoxyribonucleoside triphosphates with activated DNA template. On the other hand, both enzymes become partially heat labile in aging cells. Also, the activity of DNA polymerase alpha(a) from young cells was stimulated by 2--10 mM adenosine or cytidine triphosphates, whereas the same enzyme from old cultures was inhibited by these agents. Conversely, these ribonucleoside triphosphates inhibited the activity of polymerase alpha(b) in young cells but slightly stimulated this enzyme derived from senescent fibroblasts. In addition, the relative ability of DNA polymerase alpha(a) to copy oligo(dG)-poly(dC) decreased in aged cells, whereas that of DNA polymerase alpha(b) increased. We have also observed significant differences in the effects of potassium chloride and N-ethylmaleimide on the activity of DNA polymerase alpha(a) from old cells as compared to young cells. These age-related alterations in the properties of the two avian DNA polymerases may reflect structural or conformational changes in these enzymes.
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PMID:Altered nuclear deoxyribonucleic acid alpha-polymerases in senescent cultured chick embryo fibroblasts. 98 31

Temperature-sensitive "leaky" mutants of phage MS2 having white dense ring around negative colonies are described. As these mutants are used for quantitative genetic studies, the white ring presents interest. Typical mutant 40 is used as a model for investigation. Light microscopy has shown, that cells from white ring zone have spore-like inclusions, which determine the characteristic structure of surrounding mutant negative colonies. Cytochemical reactions for the presence of glicogen, lipids, volutin, nuclear material and spores were negative. Electrone microscopy of negatively stained samples and ultrathin sections has revealed that cells from white ring zone, unlike phage-infected wild type cells, have two types of electron dense inclusions: 1) crystalline structures formed with great number of closely packed mature phage particles, and 2) large amorphic bodies. Electrone microscope-cytochemical data showed that inclusions remain intact under treatment of ultrathin sections of white zone ring with DNase and perchloric acid, while nuclear material was completely destroyed. Amorphic bodied were completely destructed after the treatment with RNase, while nuclear material and crystalline phage aggregated remained unchanged. Therefore, amorphic bodies consist of RNA, which has not been used to form virions. Single cycle of the development of mutant 40 at 37 degrees and 43 degrees C and under the temperature of incubation 37 degrees leads to 43 degrees C and 43 degrees leads to 37 degrees C in the course of intracellular reproduction is investigated. Influence of the phage on growth on infected culture is studied. The data obtained draw to a conclusion that the impaired function belongs to cystron protein of the phage membrane. As certain mutations in this cystrone of RNA-containing phage result in the depression of cystrone RNA polymerase, it is supposed that the formation of RNA containing bodies in infected cells, determining the formation of white rings in NA, together with cristalline aggregates of cells, is a result of mutation damage of cystrone protein of the phage MS2 membrane.
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PMID:[Effect of mutagens on RNA-containing phages and its infectious RNA. VII. Genetic nature of morphologic mutants of RNA-containing phage MS2]. 99 65

Escherichia coli RNA polymerase (EC 2.7.7.6), bound in a tight complex at an early T7 promoter, protects 41 to 43 base pairs of DNA from digestion by DNase. I. The protected DNA fragment contains both the binding site for RNA polymerase and the mRNA initiation point for the promoter. The sequence of the DNA fragment and the sequence of the mRNA that it codes for are presented here. A seven-base-pair sequence, apparently common to all promoters, is implicated in the formation of a tight binary complex with RNA polymerase.
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PMID:Nucleotide sequence of an RNA polymerase binding site at an early T7 promoter. 109 68

DNA-dependent RNA polymerase was isolated from rat spleen cell nuclei and was identified as A and B RNA polymerases by data on DEAE- and P-cellulose ionic exchange chromatography and on concentration dependency on bivalent ions and (NH4)2SO4. Two forms of the enzyme differed from each other in the activity in RNA synthesizing system, and their activity was completely inhibited by actinomycin, DNase and RNase.
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PMID:[DNA-dependent RNA polymerase from the nuclei of the spleen of white rats]. 113 3

A special class of non-histone protein ("tight protein") is identified in purified HeLa cell chromatin on the basis of its failure to dissociate from the DNA at very high ionic strength (2.5 M NaCl-5.0 M urea), where over 92% of the total chromatin protein is released. The tight proteins are insoluble in 0.4 N H2SO4 and lack histones as determined by polyacrylamide gel electrophoresis. They have molecular weights between 14,000 and 85,000 with over 70% of the polypeptide chains between 14,000 and 30,000 mol wt. This is the same size range as the non-histone proteins which others have found to display species-specific DNA binding in vitro. There is approximately one molecule of tight protein per 275 DNA base pairs. The tight proteins are characterized by much higher rates of labeling with amino acids than the histones and non-histone chromatin proteins that are dissociated from the DNA by high ionic strength, but they have the lowest phosphorylation levels. Chromatin fractionation experiments were performed to investigate the distribution of tight proteins between template-active and template-inactive regions. Under specific conditions, spleen DNase (DNase II) selectively shears those portions of HeLa cell chromatin that contain nascent RNA transcripts. This nascent RNA-enriched chromatin fraction also contains a high level of the proteins known to be complexed with heterogeneous nuclear RNA in ribonucleoprotein particles and contains over 70% of the RNA polymerase activity of total chromatin. When this method was employed to investigate the distribution of tight proteins, they were found to be almost entirely confined to the template-inactive fraction. Although these experiments do not elucidate the precise function of these proteins, they identify, for the first time, a particular subclass of non-histone chromosomal protein which is distributed asymmetrically between transcriptionally active and inactive chromatin regions.
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PMID:A special class of non-histone protein tightly complexed with template-inactive DNA in chromatin. 114 2

1. The 5'-terminal sequence of the RNA transcribed from bacteriophage fd replicative form DNA under the control of promotor region I has been determined to be ppp(Gp)nUpApApApGpApCpCpUpGpApUpUp. . . 2. This sequence is complementary to the 5'-terminal sequence of the minus strand of the corresponding RNA polymerase binding site I, the starting point for RNA synthesis lying approximately in the middle of the binding site. 3. This initial sequence is also transcribed faithfully from isolated complexes of RNA polymerase and binding site I, obtained by DNase digestion of complexes between RNA polymerase and fd replicative form DNA. These highly stable complexes can not be reconstituted from binding site and enzyme. 4. It is concluded that RNA polymerase binding site and initiation site are identical parts of a promoter region, and that no "drift" between these sites is required as a step in RNA chain initiation. An additional non-transcribed outside region is implicated as essential for full promoter function.
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PMID:Initiation of transcription within an RNA-polymerase binding site. 117

Under specific binding conditions RNA polymerase forms complexes at several sites of the replicative form DNA of bacteriophage fd. One of these complexes becomes stable to both high salt and low temperature after incubation with GTP. None of the complexes is stabilized by ATP. The stabilization by GTP results from the synthesis of an oligo(G) chain, which is bound in the complex. Size and pyrimidine fingerprints of the DNA segment protected by the enzyme against digestion with DNase are not changed upon initiation of oligo(G) synthesis. This result indicates that binding site and initiation site are identical parts of a promoter region.
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PMID:Stabilization of promoter complexes with a single ribonucleoside triphosphate. 117 37

Ribonucleic acid (RNA)-dependent RNA polymerase activity was demonstrated in the microsomal and ribosomal fraction from the spleen cells of immunized mice. The enzyme activity was solubilized by Triton X-100 from the fraction and partially purified by Biogel A 1.5 m column chromatography. The RNA-dependent RNA polymerase activity was eluted in a single peak from the column. High activity was demonstrated with an RNA polymerase activity was eluted in a single peak from the column. High activity was demonstrated with an RAN preparation (iotaRNA) as template made from the spleens of immunized mice but very low activity was found with an RNA preparation made from the spleens of normal mice. Incorporation of 3H-UTP markedly decreased in the presence of RNase but not in the presence of DNase. DNA preparations made from the spleens of immunized mice were inactive as template for this enzyme. The iotaRNA preparation was fractionated by sucrose density gradient centrifugation. A fraction corresponding to 12-13 S was most active as a template. It was followed by a fraction corresponding to 6-7 S. Sucrose gradient analysis of the 3H-UTP-labeled product was attempted. Some properties of this enzyme are described.
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PMID:Ribonucleic acid-dependent ribonucleic acid polymerase in the immune response. 123 May 9

The structure of the elongation complex of vaccinia RNA polymerase halted at discrete template positions was examined by DNase I footprinting. The leading edge of the footprint bore a constant relationship to the catalytic template position, being 22-24 nucleotides (nt) in advance on the nontemplate strand and 17 nt on the template strand. DNase hypersensitivity of the nontemplate strand at the leading edge suggested that the DNA might be distorted as it entered the polymerase molecule. The region of DNA unwinding at the transcription bubble extended at least 12 nt 5' from the catalytic center, as indicated by the reactivity of adenosine residues to diethylpyrocarbonate. Cu-phenanthroline-hypersensitive sites located 13 nt 5' and 4 nt 3' of the growing point appeared to demarcate the margins of the bubble. Strand asymmetry of chemical modification within the bubble was consistent with an RNA-DNA hybrid of no more than 10 base pairs.
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PMID:Structural analysis of ternary complexes of vaccinia RNA polymerase. 143 98

Intact nuclei derived from poorly or highly liver-metastatic murine large-cell lymphoma cell line RAW117 were digested to discrete subchromatin deoxyribonucleoprotein/ribonucleoprotein (DNP/RNP) complexes with Msp-I. The DNP/RNP complexes were composed of DNP/RNPs which were derived from the DNP/RNP complexes by incubation in the presence or absence of DNase-I and subsequent isolation by two-dimensional [isoelectric focusing/sodium dodecylsulfate (SDS)] polyacrylamide gel electrophoresis (PAGE), electroelution from the gel, and removal of SDS. Approximately 450 DNP/RNPs in the two-dimensional gels corresponding to discrete spots or in some cases streaks were analyzed for the presence of v-abl, p53, c-neu, c-H-ras, beta-casein, 18s rDNA, and mu-chain immunoglobulin genes using a hybridization technique. Ten DNP/RNP complexes contained tightly associated p53 DNA, whereas six contained c- or v-abl, four contained mu-chain gene, two contained c-H-ras, one contained dot-blot beta-casein, two contained 18s rDNA, and c-neu was found in one of the DNP/RNPs. The DNP/RNPs were also analyzed for in vitro RNA polymerase and primase activities. To assess the potential transcription abilities of the isolated DNP/RNPs, individual DNP/RNPs or DNP/RNP mixtures (reconstituted after SDS-PAGE separation) were examined for RNA polymerase initiation and synthesis. When RNA products were formed, these were purified by extracellulose chromatography and used as back-hybridization probes for the genes of interest. The RNA products were also analyzed by RNA gel electrophoresis. RNA formation was inhibitable by actinomycin D, and the RNAs formed ranged in size from approximately 80 kbp to approximately 1 kbp. By mixing various DNP/RNP complexes together, different patterns of RNA synthesis were found. For example, one DNP/RNP of M(r) approximately 140,000, isoelectric point (pl) approximately 5.8 synthesized a high molecular weight RNA in vitro that hybridized with beta-casein cDNA, but beta-casein is not expressed in RAW117 cells, suggesting that the silencing of the beta-casein gene was negated by isolation of the DNP/RNP. Mixing this DNP/RNP with two other specific DNP/RNPs again inhibited the synthesis of beta-casein RNA, suggesting that interactions between DNP/RNP complexes can result in differential RNA expression or regulation of RNA polymerases in vitro.
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PMID:Nucleoproteins derived from subnuclear RNA polymerase complexes of metastatic large-cell lymphoma cells possess transcription activities and regulatory properties in vitro. 146 66


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