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)

At concentrations of 7 times 10(-6) to 7 times 10(-5) M, derivatives consisting of the polycylic ring structures fluoranthene, fluorenone, fluorene, anthraquinone, xanthenone, and dibenzofuran with appropriate amine side chains inhibited by over 90% the purified RNA-directed DNA polymerase of avian myeloblastosis virus acting on poly(deoxyadenylate-deoxythymidylate) [poly(dA-dT)]. Of these, only the fluoranthene derivatives were strong inhibitors of the viral DNA polymerase directed by polyadenylate-oligodeoxythymidylate [poly(A)-(dT)12-18]. Low levels of fluoranthene derivatives (1 times 10(-5) M) also strongly inhibited polymerase with polyinosinate-oligodeoxycytidylate [poly(I)-(dC)12-18], activated calf thymus DNA, and viral 70S RNA as templates, but not with polycytidylate-oligodeoxyguanylate as template. A comparison of the activity of 11 fluoranthene derivatives with different side chains showed that the structure of the amine side chain influenced both the extent of antipolymerase activity with a given template and the relative inhibition with different synthetic DNA and RNA templates. The naturally occurring polyamines, spermine, spermidine, and putrescine, did not inhibit the activity of the viral DNA polymerase. Studies on the mechanism of action indicated that the synthetic derivatives inhibited polymerase activity by binding to the template and not to the enzyme: 1) inhibition by fluoranthene derivatives was overcome by the addition of excess template including poly(dA-dT), poly(A)-(dT)12-18, poly(I)-(dC)12-18, viral 70S RNA, and activated calf thymus DNA; 2) the degree of inhibition by fluoranthene derivatives was unaffected by the addition of the creased viral DNA polymerase; 3) with the same template, Escherichia coli DNA-directed RNA polymerase and the viral RNA-directed DNA polymerase were inhibited to about the same extent; and 4) the derivatives formed a complex with DNA, poly(I), and poly(A) that was stable to exclusion chromatography on Sephadex G-100. Several derivatives also had biologic activity, since they blocked the ability of the murine sarcoma virus to transform cells.
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PMID:Inhibition of purified DNA polymerase of RNA tumor viruses by fluoranthene derivatives and analogues of tilorone hydrochloride. 5 Oct 87

Cibacron blue F3GA is a potent inhibitor of the Azotobacter vinelandii DNA-directed RNA polymerase. Addition of 8 micrometer Cibacron blue F3GA prior to initiation results in a greater than 90% inhibition of the poly[d(A-T]-directed synthesis of poly[r(A-U)] while addition of the dye during the course of the reaction is without effect on chain elongation. Binding of RNA polymerase to [3H]poly[d(A-T)] is inhibited by only 15% in the presence of 8 micrometer Cibacron blue F3GA. Inhibition by Cibacron blue F3GA is noncompetitive with regard to ATP, UTP, or template. The poly[d(A-T)]-directed pyrophosphate exchange reaction is relatively resistant to inhibition by Cibacron blue F3GA. Rifampicin added to a similar reaction (in the presence of absence of Cibacron blue F3GA) results in 95% inhibition of the exchange reaction. The interaction of the RNA polymerase core enzyme with Cibacron blue F3GA is shown by the formation of a difference spectrum with a positive maximum at 675 nm which is not affected by the presence of a high concentration (4 micrometer) of rafampicin. The data indicate that Cibacron blue F3GA acts by binding to RNA polymerase and inhibits a step between the synthesis of the initial phosphodiester bond and formation of a stable ternary elongation complex.
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PMID:Inhibition of Azotobacter vinelandii RNA polymerase by cibacron blue F3GA. 88 77

A procedure utilizing the specific inhibition of calf thymus DNA-directed RNA polymerase B has been applied to the quantitation of amanitins. This procedure has permitted the accurate quantitation of alpha-amanitin in amounts as low as 0.05 nanogram, a sensitivity 2000-fold greater than chemical detection methods used following tlc. Analysis of extracts of specimens of Amanita verna identified by morphological criteria has demonstrated that while toxin concentration is variable, some specimens are practically devoid of amanitins and may represent a variety of A. verna or a distinct species.
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PMID:Quantitation of amanitins in Amanita verna with calf thymus RNA polymerase B. 109 15

DNA-directed RNA polymerase was solubilized from total HeLa cells. Three distinct classes of the enzyme could be clearly differentiated by their sensitivity toward alpha-amanitin. While form A is completely resistant to high concentrations (133 mug/ml) of this toxin, enzyme B is highly sensitive and is completely inhibited by concentrations of 0.1 mug/ml. In contrast, RNA polymerase C shows an intermediate behaviour (50% inhibition at 30% mug/ml). Separation of the three individual enzymes was achieved by chromatography on DEAE-cellulose (to separate enzyme B from A and C) and DEAE-Sephadex (to separate polymerase A from C). All three RNA polymerases were subsequently purified by phosphocellulose chromatography followed by sedimentation through glycerol gradients. Analysis of the purified enzymes by gel electrophoresis under denaturating conditions showed that the A enzyme consists of five subunits with molecular weights of 185, 128, 65, 41 and 32 X 10(3). In contrast, polymerase B is composed of seven subunits in variable stoichiometry with molecular weights of 215, 175, 145, 123, 68, 43 and 31 X 10(3) respectively. The subunit structure of enzyme C is not entirely clear at present and remains to be established. In addition, RNA polymerase activities were solubilized from mitotic and middle-S phase cells in comparison to controls. With respect to amounts and/or activities of all three RNA polymerases A,B and C no significant differences were detectable between logarithmically growing, mitotic and middle-S phase cells.
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PMID:DNA-directed RNA polymerase from HeLa cells. Isolation, characterization and cell-cycle distribution of three enzymes. 119 1

A thymic factor causes a strong inhibition of the DNA-directed RNA polymerase reaction in vitro. The active factor was isolated from aqueous ultrafiltered thymus extracts and purified by means of chromatography on DEAE-cellulose and then on Dowex 50 WX2. The purified thymic factor was characterized as a peptide of low molecular weight (less than 5000). The biological activity of the thymic factor cannot be attributed to the presence of a nuclease or of a histone fragment. The RNA synthesis is controlled by this factor by means of electrostatic interactions between the peptide compound and DNA. Inhibitory activity on RNA synthesis was absent from kidney extracts.
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PMID:Evidence for the presence in calf thymus of a peptidic factor controlling DNA transcription in vitro. 119 3

Electron microscopy of HeLa cells exposed to spermine diacridine shows nucleolar distortions which disappear after several days despite the persistence of the metabolic changes promoted by spermine diacridine. This compound inhibits ribosomal RNA synthesis and appears to act independently of any particular phase of the cell cycle. The DNA content of the HeLa cells remains unchanged and the cell distribution is not significantly disturbed from its normal distribution in the various phases of the cell cycle. Spermine diacridine and other diacridines inhibit primarily chain initiation but also chain elongation by DNA-directed RNA polymerase of Azotobacter vinelandii.
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PMID:Diacridines: bifunctional intercalators. III. Definition of the general site of action. 124 47

Using segments of the Escherichia coli rpoB and rpoC genes as heterologous probes, we have identified and cloned an 8.3 kb PstI fragment from the Staphylococcus aureus genome containing the rpoB and rpoC genes, which respectively encode the beta and beta' subunits of DNA-directed RNA polymerase. This region is almost certainly equivalent to the rif locus, located near to fus at interval 12/13 on the S. aureus linkage map. Limited DNA sequencing revealed the gene order rpoB-rpoC (transcribed from left to right) and identified the rplL gene, encoding ribosomal protein L7/L12, upstream of rpoB. This and other evidence suggests that the rpoBC genes of S. aureus form part of a large gene cluster encoding components of the transcription and translation apparatus which is well-conserved in other eubacteria.
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PMID:Cloning and physical mapping of the Staphylococcus aureus rplL, rpoB and rpoC genes, encoding ribosomal protein L7/L12 and RNA polymerase subunits beta and beta'. 140 88

DNA-directed RNA polymerase is responsible for gene expression. Despite its importance, many details of its function and higher-order structure still remain unknown. We report here a local sequence similarity between the second largest subunit of RNA polymerase II and bacterial RNases Ba (barnase), Bi, and St. The most remarkable similarity is that the catalytic sites of the RNases are shared with the eukaryotic RNA polymerase II subunits of Drosophila melanogaster and Saccharomyces cerevisiae. Several amino acids conserved among the RNases and the RNase-like domains of the RNA polymerase subunits are located in the neighborhood of the catalytic sites of barnase, whose three-dimensional structure has been resolved. This observation suggests the functional importance of the RNase-like domain of the RNA polymerase subunits and indicates that the RNase-like domain may have RNase activity. The location of the RNase-like domain relative to the region necessary for RNA polymerization is similar to the relative proximity of 5'----3' or 3'----5' exonuclease and the region of polymerase activity of DNA polymerase I. The RNase-like domain might work in proofreading, as in RNA-directed RNA polymerase of influenza virus, or it may contribute to RNA binding through an unknown function.
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PMID:RNase-like domain in DNA-directed RNA polymerase II. 192 68

The DNA-directed RNA polymerase from the extremely thermophilic eubacterium Thermus thermophilus HB8 was purified employing a new and rapid method. The subunit pattern of the enzyme, analyzed by SDS gel electrophoresis, was interpreted as: 140 kDa and 170 kDa for beta and beta', 40 kDa for alpha and 92 kDa for sigma. The RNA polymerase is active at elevated temperatures (65 degrees C). Kinetic data provide evidence for the existence of two NTP binding sites with very strong cooperativity. The promoter site specificity of the isolated enzyme has been proven by in vitro transcription employing two T. thermophilus templates whose in vivo starts of transcription were characterized by nuclease S1 mapping.
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PMID:Isolation and physical properties of the DNA-directed RNA polymerase from Thermus thermophilus HB8. 238 94

In Mycoplasma hyopneumoniae, the single genes for 16S and 23S rRNAs are clustered in one operon from which the 5S rRNA gene is separated by more than 4 kbp. This operon, gene 2413 and gene X from M. hyopneumoniae and the 5' ends of both rRNA operons from M. capricolum were cloned and used for analysis of the following gene expression signals: promoters and terminators of the DNA-directed RNA polymerase, ribosomal binding sites of mRNA, and sites for processing of precursor rRNA. The analyses were performed by nuclease S1 protection experiments, the primer extension technique, and DNA sequencing. From these studies we conclude that putative promoter sequences in M. hyopneumoniae deviate significantly from those in Escherichia coli and Bacillus subtilis in having its -35 consensus sequence replaced by A-T rich sequences, whereas the characterized M. capricolum promoter resembles more closely a typical E. coli promoter. The other expression signals show sequences or structures similar to those found in other eubacteria, indicating related underlying principles.
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PMID:Gene expression signals in Mycoplasma hyopneumoniae and Mycoplasma capricolum. 244 58


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