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)

Procedures were established for the isolation and partial purification of DNA polymerase, RNA polymerase and poly(A) polymerase activities from the cytoplasm and nuclei of NIH-Swiss mouse embryos. Based on the elution pattern of these enzyme activities from DEAE-cellulose and phosphocellulose columns in Tris-HCl buffer, pH 8.0, the apparent basicities of the enzymes can be arranged as follows: cytoplasmic(C) poly(A) polymerase greater than (C)DNA polymerase beta greater than (C)DNA polymerase alpha and nuclear(N) poly(A) polymerase greater than (N)DNA polymerase greater than (N)RNA polymerase I greater than (N)RNA polymerase II. Twenty rifamycins, including rifamycin B, rifamycin S, rifamycin SV, and rifamycin SV derivatives, were examined for their ability to inhibit the above mentioned nucleic acid polymerizing enzymes and Simian sarcoma virus type I (SSV-1) reverse transcriptase. Rifamycin SV 3'-formyldiphenylhydrazone, rifamycin SV 3'-formyl-n-octyloxime (AF/013) and rifamycin SV 3'-formyldiphenylmethyloxime (AF/05) inhibited all the tested enzyme activities. Rifamycin SV 3'-formylpropylphenyloxime (AF/015) inhibited cellular nucleic acid polymerase activities but not SSV-1 DNA polymerase activity. Rifamycin SV 3'-formyldinitrophenylhydrazone (AF/DNFL) strongly inhibited reverse transcriptase activity but did not inhibit cellular DNA polymerase activities. AF/DNFI slightly inhibited RNA and poly(A) polymerase activities. Rifamycin SV 3'-formyldipropylhydrazone (AF/DPI) and 2,6-dimethyl-4-N-benzyldemethyl-rifampicin (AF/ABDMP) slightly inhibited reverse transcriptase activity but did not inhibit cellular nucleic acid polymerase activities. Active rifamycin derivatives inhibited enzyme reactions by interacting with the enzyme proteins. Nascent polynucleotide chain elongation continued although at a reduced rate in the presence of inhibitor. The addition of increasing concentrations of nonionic detergent (Triton X-100) to rifamycin-inhibited enzyme reactions fully restored enzyme activities. The presence of highly lipophilic 3'-side chains on active rifamycins and the reversibility of enzyme inhibition by Triton X-100 suggest that the tested nucleic acid polymerizing enzymes may have hydrophobic regions with which inhibitory rifamycins interact.
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PMID:Interaction of rifamycins with mammalian nucleic acid polymerizing enzymes. 6 93

The integrity and stability of nucleosomes under transcription assay conditions has been found to depend on concentration and ionic environment. Rifamycin AF/013, a commonly used inhibitor of initiation, is particularly effective in destabilisation of nucleosomes. Intact nucleosomes are refractory to transcription by wheat RNA polymerase II, the histone core preventing initiation. Template titration suggests that the polymerase can, however, bind to nucleosomes, and a 15--16S complex has been observed on sucrose gradients. DNase I digestion of polymerase-nucleosome incubations indicates that whilst histone is still present in the complex, the nucleosome conformation is altered resulting in enhanced nucleolysis at sites near the DNA centre but reduced overall kinetics of digestion.
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PMID:The nature of the interaction of nucleosomes with a eukaryotic RNA polymerase II. 49 50

Specific activities are determined of two functional fractions of alpha-amanitin sensitive DNA-dependent RNA polymerases in nucleic from human normal and chronic lymphocytic leukemia lymphocytes. Specific activity of "free" RNA polymerase in CLL corresponds ot 0.133 pmoles (3H)-UMP/10(6) cells as compared to 0.209 in normals. Activities of the "engaged" enzymes are 0.139 in CLL and 0.132 in normals. "Free" enzymes in NL and CLL are completely inhibited by 400 ng/ml Rifamycin AF/013, while the "engaged" enzymes exhibit 70% of their original activity. 1.0 ng/ml alpha-amanitin suppress 50% of the activity of the "free" enzyme in CLL. The "free" enzyme in NL and the "engaged" enzymes in NL and CLL do not show any residual activity in the presence of 1.0 ng/ml alpha-amanitin.
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PMID:[Free and template-bound RNA polymerase in normal and leukaemic human lymphocytes (author's transl)]. 125 8

Transcription by RNA polymerase II occurs after formation of a transcription complex. This complex is assembled in stages by the interaction of transcription factors with the template and/or with each other. We report on the ability of six drugs to inhibit the assembly of the RNA polymerase II transcription complex. Assembly of the complex on the adenovirus major late promoter requires several transcription factors. The normal assembly process requires that the DNA first interact with TFIIA, then with TFIID, and finally with at least four additional transcription factors (one of which is RNA polymerase II). We observed that streptolydigin (10 micrograms/ml) inhibits association of ILA and IID, and at higher concentrations (100 micrograms/ml) inhibits that IIA/IID complex from binding to DNA. Streptovaricin (100 micrograms/ml) appears to inhibit the IIA/IID interaction with DNA and prevents reinitiation (at 500 micrograms/ml). Adriamycin (1 microgram/ml) inhibits the interaction of TFIID with the IIA/DNA complex and inhibits an additional event immediately prior to, or during, elongation. Daunorubicin may be an elongation inhibitor. Heparin at 10 micrograms/ml inhibits further assembly after the IIA/IID/DNA complex has formed, and at 100 micrograms/ml also inhibits a late event in the assembly process and blocks reinitiation. Rifamycin AF/013 (100 micrograms/ml) inhibits the early events necessary to form the IIA/IID/DNA complex and (at 10 micrograms/ml) an assembly event following formation of the IIA/IID/DNA complex. Therefore, these compounds should be useful as probes for further examination of the assembly process.
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PMID:Drug inhibitors of RNA polymerase II transcription. 257 59

We investigated the effects of six drugs on an RNA polymerase III in vitro transcription system. Adriamycin, daunorubicin, heparin, rifamycin AF/013, streptolydigin, and streptovaricin all inhibit RNA synthesis from a tRNA gene or the adenovirus 2 (AD2) VA1 RNA gene. The completed RNA polymerase III transcription complex is formed by the sequential, ordered addition of protein factors. Although both genes reportedly use the same transcription fractions for in vitro RNA synthesis, some of these drugs interfere differentially with these genes. A drug concentration that inhibits transcription from one gene may not inhibit transcription from the other gene. Adriamycin seems to block transcription if added between the binding of the individual transcription fractions. Daunorubicin appears to inhibit VA transcription only if added prior to both transcription fractions, but inhibits tRNA synthesis before and during transcription factor binding. Heparin blocks both genes between factors binding to DNA and after factor binding. Rifamycin blocks VA synthesis more effectively than tRNA synthesis. Streptolydigin blocks transcription of both genes. Streptovaricin probably blocks transcription by inhibiting early transcription complex assembly events. These drugs appear useful as appropriate probes to investigate transcription complexes since several discriminate between complexes formed on different genes during the assembly process.
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PMID:Effects of antibiotics on RNA polymerase III transcription. 290 35

A new class of rifamycin-resistant mutants of Escherichia coli was obtained by lysogenic insertions of bacteriophage Mu Amp DNA. Rifamycin resistance is closely linked to the ampicillin resistance conferred by the prophage. Mapping by conjugation with auxotrophic markers revealed that the rifamycin-resistant mutations are located between 28 and 37 min on the E. coli chromosome standard map, some distance from the rpoB gene at 89.5 min. The DNA-dependent RNA polymerase of these mutants is highly sensitive to rifampicin.
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PMID:Mu-induced rifamycin-resistant mutations not located in the rpoB gene of Escherichia coli. 352 57

A soluble enzyme system has been prepared from a phage P4-infected Escherichia coli strain that supports the replication of exogenous, supercoiled P4 DNA. This DNA synthesis in vitro depends upon the four deoxyribonucleotides and ATP, but is enhanced about four- to fivefold by the presence of other ribonucleotides. E. coli DNA polymerase III holoenzyme, the E. coli single-strand DNA binding protein, and the partially purified P4 alpha gene product are required for replication in vitro. Rifamycin does not inhibit P4 replication in vitro. Since the P4 alpha gene codes for a rifamycin-resistant RNA polymerase (Barrett et al., 1983), and since P4 DNA replication is independent of the host primase (Bowden et al., 1975), we believe the alpha gene product is functioning as a P4-specific DNA primase.
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PMID:The replication of bacteriophage P4 DNA in vitro. Partial purification of the P4 alpha gene product. 387 88

Four peaks of DNA-directed RNA polymerase activity are resolved by salt gradient elution of a sonicated yeast cell extract on DEAE-Sephadex. The enzymes, which are named IA, IB, II, and III in order of elution, all appear to come from cell nuclei. Only enzyme II is sensitive to alpha-amanitin. All enzymes are more active with Mn(++) than with Mg(++) as divalent ion. Enzymes IB and II have salt optima in the range 0.05-0.10 M (NH(4))(2)SO(4), whereas enzyme III is maximally active at 0.20-0.25 M (NH(4))(2)SO(4). With optimal salt concentration and saturating DNA, the template preference ratio, activity on native calfthymus DNA divided by activity on denatured calf-thymus DNA, is 2.2 for IB, 0.4 for II, and 3.5 for III. None of the yeast polymerases was inhibited by rifamycin SV. Rifamycin AF/013 effectively inhibited polymerases IB, II, and III.
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PMID:Transcription in yeast: separation and properties of multiple FNA polymerases. 455 56

The DNA of helper-dependent coliphage P4 and the DNA of its helper-P2-show no detectable sequence homology as measured by DNA.DNA hybridization. The lack of cross-hybridization permits direct analysis of P4 as well as of P2 transcription in P4-infected P2 lysogens by RNA.DNA hybridization. P4-transactivated P2 transcription can be detected around 20 min after P4 infection of the P2 lysogen and the rate (per infected cell) of that transcription becomes equal to that of the P4 transcription at the end of the latent period of P4. Furthermore, P4 transcription appears to be stimulated by the presence of the helper. Conceivably, P2 codes for a stimulator of P4 transcription. Rifamycin has been used to investigate the role of the host RNA polymerase during P4 transactivation of P2 transcription. The results exclude the participation of a P4-coded RNA polymerase and indicate that the original host RNA polymerase is responsible for the bulk of P4 and P2 transcription during transactivation.
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PMID:Expression of phage transcription in P2 lysogens infected with helper-dependent coliphage P4. 460 65

Mitochondrial RNA polymerase activity from rat liver has previously been demonstrated in intact organelles. This activity has now been solubilized, partially purified, and shown to be a true polymerase, free of nuclease. The enzyme is derived from mitochondria and is not from contaminating bacteria or nuclear components. The enzyme is distinguished from its nuclear counterparts by its behavior on ammonium sulfate fractionation and lack of inhibition by alpha-amanitin. Rifamycin inhibits the crude enzyme, but only inconsistently inhibits the more purified preparation.
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PMID:Partial purification of mitochondrial RNA polymerase from rat liver. 528 62


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