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)

The synthesis of rRNA in the ribosome-free extracts S100 of E. coli cells was about 30 and 60% of total transcript when E. coli DNA and DNA of lambda rifd 18 phage were used respectively. The synthesis of rRNA with both types of DNA was inhibited in 5--6 times by 0.8 mM ppGpp, while the synthesis of total RNA decreased only two-fold. Selective action of ppGpp on rRNA synthesis is due to the intensive inhibition of the initiation of transcription of the appropriate genes. The rRNA synthesis and the inhibitory capacity of ppGpp was shown to dependend on the KCl concentration in S 100 extracts. These results indicate that ppGpp is the main factor controlling rRNA synthesis both in isolated RNA polymerase system and in cell-free extracts.
Biokhimiia 1978 Dec
PMID:[The effect of guanosinetetraphosphate on rRNA synthesis in E. coli extracts]. 36 18

In vivo, termination of transcription at the attenuator site of the tryptophan (trp) operon of E. coli is influenced by the protein termination factor rho. In vitro, termination does not depend on rho factor, and is very efficient in a purified system consisting only of RNA polymerase, the DNA template, nucleoside triphosphates, and buffer. The extent of termination in this system is unaffected over a wide range of salt and nucleoside triphosphate concentration. However, there is a 10-fold stimulation of trp leader mRNA synthesis if rho factor is present during the transcription reaction. This stimulation occurs only at low molar ratios of polymerase to template, and can be blocked by rifampicin. It is thus most likely due to the recycling of RNA polymerase molecules that have been released from the attenuator site by rho factor. In fact, transcription of the trp leader region in vitro results in the fomration of a stable termination complex which can be observed on sucrose gradients or by binding to nitrocellulose filters. These data indicate that a major function of rho at the trp attenuator is to release completed transcripts from a pre-formed termination complex, rather than to cause the cessation of elongation.
Nucleic Acids Res 1978 Dec
PMID:The attenuator of the tryptophan operon in E.coli: rho-mediated release of RNA polymerase from a transcription termination complex in vitro. 37 Jul 76

A new class of fluorescent nucleotide analogs which contain the fluorophore 1-aminonaphthalene-5-sulfonate attached via a gamma-phosphoamidate bond has been synthesized. Both the purine and pyrimidine analogs have fluorescence emission maxima at 460 nm. Cleavage of the alpha-beta-phosphoryl bond produces change in both the absorption and fluorescence emission spectra. The fluorescence of the pyrimidine analogs is quenched; cleavage of the alpha-beta-phosphoryl bond of the UTP analog produces about a 14-fold increase in fluorescence intensity at 500 nm. Under the same conditions the fluorescence of the CTP analog increases about 8-fold, whereas the fluorescence of the purine analogs shows only a slight change. These derivatives are good substrates for Escherichia coli RNA polymerase with only slightly increased Km values and with Vmax values about 50 to 70% that of the normal nucleotides. They are used less efficiently by wheat germ RNA polymerase II. The ATP analog can be used by E. coli RNA polymerase to initiate RNA chains.
J Biol Chem 1979 Dec 10
PMID:Synthesis and properties of fluorescent nucleotide substrates for DNA-dependent RNA polymerases. 38 81

We report the effect of novel synthetic polymers on deoxyribonucleic acid (DNA) directed ribonucleic acid (RNA) synthesis in vitro. Polymers contained base-selective monomers, including a GC-specific phenazine derivative and an AT-specific triphenylmethane dye. Radical chain polymerization was carried out in aqueous solution by using monomers bound to a template DNA, which was obtained from either lambda or T7 bacteriophage. Polymers were isolated and reannealed with DNA samples, including competitive mixtures of T7 and lambda DNAs. We measured transcription from DNA-polymer complexes by using Escherichia coli RNA polymerase and determined not only the reduction in total transcription levels but also the relative inhibition of lambda- or T7-specific transcription by using a hybridization assay. The results show that micromolar concentrations of individual dyes are sufficient to cause substantial inhibition of transcription when the dyes are incorporated into polymers. More significantly, a number of the polymers inhibited more strongly transcription from the DNA which had served as template for polymer synthesis than from the DNA present as competitor in the annealing process. We conclude that template synthesis of DNA-binding polymers can lead to preferential inhibition of function of the original template. The apparent relative affinity of polymer for competing DNAs can be altered by at least an order of magnitude depending on which DNA was used as the synthesis template. The results offer a new approach to improving the specificity of DNA-binding drugs.
Biochemistry 1979 Dec 25
PMID:Selective repression of transcription by base sequence specific synthetic polymers. 39 Dec 75

The transcription of transfer RNA genes (tDNAs) and processing of the transcripts have been studied by injecting cloned tDNAs into Xenopus oocyte nuclei. Three main conclusions can be drawn. First, eucaryotic nuclear tRNA genes, but neither procaryotic nor mitochondrial tRNA genes, are expressed in injected oocytes. While both nematode and yeast tDNAS direct the synthesis of authentic tRNAs, neither E. coli tDNA nor human mitochondrial tDNAs support the synthesis of defined tRNAs when injected into oocytes. Second, competition experiments with co-injected 5S genes and inhibition experiments with alpha-amanitin show that injected tDNAs are transcribed by RNA polymerase III. Third, oocytes injected with a nematode tDNA synthesize a tRNA precursor which is processed post-transcriptionally by removal of a 5' leader sequence. This precursor is found exclusively in the nucleus and is processed in the nucleus before the mature tRNA enters the cytoplasm.
Cell 1979 Dec
PMID:Transcription of cloned tRNA genes and the nuclear partitioning of a tRNA precursor. 39 7

A procedure has been developed to separate the subunits of Bacillus subtilis RNA polymerase rapidly and in good yield. The method involved the use of a blue dextran-Sepharose column which bound the beta' subunit. A phosphocellulose column was used to separate the alpha and beta subunits. During purification, the enzyme eluted from the DNA-cellulose column in three separate forms in the order alpha2betabeta'deltaomega1,alpha2betabeta'omega1, and alpha2betabeta'omega1sigma. Subunit reconstitution studies with RNA polymerase subunits from wild type and a rifampicin-resistant mutant indicated that the largest polypeptide was responsible for rifampicin resistance. Thus, this subunit is referred to as beta. The mobility of the subunits in sodium dodecyl sulfate-polyacrylamide gel electrophoresis cannot be used as the sole criterion for designating the functions of the subunits of RNA polymerase.
J Biol Chem 1977 Dec 25
PMID:Reconstitution studies show that rifampicin resistance is determined by the largest polypeptide of Bacillus subtilis RNA polymerase. 41 92

The antiestrogen tamoxifen has been used successfully in the treatment of breast cancer. In an attempt to elucidate its mode of action, its effects on steroid hormone receptor concentration and RNA polymerase activities in the uteri of ovariectomized rats have been compared with those of estradiol. A single dose of estradiol and tamoxifen, separately or in combination, produced slight increases in uterine wet weight 12 h after injection. Whereas both estradiol and tamoxifen could promote translocation of the estrogen receptor, only estradiol caused cytoplasmic replenishment of the receptor. Both compounds, separately and in combination, stimulated the production of cytoplasmic progesterone receptor 12 h after treatment. Estradiol produced and maintained significant elevations in RNA polymerase I activity, whereas the effects on this enzyme brought about by taxoxifen were less and transitory. However, estrogen and antiestrogen caused equal increases in RNA polymerase II activity, but, again, the effects of taxoxifen were shortlived when compared to those brought about by estradiol. Stimulation of RNA polymerase II activity was due to the availability of increased numbers of apparent initiation sites. These results point to a basic inefficacy in the antiestrogen-receptor complex; although it is able to promote early tissue responses characteristic of an estrogen, these cannot be sufficiently maintained.
Endocrinology 1979 Dec
PMID:Effects of estradiol and the antiestrogen tamoxifen on steroid hormone receptor concentration and nuclear ribonucleic acid polymerase activities in rat uteri. 49 77

Spontaneous and EMS-induced alpha-amanitin-resistant Aedes albopictus cells have been isolated and characterized. Two mutant sublines, one of intermediate resistance (alpha A2) and the other highly resistant (Ama18) contained RNA polymerase II activity, the resistance of which in vitro to alpha-amanitin correlated well with the resistance of these cells in vivo. The resistance of these cells to alpha-amanitin can likely be attributed to the presence of an altered RNA polymerase II.
Cell Biol Int Rep 1979 Dec
PMID:alpha-Amanitin resistant RNA polymerase II from Aedes albopictus cell mutants resistant to alpha-amanitin. 50 43

Reovirus mRNA's containing a 5'-terminal methylated cap structure (m(7)GpppG(m)) were shown to be effective primers for influenza viral RNA transcription in vitro catalyzed by the influenza virion transcriptase. Priming activity required the presence of methyl groups in the cap since reovirus mRNA's with 5'-terminal GpppG were inactive as primers. Both the cap and internal nucleotides were physically transferred from radiolabeled reovirus mRNA to influenza viral complementary RNA (cRNA) during transcription in vitro. By using reovirus mRNA's with methyl-(3)H-labeled caps as primers, we showed that the influenza viral cRNA synthesized in the presence of unlabeled nucleoside triphosphates contained [methyl-(3)H]m(7)GpppG(m), identical to that found in the reovirus mRNA primer. To demonstrate transfer of internal residues, reovirus mRNA's synthesized in the presence of all four alpha-(32)P-labeled ribonucleoside triphosphates were used as primers. The resulting influenza viral cRNA was (32)P-labeled. Diethyl-aminoethyl-Sephadex chromatography of the RNase T2 digest of this cRNA demonstrated (32)P radiolabel in both internal residues (charge -2) and the cap (charge -4.6). Approximately 25 internal nucleotides along with the cap of reovirus mRNA were transferred to each chain of influenza viral cRNA. Gel electrophoretic analysis indicated that the segments of influenza viral cRNA primed by reovirus mRNA were approximately the same size as those primed by a different mRNA, globin mRNA, strongly suggesting that the influenza virion transcriptase complex transfers approximately the same number of nucleotides plus the cap from different mRNA primers to the 5' end of influenza viral RNA transcripts.
J Virol 1979 Dec
PMID:Cap and internal nucleotides of reovirus mRNA primers are incorporated into influenza viral complementary RNA during transcription in vitro. 51 5

The effect of halothane on precursor incorporation into nucleic acids was studied in Tetrahymena pyriformis, a ciliate protozoan. At concentrations that blocked cell division (1.2 and 2.4 per cent), halothane inhibited incorporation of 14C-thymidine and 14C-uridine into DNA and RNA, respectively, in intact cells. However, in nuclei isolated from T. pyriformis, the anesthetic did not inhibit DNA and RNA synthesis when these processes were assayed using the nucleoside triphosphates (3H-thymidine triphosphate and 3H-uridine triphosphate) as precursors. It is concluded that halothane does not directly inhibit nucleic acid synthesis (i.e., the nucleic acid polymerase reactions), and that the inhibition of precursor incorporation observed in intact cells is due to an effect at a locus other than the DNA and RNA polymerase reactions.
Anesthesiology 1979 Dec
PMID:Halothane does not inhibit synthesis of nucleic acids in Tetrahymena pyriformis. 51 77


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