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)

1. Contact-inhibited confluent monolayers of WI-38 human diploid fibroblasts can be stimulated to divide by replacing the medium with fresh medium containing 30% foetal calf serum. 2. Of the cells 40-75% are stimulated to divide with a peak DNA synthesis between 15 and 21h and a peak mitotic index between 28 and 30h after stimulation. 3. In the first 12h before the initiation of DNA synthesis there is a biphasic increase in the incorporation of [(3)H]uridine into RNA of whole cells. 4. This is paralleled by a similar biphasic stimulation of chromatin template activity measured in vitro in a system in which purified cell chromatin is incubated with an exogenous RNA polymerase isolated from Escherichia coli. 5. The changes in chromatin template activity are believed to represent activation of the genome, with more sites available for RNA synthesis, and to account almost entirely for the changes in RNA synthesis occurring in the whole cell.
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PMID:Template activity of chromatin during stimulation of cellular proliferation in human diploid fibroblasts. 516 6

To study the process of hormone action, we have developed an in vitro system utilizing minced oviduct from estrogen-treated chicks incubated in tissue culture medium. Progesterone added to the medium induced synthesis of a specific protein, avidin, that continued for up to 96 hr. During this period there was no increase in total oviduct protein, ovalbumin, or lysozyme, which suggests the specificity of the progesterone effect. The induction process was dependent on new protein synthesis, since cycloheximide inhibited the induction completely. Actinomycin D in doses that prevented nuclear RNA synthesis, but not general protein synthesis, inhibited avidin production 70-90%. Avidin synthesis was not affected by 5-fluorouracil. The rate of DNA synthesis examined by thymidine-(3)H pulse labeling was not stimulated during avidin induction. Hydroxyurea (an inhibitor of DNA synthesis) and colchicine (a mitotic inhibitor) did not prevent induction. Studies utilizing uridine-(3)H pulses showed an effect on rapdly labeled nuclear RNA coincident with induction. Nuclear RNA polymerase activity increased before avidin induction. Since avidin was the only new protein synthesized in response to progesterone, the early stimulation of nuclear RNA synthesis and RNA polymerase activity would suggest a mechanism of action for this steroid at the transcription level of protein synthesis.
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PMID:Studies on the mechanism of action of progesterone in regulation of the synthesis of specific protein. 563 49

Deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase activity was assayed on nuclear preparations of chick embryo fibroblast cells at various times after infection with an influenza A virus (fowl plague virus) and was compared with the activity of uninfected cells. Polymerase activity was increased by about 60% by 2 hr after infection, and this increase coincided with an increase in RNA synthesis in infected cells, as determined by pulse-labeling with uridine. No difference could be detected between the polymerases of infected and uninfected cells as to their requirements for DNA primer, divalent cations, and nucleoside triphosphates, and they were equally sensitive to addition of actinomycin D to the reaction mixture. It is possible that host cell DNA-dependent RNA polymerase is involved in the replication of influenza virus RNA.
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PMID:Deoxyribonucleic acid-dependent ribonucleic acid polymerase activity in cells infected with influenza virus. 574 27

Two distinct ribonucleic acid polymerase activities were induced in HeLa cells by poxvirus infection. These activities differ both in their properties and the time of their appearance after infection. One catalyzes the dAT (copolymer of deoxyadenylate and deoxythymidylate)-primed conversion of adenosine triphosphate and uridine triphosphate into an acid-insoluble product. This enzyme is detectable only if deoxyribonucleic acid synthesis has been blocked. In contrast, the accumulation of progeny genomes is a necessary condition for induction of the second enzyme. The latter activity, which is unmasked by detergent treatment, is found exclusively in maturing virus particles. The possibility that both enzymes are involved in transcribing the viral genome is discussed.
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PMID:Induction of poxvirus ribonucleic acid polymerases. 574 7

Preparations of purified and disrupted suspensions of Coxiella burnetii are able to incorporate ribonucleotides into polymers in the presence of adenosine, guanosine, cytidine, and uridine triphosphates. Nucleotide incorporation requires the presence of all four ribonucleoside triphosphates. The reaction is enhanced by the addition of phosphoenolpyruvate and pyruvic kinase, and exogenous deoxyribonucleic acid, and is inhibited by deoxyribonuclease and actinomycin D. Incorporation is maximal between pH 7.0 and 8.0, and at 37 C. The synthesized polymer is relatively insensitive to deoxyribonuclease and is sensitive to ribonuclease and dilute alkaline hydrolysis. The data indicate the presence of an autonomous deoxyribonucleic acid-dependent ribonucleic acid polymerase in the rickettsial agent.
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PMID:Physiology of rickettsiae. VI. Host-independent synthesis of polyribonucleotides by Coxiella burnetii. 602 13

Influenza virus infection has adverse effects on the metabolism of two representative RNA polymerase II transcripts in chicken embryo fibroblasts, those coding for beta-actin and for avian leukosis virus (ALV) proteins. Proviral ALV DNA was integrated into host cell DNA by prior infection with ALV. Within 1 h after influenza virus infection, the rate of transcription of beta-actin and ALV sequences decreased 40 to 60%, as determined by labeling the cells for 5 min with [3H]uridine and by in vitro, runoff assays with isolated nuclei. The transcripts that continued to be synthesized did not appear in the cytoplasm as mature mRNAs, and the kinetics of labeling of these transcripts strongly suggest that they were degraded in the nucleus. By S1 endonuclease assay, it was confirmed that nuclear ALV transcripts disappeared very early after infection, already decreasing ca. 80% by 1 h postinfection. A plausible explanation for this nuclear degradation is that the viral cap-dependent endonuclease in the nucleus cleaves the 5' ends of new polymerase II transcripts, rendering the resulting decapped RNAs susceptible to hydrolysis by cellular nucleases. In contrast to the nuclear transcripts, cytoplasmic beta-actin and ALV mRNAs, which are synthesized before infection, were more stable and did not decrease in amount until after 3 h postinfection. Similar stability of cytoplasmic host cell mRNAs was observed in infected HeLa cells, in which the levels of actin mRNA and two HeLa cell mRNAs (pHe 7 and pHe 28) remained at undiminished levels for 3 h of infection and decreased only slightly by 4.5 h postinfection. The cytoplasmic actin and pHe 7 mRNAs isolated from infected HeLa cells were shown to be translated in reticulocyte extracts in vitro, indicating that host mRNAs were not inactivated by a virus-induced modification. Despite the continued presence of high levels of functional host cell mRNAs, host cell protein synthesis was effectively shut off by about 3 h postinfection in both chicken embryo fibroblasts and HeLa cells. These results are consistent with the establishment of an influenza virus-specific translational system that selectively translates viral and not host mRNAs.
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PMID:Metabolism and expression of RNA polymerase II transcripts in influenza virus-infected cells. 609 46

The uptake of nucleosides and the synthesis of RNA in Tetrahymena thermophila were examined following amino acid starvation. Omission of leucine, phenylalanine, or arginine from the medium resulted in a rapid decrease in the incorporation of [3H]uridine into the acid-soluble pool and acid-insoluble material (RNA). Amino acid starvation inhibited the uptake of all ribo- and deoxyribonucleosides tested but did not affect the uptake of amino acids or glucose. In addition, under the conditions used, the omission of an amino acid did not result in a large decrease in amino acid incorporation into total protein. Treatment of cells with cycloheximide or emetine gave results similar to the effects of amino acid starvation, but in these experiments the inhibition of protein synthesis was essentially complete. Nucleotide pool sizes were also measured following amino acid starvation. ATP and UTP levels were essentially unchanged, but the dTTP pool size was decreased by 40%. The decrease in RNA synthesis in vivo in the absence of an essential amino acid was reflected in the endogenous RNA synthetic activity of isolated nuclei. However, when solubilized RNA polymerase activity was measured with calf thymus DNA as template, no significant difference was observed between control and amino acid-starved cells.
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PMID:The effect of amino acid starvation on nucleoside uptake and RNA synthesis in Tetrahymena. 615 97

Ribonucleic acid (RNA) synthesis was examined in cold-shocked Bacillus subtilis cells. The cells were grown to mid-log stage, harvested, and cold shocked. RNA synthesis was monitored by the incorporation of [3H]uridine triphosphate or [alpha 32P]adenosine triphosphate into trichloroacetic acid-precipitable material in the presence of all four nucleoside triphosphates. The inhibition of RNA synthesis in cold-shocked cells by lipiarmycin, ethidium bromide, rifampin. or streptolydigin was analyzed using mutant or wild-type cells. Also examined were the effects of temperature, salt concentration, and the addition of polyamines or highly phosphorylated nucleotides. In ultraviolet-irradiated and cold-shocked cells, RNA wynthesis decreased to low levels. The addition of exogenous phi 29 or TSP-1 template to these cells caused a 13- to 20-fold increase in RNA synthesis, as monitored by trichloroacetic acid-precipitable counts. RNA synthesized in the presence of phi 29 deoxyribonucleic acid (DNA) hybridizes mainly to EcoRI fragments A and C of phi 29 DBA, These two fragments direct transcription by purified RNA polymerase in vitro and hybridize to early phi 29 DNA produced in vivo. Our results with TSP-1 DNA in this system indicated that the RNA produced hybridizes to the same fragments as early RNA produced in vivo. Plasmic pUB110 DNA was not transcribed in this system.
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PMID:Transcription of exogenous and endogenous deoxyribonucleic acid templates in cold-shocked Bacillus subtilis. 615 74

Low concentrations (0.10 to 1.0 microgram/ml) of alpha-amanitin inhibit wheat embryo germination. Labeled RNA, synthesized in vivo by embryos imbibed in the presence of [3H]uridine and various concentrations of alpha-amanitin, was analyzed by oligo(dT)-cellulose chromatograhy and by gel electrophoresis (acrylamide and agarose) coupled with fluorography. Low concentrations of alpha-amanitin (0.10 to 1.0 microgram/ml) strongly and selectively inhibited in vivo poly(A) + RNA synthesis in a manner which closely paralleled alpha-amanitin inhibition of purified RNA polymerase II. These results suggest that de novo mRNA transcription is required for germination. Higher concentrations of alpha-amanitin inhibited in vivo 5 S rRNA and tRNA synthesis in a manner which closely paralleled alpha-amanitin inhibition of purified RNA polymerase III. High concentrations of alpha-amanitin also inhibited accumulation of radioactivity into the rRNA precursor as well as into mature 25 S and 18 S rRNAs in a manner which also closely paralleled alpha-amanitin inhibition of RNA polymerase III. The discrepancy of the in vivo inhibitory effect of high alpha-amanitin concentrations on rRNA synthesis versus a lack of effect on purified RNA polymerase I, which presumably transcribes these genes, can be explained if continued transcription of the large rRNA precursor by RNA polymerase I requires ongoing transcription by RNA polymerase III, or if there is degradation (wastage) of rRNA precursor and/or processed products in the absence of transcription by RNA polymerase III.
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PMID:The use of alpha-amanitin to inhibit in vivo RNA synthesis and germination in wheat embryos. 615 86

The abortive initiation reaction of RNA polymerase has been used to prepare adenylyl-(3'--5')-uridine 5'-phosphate (pApU) in 74% yield from AMP and UTP. The reactive intermediate p-azidophenyl phosphorimidazolidate has been prepared by starting from p-nitrophenyl phosphate. Reaction of this compound with the terminal phosphates of adenosine 5'-phosphate and adenylyl-(3'--5')-uridine 5'-phosphate gives the corresponding beta-substituted 5'-diphosphates. These products are incorporated into the 5' (leading) end of RNA by RNA polymerase (Escherichia coli) and can be photoactivated at a specific stage of RNA elongation. The dinucleotide photoaffinity label beta-(4-azidophenyl) adenylyl-(3'--5')-uridine 5'-diphosphate stimulates RNA synthesis more strongly than adenylyl-(3'--5')-uridine.
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PMID:Synthesis of mono- and dinucleotide photoaffinity probes of ribonucleic acid polymerase. 616 87


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