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)

The endogenous RNApolymerase activity of isolated cell nuclei and chloroplasts from young pea plants (Pisum sativum) has been studied. The presence of all four nucleoside triphosphates and Mg2+ ions is necessary for the reaction. The missing of one of these nucleotides from the reaction mixture, especially ATP, sharply decreases the transcription. Chloroplasts synthesize RNA per DNA unit more intensively, than nuclei. In spring such predominance is especially pronounced. Maximal synthesis of RNA is observed at pH 8.3 both in nuclei and chloroplasts. Maximal transcription was observed at 25 degrees in chloroplasts and at 30--35 degrees in nuclei. Actinomycin D inhibited the process of transcription both in nuclei and some stimulation in chloroplasts were observed, when rifamicin B was added. It is suggested that there are differences in nuclear and chloroplast forms of RNA polymerase.
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PMID:[Comparative study of endogenous RNA-polymerase activity of the cell nuclei and chloroplasts of pea leaves]. 0 71

The properties of poly(G) polymerase and poly(A) polymerase activities in the DNA-dependent RNA polymerase [nucleosidetriphosphate: RNA nucleotidyltransferase EC 2.7.7.6] I fraction from cauliflower (Brassica oleracea var. botrytis) were comparatively investigated. The pH optimum, the effect of ionic strength, the effect of substrate concentration on the rate of synthesis, the effect of divalent metal ion concentration, and the time course of synthesis at different temperatures were all different for the three polymerase activities. The enzyme fraction preferentially utilized denatured DNA. Synthetic poly(C) and poly(U) were more effectively utillized for the synthesis of polyguanylate and polyadenylate, respectively. Further, it was found that poly(G) and poly(A) formed in vitro by the enzyme fraction had chain length of 25-28 and 84-89 nucleotides, respectively, and that poly (adenylate-gluanylate) chain was hardly formed when ATP and GTP were added together as substrates in the same reaction medium.
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PMID:Comparative studies on polyguanylate polymerase and polyadenylate polymerase activities in the DNA-dependent RNA polymerase I fraction from cauliflower. 0 54

Nucleoside triphosphate phosphohydrolase [EC 3.6.1.15] activity was found to be included in silkworm cytoplasmic polyhedrosis (CP) virus, which synthesizes mRNA carrying the 5'-terminal modification. This enzyme releases orthophosphate from the gamma-position in a nucleoside triphosphate, leaving nucleoside diphosphate. The rate of hydrolysis of ATP is faster than that of any other ribonucleoside triphosphate. Deoxy ATP is hydrolyzed rather faster than ATP. However, polynucleotides carrying triphosphate at the 5'-terminus, that is, 4S RNA which was synthesized by E. coli RNA polymerase [EC 2.7.7.6] using calf thymus DNA as a template, and the phage Q beta RNA (30S), are not effective substrates for this enzyme. Although the CP virion loses the viral genome and one kind of protein component on proteolytic treatment with pronase, the partially degraded virion still retains phosphohydrolase activity. The phosphohydrolase must therefore be associated firmly with the virion. This enzyme does not require the presence of nucleic acid for its function. Phosphohydrolysis of ATP by this enzyme activity represents a first step in the synthesis of the 5'-terminal modified mRNA of CP virus.
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PMID:Nucleoside triphosphate phosphohydrolase associated with cytoplasmic polyhedrosis virus. 1 44

A phosphoprotein kinase (ATP : protein phosphotransferase, EC 2.7.1.37) from calf thymus nuclei was purified by DEAE-cellulose chromatography, hydroxyapatite, and Sepharose 6B gel filtration. The enzyme is a cyclic AMP-independent protein kinase by the following criteria: (a) the protein kinase did not bind cyclic AMP; (b) no inhibition of activity was obtained with the heat-stable protein kinase inhibitor from rabbit skeletal muscle; (c) the regulatory subunit of cyclic AMP-dependent protein kinase had no effect on activity; and (d) no inhibition was obtained with antibody to cyclic AMP-dependent protein kinase. The nuclear cyclic AMP-independent protein kinase readily phosphorylated protamine on serine and to a lesser extent on threonine. Homologous nucleoplasmic RNA polymerase (EC 2.7.7.6) is a better substrate than arginine-rich histone, phosvitin or casein. Physical characteristics of the enzyme are described.
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PMID:Purification and properties of a cyclic AMP-independent protein kinase from calf thymus nuclei. 2 35

Studies on the effects of substrates on RNA polymerase I [EC 2.7.7.6] in vitro showed that nucleolar RNA synthesis was inhibited by an excess of substrate nucleoside triphosphates in the presence of Mg2+. GTP and UTP were more inhibitory than CTP and ATP. These compounds specfically inhibited nucleolar RNA synthesis and a concentration of GTP that strongly inhibited nucleolar RNA synthesis did not inhibit RNA synthesis by partially purified RNA polymerase I. The inhibition of nucleolar RNA synthesis disappeared at pH 9.0 without any change in the apparent Km for GTP or the Vmax of RNA synthesis.
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PMID:Inhibitory effects of nucleoside triphosphates on nucleolar RNA synthesis. 3 1

We have studied the effect of protein phosphokinase (EC 2.7.1.37; ATP:protein phosphotransferase) and phosphoprotein phosphatase (EC 3.1.3.16; phosphoprotein phosphohydrolase) on reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) activity of Rous sarcoma virus. Protein kinase from Rous sarcoma virus-transformed chick embryo fibroblasts was purified by DEAE-cellulose chromatography, Sephadex gel filtration, and isoelectric focusing. Purified reverse transcriptase from Rouse sarcoma virus was preincubated with protein kinase and ATP under conditions allowing incorporation of phosphate into substrate protein. After the preincubation, reverse transcriptase activity was assayed in the presence of poly(rA).oligo(dT) as template. A 2- to 5-fold increase of reverse transcriptase activity was found after the preincubation of reverse transcriptase with protein kinase and ATP. Incubation of reverse transcriptase with heat-treated, inactive protein kinase and ATP had no effect on transcriptase activity. When the transcriptase preparation was incubated with protein kinase and [gamma-32P]ATP and subsequently purified by chromatography on phosphocellulose and Sephadex gel filtration, significant amounts of 32P-labeled proteins were found in the fractions exhibiting reverse transcriptase activity, suggesting 32P incorporation into transcriptase or transcriptase-associated proteins. A 20-60% decrease of reverse transcriptase activity was observed after incubation of reverse transcriptase with phosphatase. The results suggest that phosphorylative modification of reverse transcriptase may be critical in the regulation of reverse transcriptase-catalyzed DNA synthesis.
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PMID:Protein kinase and its regulatory effect on reverse transcriptase activity of Rous sarcoma virus. 5 72

To determine the special feature of ribosomal RNA promoters that might account for the highly efficient and regulated synthesis of rRNA in E. coli, we have analyzed the beginnings of two ribosomal RNA operons, rrnD and rrnX. DNA sequences for 425 bp preceding those specifying mature 16s rRNA are reported. In vitro transcription of restriction endonuclease fragments containing this region from either operon reveals the presence of two promoters about 110 nucleotides apart; they are denoted P1 and P2. RNA synthesis from P1 is initiated with GTP at position -284 (relative to 16s sequences) in rrnD and with ATP at position -285 in rrnX. At P2, the RNA starts with CTP primarily at position-176 in both operons. The DNA sequences of the two operons are identical for 231 bp preceding the 16s rDNA (including a substantial region around P2); they then diverge almost completely, except for a notable 18 bp homology just preceding the transcription start site for P1. Certain sequences implicated in the recognition of promoters by E. coli RNA polymerase are clearly identifiable in both P1 and P2; other features include an extended region preceding P1 which is strikingly rich in AT base pairs. Possible mechansims by which these tandem promoters contribute to the high frequency of rRNA transcription and to the differential expression of the E. coli rrn operons are discussed.
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PMID:Tandem promoters direct E. coli ribosomal RNA synthesis. 11 Apr 60

Adenosinetriphosphatase (ATPase) [EC 3.6.1,3] activity has been found to exist in most preparations of DNA-dependent RNA polymerase [EC 2.7.7.6] obtained from Escherichia coli by a number of purification procedures so far established. Electrophoretic analysis on polyacrylamide gels demonstrated that ATP hydrolysis and RNA synthesis were catalyzed by two distinct enzyme proteins. It appears that the two enzymes are associated or have similar molecular properties. Separation of the two enzymes, the object of the present work, was achieved by three independent methods: ion exchange chromatography on a phosphocellulose column, electrophoresis in glycerol gradients, or high-salt glycerol gradient centrifugation.
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PMID:A novel adenosine triphosphatase isolated from RNA polymerase preparations of Escherichia coli. I. Copurification and separation. 13 29

Crude extracts of Escherichia coli selectively convert fd viral DNA and not phiX174 DNA to duplex DNA via a complex series of reactions one of which involves RNA polymerase. Reactions leading to formation of fd duplex-replicative (RFII) structures have been reconstituted with purified proteins from E. coli. Maximal synthesis requires the combined action of E. coli binding protein, DNA elongation factor I, DNA elongation factor II preparations (which are a mixture of dna Z and DNA elongation factor III), DNA polymerase III, DNA-dependent RNA polymerase, Mg2+, dATP, dGTP, dCTP, dTTP, and ATP, GTP, CTP, and UTP. In contrast to crude extracts of E. coli, purified protein fractions do not distinguish between fd DNA and phiX174 DNA in duplex DNA formation. The addition of crude fractions of E. coli to the purified components listed above selectively permits fd RFII formation and prevents phiX RFII formation. This selective inhibition was used as an assay to isolate proteins essential for this phenomenon; they include RNase H, discriminatory factor alpha, and discriminatory factor beta.
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PMID:Selective inhibition of in vitro DNA synthesis dependent on phiX174 compared with fd DNA. I. Protein requirements for selective inhibition. 14 Jan 66

The synthesis of RNA by chromatin-bound RNA polymerase (E.C. 2.7.7.6.) from white potato tubers proceeds at a low rate, which is enhanced after slicing the tissue, however. Concomitantly DNA template availability as measured with saturating amounts of Escherichia coli polymerase is diminished drastically. Nearest neighbor frequency analysis proved that the RNA synthesized on chromatin of intact tubers is different from that synthesized on chromatin of sliced tissue. The RNA polymerase of white potato tubers is dependent on all four ribonucleoside triphosphates and a divalent metal ion such as Mg2+ or Mn2+ and totally inhibited by the presence of pyrophosphate. Actinomycin D blocks the formation of the RNA product, which could be shown to be a heteropolymer by nearest neighbour frequency technique. The Km of the chromatin-bound enzyme with regard to ATP, GTP, CTP and UTP was 5.1 X 10(-5) M, 1.6X10(-5) M, 0.9X10(-5) M and 0.45X10(-5) M/l respectively. alpha-amanitin inhibits the overall activity to about 50%, which indicates the presence of equal amounts of polymerase I and polymerase II.
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PMID:Activation of chromatin-bound DNA-dependent RNA polymerase (E.C. 2.7.7.6.) in plant storage tissue slices. 14 5


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