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)

Non-glucosylated T4 DNA was restricted with the endonuclease EcoRI and the mixture of DNA fragments separated by gel electrophoresis and transcribed with purified Escherichia coli RNA polymerase. Three purified fragments were shown to act as templates for tRNA synthesis. A smaller fragment, shown to be hybridizable to 32P-labeled T4 tRNA was not transcribable. It was concluded that the promoter for T4 tRNA synthesis had been separated from the structural genes in the smaller fragment by EcoRI and that the distal portion of the tRNA gene cluster lacks internal promoters which display in vitro activity. Preparations of non-glucosylated T4 DNA were never fully restricted with EcoRI and when the larger purified fragments carrying the tRNA were restricted with excess enzyme only a slight cleavage to yield the smaller fragments was obtained. The property of the DNA-limiting complete restriction is not know.
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PMID:Isolation of the transfer RNA genes of bacteriophage T4 and transfer RNA synthesis in vitro. 42 Aug 49

Although cordycepin 5'-triphosphate (3'-dATP), at low concentrations, preferentially inhibits chromatin-associated poly(A) synthesis in isolated nuclei, higher levels of the inhibitor prevent both rRNA (RNA polymerase I activity) and hnRNA (RNA polymerase II activity) synthesis in vitro (Rose, K.M., Bell, L.E. and Jacob, S.T. (1977) Nature 267, 178-180). The present studies demonstrate that this nucleotide can also inhibit tRNA and 5 S RNA synthesis (RNA polymerase III activity). At 50-200 microgram/ml, 3'-dATP inhibits incorporation of [3H]UTP into tRNA and 5 S RNA by approximately 65%, whereas the syntheses of these RNAs were completely blocked when [3H]GTP was used as the substrate. These data suggest the formation of poly(U) in the tRNA and 5 S RNA regions, which is resistant to 3'-dATP. In contrast, another ATP analog, Ara-ATP, which selectively inhibits poly(A) synthesis, does not block tRNA and 5 S RNA synthesis in isolated nuclei. The production of these RNA species in isolated nuclei is also insensitive to Ara-CTP and 2'-dATP. These data suggest that 3'-dATP exerts general inhibitory effects on RNA synthesis and further substantiate the conclusion that Ara-ATP is a selective inhibitor of the polyadenylation reaction in vitro.
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PMID:Differential effects of cordycepin triphosphate and 9 beta-D-arabinofuranosyladenine triphosphate on tRNA and 5 S RNA synthesis in isolated nuclei. 49 5

A procedure suitable for en masse preparation of germinal vesicles (GV) from X.laevis oocytes (Scalenghe et al., 1978) has been adapted for studies of transcription. Extracts from GV contain activities for transcription of tRNA genes and for processing the transcription product. The two activities have been separated by column chromatography. One fraction allows synthesis of tRNA precursor molecules in the presence of X.laevis RNA polymerase III. Another fraction contains the activity that cuts and splices those precursors which contain an intervening sequence. Transcription occurs faithfully on linear DNA fragments.
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PMID:Separation of RNA transcription and processing activities from X. laevis germinal vesicles. 51 51

The phage DNA-directed synthesis of beta-galactosidase has been examined in a system containing the following purified Escherichia coli factors: RNA polymerase; cyclic AMP receptor protein; N10-formyltetrahydrofolate Met-tRNAf transformylase; initiation factors 1, 2, and 3; elongation factors Tu, Ts, and G; release factors 1 and 2; 20 aminoacyl-tRNA synthetases; L factor (Kung, H. F., Spears, C., and Weissbach, H. (1974) J. Biol. Chem. 250, 1556-1562); and Lalpha (Kung, H.-F., Spears, C., and Weissbach, H. (1976) Fed. proc. 35, 1537). Under these conditions, beta-galactosidase synthesis occurs at less than 1% of the rate obtained with unfractionated extracts, which suggested that other required components were lacking. The difficulty in obtaining large amounts of the purified aminoacyl-tRNA synthetases for these studies made it necessary to modify the system. It was possible to conserve many of the purified aminoacyl-tRNA synthetases since at least 13 of them could be replaced by an Ehrlich ascites extract. The ascites extract plus other E. coli purified factors was used as a basic system to search for additional components required for beta-galactosidase synthesis. The present report describes the purification from E. coli extracts of three fractions, called Lbeta, Lgamma, and Ldelta, that are needed to restore enzyme synthesis.
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PMID:DNA-directed in vitro synthesis of beta-galactosidase. Studies with purified factors. 56 Oct 72

Crude nuclei were isolated from trunks of 13-day-old chicken embryos under conditions which prevent leakage of RNA polymerases from nuclei. RNA polymerases were solubilized by subsequent incubation in alkaline buffer and sonication at high salt concentration. Purification of RNA polymerases A, B, and C was achieved by conventional column chromatographic procedures. RNA polymerase B was freed from an UTP:polynucleotidyl exotransferase by chromatography on a tRNA-Sepharose column. Purified RNA polymerase A contained six putative subunits with molecular weights 190 000 (A1), 117 000 (A2), 57 000 (A3), 50 000 (A4), 25 000 (A5), 19 000 (A6); RNA polymerase B contained eight putative subunits with molecular weights 98 000 (B2'), 86 000 (B2''), 155 000 (B3), 44 000 (B4), 31 000 (B5), 28 000 (B6), 26 000 (B7), 19 000 (B8); RNA polymerase C contained nine putative subunits with molecular weights 170 000 (C1), 117 000 (C2), 84 000 (C3), 60 000 (C4), 49 000 (C5), 36 000 (C6), 33 000 (C7), 22 000 (C8), 19 000 (C9).
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PMID:Purification of class A, B, and C DNA-dependent RNA polymerases from chicken embryos. 71 15

The antibiotic rifampicin forms a very tight complex with DNA-dependent RNA polymerase of Escherichia coli. The rate constants of association and dissociation of this complex have been measured and found to be dependent on the purity of the enzyme. Thus a crude RNA polymerase (fraction-3 enzyme) has rate constants different from those of an enzyme further purified by DEAE-cellulose chromatography (fraction-4 enzyme). The complex produced by the antibiotic and the fraction-3 enzyme is about ten times more stable and is formed about ten times more slowly than the complex with fraction-4 enzyme. It has been shown that the RNA present in the crude enzyme and removed by chromatography on DEAE-cellulose is the cause of the change in the kinetics of the complex. tRNA of rat liver and crude rat liver RNA added to purified RNA polymerase have a similar effect. Mg2+, which has no intrinsic influence, augments the effect of the nucleic acids, whereas monovalent cations do not. Since nucleic acids increase the stability of the complex, but at the same time decrease the rat of its formation, the equilibrium constant, Keq, remains almost the same. The possible effects of nucleic acids on the rifampicin binding site are discussed.
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PMID:On the kinetics of the rifampicin-RNA-polymerase complex. Differences between crude and purified enzyme fractions. 78 Jan 10

E. coli fMet-tRNAfMEet and E. coli RNA plymerase (RNA nucleotidyltransferase; EC 2.7.7.6; nucleoside-triphosphate:RNA nucleotidyltransferase) form a 1:1 complex with an apparent association constant of 9.0 X 10(6)M-1 at 37 degrees. The affinity of polymerase to tRNA depends on the tRNA as well as the formyl methionine moiety. Core polymerase has a greatly reduced affinity for initiator tRNA. Optimal binding conditions are similar to those that are also optimal for binding initiator tRNA to ribosomes. Binding of initiator tRNA to polymerase stimulates the transcription of lambda plac DNA, as determined in a crude cell-free system for beta-galactosidase (EC 3.2.1.23; beta-D-galactoside galactohydrolase) synthesis as well as in a highly purified transcription system.
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PMID:Specific binding of formylated initiator-tRNA to Escherichia coli RNA polymerase. 78 83

The effects of a partial restriction of valyl-tRNA aminoacylation on the synthesis of aminoacyl-tRNA synthetases, ribosomal proteins, and other translation and transcription proteins were examined in otherwise isogenic stringent (relA+) and relaxed (relA1) derivatives of E. coli B. The synthesis of individual ribosomal proteins, elongation factor G, and to a lesser extent elongation factors Tu and Ts, and the valyl- and arginyl-tRNA synthetases was found to be subject to the influence of the stringent control system. The synthesis of the alpha and beta subunits of RNA polymerase and several of the aminoacyl-tRNA synthetases, in contrast, is either not subject to the influence of the stringent control system, or is subject to additional regulatory constraints.
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PMID:The effects of the relA gene on the synthesis of aminoacyl-tRNA synthetases and other transcription and translation proteins in Escherichia coli A. 79 47

RNA synthesis in yeast is rapidly inhibited by 8-hydroxyquinoline and the phenazine antibiotic lomofungin (5-formyl-1-methoxycarbonyl-4,6,8-trihydroxyphenazine). It is shown that lomofungin, like 8-hydroxyquinoline, is a chelating agent for bivalent cations. The mechanism of inhibition of RNA synthesis by lomofungin and 8-hydroxyquinoline was investigated in experiments with isolated Escherichia coli RNA polymerase. The results show that both inhibitors are capable of inhibiting polymerase activity solely by chelating the dissociable cations Mn2+ and Mg2+. Evidence is presented which shows that inhibition may occur in the absence of any direct contact between the RNA polymerase or DNA template and the inhibitor. The possibility that inhibition might also occur by chelation of the Zn2+, which is tightly bound to the polymerase, is discussed: it is concluded that lomofungin or 8-hydroxyquinoline is likely to inhibit the enzyme by removal of Mn2+ and Mg2+ before chelating the Zn2+. On the basis of inhibition by chelation of Mn2+ and Mg2+, explanations are proposed for why lomofungin and 8-hydroxyquinoline inhibit synthesis of ribosomal and polydisperse RNA more than that of 5S RNA and tRNA, and for why protein synthesis is not immediately inhibited in the intact yeast cell.
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PMID:The mechanism of inhibition of ribonucleic acid synthesis by 8-hydroxyquinoline and the antibiotic lomofungin. 81 Jan 37

The influenza virion transcriptase is capable of synthesizing in vitro complementary RNA (cRNA) that is similar in several characteristics to the cRNA synthesized in the infected cell, which is the viral mRNA. Most of the in vitro cRNA is large (approximately 2.5 X 10(5) to 10(6) daltons), similar in size to in vivo cRNA. The in vitro transcripts initiate in adenosine (A) or guanosine (G) at the 5' end, as also appears to be the case with in vivo cRNA (R.M. Krug et al., 1976). The in vitro transcripts contain covalently linked polyadenylate [poly(A)] sequences, which are longer and more heterogeneous than the poly(A) sequences found on in vivo cRNA. The synthesis in vitro of cRNA with these characteristics requires both the proper divalent cation, Mg2+, and a specific dinulceside monophosphage (DNMP), ApG or GpG. These DNMPs stimulate cRNA synthesis about 100-fold in the presence of Mg2+ and act as primers to initiate RNA chains, as demonstrated by the fact that the 5'-phosphorylated derivatives of these DNMP's, 32pApG or 32pGpG, are incroporated at the 5' end of the product RNA. The RNA synthesized in vitro differs from in vivo cRNA in that neither capping nor methylation of the in vitro transcripts has been detected. The virion does contain a methylase activity, as shown by its ability to methylate exogenous methyl-deficient Escherichia coli tRNA.
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PMID:Influenza virion transcriptase: synthesis in vitro of large, polyadenylic acid-containing complementary RNA. 83 24


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