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 abilities of H1 and H5 histones from immature and mature pigeon erythroid cells and subfractions of H5 histones with different content of alkali-labile phosphorus to restrict RNA synthesis were compared in an in vitro transcription system with bacterial RNA polymerase. It has been found that: a) H1 histones from both sources exhibit similar efficiency. b) H5 histones from immature cells restrict transcription to a lesser extent than the same histone from the mature erythrocyte. c) The subfraction of H5 histone from immature cells with the higher content of alkali-labile phosphorus restrict transcription less than the subfraction with the lower degree of phosphorylation. The results suggest that H5 histone, which first appears in the erythroblasts in a highly phosphorylated form, does not display its potential 'repressor' properties. During erythrocyte maturation H5 histone is dephosphorylated and this causes the massive inactivation of erythrocyte genome.
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PMID:Existence of differences in repressor properties between serine-rich histones (H5, F2c) from immature and mature pigeon erythroid cells. 64 Mar 4

The phosphodiester bond formation by DNA-dependent RNA-polymerase (RNA nucleotidyltransferase, nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) can in principle result in retention, inversion, or racemization of configuration at the alpha-phosphorus of the nucleoside 5'-triphosphate being polymerized. As a first step in elucidating the stereochemistry of this reaction, one diastereomer (A) of adenosine 5'-O-(1-thiotriphosphate) (ATPalphaS) was polymerized with UTP in the presence of poly(dA-dT)-poly(dA-dT). The resulting polymer was enzymatically cleaved to uridine 2',3'-cyclic phosphorothioate which was determined to be the endo-isomer by comparison with an authentic sample. This shows that no reacemization had occurred and that isomer A of ATPalphaS gives a phosphorothioate diester bond with the R-configuration. Whether this represents inversion of retention of configuration awaits elucidation of the absolute configuration of isomer A for ATPalphaS.
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PMID:Stereochemistry of polymerization by DNA-dependent RNA-polymerase from Escherichia coli: an investigation with a diastereomeric ATP-analogue. 78 80

The loosely bound chromatin proteins of Ehrlich ascites hyperdiploid cells have been prepared by extraction of chromatin with 0.35 M NaCl. Sodium dodecyl sulfate gel electrophoresis of the 0.35 M NaCl-soluble chromatin proteins reveals high heterogeneity with a molecular weight range of 10,000 to 170,000. The 0.35 M NaCl-soluble chromatin proteins contain many components similar to the more tightly bound non-histone chromatin proteins complex with the loosely bound chromatin proteins by gradient dialysis, the inhibitory effect of histones on transcription of DNA in vitro was reduced. The reconstituted complex manifested a level of template activity similar to that of native chromatin as measured in an Ehrlich ascites tumor RNA polymerase reaction. The loosely bound chromatin proteins contain RNA as well as phosphoproteins. Phenol extraction or DNA affinity chromatography of these proteins yielded fractions enhanced 25- to 30-fold in phosphorus which were capable of stimulating DNA-templated RNA synthesis in vitro. The stimulation of transcription from DNA was template-specific, effective only with a DNA template prepared from Ehrlich ascites tumor, but not from rat liver, calf thymus, or chicken erythrocytes. In addition, the stimulatory effect of the specific DNA-binding proteins appears to be RNA polymerase-specific, the stimulation being manifested with Ehrlich ascites tumor nucleoplasmic RNA polymerase and not with Micrococcus luteus RNA polymerase. Thus, the loosely bound chromosomal proteins from Ehrlich ascites tumor contain a fraction that specifically binds to Ehrlich ascites tumor DNA and exhibits a template- and RNA polymerase-specific stimulatory effect on transcription from DNA.
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PMID:Study of the loosely bound non-histone chromatin proteins. Stimulation of deoxyribonucleic acid-templated ribonucleic acid synthesis by a specific deoxyribonucleic acid-binding phosphoprotein fraction. 111 17

A non-histone protein has been isolated from Ehrlich ascites tumor chromatin. The minimum molecular weight of this non-histone protein, estimated by sodium dodecyl sulfate gel electrophoresis and amino acid analysis, is approximately 10 to 11,000. This non-histone protein is acidic, contains 2.7% alkalilabile phosphorus, binds to DNA, and inhibits transcription of DNA in vitro by the homologous RNA polymerase. The per cent inhibition of RNA synthesis is not affected by increasing amounts of RNA polymerase, but is reduced by addition of excess DNA. In the presence of the non-histone protein, incorporation of [gamma-32P]ATP into RNA in the in vitro RNA synthesizing system is inhibited, with no apparent change in the average chain length of the RNA product. Inhibition of RNA synthesis is completely eliminated if the DNA template is allowed to interact with ATP prior to the addition of the non-histone protein. These results indicate that the observed repression of in vitro RNA synthesis is due to the effect of the non-histone protein on the DNA, inhibiting the initiation of RNA chain formation.
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PMID:Inhibition of transcription in vitro by a non-histone protein isolated from Ehrlich ascites tumor chromatin. 119 69

The term vitamin D includes various chemical species. Vitamin D3 a true endogenous or alimentary prohormone is converted into its main metabolite, calcitriol, by successive hydroxylations in the liver in position 25 and in the kidney in position 1, the production of which is controlled by several factors including parathyroid hormone, blood calcium and phosphorus or insulin as well as by the metabolites of the hormone itself. It controls the synthesis of numerous peptides by acting on gene expression. Indeed, several structural proteins are involved including procollagen alpha 1l, core protein of proteoglycans, diverse regulatory peptides such as protooncogene c-myc and growth factors, "Tumor Necrosis Factor or TNF" and "Nerve Growth Factor or NGF" or hormones such as parathyroid hormone, and finally constitutive proteins of the mineralized tissues such as osteonectin, osteocalcin, osteopontin and calbindins. Therefore, it modulates very different cellular processes. It acts via a nuclear receptor the structure and function of which have been investigated by genetic engineering (cloning of genes encoding for the receptor and hormono-dependent peptides, transfection assays, directed mutagenesis). Actual studies investigate its role in the formation of the complex for transcription initiation near ADN sites, the "Vitamin D Responsive Element or VDRE", located upstream vitamin D-responsive genes and approximately RNA polymerase II. The receptor, which is present in many cell types at various concentrations, would determine spatial and temporal patterns of calcitriol action during development in conjunction with chromatin factors.
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PMID:[Vitamin D: biosynthesis, metabolism and mechanism of action at the cellular level]. 164 84

Transcription by T7 RNA polymerase has been studied using a chiral ATP analogue. The Sp diastereoisomer of adenosine 5'-O-(1-thiotriphosphate) (ATP alpha S) was incorporated into RNA with an apparent KM of approximately 15 microM, similar to that for ATP; the Rp diastereoisomer was neither a substrate nor a competitive inhibitor. The configuration of the phosphodiester link in the RNA produced was analyzed with stereospecific nucleases. The rate of nuclease digestion was compared with the rate of digestion of phosphorothioate-substituted RNA of known stereochemistry synthesized by E. coli RNA polymerase. Surprisingly, the nucleases exhibited reduced discrimination compared with their activity on dinucleotides. The results show that phosphorothioate-substituted RNA transcribed by T7 RNA polymerase has the same configuration as that transcribed by E. coli RNA polymerase, ie. Rp. Thus, the reaction proceeds with inversion of configuration at phosphorus.
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PMID:Stereospecificity of nucleases towards phosphorothioate-substituted RNA: stereochemistry of transcription by T7 RNA polymerase. 243 52

The complex [promoter A2 X E. coli RNA polymerase] was treated with phosphoamides, derivatives of 4-[N-methyl, N-(2-chloroethyl)]-aminobenzylamine and guanosine-5'-mono-, di-, and triphosphates with the alkylating group attached to the terminal phosphates. After this, [alpha-32P]CTP was added. Residues of the affinity reagents bound covalently at the first stage were elongated by radioactive -pC residues due to the catalytic action of the active centre of RNA polymerase. Affinity labelled were beta-and sigma-subunits of the enzyme, and the promoter. The affinity label was localized on -pGpC residues. A guanine residue was alkylated in the promoter as suggested by radioactivity elimination kinetics. As the data obtained and the previously known length of the reagent (maximum distance between the alpha-phosphorus atom of the reagent and the point of alkylation is less than 0.6 nm) indicate, there is a direct rather than protein-mediated contact between the template and the substrate within the complex [promoter X RNA polymerase].
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PMID:[Highly selective affinity labeling of a promoter in a complex with E. coli RNA-polymerase by alkylating derivatives of initiating substrates]. 330 Jun 59

Oligonucleotides 2 to 7 nucleotide residues long, complementary to the codogenic strand of T7 promoter A2, have been synthesized; all of them contained a ribo-unit at the 3'-end. They were converted into 5'-(N-methyl)phosphoimidazolides, and the affinity reagents obtained were allowed to bind covalently to RNA polymerase in the presence of a promoter. Some of the nucleotide residues covalently attached occupied proper positions relative to the active centre of the phosphodiester bond synthesis and on addition of [alpha-32P]UTP were elongated, so that highly selective affinity labelling occurred. With oligonucleotides of various lengths, different distribution of the label between beta, beta' and sigma subunits of RNA polymerase took place. Most efficient was labelling of beta-subunit by the residue--pCpGpCpU, and of sigma-subunit by the residue--pApApApTp-CpGpCpU (p--radioactive phosphorus atom). In both cases, the amino acid residues labelled were histidines.
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PMID:[Affinity modification of E. coli RNA-polymerase in a complex with the promoter by phosphorylating derivatives of primer oligonucleotides]. 354 19

1. Liver RNA synthesis was studied within 24h after whole-body X-irradiation of guinea pigs that had been starved for 22-24h. 2. Microsomal RNA was labelled in vivo for 3h with [(14)C]orotic acid and the isolated labelled RNA was fractionated by sucrose-density-gradient centrifugation. Incorporation was 50-100% higher between 3 and 12h after 2000rd X-irradiation and at 22h was not elevated any further. Whole nuclear RNA was labelled with [(14)C]orotic acid for 15min. At 5h after irradiation the incorporation showed a 50-100% increase. Incorporation increased in all types of RNA studied. 3. The RNA phosphorus/DNA phosphorus ratio of whole liver gradually increased after X-irradiation. Maximal increase was found between 24 and 36h, which corresponds to a value about 40% above that of the starved control. The RNA phosphorus content of isolated ribonucleoproteins obtained from various cell fractions of the liver was similarly increased after X-irradiation. 4. Liver microsomes were obtained from X-irradiated and control animals. Microsomes were incubated in vitro with [(14)C]phenylalanine in the presence and absence of polyuridylic acid. After the incubation the microsomes were fractionated by sucrose-density-gradient centrifugation. The polyuridylic acid enhancement was twice as great in the microsomes of the control preparation as in the irradiated one. The experiment demonstrated a higher saturation of microsomes by endogenous messenger after X-irradiation. 5. RNA polymerase activity of the purified nuclear preparation was assayed. The activity of the Mg(2+)-dependent RNA polymerase activity was 50 and 200% respectively above the control values at 6 and 9h after X-irradiation. 6. Animals were treated with actinomycin D shortly before X-irradiation. This treatment abolished the radiation-induced enrichment of polyribosomes and the increase of protein-synthesizing activity. The effect of X-irradiation on the transcription of the genetic code of the liver is discussed.
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PMID:The effect of whole-body x-irradiation of guinea pigs on liver ribonucleic acid synthesis. 543 93

Nuclear magnetic resonance studies were performed to investigate the effect of DNA template on the interaction of initiating nucleotide ATP with Escherichia coli RNA polymerase (RPase) in which one of the two intrinsic Zn ions was substituted with a Co(II) (Co-Zn RPase) or Mn(II) (Mn-Zn RPase) ion. This intrinsic metal ion is located at the initiation site in the beta subunit of RPase. The paramagnetic effects of Co-Zn and Mn-Zn RPases on the relaxation rates of 1H- and 31P-nuclei of ATP were used to determine the distances from the intrinsic metal to various atoms of ATP bound at the initiation sites in the presence of DNA. The distances from the metal to H2, H8, H1', alpha-P, beta-P, and gamma-P atoms were estimated to be 6.7 +/- 0.9, 4.1 +/- 0.6, 6.0 +/- 1.2, 7.5 +/- 0.8, 9.4 +/- 1.0, and 9.8 +/- 1.0 A, respectively. These distances were compared with those measured in the absence of DNA (Chatterji, D., and Wu, F. Y.-H. (1982) Biochemistry 21, 4657). In both the presence and absence of DNA, the close proximity between the intrinsic metal and the H8 atom strongly indicates that the metal is coordinated directly to the base moiety of ATP. Such a coordination may provide a structural basis for the selection of a purine nucleotide during the initiation process. The presence of DNA causes the H2 atom to move away (greater than 2 A) from the intrinsic metal, whereas all three phosphorus atoms shift closer (greater than 3 A) toward the metal. The possible mechanistic implications of the conformational alteration of ATP at the initiation site induced by the DNA template is discussed.
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PMID:Nuclear magnetic resonance studies on the role of intrinsic metals in Escherichia coli RNA polymerase. Effect of DNA template on the nucleotide-enzyme interaction. 636 37


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