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)

Virus-specific RNA polymerase activity of mengovirus-infected Ehrlich ascites carcinoma (EAC) cells was maximal 7 hours after infection in a one-step growth cycle. In a cell-free system with the mitochondrial-microsomal fraction (MMF) derived from mengovirus-infected EAC cells in a nucleoside-triphosphate medium, polymerase activity increased up to 60 min (when MMF was obtained by a homogenizer) or 120 min (when MMF was prepared by sodium deoxycholate disruption). Subsequently RNA polymerase activity decreased between 150-180 min of incubation at 37 degrees C and then formed a plateau up to 300 min. The cell-free system used is able to give valuable information as regards testing of RNA polymerase inhibitors in an antiviral screening programme.
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PMID:Parameters of RNA-dependent RNA polymerase activity in a mengovirus-infected Ehrlich ascites carcinoma cell-free system. 20 90

Polyoma virus complementary RNA, synthesized in vitro by using highly purified Escherichia coli RNA polymerase and nondefective form I polyoma DNA, was translated in a wheat germ cell-free system. Polypeptides were synthesized that comigrated on sodium dodecyl sulfate-polyacrylamide gels with the polyoma capsid proteins VP1 and VP2, although most of the cell-free products were of smaller molecular weights. The VP1-size protein specifically immunoprecipitated with anti-polyoma virus serum, and upon digestion by trypsin yielded [35S]methionine-labeled tryptic peptides that co-chromatographed with the [3H]methionine-labeled tryptic peptides of virion-derived VP1 on both cation-exchange and anion-exchange resins. The VP2-size in vitro product contained all the virion VP2 methionine-labeled tryptic peptides, as shown by cation- and anion-exchange chromatography and two-dimensional fingerprinting on cellulose. We conclude that full-length polyoma VP1 and VP2 are synthesized in response to complementary RNA and consequently that the viral capsid proteins VP1, VP2, and VP3 are entirely virus coded.
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PMID:Polyoma virus complementary RNA directs the in vitro synthesis of capsid proteins VP1 and VP2. 20 20

Isolation of the Mengo virus stable non-capsid virus polypeptides E, F, G and I from infected L cells has been achieved. Unstable precursors were eliminated by incubation in the presence of pactamycin and capsid polypeptides were removed by ultracentrifugation and affinity chromatography. Subsequent sodium dodecyl sulphate (SDS)-hydroxylapatite chromatography resolved the non-capsid proteins into two major peaks which comprised F plus G and E plus I, respectively. The individual polypeptide species were separated by gel filtration on Sephadex G-100 in the presence of SDS. Polypeptide E was isolated in an undenatured form by gel filtration of infected cell extracts (from which precursor and capsid polypeptides had been removed) on Bio-Gel A-5m agarose beads. Purified polypeptide E was found to co-sediment with Mengo virion RNA during centrifugation in a sucrose density gradient and it was also capable of binding to poly(A)-Sepharose. Assay mixtures containing polypeptide E exhibited an RNA polymerase activity which was dependent upon exogenous virus RNA template and oligo(U) primer and which was not affected by the addition of virus capsid polypeptides or extracts from uninfected cells.
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PMID:The isolation of Mengo virus stable non-capsid polypeptides from infected L cells and preliminary characterization of an RNA polymerase activity associated with polypeptide E. 23 Feb 90

A method of steady-state electrophoresis in polyacrylamide gels was used to analyze the presence of cyclic nucleotide binding components in cell extracts. Multiple cyclic AMP and cyclic GMP binding components were detected in soluble cytoplasmic and nuclear extracts derived from avian liver, but only a single cyclic GMP binding protein was found in the 0.3 M NaCl extract of liver nucleoli. In the presence of cyclic GMP, this protein phosphorylated efficiently a calf thymus histone mixture and an endogenous nucleolar protein, which migrated identically with histone H4 in sodium dodecyl sulfate polyacrylamide gel electrophoresis. The isoelectric point of the cyclic GMP-binding protein was 4.8. Addition of cyclic GMP did not influence the activity of the endogenous nucleolar RNA polymerase.
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PMID:A cyclic GMP-dependent histone kinase bound to liver nucleoli. 23 90

A cyclic adenosine 3',5'-monophosphate-dependent histone kinase (ATP: protein phosphotransferase, EC 2.7.1.37) was isolated from pig brain. The enzyme has been purified 1140-fold; it is homogeneous on polyacrylamide gel electrophoresis and gel filtration. The estimated molecular weight of the enzyme is 120 000. Histone kinase dissociates into a catalytic subunit and a regulatory one (molecular weights 40 000 and 90 000, respectively). The catalytic subunit has been obtained in homogeneous state as evidenced by sodium dodecylsulphate-polyacrylamide gel electrophoresis. At all purification steps, enzymatic activity is stimulated 5-fold by cyclic AMP. An apparent Km value for cyclic AMP is about 3.3 - 10- minus 7 M. In the presence of cyclic AMP(5 - 10- minus 6 M), the Km value for ATP and F1 histone were 1.2 - 10- minus five and 3 - 10- minus 5 M, respectively. Optimum pH value for histone kinase is 6.5, its isoelectric point is situated at pH 4.6. The purified enzyme displays high specificity for the lysine-rich and moderately lysine-rich histones F1, F2a2 and F2b. Arginine-rich histones and other known protein substrates for cyclic AMP-dependent protein kinases (casein, Escherichia coli RNA polymerase, etc.) are extremely poor substrates for this enzyme.
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PMID:A cyclic adenosine 3',5'-monophosphate-dependent histone kinase from pig brain. Purification and some properties of the enzyme. 23 2

A procedure for the simultaneous purification of RNA polymerases I, II, and III from Saccharomyces cerevisiae is described. High yields of each enzyme activity are obtained, allowing the preparation of approximately 10 mg of polymerase I, 25 mg of polymerase II, and 12 mg of polymerase III from 1.2 kg of cells (wet weight). Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicates RNA polymerase I contains polypeptides with molecular weights 185 000, 137 000, 41 000, 35 000, 28 000, 24 000, 20 000, 16 000, 14 500, and 12 300; RNA polymerase II contains subunits with molecular weights 170 000, 145 000, 41 000, 33 500, 28 000, 24 000, 18 000, 14 500, and 12 500; and RNA polymerase III contains polypeptides with molecular weights 160 000, 128 000, 82 000, 53 000, 41 000, 37 000, 34 000, 28 000, 24 000, 20 000, 14 500, and 10 700.
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PMID:Isolation of ribonucleic acid polymerases I, II, and III from Saccharomyces cerevisiae. 31 51

The quaternary structure of Escherichia coli RNA polymerase has been studied by cross-linking with a periodate-cleavable bis(imido ester), N,N'-bis(2-carboximidoethyl)tartaramide dimethyl ester dihydrochloride (CETD). The cross-linked holoenzyme gives a characteristic five-band pattern after electrophoresis on sodium dodecyl sulfate-polyacrylamide gels. The components of each band have been unambiguously identified by (a) molecular-weight measurements, (b) comparisons of cross-linking patterns of holoenzyme and core enzyme, and (c) periodate cleavage of cross-links followed by a second dimension sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The bands are (1) alphabeta and alphabeta', (2) sigmabeta and sigmabeta', (3) alphasigmabeta', (4) betabeta', and (5) sigmabetabeta'. Bands 2 and 4 are the most prominent at low reagent concentrations (up to 2.5 mM) but band 5 becomes the most prominent at higher concentrations. There are no bands corresponding to alphaalpha and alphasigma; a faint band has been tentatively identified as alphabetabeta'. Shorter bis(imido esters) are much less effective cross-linking reagents than CETD and they do not give rise to any other cross-linked species. On the basis of these observations, a model for the subunit arrangement of RNA polymerase is proposed.
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PMID:A study of the quaternary structure of Escherichia coli RNA polymerase using bis(imido esters). 32 Oct 15

A set of F' strains of Escherichia coli K-12 partially diploid for various chromosomal segments has been examined for possible gene dosage effects in the synthesis of sigma factor of the DNA-dependent RNA polymerase (RNA nucleotidyltransferase; nucleoside-triphosphate:RNA nucleoti-dyltransferase, EC 2.7.7.6). It was found that all F' strains diploid for the dnaG region synthesize sigma at rates two to three times higher than other F' or F- strains. Moreover, strains of Salmonella typhimurium harboring these F' plasmids produce E. coli sigma in addition to Salmonella sigma. This has been shown on the basis of the finding that Salmonella sigma can be precipitated with antiserum against E. coli RNA polymerase but is distinguishable from E. coli sigma in its mobility in sodium dodecyl sulfate/polyacrylamide gel electrophoresis. E. coli sigma polypeptides thus produced seem to be stable in cells of S. typhimurium. These results indicate that a structural gene for sigma (rpoD) is located at the metC-argG region, probably near the dnaG locus (66 min on the current genetic map of E. coli).
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PMID:Chromosomal location of a structural gene for the RNA polymerase sigma factor in Escherichia coli. 32 55

Bacteriophage T7-coded inhibitor of Escherichia coli RNA polymerase, termed I protein, was purified from an inactive E. coli RNA polymerase-I protein complex isolated from phage T7-infected cells. A molecular weight of about 7,000 to 9,000 was assigned to the purified I protein by acrylamide-sodium dodecyl sulfate gel electrophoresis, Sephadex G-50 gel filtration, and glycerol gradient centrifugation analysis. I protein inhibits initiation of RNA synthesis by directly binding to the RNA polymerase holoenzyme and prevents the binding of the enzyme to the promoter sites on the template T7 DNA. However, once a highly stable transcriptional preinitiation complex between RNA polymerase holoenzyme and T7 DNA is formed at the promoter site on T7 DNA in the absence of nucleoside triphosphates, I protein does not inhibit the initiation of RNA synthesis by this preformed complex upon addition of nucleoside triphosphates. RNA synthesis by the core RNA polymerase and the binding of core RNA polymerase with template DNA are not inhibited by I protein, although a partial association between the core enzyme and I protein can be observed. I protein does not bind to sigma factor or T7 DNA. Therefore, binding of I protein with the RNA polymerase, which results in the inhibition of initiation of RNA synthesis, requires the presence of sigma factor in the RNA polymerase holoenzyme form.
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PMID:I protein: bacteriophage T7-coded inhibitor of Escherichia coli RNA polymerase. 33 33

Yeast nuclear RNA polymerase III was purified by batch adsorption to phosphocellulose, followed by ion-exchange chromatography on DEAE-Sephadex and affinity chromatography on DNA-Sepharose. Polyacrylamide gel electrophoresis of the purified enzyme showed a single protein band which contained polymerase activity. The molecular weight estimated by sedimentation velocity centrifugation in a glycerol gradient was 380 000. Enzyme activity was inhibited 50% at 0.1 mM 1,10-phenanthroline and 100% of 1.0 mM, but was restored when 1,10-phenanthroline was removed by dialysis. Enzyme activity was not inhibited by 7,8-benzoquinoline, a nonchelating structural analogue of 1,10-phenanthroline. These results strongly suggest that inhibition of enzyme activity occurs by the formation of a reversible enzyme-zinc-phenanthroline ternary complex. The zinc content, measured by atomic absorption spectroscopy, was 2 g-atoms per mol of enzyme. Zinc was not removed from the enzyme by gel filtration on Sephadex G-25, by passage through Chelex-100 resin, or by dialysis against buffer containing 1,10-phenanthroline. Enzyme-bound zinc was removed by dialysis after denaturation of the enzyme with heat and sodium dodecyl sulfate. Enzyme-bound zinc did not exchange with free zinc. These results establish yeast nuclear RNA polymerase III as a zinc metalloenzyme.
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PMID:Saccharomyces cerevisiae DNA-dependent RNA polymerase III: a zinc metalloenzyme. 33 47


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