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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)

DNA-dependent RNA polymerases were extracted from the nuclei of poorly differentiated tumor, Morris hepatoma 3924A, and purified by an initial chromatography on a DEAE-Sephadex column followed by fractionation on phosphocellulose and finally on a second DEAE-Sephadex column. Three major forms of RNA polymerase (IA, IB and II) were resolved chromatographically. Enzymes IA, IB and II eluted from DEAE-Sephadex at 75, 150 and 210 mM (NH4)2SO4, respectively. The specific activities (nmol UMP incorporated mg protein per 15 min) of polymerases IA, IB and II were 40, 43 and 182, respectively. Concurrently, DNA-dependent RNA polymerases were extracted from normal liver and subjected to similar chromatographic procedure. Upon the final DEAE-Sephadex chromatography, enzymes IA, IB and II eluted at 110, 180 and 210 mM (NH4)2SO4, respectively. The recovery of polymerases IA, IB and II after purification was 0.21, 0,28 and 0.42 unit/mg DNA, respectively, for hepatoma enzymes and 0.07, 0.05 and 0.42 unit/mg DNA for the corresponding liver enzymes.
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PMID:RNA polymerases from a rat hepatoma. Partial purification and comparison of properties with corresponding liver enzymes. 17 77

The RNA-dependent RNA polymerase associated with vesicular stomatitis virus was isolated to apparent homogeneity by a newly developed procedure, which includes stepwise removal of proteins from virions by successive treatment with high concentrations of cesium sulfate and cesium chloride, followed by glycerol gradient centrifugation or chromatography on phosphocellulose or DEAE-Sephadex column. The polymerase thus purified contained L (large protein) and NS proteins as the intrinsic subunits and multiple species of enzyme were found which differ in the molar ratio of L to NS. Since the enzyme with the highest activity was composed of equimolar amounts of the two subunits and exhibited the sedimentation coefficient of approximately 11 S in a buffer containing 0.2 M NaCl, the structure of active protomer was suggested to be (L)1(NS)1. In accordance with this conclusion, enzyme preparations deficient in the content of NS protein, were activated by the addition of preparations deficient in the content of NS protein. The purified RNA polymerase catalyzed the synthesis of poly(A), which was covalently attached to the 3' termini of RNA products, and RNA, only in the presence of all 4 substrates. The present finding might be the first which indicates that the transcriptase itself catalyzes post-transcriptional modification of mRNA by adding poly(A) sequences to the 3'-OH termini. The molecular mechanism of the switch from transcription to poly(A) synthesis, however, remains to be investigated.
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PMID:Function and structure of RNA polymerase from vesicular stomatitis virus. 18 23

DNA-dependent RNA polymerases (EC 2.7.7.6) were extracted and partially purified form the nuclei of rat ascites hepatoma cells (AH-130) induced by 4-dimethylaminoazobenzene. The patterns of RNA synthesis and the properties of these enzymes were compared with enzymes from the nuclei of rat liver. The specific activity of RNA polymerase in the homogenate from the nuclei of AH-130 cells was the same as normal rat liver nuclei. RNA polymerase was solubilized from the homogenate at high ionic strength and separated into two forms by DEAE-Sephadex column chromatography. Enzymatic characterization showed that these enzymes corresponded to RNA polymerase I and II. RNA polymerase I more effectively transcribed native DNA than denatured DNA at low salt concentration, but at high salt concentration RNA polymerase I effectively transcribed denatured DNA. RNA polymerase II more effectively transcribed denatured DNA. In AH-130 cells the activity of RNA polymerase I was 4 to 5 times higher than RNA polymerase II, and in rat liver the activity of RNA polymerase I was 1.5 to 2 times higher than RNA polymerase II. The activity of RNA polymerase I in AH-130 cells may have increased by induction.
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PMID:A comparative study of DNA-dependent RNA polymerases from rat ascites hepatoma cell nuclei and from rat liver nuclei. 18 Jul 54

Cellular RNA synthesis was studied in mouse L-929 cells and in these cells infected with mengovirus. RNA polymerases I, II, and III were partially purified and their chromatographic properties were analyzed by DEAE-Sephadex A-25 chromatography. RNA polymerase II was purified from mouse liver and its subunit structure was compared to that of normal and virus-infected L-929 cells by two-dimensional gel electrophoresis. By these criteria, the enzymes from all three sources were identical. The RNA synthetic activities and capacities of chromatins from normal and virus-infected cells were compared under a variety of conditions. The endogenous activity in chromatin from infected cells was inhibited relative to controls but the residual activity responded normally to stimulation by ammonium sulfate, heparin, and Sarkosyl. The template capacity of the chromatins was compared with added RNA polymerase II and by a rifampicin challenge assay utilizing Escherichia coli RNA polymerase. Identical results were obtained in each case. The number of growing RNA chains and the rates of their elongations were determined. The results showed that nuclei and chromatin from infected cells have a smaller number of RNA polymerase II molecules engaged in RNA synthesis than normal cells do but that the active molecules elongate RNA chains at the same rate.
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PMID:Cellular RNA synthesis in normal and mengovirus-infected L-929 cells. 20 39

The 5'-cap-containing leader sequence of the most abundant 19S and 16S mRNAs of simian virus 40 (SV40) was previously mapped between 0.67 and 0.76 map units. We now find that the two late mRNA species contain multiple 5' ends. Eight different RNase T2-resistant cap structures were identified:m7GpppmAmpU (47%); m7GpppmAmpUmpU (19%); m7GpppmAmpC (16%); m7GpppmAmpCmpA (5%); m7GpppmAmpG (6%); m7GpppGmpC (3%); m7GpppmAmGmpA (2%); m7GpppGmpCmpG (2%). Capped T1 oligonucleotides of 19S and 16S mRNAs have been isolated by two different procedures: (i) chromatography on a DEAE-cellulose column followed by paper electrophoresis and (ii) two-dimensional electrophoresis/homochromatography. Cap structures of the isolated 5' oligonucleotides were identified. Each of the major caps was found to be associated with a few differential 5' oligonucleotides, implying a vast heterogeneity at the termini of SV40 late mRNAs. The results suggest that on SV40 DNA, RNA polymerase II has a reportoire of initiation points. In most of the cases, initiation takes place with adenosine triphosphate followed by a pyrimidine. Alternatively, transcription may start at one specific point but a unique mechanism of processing generates heterogeneous populations of termini with a common 5' adenosine triphosphate.
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PMID:Sequence heterogeneity at the 5' termini of late simian virus 40 19S and 16S mRNAs. 22 54

A single peak of DNA polymerase activity was detectable by phosphocellulose chromatography of leukemic guinea pig lymphoblast whole cell extracts. The inability to detect multiple peaks of activity as described with other cell types is shown to be due to the insolubility of a large proportion of the DNA polymerase activity under the extraction condition used. Multiple forms of DNA polymerase with different template specificities were recognized in extracts of the subcellular fractions of these cells after chromatography on phosphocellulose and DEAE cellulose. On Sephadex G-200 gel filtration these enzymes had apparent molecular weights in excess of 140,000 daltons. No RNA polymerase (reverse transcriptase) was detected in any subcellular fraction despite the presence of oncornavirus like particles in these cells.
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PMID:Studies of the template preference and other characteristics of the DNA polymerases of leukemic guinea pig lymphoblasts. 29

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

T7 gene 6 exonuclease has been shown to have an RNase H activity as well as a double-strand specific DNase activity by the following experiments: The RNase H activity coelutes with the DNase activity from DEAE-cellulose, phosphocellulose, hydroxyapatite, and Sephadex G-200 columns. Gene 6 exonuclease specified by a T7 strain with a temperature sensitive mutation in gene 6 has an extremely heat-labile RNase H activity as well as a heat-labile DNase activity. T7 gene 6 exonuclease degrades the RNA region of a poly(A) . poly(dT) hybrid polymer exonucleolytically from the 5' terminus, releasing a ribonucleoside 5'-monophosphate product. When the RNA strand of a 0X174 RNA . DNA hybrid molecule synthesized with E. coli RNA polymerase is degraded, a ribonucleoside triphosphate is produced from the 5'-triphosphate terminus. Participation of T7 gene 6 exonuclease in the removal of primer RNA in discontinuous replication of T7 DNA is discussed.
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PMID:T7 gene 6 exonuclease has an RNase H activity. 36 24

The DNA-dependent RNA polymerase I (or A) from the lower eukaryote Aspergillus nidulans has been purified on a large scale to apparent homogeneity by homogenizing the fungal hyphae in liquid nitrogen, extraction of the enzyme at high salt concentration, precipitation of RNA polymerase activity with polymin P (a polyethylene imine), elution of the RNA polymerase from the polymin P precipitate, ammonium sulphate precipitation, molecular sieving on Bio-Gel A-1.5m, binding to ion-exchangers and DNA-cellulose affinity chromatography. By this procedure 1.6 mg of RNA polymerase I can be purified over 2000-fold from 500 g wet weight of starting material with a yield of 30--35%. The isolated RNA polymerase I is stable for several months at -20 degrees C. The subunit compostion has been resolved by polyacrylamide gel electrophoresis on two-dimensional gels, using either non-denaturing of 8 M urea (pH 8.7) cylindrical gels in the first dimension and sodium dodecyl sulphate slab gels in the second dimension. The putative subunits have molecular weights of 190,000, 135,000, 63,000, 62,000, 43,000, 29,000, (28,000), 16,000 and probably 13,000 and 12,000. Two distinct forms of RNA polymerase I (Ia and Ib) have been resolved by DEAE-Sephadex A-25 chromatography showing ample differences in enzymatic properties and subunit pattern. Additional information is given on RNA polymerase II (or B) which appears to be highly insensitive to alpha-amanitin at concentrations up to 400 micrograms/ml.
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PMID:RNA polymerase from the fungus, Aspergillus nidulans. Large-scale purification of DNA-dependent RNA polymerase I (or A). 38 Sep 97

A new procedure for the purification of B. subtilis RNA polymerase, based on mild lysis of cells, low speed centrifugation, gel filtration, DEAE-Sephadex chromatography and affinity chromatography on DNA-cellulose, yields three forms of enzyme referred here as enzyme A, B and C. As revealed by SDS gel electrophoresis, enzyme A has the subunit structure of core polymerase plus some small polypeptides. Its catalytic properties are similar to those of core polymerase. Enzyme B has the composition of core polymerase. Both enzymes A and B can be stimulated by the addition of beta factor. Enzyme C has the holo-enzyme composition. The pattern of sensitivity of the three forms of enzyme towards KCl are very different: enzymes A and B, even at low concentration of salt, are inhibited with all the DNA templates tested, whereas enzyme C shows a pattern of stimulation specific for each DNA tested. The transcripts of the three enzymes on phage SPP1 DNA template have been analyzed by hybridization to the separated strands. Only enzyme C selectively transcribed the H strands.
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PMID:RNA polymerase from Bacillus subtilis: isolation of core and holo enzyme by DNA-cellulose chromatography. 40 60


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