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

---

Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed two procedures which allow the very rapid purification of glutamine synthetase (GS) from a diverse variety of bacteria. The first procedure, based upon differential sedimentation, depends upon the association of GS with deoxyribonucleic acid in cell extracts. The second procedure, derived from the method of C. Gross et al (J. Bacteriol. 128:382-389, 1976) for purifying ribonucleic acid polymerase by polyethylene glycol (PEG) precipitation, enabled us to obtain high yields of GS from either small or large quantities of cells. We used the PEG procedure to purify GS from Klebsiella aerogenes, K. pneumoniae, Escherichia coli, Salmonella typhimurium, Rhizobium sp. strain 32H1, R. meliloti, Azotobacter vinelandii, Pseudomonas putida, Caulobacter crescentus, and Rhodopseudomonas capsulata. The purity of the GS obtained, judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was high, and in many instances only a single protein band was detected.
...
PMID:Purification of glutamine synthetase from a variety of bacteria. 610 84

A novel procedure of operational ease and reproducibility for the partial purification of DNA-dependent RNA polymerase [EC 2.7.7.6] from Escherichia coli is reported. It utilizes liquid phase partitions with polyethylene glycol and Dextran, ammonium sulfate fractionations and chromatography on a QAE-Sephadex A-50 column. A copurified protein in the partially purified preparation was isolated and identifed as glutamine synthetase [L-glutamate : ammonia ligase (ADP) EC 6.3.1.2].
...
PMID:Glutamine synthetase in preparations of RNA polymerase of Escherichia coli: a novel purification procedure. 612 39

We have further characterised a fraction of polynucleosomal chromatin from mouse cells which is enriched in transcribing regions, after separation by multistep partition in a dextran /poly(ethylene glycol) two-phase mixture [Faber, A. J. (1972) Methods Cell Biol. 16, 447--457]. This fraction contains an average of 16% of the total DNA and 63% of the 3-min pulse-labelled RNA in chromatin which, by a number of criteria, represents nascent RNA transcripts. Of the total transcribing RNA polymerase B molecules in chromatin, 52% are found in this fraction by titration with radioactive alpha-amanitin. About 28% of the single-copy DNA sequences in this fraction hybridise to nuclear polyadenylated RNA, compared with only 1.5% of the single-copy sequences in the remaining (nontranscribing) chromatin fraction.
...
PMID:Characterisation of a chromatin fraction bearing pulse-labelled RNA. 1. Nascent RNA, RNA polymerase B and transcribed DNA sequence content. 617 75

Simian virus 40 (SV40) virions were dissociated in vitro by treatment with ethylene glycol-bis-N-N'-tetraacetic acid and dithiothreitol. The compact nucleo-protein core released as a result of the dissociation had a sedimentation value of 110 to 115S compared with a value of 240S for intact virions. The viral cores contained a fraction of the viral proteins VP(1) and VP(2) in addition to the proteins found associated with the viral minichromosome, i.e., VP(3) and histones H(2)A, H(2)B, H(3), and H(4). Our results suggest that the association of VP(1), VP(2), or both with the viral minichromosome, in addition to maintaining a highly compact structure, modifies the transcriptional properties of the nucleoprotein complex. In the presence of saturating amounts of Escherichia coli RNA polymerase, 95 to 100% of the SV40 nucleoprotein cores were able to form transcriptional complexes. Sedimentation analysis of the core transcriptional complex indicated that the initiation and elongation of nascent RNA chains occurred on the compact SV40 core. Cesium chloride density gradient analysis of the SV40 virion core before and after transcription indicated that no substantial loss of protein occurred during the process of transcription. RNA synthesized from SV40 cores was a fairly homogeneous 16 to 18S species with an average chain length of approximately 2,300 nucleotides. Hybridization analysis of this RNA indicated that specific recognition of RNA polymerase promoter sites was preserved, since transcription was asymmetric, occurring preferentially on the "early" SV40 DNA strand. The rate of incorporation of ribonucleoside triphosphates into acid-insoluble RNA with SV40 cores as the template was 70 to 95% of that obtained with supercoiled SV40 form I DNA. SV40 minichromosomes, under identical transcription assay conditions, had an incorporation rate which was 20% of that obtained with SV40 form I DNA. These results show that association of protein VP(1) or VP(2) or both enhances the transcriptional activity and suggest that these "late" viral proteins may play a role in the regulation of expression of the SV40 genome.
...
PMID:Efficient transcription of a compact nucleoprotein complex isolated from purified simian virus 40 virions. 625 78

Foot-and-mouth disease virus (FMDV) RNA polymerase was purified from the polyethylene glycol (PEG)-treated supernatant of infected cell media by a combination of ion-exchange chromatography, membrane molecular filtration, and affinity chromatography. The purified RNA polymerase which migrated as a single band of 56,000 molecular weight on a polyacrylamide gel was subjected to automated Edman degradation and the sequence of the first 30 amino acid residues established. On the basis of previous evidence, which indicated that the RNA polymerase was the most 3'-translated polypeptide, plasmids containing cDNA mapping at the 3' end of the genome were characterized by restriction enzyme analysis and nucleotide sequencing. These investigations definitively established the derived amino acid sequence by confirmation of 28 of the amino terminal residues determined by amino acid sequence analysis; the location of the FMDV RNA polymerase coding region at the extreme 3' end of the genome, 96 nucleotides from the poly(A) tail; and the N-terminal cleavage point of the RNA polymerase from its precursor P100 was found to be a glutamic acid-glycine bond.
...
PMID:Identification of amino acid and nucleotide sequence of the foot-and-mouth disease virus RNA polymerase. 630 4

Polyclonal antibodies to calf thymus RNA polymerase II were raised in laying hens. Up to 75 mg of immunoglobulin/egg yolk were extracted by the polyethylene glycol procedure of Roeder (Roeder, R.G. (1976) in RNA Polymerase (Losick, R., and Chamberlin, M., eds) pp. 285-330, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY). The concentration of specific antibody in egg yolks (IgY) was comparable to that of serum as measured by enzyme-linked immunoassay. Purified antibody was shown to be directed against enzyme by removal of enzyme activity in immune complexes precipitated by rabbit anti-chicken IgY. The antibodies recognized several of the subunits of the enzyme as determined by their reactivity with polypeptides transferred to nitrocellulose paper after gradient sodium dodecyl sulfate-gel electrophoresis. Production of antibodies in laying hens may facilitate the study of other highly conserved antigens that are poorly immunogenic in mammalian hosts.
...
PMID:Antibodies to calf thymus RNA polymerase II from egg yolks of immunized hens. 633 47

DNA dependent RNA polymerase II was purified to approximately 8300 fold from sonicated nuclear extract of cherry salmon (Onchorhynchus masou) liver by the following purification steps: polyethylene glycol treatment, DEAE=Sephadex A-25 column chromatography, heparin-Sepharose column chromatography, and affinity chromatography on DNA-cellulose. Final preparation of this enzyme has a specific activity of 157 nmole UMP incorporation into RNA per mg of protein per 10 min at 25 degrees. RNA polymerase I was also purified to approx. 3800 fold in a similar manner. Its specific activity was calculated as 26.2 nmole/mg/10 min. Utilization of various UTPs of these enzymes was studied by substitution experiments under the condition of limited synthesis. 5-Methyl UTP (rTTP) could be utilized by the RNA polymerase I 1.7 fold more efficiently compared with UTP. In contrast, the RNA polymerase II recognized rTTP as a substrate as efficiently as UTP. Similar experiments using other alkyl UTPs have been performed.
...
PMID:Utilization of 5-alkyl UTPs by DNA-dependent RNA polymerase I and II purified from cherry salmon (Onchorhynchus masou) liver. 725 91

Reverse transcriptase (RT) from the human immunodeficiency virus type 1 has been crystallized in four closely related forms, the best of which diffract X-rays to 2.2 A resolution. The RT was crystallized as a complex with a non-nucleoside inhibitor, either nevirapine or a nevirapine analogue. Crystals grew from 6% PEG 3400 buffered at pH 5. These were of space group P2(1)2(1)2(1) with unit cell parameters a = 147 A, b = 112 A, c = 79 A (form A), with one RT heterodimer in the asymmetric unit. Changes in unit cell parameters and degree of crystalline order were observed on soaking pregrown crystals in various solutions, giving three further sets of unit cells. These were a = 143 A, b = 112, A, c = 79 A (form B), a = 141 A, b = 111 A, c = 73 A (form C), a = 143 A, b = 117 A, c = 66.5 A (form D). The last two forms diffract X-rays to 2.2 A resolution. Structure determinations of these latter crystal forms of RT should give a detailed atomic model for this therapeutically important drug target.
...
PMID:Crystals of HIV-1 reverse transcriptase diffracting to 2.2 A resolution. 752 79

Leishmania RNA virus 1 produces a short viral RNA transcript corresponding to the 5' end of positive-sense single-stranded RNAs both in virally infected cells and in in vitro polymerase assays. We hypothesized that this short transcript was generated via cleavage of full-length positive-sense single-stranded RNA. A putative cleavage site was mapped by primer extension analysis to nucleotide 320 of the viral genome. To address the hypothesis that the short transcript is generated via cleavage at this site, two substrate RNAs that possessed viral sequence encompassing the putative cleavage site were created. When incubated with sucrose-purified viral particles, these substrate RNAs were site-specifically cleaved. The cleavage site of the in vitro-processed RNAs also mapped to viral nucleotide 320. The short-transcript-generating activity could be specifically abolished by proteinase K treatment of sucrose-purified viral particles and high concentrations of EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid], suggesting that the activity requires a proteinaceous factor and possibly intact viral particles. The cleavage activity is directly associated with short-transcript-generating activity, since only viral particle preparations which were capable of generating the short transcript in polymerase assays were also active in the cleavage assay. Furthermore, the short-transcript-generating activity is independent of the viral polymerase's transcriptase and replicase activities. We present a working model whereby cleavage of Leishmaniavirus RNA transcripts functions in the maintenance of a low-level persistent infection.
...
PMID:The short transcript of Leishmania RNA virus is generated by RNA cleavage. 774 92

GreA is a 17.6 kDa protein from Escherichia coli that induces cleavage of the nascent transcript in the elongating complex of RNA polymerase, followed by release of the 3'-terminal fragment. Crystals of GreA have been obtained from polyethylene glycol 4000, 2-propanol and sodium citrate, pH 5.6 and have been propagated by a novel seeding procedure. The crystals diffract beyond 2 A resolution and belong to the orthorhombic space group P2(1)2(1)2(1), with cell dimensions a = 101.7 A, b = 42.22 A, c = 40.05 A and with one molecule in the asymmetric unit.
...
PMID:Crystallization of GreA, a transcript cleavage factor from Escherichia coli. 793 13


<< Previous 1 2 3 4 5 6 Next >>

---