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)

RNA polymerase from T4 infected cells supplemented with E. coli sigma polypeptide has a lower affinity for rRNA promoters than RNA polymerase from uninfected cells. The pattern of transcription by the phage modified polymerase is qualitatively similar to that of the vegetative polymerase in the presence of ppGpp. We suggest that E. coli polymerase holoenzyme normally exists in at least two conformational states, one with a high affinity for rRNA promoters and another with a low affinity, and that T4 infection stabilises the low affinity form.
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PMID:Phage T4 infection restricts rRNA synthesis by E. coli RNA polymerase. 78 64

An inhibitor of the Escherichia coli RNA polymerase has been isolated from E. coli and has been partially characterized. The inhibitor, a polypeptide of molecular weight 70000, acts to shut off RNA synthesis at about the time that the first round of RNA synthesis is over, preventing any further RNA synthesis. The inhibitor apparently does not recognize specific termination sequences in the DNA template, since it works equally well with double-stranded DNA, single-stranded DNA and poly[d(A-T)] as templates for RNA synthesis, and because the RNA molecules synthesized from T7 DNA appear to be terminated at the same site either in the presence or absence of the inhibitor. Several experiments indirectly indicate that the inhibitor may reversibly bind to the RNA polymerase at the termination step, in a ratio of approximately one inhibitor molecule per polymerase molecule.
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PMID:Isolation and properties of an inhibitor of Escherichia coli RNA polymerase. 79 63

Ts+ reversions of amber mutations tsR on the beta-subunit of Escherichia coli RNA polymerase (79 min on the genetic map) were investigated. TsR mutants are viable due to the partial suppression of amber mutations by su2 suppressor. Three types of reversions were isolated in the course of the selection for Ts+ character, namely, intragenic reversions and two types of extragenic reversions, located at different regions of the bacterial chromosome. The mutation N5, located between 0 and 15 min. on the map, increases practically to normal the amount of RNA polymerase beta-polypeptide, which is diminished as a result of ts22 amber mutation action, and increases the plating efficiency of several T4 phage amber mutants. The mutations designated as D are located on the chromosome near the spcA locus (64 min. on the E. coli map). These mutations are characterized by pleiotropic effect. They have properties of a weak suppressor increasing the efficiency of su2 action on amber mutations of E. coli and phage T4. At the same time D mutations are capable to decrease sharply the efficiency of the crosses with F' strains. Both these characters determined by D mutations do not segregate in transduction. It is suggested that the decrease of sexduction by D mutations depends on their influence on replication of episomes in the recipient cells.
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PMID:[Reversion of RNA-polymerase mutations affecting F'-factor stability]. 79 16

An RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) has been purified from phage-SP01-infected Bacillus subtilis that copies RNA almost exclusively from the heavy strand of native SP01 DNA, the DNA strand from which "middle" and "late" classes of RNA are copied in vivo. Hybridization-competition established that this RNA polymerase termed enzyme A, preferentially synthesizes middle RNA in vitro. Enzyme A contains beta',beta, alpha, and two newly identified host polypeptides, variation of (21,500 daltons) and omega (11,000 daltons). All of these polypeptides are associated with highly purified RNA polymerase from uninfected bacteria. In addition, enzyme A contains phage-induced subunits of 26,000, 24,000, and 13,500 daltons. Enzyme A lacks sigma polypeptide, and strand-selective transcription by this enzyme is resistant to anti-sigma antibody. A reconstitution experiment strongly suggests that the host variation of protein is required in addition to a phage-induced subunit(s) (or an unidentified phage-induced modification) for strand-selective transcription of SP01 middle genes in vitro.
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PMID:Highly asymmetric transcription by RNA polymerase containing phage-SP01-induced polypeptides and a new host protein. 80 30

Antibody directed against rho factor from vegetative Bacillus subtilis was prepared by immunizing a rabbit with denaturated rho polypeptide isolated by electrophoresis of partially purified DNA-dependent RNA polymerase on a sodium dodecyl sulfate-polyacrylamide slab gel. Antiserum to rho reacted specifically with native rho polypeptide but not with core RNA polymerase as judged by complement fixation and by an immunodiffusion assay. Anti-rho antibody also inhibited the ability of rho to stimulate transcription of phage phie DNA but failed to inhibit transcription of poly(dA-dT) by core enzyme. Specific antibody was also raised against a mixture of the beta and beta' subunits of RNA polymerase purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The effect of the anti-rho gamma-globulin on the transcription of phage phie DNA by RNA polymerase in crude extracts of vegetative and sporulating cells was examined. Anti-rho antibody markedly inhibited the transcription of phage DNA by RNA polymerase partially purified from vegetative bacteria by ammonium sulfate fractionation but had little effect on transcription of the phage DNA template by enzyme from sporulating cells. Addition of purified rho to a vegetative extract that had been depleted of rho by treatment with the anti-rho antibody restored active transcription of phage DNA. However, addition of purified rho to an antibody-treated extract of sporulating cells had little effect on phie RNA synthesis. These findings suggest that sporulating cells contain a component that interferes with the activity of the rho subunit of RNA polymerase.
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PMID:Antibody directed against Bacillus subtilis rho factor purified by sodium dodecyl sulfate slab gel electrophoresis. Effect on transcription by RNA polymerase in crude extracts of vegetative and sporulating cells. 81 Apr 88

Bacillus subtilis strain PB 2427 temperature sensitive in the synthesis of RNA during spore germination and outgrowth has been characterized to some extent. At non permissive temperature (46 degrees C) strain PB 2427 synthesizes stable and unstable RNA for 50 min from the beginning of germination and then stops. Most of the stable RNA is degraded to shorter molecules but can be identified as ribosomal RNA by hybridization-competition experiments. At non permissive temperature, in the presence of chloramphenicol, synthesis of RNA proceeds, though at a reduced rate, for at least 90 min. By hybridization-competition experiments it can also be shown that the RNA synthesized at 46 degrees C in the presence of chloramphenicol includes transcripts that are absent, from the RNA synthesized at 46 degrees C in the absence of drug. The RNA polymerase (holo and core) purified from vegatative cells of the mutant strain does not appear to have a greater heat-lability as compared with the enzyme purified from the parental strain. At non permissive temperature only six polypeptide chains with MW ranging from 47,000 to 78,000 daltons are synthesized by the germinating spores of the mutant.
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PMID:Synthesis of RNA and protein in a mutant of Bacillus subtilis temperature sensitive during spore germination. 82 46

We have previously presented a rapid, high yield method for the large scale purification of homogeneous RNA polymerase II from wheat germ (Jendrisak, J.J., and Burgess, R.R.(1975), Biochemistry 14, 4639), and we now report a detailed study of its subunit structure. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicates that polypeptides with molecular weights of 220 000, 140 000, 40 000, 27 000, 25 000, 21 000, 20 000, 17 800, 17 000, 16 500, 16 000, and approximately 14 000 are associated with the enzyme. Two-dimensional polyacrylamide gel electrophoresis, by which the subunits were separated in the first dimension in the presence of 8 M urea at pH 8.7 and in the second dimension in the presence of 0.1% sodium dodecyl sulfate, indicates that the 40 000 molecular weight component is composed of two nearly identical polypeptides and that the low molecular weight components (smaller than or equal to 40 000) are acidic proteins except for the 25 000 molecular weight polypeptide.
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PMID:Studies of the subunit structure of wheat germ ribonucleic acid polymerase II. 85 83

During purification of DNA-dependent RNA polymerase II (or B) from cell cultures of parsley a protein fraction was separated by phosphocellulose chromatography which enhanced RNA synthesis in the presence of native homologous DNA. This 'stimulatory factor' was characterized in respect to some effects on the reaction catalyzed by RNA polymerase II. In the presence of the factor the metal ion requirements as well as the ionic strength for optimal RNA synthesis were markedly changed; addition of the factor to RNA polymerase II purified by cellulose chromatography restored those enzyme properties which had apparently changed upon this purification step. The chain length of the RNA product synthesized is favouring the view that the factor acts mainly by stabilizing the elongation step during transcription. The stimulatory factor was further purified by several steps of column chromatography. As derived from the results of gel electrophoresis under denaturing conditions the factor consists of several small polypeptides. Those of Mr = 26000, 25000 and 14000 apparently have counterparts among the smaller subunits of highly purified RNA polymerase II from parsley cells. Another polypeptide of the factor, with Mr = 30000, was only found in those preparations of RNA polymerase II which had not been subjected to phosphocellulose chromatography.
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PMID:Characterization of a protein factor stimulating RNA synthesis by DNA-dependent RNA polymerase II from plant cell cultures. 88 Sep 45

The avian viral agent S1133 has previously been classified serologically as a member of the avian reovirus group. This viral agent grows in chicken embryo fibroblast cells, bands at a density of 1.37 g/ml in CsCl equilibrium density gradients, has a particle diameter of 75 nm, and has a morphology similar to that of human reovirus type 3. Its nucleic acid is comprised of double-stranded RNA and adenosine-rich oligonucleotides. The dsRNA is distributed among 10 segments with molecular weights of 2.7 x 10(6), 2.6 x 10(6), 1.7 x 10(6), 1.5 x 10(6), 1.3 x 10(6), 1.2 x 10(6), 0.80 x 10(6), 0.74 x 10(6), and 0.68 x 10(6) for the largest (L1) to the smallest (S4) segment, respectively, as determined by polyacrylamide gel electrophoresis. These 10 segments migrate differently on polyacrylamide gels compared to those of human reovirus type 3. The capsid proteins of avian reovirus consist of eight species of polypeptides as determined by polyacrylamide gel electrophoresis. These are lambda1, lambda2, lambda3, mu1, mu2, sigma1, sigma2, and sigma3 with molecular weights of 140, 125, 115, 85, 72, 40, 36, and 32 x 10(3), respectively. Only polypeptide sigma2, which resides in the inner capsid or core, comigrated with the sigma2 polypeptide of type 3 reovirus. Antiserum against type 3 reovirus did not neutralize avian reovirus. Avian reovirus core particles were found to possess a transcriptase and a methylase activity.
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PMID:Physical and chemical characterization of an avian reovirus. 98 52

A rapid method suitable for purifying large amounts of mitochondria from rat liver using isopycnic zonal centrifugation is described. The RNA polymerase isolated from the purified mitochrondria was found associated with one peak when resolved by DEAE Sephadex chromatography. The enzyme was next fractionated on a phosphocellulose column followed by glycerol gradient centrifugation. A 600-fold purification was achieved when the enzyme was finally filtered through agarose gel. This final enzyme fraction consisted of one polypeptide chain as shown by polyacrylamide gel electrophoresis profiles. The enzyme has a greater preference for poly [d(A-T)] templates than for rat liver mitochondrial DNA. Inhibition of the enzyme activity required high concentrations of the inhibitors. The resistance of the enzyme to alpha-amanitin indicated that there was no contamination from nuclear RNA polymerase II. The conclusion is drawn that the mitochondrial RAN polymerase activity is associated with a single polypeptide.
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PMID:Some properties of rat liver mitochondrial RNA polymerase. 100 1


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