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)

Deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase (EC 2.7.7.6) from Acinetobacter calcoaceticus was purified to apparent homogeneity and its properties were compared with those of the Escherichia coli B enzyme. The molecular weights of the two native active enzymes as well as their alpha and beta subunits appeared to be similar. No subunit corresponding to that of sigma from E. coli was found, and furthermore no separation between the beta subunits could be detected by gel electrophoresis. A number of different DNAs were transcribed by the enzyme from A. calcoaceticus. Maximal RNA synthesis occurred at pH 8.7, 10 mM Mg2+, or 0.3 mM Mn2+ and at a total ionic strength of 0.1. Higher ionic strengths led to increasing inhibition of transcription and at mu = 0.4 complete inhibition was observed. The mechanism of inhibition of salt was not related to the initiation event as observed with T4 core RNA polymerase (R.Kleppe, 1975). In an attempt to understand the mechanism of inhibition by salt, the effect of ionic strength on the sedimentation properties of the enzyme was investigated. At low ionic strength, enzyme species with sedimentation coefficients, s20,w, of 5.8S, 12.4S, and 19.3S were present. In buffers with higher ionic strengths the relative amounts of the 12.4S species decreased. It is suggested, therefore, that the inhibition of activity at higher salt concentrations is caused by a decrease in concentration of the active enzyme species.
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PMID:Preparations and properties of ribonucleic acid polymerase from Acinetobacter calcoaceticus. 0 80

Deoxyribonucleic acid isolated from argA and argECBH transducing phages was utilized to study the in vitro synthesis of argA, argE, and argCBH messenger ribonucleic acid. The specific regulation of these operons by the arginine holorepressor was demonstrated, providing evidence that the majority, if not all, of the control of these operons is exercised at the transcriptional level. Data are presented which indicate that the arginine holorepressor functions by binding to the operator region and concomitantly prevents the binding of ribonucleic acid polymerase to the corresponding promoter region.
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PMID:In vitro transcription of the Escherichia coli K-12 argA, argE, and argCBH operons. 40 Jul 84

Deoxyribonucleic acid-dependent ribonucleic acid polymerase mutants of Bacillus subtilis strain Marburg were isolated after mutagenesis of spores with ethyl methane sulfonate. Genetic analysis by PBS1-mediated transduction and by transformation indicated that mutations responsible for all of the four phenotypic classes studied (rifampin resistance, streptovaricin resistance, streptolydigin resistance, and temperature sensitivity) were clustered close to the cysA14 locus. Three-factor transformation analysis has indicated the most probable marker order as follows: Rif(R)(Stv)(R)-Std(R)-Ts(418)-Ts(427). In addition, further characterization of the classical group I reference marker, cysA14, is reported.
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PMID:Genetic analysis of ribonucleic acid polymerase mutants of Bacillus subtilis. 414 88

Conditions affecting the synthesis of simian virus 40-specific ribonucleic acid (RNA) in nuclei isolated from lytically infected cells were investigated. Deoxyribonucleic acid-RNA hybridization results show that an alpha-amanitin-sensitive RNA polymerase activity is responsible for transcription of simian virus 40 deoxyribonucleic acid.
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PMID:Inhibition by -amanitin of simian virus 40-specific ribonucleic acid synthesis in nuclei of infected monkey cells. 434 54

Deoxyribonucleic acid (DNA) of Escherichia coli was found to be attached to the cell membrane at about 20 points. This was determined by fractionation of X-irradiated cells with the M band (magnesium-Sarkosyl crystals) technique. The number of attachment points was computed from the relationship between the amount of DNA in M bands and the number of double-strand breaks introduced by the X-ray treatment. The number of attachment points was decreased fourfold by treatment of cells with rifampin. This effect was apparently due to the action of the drug on ribonucleic acid (RNA) polymerase since the drug did not affect a mutant whose RNA polymerase is resistant to rifampin. This suggests that there may be two classes of attachment points of DNA on the membrane, some of which are removed by rifampin treatment and some which are not. Rifampin treatment also resulted in the uncondensing of isolated nucleoids and in an axial appearance of the nucleoids in ultrathin sections. The results suggest that RNA polymerase plays a role, direct or indirect, in maintaining the structure of the bacterial nucleoid and in some of its attachment to the membrane.
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PMID:Effect of rifampin on the structure and membrane attachment of the nucleoid of Escherichia coli. 458 13

Deoxyribonucleic acid-dependent ribonucleic acid (RNA) polymerase (EC 2.7.7.6) was purified from the dimorphic bacterium Caulobacter crescentus at three stages in development. Enzyme from pure populations of stalked cells, as well as populations enriched in swarmer and predivisional cells, appeared identical in subunit structure and template requirements. The molecular weights of the enzyme subunits were 165,000, 155,000, 101,000, and 44,000, respectively. By analogy with RNA polymerase from other bacterial sources, they are considered to be components of the C. crescentus holoenzyme, beta', beta, sigma, and alpha, respectively. The C. crescentus enzyme appeared similar to the Pseudomonas aeruginosa enzyme and unlike the Escherichia coli enzyme with respect to subunit molecular weights and failure to separate into core and sigma components upon phosphocellulose chromatography. In addition, the effects of ionic strength on the time course of polymerization varied both with the sources of bacterial polymerase and bacteriophage DNA.
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PMID:Deoxyribonucleic acid-dependent ribonucleic acid polymerase of Caulobacter crescentus. 473 61

Deoxyribonucleic acid (DNA) synthesis in T4rII-infected, lambda-lysogenic strains of Escherichia coli proceeds with one-half the rate of T4 wild-infected bacteria and stops 16 min after infection at 37 C. The rates of ribonucleic acid (RNA) synthesis, however, are the same with T4rII and T4 wild. The turnover of pulse-labeled RNA is slow in K strains (half-lives 10 to 20 min) as compared with B strains (half-lives 2.5 to 6 min). Lambda-lysogeny increases the apparent messenger (m) RNA half-lives in pulse-chase experiments. The shutoff of host RNA synthesis in T4rII infected K(lambda) is incomplete. Moreover, the preferential transcription of T4 DNA ceases 13 min after infection, and transcription of host and prophage lambda DNA is resumed. The T4 RNA synthesized in rII-infected K(lambda) contains no late T4 mRNA. The early portion of the T4 genome, however, is transcribed completely. The T4-induced early modification of bacterial RNA polymerase does occur. Resumption of host DNA transcription at 13 min after infection is not associated with a reversal of the above polymerase modification. It is concluded that in lambdalysogenic bacteria T4rII infections are abortive because RNA polymerase is prevented from transcribing late T4 genes.
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PMID:Control of gene function in bacteriophage T4. I. Ribonucleic acid and deoxyribonucleic acid metabolism in T4rII-infected lambda-lysogenic hosts. 490 33

Deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase (EC 2.7.7.6) isolated from a rifampin-sensitive strain of Mycobacterium smegmatis was 90% inhibited by 1 mug of rifampin per ml; enzyme from a rifampin-resistant mutant was not affected by this concentration of antibiotic. Inhibition of phenylalanine-1-(14)C incorporation by rifampin in growing cultures was complete about 6 min after addition of antibiotic. Under the same conditions, uracil-2-(14)c incorporated was blocked after 1.5 to 2 min. Rifampin kills M. smegmatis very slowly. When rifampin-inhibited cultures were transferred to a rifampin-free medium, there was a partial resumption of uracil-2-(14)C incorporation, even in the presence of chloramphenicol. We conclude that a primary event in the inhibition of M. smegmatis by rifampin is the block of DNA-dependent RNA polymerase.
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PMID:Mechanism of action of rifampin on Mycobacterium smegmatis. 494 61

Cutler, Richard G. (University of Houston, Houston, Tex.), and John E. Evans. Synchronization of bacteria by a stationary-phase method. J. Bacteriol. 91:469-476. 1966.-Cultures of Escherichia coli and Proteus vulgaris have been synchronized, with a high percentage phasing, in large volumes and at high cell densities by a method which takes advantage of a tendency of cells to synchronize themselves when entering the stationary phase of growth. The method consists of growing the bacteria to an early stationary phase, harvesting them quickly under minimal conditions of stress, and inoculating them into fresh medium at a dilution of about sevenfold. Cellular division is then partially synchronized. Four-generation cycles of a high percentage of phasing are obtained by repeating this procedure on the partially synchronized culture. Deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein analyses were made throughout all phases of the growth curve. Advantage has been taken of this method of synchrony to isolate selected segments of the bacterial genome in significant amounts. A working hypothesis to explain the synchrony suggests that the unfavorable conditions of growth as the bacteria near the stationary phase are detected by a decrease in the amino acid pool size, and that this results in a gradual decrease of DNA transcription activity through the inhibition of RNA polymerase by transfer RNA. The synchronizing method may be unique in producing cultures that grow both in cellular division and in genomic synchrony.
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PMID:Synchronization of bacteria by a stationary-phase method. 532 75

The synthesis of cell-specific ribonucleic acid (RNA) appeared to be stimulated in human embryonic kidney (HEK) cultures infected with adenovirus 2 or 12. Deoxyribonucleic acid (DNA)-RNA hybridization experiments revealed that by 44 to 70 hr after infection with either virus, the relative amount of pulse-labeled RNA capable of hybridizing with HEK cell DNA increased considerably; such RNA was detected in both nuclear and cytoplasmic fractions. The main increase in apparent host RNA synthesis was preceded by (i) a relatively early transient stimulation of the DNA-dependent RNA polymerase activity in isolated nuclei, and (ii) a small but consistently observed increase in the rate of acetylation of lysine-rich and arginine-rich histone fractions. The Mn(2+)-(NH(4))(2)SO(4) and Mg(2+)-activated RNA polymerase reactions measured in nuclei isolated from cells infected with adenovirus 2 or 12 were stimulated at about the same time; a rapid loss of polymerase activity followed. The augmentation of the two RNA polymerase reactions found in adenovirus 12-infected cells was independent of protein synthesis. After the initial increase, the acetylation rate of histones of cells infected with adenovirus 2 or 12 declined, until late in infection it was approximately 40 to 70% of the control cell rate.
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PMID:Transient stimulation of deoxyribonucleic acid-dependent ribonucleic acid polymerase and histone acetylation in human embryonic kidney cultures infected with adenovirus 2 or 12: apparent induction of host ribonucleic acid synthesis. 547 77


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