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)

In herpes simplex virus type 1 (HSV-1)-infected HEp-2 cells, amanitin added before or at various times after infection always reduced viral multiplication. Also, the three waves of transcription of HSV-1 DNA, which led to the synthesis of alpha, beta-, and gamma-polypeptides, were all sensitive to amanitin in HEp-2 cells, and the amanitin-sensitive RNA polymerase activities of isolated nuclei were equally sensitive to the inhibitor before and during the infection. On the contrary, HSV-1 DNA transcription was totally unaffected by amanitin in AR1/9-5B cells, a mutant subline of CHO cells that possesses an amanitin-resistant RNA polymerase B. Together, these results strongly suggest that HSV-1 DNA utilizes for its transcription a polymerase undistinguishable from host cell RNA polymerase B with respect to its sensitivity to amanitin.
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PMID:Evidence that herpes simplex virus DNA is transcribed by cellular RNA polymerase B. 19 58

Synthesis of RNA polymerase subunits and of transcription termination factor p was studied after thermoinduction of prophage lambdac1857 located at several unusual sites on the chromosome of Escherichia coli. When a lysogen carrying the prophage at the bfe gene was induced at 42 degrees C, the rate of synthesis of core polymerase subunits (alpha, beta and beta') rapidly decreased, followed by a marked increase after about 10 min. The latter increase was observed specifically in the "bfe lysogen" and not in any of the other lysogens tested. Similarly, the rate of synthesis of p factor increased appreciably in the induced ilv lysogen carrying the prophage at the ilv gene, and possibly in the bfe lysogen as well, but not in other lysogens examined. Taken together with other evidence, these results suggest that the enhanced syntheses of beta and beta' subunits of RNA polymerase and of p factor observerd represent "escape synthesis", resulting from the close linkage of the prophage genome to the respective structural genes. In contrast, omega factor synthesis was stimulated upon induction of any of the lysogens used without respect to the site of prophage location, suggesting the involvement of an entirely different mechanism.
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PMID:Escape synthesis of RNA polymerase subunits and termination factor rho following induction of prophage lambda in Escherichia coli. 32 39

DNA-dependent RNA polymerase from Micrococcus luteus can be isolated from cell extracts after removal of an excess of nucleic acids by fractionation with ammonium sulfate, followed by two consecutive gel filtrations through agarose and chromatography on cellulose phospate. Either homogeneous holoenzyme or a mixture of core and holoenzyme is obtained in this way, as is indicated by electrophoresis in polyacrylamide gels in the absence of detergent, where core enzyme migrates ahead of holoenzyme. Homogeneous core enzyme can be isolated from holoenzyme by chromatography on DEAE-cellulose. Core enzyme contains the subunits alpha, beta and beta' previously described [U.I. Lill et al., (1975) Eur. J. Biochem. 52, 411-420] in a molar ratio of 2:1:1. Holoenzyme contains an additional subunit sigma of 80 000 molecular weight (molar subunit composition alpha2 betabeta' sigma) and two relatively small polypeptides (molecular weight 14 000 and 25 000, respectively). Subunit sigma may be isolated from holoenzyme by chromatography on DEAE-cellulose at pH 6.9 in the presence of low concentrations of glycerol. The behaviour of holoenzyme during sedimentation in a glycerol gradient at low ionic strength indicates its occurrence as a dimer of the alpha2betabeta'sigma-protomer, whereas the monomeric form is preferred by core enzyme. Holoenzyme is much more active than core enzyme in RNA synthesis on bacteriophage T4DNA as template. The activity of the latter is stimulated by isolated sigma. M. luteus sigma as well as holoenzyme enhances also the activity of core enzyme fro- Escherichia coli. The formation of a hybrid between micrococcal sigma and E. coli core polymerase is also suggested by the influence of sigma on the oligomerisation of the enzyme from E. coli.
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PMID:Purification and characterization of the DNA-dependent RNA polymerase and its subunit sigma from Micrococcus luteus. 59 Sep 42

As an effort to elucidate the control of quality and quantity of the DNA-dependent RNA polymerase in Escherichia coli, the rate of synthesis of the individual subunits was determined during shift-up and -down of nutrients. When the strain B/r grown in a succinate medium was imposed to a shift-up by adding a mixture of glucose and amino acids, rapid rise was observed of the differential rates of the synthesis of alpha, beta and beta' subunits, the constituents of core enzyme, leading to the increase of core polymerase concentration. The differential rates decreased thereafter to the level characteristic of the post-shift rate of cell growth. Compared to the strain B/r, the adaptation was slow in the strain K12 W3350. On the other hand, upon transfer of the strain B/r from a glucose-amino acids medium to a glucose medium lacking amino acids, the differential rate of core polymerase synthesis decreased rapidly and then regained the rate characteristic of the new growth rate. Similar control was also observed on the rate of ribosomal protein synthesis suggesting the coordinate expression of genes for the core polymerase subunits and ribosomal proteins. Thus, the intracellular concentration of RNA polymerase as well as of ribosomes might be one of the most important factors that affect the rate of bacterial growth. The rate of alpha subunit synthesis, however, exhibited little change during the shift-up but a considerable decrease was observed during the shift-down.
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PMID:Biosynthesis of RNA polymerase in Escherichia coli. II. control of RNA polymerase synthesis during nutritional shift up and down. 76 37

Upon release of rifampicin inhibition of Escherichia coli cells, the initiation of transcription will resume. The sequential resumption of the synthesis of proteins after release of rifampicin inhibition reflects the genetic order and size of the corresponding transcriptional units. We have used this approach to analyze whether the genes for alpha and sigma are on the same transcriptional unit as the genes for beta and beta', employing a method, which allowed us to measure the amounts of RNA polymerase subunits, alpha, beta, beta' and sigma in crude extracts. We have found that the alpha and sigma subunits are synthesized concurrently with the beta subunit in the rifampicin restart experiment, which suggests that the genes for alpha and sigma belongs to different transcriptional units.
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PMID:Biosynthesis of Escherichia coli RNA polymerase subunits upon release of rifampicin inhibition. 76 61

1. RNA polymerase from Escherichia coli is selectively and strongly retained by a heparin-substituted agarose and can be eluted therefrom by a neutral buffer containing 0.6 M salt. The method is applicable to relatively crude preparations of the enzyme on a preparative scale giving highly purified RNA polymerase in excellent yield. The enzyme obtained by this procedure shows the highest specific activity so far reported and is pure and enriched in factor sigma as indicated by dodecylsulfate gel electrophoresis. 2. Based on the differential affinity of the subunits of the enzyme for the heparin-carrying gel matrix, a method for separation of alpha, beta' + beta and sigma subunits by application of urea and salt-containing buffers is described. Upon recombination and dialysis with urea-free buffer 40-50% of the enzyme activity is restored.
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PMID:Rapid isolation of highly active RNA polymerase from Escherichia coli and its subunits by matrix-bound heparin. 110 37

1. Nucleolar RNA polymerase Ib obtained from auxin-treated lentil roots exhibits a higher transcriptional activity than the enzyme obtained from control roots. This difference is due to a change in the enzyme properties after auxin treatment. It is suggested that the hormonal effect is mediated by a factor that changes the molecular properties of nucleolar RNA polymerase. 2. Four fractions, alpha, beta, gamma and delta, that stimulate the activity of RNA polymerase Ib, have been extracted from lentil roots. Two of them, gamma and delta have been studied. Factor delta can stimulate nucleolar polymerase Ib and the nucleoplasmic enzyme II equally well, while factor gamma is specific for polymerase Ib. 3. The curve of UMP incorporation in vitro, with and without factors gamma or delta suggests that they are initiation factors. This conclusion is reinforced by the analysis of simultaneous incorporation of [gamma-32P]ATP and [3H]UMP in the RNAs synthesized in vitro. 4. Although the level of factor delta is independent of auxin treatment, that of factor gamma is doubled in auxin-treated roots. These results suggest that factor gamma is an auxin-induced protein that modulates the specific activity of the nucleolar RNA polymerase. 5. A general model of the mode of action of auxins at the molecular level is proposed. It integrates into a unified scheme the above results as well as those obtained by other workers.
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PMID:Hormonal control of transcription in higher plants. 116 23

Assembly of RNA polymerase II with the core region of TATA box-containing promoters requires the action of the TATA factor and four transcription factors designated alpha, beta gamma, delta, and epsilon, which have each been purified to near homogeneity from rat liver. Evidence from previous studies argues that alpha and beta gamma play a crucial role in delivering RNA polymerase II to the promoter (Conaway, R. C., Garrett, K. P., Hanley, J. P., and Conaway, J. W. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 6205-6209). Here we describe the interaction of transcription factor delta with preinitiation intermediates assembled in the presence of either recombinant yeast TFIID or the high molecular mass, endogenous TATA factor tau from rat liver (Conaway, J. W., Hanley, J. P., Garrett, K. P., and Conaway, R. C. (1991) J. Biol. Chem. 266, 7804-7811). Results of template challenge experiments argue that delta enters the preinitiation complex through interactions with multiple components of the transcription apparatus. We observe that, in the presence of recombinant TFIID, delta interacts stably with the preinitiation complex only in the presence of RNA polymerase II, alpha, and beta gamma, whereas, in the presence of tau, delta is capable of interacting stably with the Initial Complex independently of RNA polymerase II. Results of restriction site protection experiments reveal that delta and epsilon promote binding of the transcription apparatus to the Initiator element and support the model that RNA polymerase II assembles at the core promoter in at least two discrete steps, first "touching down" near the TATA element and finally extending its interaction downstream to encompass the cap site.
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PMID:Mechanism of assembly of the RNA polymerase II preinitiation complex. Transcription factors delta and epsilon promote stable binding of the transcription apparatus to the initiator element. 157 84

Accurate initiation at promoters by RNA polymerase II in a highly purified transcription system from rat liver depends on five accessory factors, which comprise two functional classes: (i) "promoter recognition" factors, designated tau and epsilon, which interact with template DNA to form an initial complex that serves as a recognition site for binding by RNA polymerase II and (ii) "RNA chain initiation" factors, designated alpha, beta gamma, and delta, which do not participate in initial complex formation, but which are essential for initiation (Conaway, J. W., Reines, D., and Conaway, R. C. (1990) J. Biol. Chem. 265, 7552-7558). Here we investigate the roles of alpha, beta gamma, and delta in accurate initiation. Kinetic evidence indicates that all three factors act in a stage prior to RNA synthesis to facilitate formation of a functional preinitiation complex. Moreover, results of "template challenge" experiments argue that all three factors become stably associated with the preinitiation complex during this stage. Neither alpha, beta gamma, nor delta functions catalytically in this process; instead, each factor appears to interact directly and stoichiometrically with intermediates in assembly of the preinitiation complex. Order of addition experiments reveal that transcription factors alpha and beta gamma assemble into the preinitiation complex by an "ordered" mechanism. We discuss two recently proposed models for assembly of the functional preinitiation complex and argue that our findings provide a plausible means of reconciling them.
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PMID:Transcription initiated by RNA polymerase II and purified transcription factors from liver. Transcription factors alpha, beta gamma, and delta promote formation of intermediates in assembly of the functional preinitiation complex. 169 22

We have fractionated rat liver and identified a set of transcription factors that are essential for accurate initiation by RNA polymerase II. These factors were resolved into five distinct enzyme fractions designated alpha, beta gamma, delta, epsilon, and tau. Four of these fractions can now be replaced with purified proteins. alpha and beta gamma were previously purified to apparent homogeneity (Conaway, J. W., and Conaway, R. C. (1989) J. Biol. Chem. 264, 2357-2362). Here, we report purification to near homogeneity of transcription factor epsilon. Epsilon has a native molecular mass of approximately 90 kDa and is composed of 34- and 58-kDa polypeptides. Both the 34- and 58-kDa polypeptides are required for runoff transcription. In addition, we show that transcription factor tau is a rat liver homologue of the TATA factor (TFIID or BTF1) that can be efficiently replaced in transcription in vitro by recombinant yeast TFIID. Comparison of the two factors reveals, however, that they differ significantly in their abilities to direct the transcription system to discriminate between promoters of different sequences.
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PMID:Transcription initiated by RNA polymerase II and transcription factors from liver. Structure and action of transcription factors epsilon and tau. 201 3


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