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)

The Escherichia coli lac and ara promoters and rrnC ribosomal RNA promoter-leader region were fused to lacZYA. Transcription termination signals were introduced into the lac genes of these fusions by Tn9 and IS1 insertions. Measurement of lac enzymes from upstream and downstream of the insertions showed that termination signals resulting from these insertions are very efficient when transcription begins at lac or ara promoters but are very inefficient when transcription begins at the rrnC promoter-leader region. The rrnC promoter-leader region must, therefore, modify RNA polymerase to enable it to read through transcription termination signals.
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PMID:Antitermination of transcription from an Escherichia coli ribosomal RNA promoter. 620 58

A prokaryotic consensus sequence promoter has been chemically synthesized and cloned in bacterial plasmid vectors. This designed sequence is biologically active and promotes efficient expression of the genes to which it is fused. It is an unusually strong promoter in vitro, capable of specifying multiple rounds of transcription even when there is a large molar excess of heparin present prior to the addition of RNA polymerase. These properties make this a useful sequence for the in vitro production of RNAs. A 2-base-pair spacer mutant and a -35 region transversion mutant have been created in vitro in the synthetic promoter by synthetic-DNA-mediated, site-specific mutagenesis. The spacer mutant has a marginal in vivo effect on promoter strength but virtually abolishes the in vitro heparin resistance. The -35 region transversion changes a highly conserved nucleotide into the statistically least preferred base. This mutation has no marked effect on in vivo or in vitro promoter strength.
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PMID:Biological expression of an Escherichia coli consensus sequence promoter and some mutant derivatives. 630 98

The Escherichia coli chromosome carries seven cistrons encoding ribosomal RNA sequences. In all cases studied, in vitro and in vivo, it has been established that transcription is initiated from two tandem promoters. The expression of the rRNA cistrons is regulated in response to growth rate as well as to aminoacyl tRNA availability. In the present study, a plasmid (pPS1) carrying the promoter region of the rrnA cistron fused to the terminator region of rrnB has been used for in vitro transcription experiments. The presence of the terminators (T1 and T2) together with the fact that supercoiled DNA is found to be a highly efficient template, provide an ideal in vitro system in which to study the functional interrelationship between the two tandem promoters of E. coli rRNA cistrons. The results suggest that the rate of rRNA synthesis in E. coli cells growing in various conditions, as reflected by the availability of RNA polymerase, is primarily dependent on the properties of the two tandem rRNA promoters.
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PMID:Functional interrelationship between two tandem E. coli ribosomal RNA promoters. 633 96

The htpR gene of E. coli encodes a positive regulator of the heat-shock response. We have fused the htpR gene to the inducible PL promoter of phage lambda. Overproduction of HtpR following a temperature upshift resulted in the overexpression of heat-shock proteins. We describe the purification and initial in vitro characterization of the factor controlling expression of heat-shock genes. The factor was the 32 kd htpR gene product. In vitro, a mixture of HtpR and core RNA polymerase initiated transcription at heat-shock promoters. The sigma factor encoded by rpoD was not required for this reaction. Therefore, HtpR is a sigma factor that promotes transcription initiation at heat-shock promoters. We propose that htpR be renamed rpoH and that the gene product be called sigma-32.
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PMID:The htpR gene product of E. coli is a sigma factor for heat-shock promoters. 638 Jul 65

Drosophila melanogaster possessing a temperature-sensitive (ts) mutation that maps to an X-linked locus ( RpII215 ) (the locus has also been called l(1)L5 and Ultrabithorax -like or Ubl ) encoding a subunit of RNA polymerase II are fertile at 22 degrees C but become sterile when shifted to 29 degrees C. Homozygous RpII215ts adult females shifted to 29 degrees C lay structurally normal eggs for 24 hr, after which increasing numbers of eggs are abnormal. Eggs left to develop at 29 degrees C die as morphologically normal late embryos or first instar larvae when produced by females maintained at 29 degrees C for less than 6 hr. However, eggs produced by females undergoing oogenesis at 29 degrees C for longer than 6 hr develop abnormally, displaying holes primarily in their ventral cuticle and possessing an abnormal pharyngeal apparatus. As exposure of females to 29 degrees C lengthens there is an increase in the severity of these defects. Some of the eggs can be rescued by either mating RpII215ts females to wild-type males or shifting the eggs to 22 degrees C. The percentage of eggs rescued decreases with increased length of oogenesis at 29 degrees C, up to 20 hr, at which point they are no longer rescuable. The terminal phenotype of eggs that fail to be rescued by the above procedure is less extreme than that of eggs for which no rescue attempt was made. Holes in the ventral cuticle are reduced or absent, but pattern formation is disrupted such that segments are often missing, incorrectly oriented or fused. Because the RpII215 locus encodes a subunit of RNA polymerase II, the developmental defects described above are most likely due to reduced or aberrant transcription during oogenesis and early embryogenesis. This postulated effect on transcription results, in part, from the maternal loading of a gene product(s) that is thermolabile in eggs.
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PMID:Developmental effects of a temperature-sensitive RNA polymerase II mutation in Drosophila melanogaster. 642 38

Mouse myeloma cells were fused with splenocytes from a mouse that had been immunized with RNA polymerase I purified from a rat hepatoma. Hybridoma cells were selected and colonies secreting antibodies directed against the enzyme were detected by analysis of cell culture supernatants in a solid phase radioimmunoassay. Two of these cell lines were grown on a larger scale and the interaction between the immunoglobulins obtained from them and RNA polymerase I was studied in detail. Antibodies from both of the hybridoma cell lines were able to inhibit DNA-dependent RNA synthesis catalyzed by RNA polymerases I and III, but not that catalyzed by polymerase II. The antibodies were also capable of reducing the RNA chain elongation reaction catalyzed either by RNA polymerase I associated with isolated nucleoli or by enzyme preinitiated in vitro on calf thymus DNA. Inhibition of RNA polymerase I activity by the monoclonal antibodies was inversely related to the nucleotide concentration. In contrast, the DNA concentration had relatively little effect on inhibition by the antibodies. Analysis of immune complex formation between the antibodies and isolated individual enzyme subunits demonstrated that the monoclonal antibodies were directed against the largest (Mr = 190,000) polypeptide of the polymerase I. These data indicate that the largest subunit of RNA polymerase I contains an immunological determinant in common with RNA polymerase III and suggest that the polymerase I polypeptide of Mr = 190,000 contains a catalytic center involved in RNA chain elongation.
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PMID:Monoclonal antibodies directed against mammalian RNA polymerase I. Identification of the catalytic center. 663 Feb 16

Using the promotor-cloning vehicle described by An and Friesen (J. Bacteriol. 140:400-410, 1979), Escherichia coli chromosomal deoxyribonucleic acid fragments derived from the lambda drifd18 transducing phage were cloned in one of several unique restriction endonuclease sites adjacent to tetracycline(tet) genes that lack their own promotor. One of these plasmids has been used to isolate nine variants having mutations that lie in a putative internal promoter which is located between rplL and rpoB. Deoxyribonucleic acid sequence analysis revealed that, in all nine mutants, a single base change, C to T, in the ribonucleic acid polymerase recognition site led to a large increase in promoter activity. Analysis of a variety of plasmids in which tet is fused to various promoters yielded the following results: (i) rplK and rplA, genes for ribosomal protein L11 and L1, respectively, were cotranscribed from a common promoter located upstream from rplK; (ii) there was a strong promoter in the region between the rplKA operon and rplJ, the gene for ribosomal protein L10; (iii) an attenuator region was located between rplL, the gene for ribosomal protein L12, and rpoB, the gene for ribonucleic acid polymerase subunit beta; (iv) transcription terminated immediately after rpoC, the gene for ribonucleic acid polymerase subunit beta'; (v) a gene coding for unknown protein U, which is located between tufB and the rplKA operon, had its own promoter; (vi) the tufB gene was separated from all of the genes described above and had its own promoter.
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PMID:Characterization of promoter-cloning plasmids: analysis of operon structure in the rif region of Escherichia coli and isolation of an enhanced internal promoter mutant. 700 14

The effect of DNA superhelicity on in vitro transcription catalyzed by purified Escherichia coli RNA polymerase or S100 crude extract proteins was examined at various KCl concentrations. DNA from a recombinant plasmid pMT48 harboring the pL promotor-controlled fused N-trp genes and the pR promotor-controlled tof (cro) gene was employed as a template. Stimulation of transcription by superhelicity is generally more pronounced with the S100 crude extract proteins than with pure RNA polymerase. At KCl concentrations lower than 100 mM with pure RNA polymerase, there is no significant difference in the template activity between the supercoiled and relaxed forms of pMT48 DNA. In contrast, the dependence of efficient template activity on superhelicity is great over a whole range of KCl concentrations from 1.7 to 400 mM in the system using the S100 crude extract. The relative insensitivity of the pR promotor to superhelicity can be observed in either transcription assay system. Analysis of the kinetics of pL-promoted synthesis of trp mRNA indicates that diminished transcription in vitro on a relaxed template results mainly from less frequent RNA chain initiations, but at least in part from premature arrest of the chain elongation.
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PMID:Comparative studies of the effect of DNA superhelicity on in vitro transcription catalyzed by Escherichia coli S100 proteins and purified RNA polymerase. 704

The introduction of chick erythrocyte nuclei into mammalian cell cytoplasms results in their reactivation as evidenced by the de novo transcription of chick genes and the synthesis of both globin and constitutive proteins. In the present study, chick erythrocytes have been fused to L6 rat myoblasts and to alpha-amanitin-resistant variants of L6 to determine whether the chick or the mammalian RNA polymerase II was responsible for transcription of chick genes. Heterokaryons formed by fusing chick erythrocytes with alpha-amanitin-resistant L6 myoblasts synthesize both chick globin and chick constitutive proteins in the continued presence of 5 micrograms/ml alpha amanitin ten days postfusion. Both the synthesis of globin and other chick polypeptides occurs at levels comparable to those observed for untreated heterokaryons. Synthesis occurs under conditions in which insignificant chick RNA polymerase II activity can be detected in wild-type heterokaryons by autoradiography. These results demonstrate that RNA polymerase II is one of the mammalian proteins that is selectively taken up by the chick nucleus during reactivation in the presence of alpha amanitin. Furthermore, the mammalian RNA polymerase II alone can account for the transcription of both differentiation specific and constitutive genes in the chick nucleus.
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PMID:Transcription of chick genes by mammalian RNA polymerase II in chick erythrocyte-mammalian cell heterokaryons. 713 Feb 93

The 5S ribosomal RNA gene of Xenopus contains a region within the gene that directs the initiation of 5S RNA synthesis. This result was obtained by enzymatically deleting a fragment of X. borealis somatic 5S DNA from the 5' side of the gene and cloning the resultant mutants. These deletion mutants were tested for their ability to support 5S RNA transcription in an oocyte nuclear extract. Mutants lacking the entire 5' flanking region synthesized 5S RNA or slightly smaller RNAs that were initiated a few nucleotides into the gene. Mutants deleted as far as 50 nucleotides into the gene synthesized discrete RNAs of 116--121 nucleotides. These RNAs were fused transcripts that were initiated in the plasmid vector, transcribed through the remainder of the 5S RNA gene and terminated at the end of the gene. Mutants deleted 55 or more nucleotides into the gene synthesized little or no 5S size RNA. When additional nucleotides were inserted between nucleotides +40 and +41 of the gene, discrete transcripts of approximately 120 nucleotides were synthesized that had initiated within the gene. We conclude that a control region within the gene directs RNA polymerase III to initiate transcription approximately 50 nucleotides upstream from the 5' border of this region. The 3' border of the control region resides between gene residues +80 and +83 as determined in work described in the accompanying paper (Bogenhagen, Sakonju and Brown, 1980). When this control region is present, the exact site of initiation is determined by the sequence around the start site.
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PMID:A control region in the center of the 5S RNA gene directs specific initiation of transcription: I. The 5' border of the region. 735 99


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