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)

A set of F' strains of Escherichia coli K-12 partially diploid for various chromosomal segments has been examined for possible gene dosage effects in the synthesis of sigma factor of the DNA-dependent RNA polymerase (RNA nucleotidyltransferase; nucleoside-triphosphate:RNA nucleoti-dyltransferase, EC 2.7.7.6). It was found that all F' strains diploid for the dnaG region synthesize sigma at rates two to three times higher than other F' or F- strains. Moreover, strains of Salmonella typhimurium harboring these F' plasmids produce E. coli sigma in addition to Salmonella sigma. This has been shown on the basis of the finding that Salmonella sigma can be precipitated with antiserum against E. coli RNA polymerase but is distinguishable from E. coli sigma in its mobility in sodium dodecyl sulfate/polyacrylamide gel electrophoresis. E. coli sigma polypeptides thus produced seem to be stable in cells of S. typhimurium. These results indicate that a structural gene for sigma (rpoD) is located at the metC-argG region, probably near the dnaG locus (66 min on the current genetic map of E. coli).
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PMID:Chromosomal location of a structural gene for the RNA polymerase sigma factor in Escherichia coli. 32 55

Using antibody-linked polymerase assay we studied the polypeptide composition of DNA-dependent RNA polymerase from Streptomyces aureofaciens and immunological cross-reaction with Escherichia coli RNA polymerase. We identified about 25 'ALPA-reactive' polypeptides which are probably involved in the transcriptional apparatus. We demonstrated that beta' and beta subunits from S. aureofaciens and E. coli are immunologically related and sigma70 (E. coli) shows immunochemical similarity with sigma35 (S. aureofaciens). According to the reconstitution of RNA polymerase holoenzyme and antibody-linked polymerase assay we identified sigma factors responsible for recognition of two promoters.
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PMID:RNA polymerase heterogeneity in Streptomyces aureofaciens: characterization by antibody-linked polymerase assay. 178 84

Hybrid 5' regulatory regions were constructed in which the upstream activator sequence (UAS) and promoter of various nif genes were exchanged with the upstream regulatory sequence (URS) of the fdhF gene from Escherichia coli. They were analysed for their regulatory response under different growth conditions with the aid of fdhF'-'lacZ or nif'-'lacZ fusions. Placement of the UAS from the Bradyrhizobium japonicum nifH gene in front of the spacer (DNA region between URS and promoter) plus promoter from fdhF renders fdhF expression activatable by the Klebsiella pneumoniae NIFA protein, both under aerobic and anaerobic conditions. This excludes the possibility that the spacer of the fdhF5' flanking region contains a site recognized by a putative oxygen- or nitrate-responsive repressor. There was also considerable activation by NIFA of fdhF expression in a construct lacking the nifH UAS but containing the fdhF spacer plus promoter. Further experimental evidence suggests that this reflects a direct interaction between NIFA and RNA polymerase at the ntrA-dependent promoter. A second set of hybrid constructs in which the URS from fdhF (E. coli) was placed in front of the nifD spacer plus promoter from B. japonicum or in front of the K. pneumoniae nifH, nifU, nifB spacers and promoters, delivered inactive constructs in the case of the nifD, nifU and nifB genes. However, a nifH'-'lacZ fusion preceded by its own spacer and promoter plus the foreign fdhF URS displayed all the regulatory characteristics of fdhF expression, i.e. anaerobic induction with formate and repression by oxygen and nitrate. Although it is not known why only one out of the four nif promoters could be activated by the fdhF URS, this result nevertheless demonstrates that the various regulatory stimuli affecting expression of fdhF in E. coli have their target at the upstream regulatory sequence.
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PMID:Construction of chimaeric promoter regions by exchange of the upstream regulatory sequences from fdhF and nif genes. 266 22

Using a gel retardation assay the protein which binds selectively to the Alu-family repeat (AFR) has been identified and partially purified from HeLa cell nuclear extract. The protein (AFR-binding protein, ABP) forms multiple discrete complexes with AFR even in the presence of 200 to 2000-fold excess of non-specific (E. coli) DNA. The most stable complex has a relative mobility in 4% polyacrylamide gel (as compared to the free Alu-fragment) of 0.54. Heterogeneity of protein-DNA bands seen in the polyacrylamide gel suggests that ABP is able to form multimeric complexes with AFR. Competition experiments show that ABP does not interact with the RNA polymerase III promoter and with the TGGCA-sequence, but a high affinity binding site for ABP was found within a 660 bp restriction fragment containing the SV40 virus promoter and replication origin.
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PMID:Alu-family repeat binding protein from HeLa cells which interacts with regulatory region of SV40 virus genome. 282 99

A minimal mechanism is proposed which describes the transcriptional and translational processes for four phage proteins (RNA polymerase, DNase, primase and DNA polymerase) involved in T3/T7 DNA replication. Phage DNA replication is also included. It is shown how lag times may be incorporated into a kinetic mechanism. The distinct three-stage transport of phage DNA into the bacterial host (E. coli) is considered. DNA transport is assumed to be rate-determining for the transcription of class I and II proteins. Transcriptional and translational lag times have been calculated on the basis of available gene mapping of T7 phages. The kinetic behavior of T7 and T3 phage infection is practically identical. The hydrolysis of bacterial DNA by phage DNase (endonculease and exonuclease) as well as the subsequent phosphorylation to the deoxymononucleoside triphosphates are assumed to be rate-determining in phage DNA replication. Good agreement with experiment is obtained in our computer simulations.
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PMID:Computer simulation of T3/T7 phage infection using lag times. 330 Aug 7

Amino acid starvation of "stringent RNA control" (RC(str)) strains of Escherichia coli (E. coli) results in the cessation of net protein and net RNA synthesis, whereas "relaxed RNA control" (RC(rel)) strains continue net RNA synthesis under the same conditions of amino acid starvation. This report tests further the hypothesis that net RNA synthesis is markedly reduced during amino acid starvation of RC(str) strains as a result of reduction in the supply of substrates of the RNA polymerase. Bacterial ribonucleoside triphosphate pool levels were measured before and after the arrest of protein synthesis in RC(str) and RC(rel) strains. Protein synthesis was inhibited either by addition of trimethoprim to the medium or by the use of a mutant having a temperature-sensitive valyl-tRNA synthetase. The ribonucleoside triphosphate pool levels do not decline significantly during inhibition of protein synthesis in RC(str) strains under either condition, and there is no apparent correlation between the measured pool levels and the residual rate of net RNA synthesis in RC(str) and RC(rel) strains. Thus, these data argue against the hypothesis that the regulation of RNA synthesis is mediated by the availability of substrates of the RNA polymerase.
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PMID:Nucleoside triphosphate pools and the regulation of RNA synthesis in E. coli. 489 29

We have developed a soluble enzyme system that replicates exogenously added plasmid DNA (lambda dv) bearing the replication origin of the bacteriophage lambda chromosome. The system contains pure phage lambda O and P replication proteins and a partially purified mixture of Escherichia coli replication proteins [the enzyme system of Fuller, R.S., Kaguni, J.M. & Kornberg, A. (1981) Proc. Natl. Acad. Sci. USA 78, 7370-7374). The features of lambda dv replication in this system closely resemble the known characteristics of phage lambda DNA replication in vivo. The system (i) depends completely on exogenously supplied DNA, (ii) specifically replicates supercoiled plasmid DNA that contains a lambda replication origin, (iii) depends on both the lambda O protein and the lambda P protein, (iv) depends on RNA polymerase, (v) depends on host replication proteins (e.g., primase, dnaB protein, and several others that function in the priming of DNA synthesis in E. coli) as judged by antibody inhibitions, and (vi) replicates as much as 32% of added lambda dv plasmid DNA through a single complete round to generate catenated daughter molecules. Furthermore, replication of lambda dv DNA in vitro requires DNA gyrase and an ATP-regenerating system. It is notable that addition of lambda O and P proteins to the mixture of E. coli replication proteins inhibits replication of plasmids bearing the origin of the E. coli chromosome. Exploitation of this enzyme system should allow a detailed investigation of the biochemical mechanisms involved in bacteriophage lambda DNA replication and its regulation.
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PMID:Initiation of bacteriophage lambda DNA replication in vitro with purified lambda replication proteins. 621 78

DNA-dependent RNA polymerase was partially purified from wheat germ extract and tested for inhibition by antinuclear autoantibodies from the sera of patients with connective tissue diseases. The enzyme was inhibited by anti-DNA and by autoantibodies to the nuclear ribonucleoprotein nRNP. Autoantibodies to other ribonucleoproteins (Sm, Ro, La) did not cause inhibition. The enzyme preparation was shown to contain material with Ro and La antigenic activity but there was no nRNP or Sm detectable by immune precipitation. Previous work [3] has shown inhibition of prokaryotic (E. coli) RNA polymerase by anti-DNA, and our results show that the eukaryotic enzyme, in this case from wheat germ, is also inhibited. The results are consistent with the suggestion that inhibition by anti-DNA is due to template masking. Inhibition of RNA polymerase by antibodies to cellular ribonucleoprotein suggests that the antigen is in some way associated with the activity of the enzyme.
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PMID:Effects of antinuclear autoantibodies on RNA polymerase. 660 60

An Azospirillum brasilense mutant (N12) pleiotropically defective in the assimilation of nitrogenous compounds (Asm-) was isolated and found lacking in the glutamate synthase (GOGAT-). The glt (GOGAT) locus of A. brasilense was identified by isolating a broad-host-range pLAFR1 cosmid clone from a gene library of the bacterium that rectified Asm- and GOGAT- defects (full recovery of activities of the nitrogenase, the assimilatory nitrate and nitrite reductases, and the glutamate synthase). A 7.5-kb EcoRI fragment of the cosmid clone that also complemented N12 was partially sequenced to identify the open reading frame for the alpha-subunit of GOGAT. The amino acid sequences deduced from the partial nucleotide sequences of the glt locus of A. brasilense showed considerable homology with that of the alpha-subunit of GOGAT coded by the gltB gene of Escherichia coli. The genetic lesion of N12 was found within the gltB gene of A. brasilense. The gltB promoter of A. brasilense showed the presence of a consensus sigma-70-like recognition site (as in E. coli) in addition to potential NtrA-RNA polymerase, IHF, and NifA binding sites.
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PMID:Isolation of a glutamate synthase (GOGAT)-negative, pleiotropically N utilization-defective mutant of Azospirillum brasilense: cloning and partial characterization of GOGAT structural gene. 790 33

Expression of the F plasmid traY promoter in vivo requires both host (E. coli) and plasmid encoded proteins. As judged by transcript size and primer extension analyses, the F plasmid traY promoter was utilized in vitro by purified E. coli sigma 70 RNA polymerase in the absence of other proteins. However, in vitro transcription required supercoiled templates. Endonuclease protection experiments showed that RNA polymerase is unable to form a stable complex at the traY promoter in linear or relaxed circular templates. In vitro transcription with linear templates could be elicited by altering the traY -10 and -35 hexamers to the consensus sequences. Alterations that reduced the effect of template supercoiling on apparent promoter strength in vitro also reduced the effect of the F plasmid TraJ protein on traY expression in vivo. Apparent traY promoter strength in vitro, estimated in template competition experiments, was unaltered by deletion of tra DNA normally upstream of the promoter, a change in promoter context that elicited high levels of promoter activity in TraJ- cells. These data suggest a model for regulated traY promoter activity in which a nucleoprotein complex involving tra DNA immediately upstream locally relaxes traY promoter DNA. TraJ and perhaps other activators could disrupt the complex, allowing promoter DNA to equilibrate at the prevailing negative superhelical density and thereby eliciting transcription initiation.
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PMID:Contributions of promoter context and structure to regulated expression of the F plasmid traY promoter in Escherichia coli K-12. 831 84


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