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 new class of Escherichia coli mutants, referred to as grn, has been isolated by localized mutagenesis. These mutations affect the sigma subunit of DNA-dependent RNA polymerase (ribonucleoside 5'-triphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) by abolishing the expression of the lambda N gene, and they are closely lniked to dnaG in the order dnaG-grn-uxaA. Detailed study of one such mutant, grn1, yielded the following results: (i) grn1 is a single mutation and the mutant cell shows cold-sensitivity in growth; (ii) the Grn phenotype of the mutant can easily be suppressed by secondary mutations in the beta subunit gene of RNA polymerase; (iii) purified holoenzyme of RNA polymerase isolated from the mutant showed an altered salt-dependency in vitro, and the mixed reconstitution of the mutant with the wild-type subunits showed that the sigma subunit of the grn1 mutant is altered; (iv) lambda phage mutants (lambda grg), which overcome the grn mutation, can be classified into two groups, the "nin-deletion" and the "N-mutant" groups (both of these are also able to grow on the previously described groN mutant of Georgopoulos and nusAB of Friedman); (iv) the mutant polymerase transcribed 12S as well as 7S RNA from lambda DNA in the presence of the rho factor in vitro. These results indicate that the grn mutation alters the sigma subunit of RNA polymerase and that the sigma subunit participates in activating the N-mediated antitermination mode of lambda phage transcription.
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PMID:Sigma subunit of Escherichia coli RNA polymerase affects the function of lambda N gene. 15 60

In this report we have presented evidence that viral sequences in the genome of AMV-infected myeloblasts can be transcribed in vitro. The RNA products synthesized in either nuclei isolated from these cells or by eukaryotic RNA polymerase B from the isolated chromatin contained approximately 1% virus-specific sequences. This result, which is in agreement with the fraction of viral RNA in infected cells (Garapin et al. 1971), is higher than expected from a random transcription of the genome, and thus shows that a degree of selectivity in transcription is maintained in both systems. The inhibition of synthesis of viral sequences in nuclei by alpha-amanitin as well as the finding that RNA polymerase B catalyzed the synthesis of viral sequences from chromatin support the hypothesis that the expression of viral information is mediated by nucleoplasmic RNA polymerase. An investigation of the properties of the chromatin-directed products led to the suggestion that RNA synthesis in vitro was initiated on single-stranded or denatured regions of the template; a limiting factor in the synthesis of large molecular weight RNA from isolated chromatin appeared to be the extent of the denatured region available to the enzyme. These findings are consistent with the suggestion that gene activation in eukaryotic organisms results from the unwinding of segments of chromatin DNA (Crick 1971).
Cold Spring Harb Symp Quant Biol 1975
PMID:AMV RNA transcription in cell-free systems and properties of in vitro chromatin-directed RNA synthesis. 16 5

A cold-sensitive mutation in the rpoB gene for the RNA polymerase beta subunit increasing the temperature of promoter opening on T2 phage DNA was obtained in Escherichia coli. The mutation also affects the stages preceding promoter opening by increasing the dissociation rate of RNA polymerase--DNA closed complexes. The affinity of RNA polymerase to T2 and lambda DNA is differentially changed by the mutation. The relative efficiency of transcription of these two templates is also changed. These results suggest a participation of the RNA polymerase beta subunit in the interaction with promoters.
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PMID:A cold-sensitive beta subunit mutant RNA polymerase from Escherichia coli with defects in promoter opening in vitro. 39 44

A cold-sensitive mutation in Escherichia coli, affecting the beta-subunit of RNA polymerase and causing an increase in the temperature of promoter opening on T2 phage DNA, was obtained. The mutation also affects the stages preceding promoter opening by increasing the dissociation rate of RNA polymerase--DNA closed complexes. The affinity of RNA polymerase to T2- and lambda-DNA is differently changed by the mutation. The relative efficiency of transcription of these two templates is also changed. These results suggest a participation of the beta-subunit of RNA polymerase in the interaction with promoters.
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PMID:[Cold-sensitive mutation in the beta-subunit of Escherichia coli RNA polymerase affecting the opening of promoters]. 39 1

RNA 1 (see end of Summary) of a cold-adapted and temperature-sensitive (ts) influenza virus mutant A/Ann Arbor/6/60 has a different mobility from RNA 1 of wild-type (wt) A/Ann Arbor/6/60 when subjected to electrophoresis through acrylamide/agarose gels in the absence of denaturing agents. Detection of this lesion in RNA 1 of the mutant virus was dependent on the temperature of the gel during electrophoresis. Because RNA 1 is believed to code for a protein involved in virus-specific RNA synthesis we compared phenotypes of virion transcriptases in the wt and mutant viruses. The enzyme of the mutant virus was found to be about 40% less active at 40 degrees C than the enzyme of the wt virus when related to their activities at 31 degrees C. Two cold-adapted ts recombinants which derive their RNA 1 from the mutant A/Ann Arbor/6/60 have virion transcriptases with a phenotype similar to that of their mutant parent. Three different cold-adapted ts recombinants, however, which also derive their RNA 1 from the mutant A/Ann Arbor/6/60, have virion transcriptases with a phenotype similar to that of wt virus. We conclude, therefore, that the conditional-lethal ts property of A/Ann Arbor/6/60 mutant and its recombinants is independent of the phenotypic marker observed for the A/Ann Arbor/6/60 mutant virion transcriptase, and that the lesion in RNA 1 of the mutant may also be unrelated to the observed difference between virion transcriptases of the mutant and wt A/Ann Arbor/6/60 viruses. The phenotypes of the virion transcriptases in recombinants did, however, correlate with the derivation of their RNA 2. This suggests that the increased temperature-sensitivity of virion transcriptase of the A/Ann Arbor/6/60 mutant is caused by either (1) a lesion (not necessarily conditionally lethal) that occurred in its RNA 2 during the course of cold-adaptation, or (2) a lesion in another gene whose product is a component of the virion transcriptase complex, but which lesion is only expressed phenotypically when there is a synergistic interaction in the transcriptase complex with the product of A/Ann Arbor/6/60 rna 2.
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PMID:Comparative studies of wild-type and cold-mutant (temperature-sensitive) influenza viruses: independent segregation of temperature-sensitivity of virus replication from temperature-sensitivity of virion transcriptase activity during recombination of mutant A/Ann Arbor/6/60 with wild-type H3N2 strains. 52 98

1. EDTA inhibited incorporation of [3H]uridine into RNA of lymphocytes, but did not decrease uptake into the cold-acid-soluble fraction of the cells. The inhibition by EDTA was largely reversible by simultaneous addition of Zn2+. 2. Low concentrations pf actinomycin D (3 ng/ml) added at the time of stimulation of the cells inhibited [3H]uridine incorporation into RNA, but concentrations of 50-100 ng/ml were required to produce the same degree of inhibition if addition of actinomycin D was delayed until just before the incorporation was measured. This difference in sensitivity did not reg within the cells. 3. When added immediately before phytohaemagglutinin, actinomycin D (3 ng/ml) and EDTA produced similar time-courses of inhibition of uridine incorporation. 4. Uridine incorporation at 32h was inhibited when actinomycin D (3 ng/ml) or EDTA was added just before stimulation of the cells, but was only slightly affected when they were added at 32h. At intermediate times the incorporation of uridine remained sensitive to addition of EDTA for longer than it was sensitive to actinomycin D. 5. Polyacrylamide-gel separation of RNA synthesized in EDTA-treated cultures in the presence or absence of added Zn2+ showed that lower availability of Zn2+ resulted in a decreased rate of transfer of radioactivity from 32S to 28S rRNA and decreased survival of 28S rRNA relative to 18S rRNA. 6. Close similarities have been shown to exist between the effects of EDTA and low concentrations of actinomycin D. Not all the effects of EDTA could be explained by postulating that Zn2+ was a constituent of RNA polymerase I, nor were the effects of actinomycin D readily explained by previously suggested mechanisms of action of this antibiotic.
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PMID:Comparison of the effects of zinc deprivation and actinomycin D on ribonucleic acid synthesis by stimulated lymphocytes. 81 Jan 42

Allopurinol, Collins' solution, and spermidine were tested for their ability to preserve nuclear function during kidney storage. Spermidine increased nuclear ribonucleic acid (RNA) polymerase activity 25 to 43 percent after 60 minutes of warm ischemia. Collins' solution was less effective and allopurinol did not protect RNA polymerase activity. Spermidine offered little additional protection over Collins' during cold storage of RNA polymerase activity. Only spermidine prevented the decrease in the molecular weight of RNA transcribed following kidney storage. Only Collins' solution prevented the breakdown of rapidly labeled heterogenous high molecular weight RNA and ribosomal precursor RNA.
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PMID:Protection of nuclear function by various agents during organ storage. 84 69

From the present experiments, we can conclude that late in infection two classes of DNA-dependent RNA polymerase transcribe the viral genome. Although we cannot definitively exclude the possibility that one or both of these enzymes are coded for by the virus, it appears more probable that these are hos enzymes, because of the coincidence of the alpha-amanitin sensitivities for synthesis of specific viral RNAs with the toxin sensitivities of the respective host RNA polymerases. Furthermore, the chromatographic properties of the enzymes, the alpha-amanitin sensitivities of the purified RNA polymerases and the levels of solubilized activities are the same for uninfected and late infected cells. It seems probable that some virus-coded or virus-induced factor(s) modifies either the selectivity or the activity of these host RNA polymerases. As an example, the "inactivation" of RNA polymerase I activity in vivo or the increased endogenous activity of isolated infected cell nuclei, without changes in the solubilized level of the respective RNA polymerases, could be mediated by such factor(s). The effect of such factors may not be detected by activity measurements on exogenous DNA, because it acts as a nonspecific template. Analysis of such factors will require reconstitution of appropriate in vitro systems, which retain some transcriptional specificity. Since several viral mRNAs synthesized at late times (Tal et al. 1974) and the 5.5S RNA (J. Pan, pers, comm.) are transcribed from the same region (R-R1 restriction enzyme fragment A), initiation and termination signals for both RNA polymerase II and III are contained in this portion of the genome. Further studies of the interaction of these two enzymes with the adenovirus 2 genome should contribute to understanding the control of transcription in eukaryotic cells, in particular in the case of virus-infected or -transformed cells.
Cold Spring Harb Symp Quant Biol 1975
PMID:The transcriptional role of host DNA-dependent RNA polymerases in adenovirus-infected KB cells. 105 77

The major cold shock protein from Bacillus subtilis (CspB) was overexpressed using the bacteriophage T7 RNA polymerase/promoter system and purified to apparent homogeneity from recombinant Escherichia coli cells. CspB was crystallized in two different forms using vapor diffusion methods. The first crystal form obtained with ammonium sulfate as precipitant belongs to the trigonal crystal system, space group P3(1)21 (P3(2)21) with unit cell dimensions a = b = 59.1 A and c = 46.4 A. The second crystal form is tetragonal, space group P4(1)2(1)2 (P4(3)2(1)2) with unit cell dimensions a = b = 56.9 A and c = 53.0 A. These crystals grow with polyethylene glycol 4000 as precipitant.
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PMID:Overproduction, crystallization, and preliminary X-ray diffraction studies of the major cold shock protein from Bacillus subtilis, CspB. 140 60

The nusA11 mutation causes reduced transcription termination and temperature-sensitive growth of Escherichia coli. Suppressor mutations that restored growth of nusA11 mutant cells were isolated and named sna mutations. The intergenic suppressor mutation sna-10 was located in the rpoC gene at 90 min, which encodes the beta' subunit of RNA polymerase. sna-10 complemented the defect in tR1 termination caused by nusA11 and by itself stimulated termination of transcription at the lambda tR1 terminator. sna-10 is specific to the nusA11 allele and unable to suppress cold-sensitive growth of the nusA10 mutant. nusA10 carried two base substitutions at positions 311 and 634, causing two amino acid changes from the wild-type sequence. During these studies, we found three -1 frameshift errors in the wild-type nusA sequence; the correct sequence was confirmed by the peptide sequence and gene fusion analyses. The revised sequence revealed that nusA1 and nusA11 are located in an arginine-rich peptide region and substitute arginine and aspartate for leucine 183 and glycine 181, respectively. The intragenic suppressor study indicated that the nusA11 mutation can be suppressed by changing the mutated aspartate 181 to alanine or changing aspartate 84 to tyrosine.
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PMID:Genetic interaction between the beta' subunit of RNA polymerase and the arginine-rich domain of Escherichia coli nusA protein. 184 65


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