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)

Rat-liver nucleoli (10-15 micrograms DNA) were digested with either 0.6 or 3 units of DNase I for various times (up to 1 h). RNA synthesis was then measured in the absence or presence of 3 units of Escherichia coli RNA polymerase. It was found that the nucleolar chromatin supporting the endogenous engaged RNA polymerase I transcription was completely destroyed in 3 min with either concentration of DNase I. The nucleolar chromatin template transcribed by E. coli RNA polymerase retained 50% of its original capacity even 60 min after 3 units of DNase I digestion. When hybridization experiments were conducted, it was found that the DNAs derived from both levels of DNase-I-digested nucleoli were incapable of forming hybrids with the labelled nucleolar RNA synthesized by the engaged RNA polymerase I from the untreated nucleoli. Since the engaged RNA polymerase I transcribes only the physiologically active genes of the nucleolar chromatin, and the RNA transcripts represent active gene product, these data suggest that DNase I digestion has completely destroyed the active genes of the nucleolar chromatin, and E. coli RNA polymerase is able to transcribe the inactive nucleolar chromatin template.
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PMID:Evidence for the transcription os physiologically inactive rat-liver nucleolar chromatin by Escherichia coli RNA polymerase. 617 57

An in vitro culture system for the proliferation of IgG-forming plasma cells from mouse bone marrow cultures has previously been described. The present study attempts to elucidate the mode of action of thymic RNA in these cultures. Autoradiography after using radiolabeled thymic RNA showed that radioactive material was mainly incorporated into the nuclei of IgG-forming plasma cells. No radiolabeled thymic RNA was incorporated into the cells except immunoblasts. The incorporated thymic RNA was acid insoluble and digested by RNase, but resistant to DNase and pronase. Radioactivity in the nucleotide pool after the cells were cultured with radiolabeled thymic RNA was negligible, indicating that reutilization of degraded RNA did not occur in the nuclei of the plasma cells. Moreover, the incorporation of radiolabeled thymic RNA by the cells was not prevented by excess unlabeled nucleosides. Escherichia coli transfer RNA, L-cell RNA and synthetic polynucleotide poly(A-U) were incorporated but were distributed in a different manner in the cells. A derivative of rifampicin, 2'5'-dimethyl N(4') benzyl-N(4')[desmethyl]rifampicin (AF/ABDMP), a possible inhibitor of RNA-dependent DNA polymerases, suppressed both the incorporation of thymic RNA and the differentiation of immunoblasts. AF/ABDMP suppressed DNA synthesis by bone marrow cultures to the same level as those pretreated with anti-mouse B-cell antibodies and complement. DNA dependent RNA polymerase activity was observed in the supernatant of bone marrow cultures stimulated by normal syngeneic thymic RNA and human gammaglobulin as antigen. These results imply a possible relationship between B-cell differentiation and RNA-dependent DNA polymerases.
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PMID:Intranuclear incorporation of thymic low molecular weight RNA by murine bone marrow immunoblasts and inhibition of plasma cell formation by a derivative of rifampicin. 617 4

A Saccharomyces cerevisiae protein fraction which binds specifically to the internal promoter regions of genes that are transcribed by RNA polymerase III is shown to function as a transcription factor. We postulate that the stable DNA binding of the factor confers stability on polymerase III transcription complexes. Analysis of the binding by DNase 'foot-printing' distinguishes three segments of the S. cerevisiae tRNALeu3 gene: a region surrounding the so-called A block of the internal promoter, a region surrounding the B block and an intermediate segment. Binding to the A and B block regions is connected, but the B block region exerts a dominant effect.
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PMID:Differential binding of a S. cerevisiae RNA polymerase III transcription factor to two promoter segments of a tRNA gene. 623 42

The sequence of almost 700 nucleotides encompassing the gene for ribosomal protein S20 of Escherichia coli has been determined using the chemical technique of Maxam and Gilbert (Maxam, A. M., and Gilbert, W. (1977) Proc. Natl. Acad. Sci. U. S. A. 74, 560-564). Comparison of this sequence with that of known bacterial promoters reveals two promoter-like sequences whose putative initiation sites for transcription lie 132 ("site 1") and 42 ("site 2") base pairs to the 5' side of the coding sequence. Partial digestion experiments demonstrate that RNA polymerase is capable of binding to and protecting both of these sites from DNase 1 digestion, consistent with their functioning as promoters. Interestingly, site 1 is more compact that any previously described bacterial promoter. A second feature of the sequence is the presence of UUG as the translational initiation codon. Finally, the nucleotide sequence supports the hypothesis (Jue, R. A., Woodbury, N. W., and Doolittle, R. F. (1980) J. Mol. Evol. 15, 129-148) that S20 is composed of three tandemly repeated domains.
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PMID:Nucleotide sequence of the gene for ribosomal protein S20 and its flanking regions. 626 39

The single-stranded DNA of bacteriophage M13 is converted to a duplex replicative form by a mechanism involving RNA-primed initiation at a single unique site on the viral DNA. The DNA sequence that specifies the RNA primer is contained largely within one of two adjacent hairpin structures protected from DNase degradation by RNA polymerase. We have used in vitro techniques to construct a series of M13 mutants having deletions in the region of the complementary strand origin. Deletions of the duplex replicative form DNA range in size from 54 to 201 base pairs. The largest deletions remove both of the RNA polymerase-protected hairpins and the entire sequence specifying the primer RNA. Mutants lacking one or both hairpins form faint plaques, give reduced phage yields, and show a lag in phage production of >30 min. The rate of conversion of the single-stranded viral DNA to the parental replicative form is reduced both in vivo and in vitro. These results indicate that both the RNA polymerase-protected hairpins and the RNA primer-coding sequence are important, but not essential, for replication. Other sequences within the origin region, or possibly elsewhere in the genome, may play a role in complementary strand initiation in these mutant phages. The M13 viral strand is initiated by extension of the 3' terminus generated by site-specific nicking of the viral strand of the replicative form DNA by the M13 gene II protein. This specific nicking site is retained in all of the M13 deletion mutants. Deletion end points do not extend into a 13-nucleotide sequence preceding the viral strand nicking site. We propose that a sequence including these 13 nucleotides is required for gene II protein action at this site.
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PMID:Viable deletions of the M13 complementary strand origin. 627 88

Using DNase footprinting and transcription assays in vitro we have probed the effect of the cAMP-cAMP receptor protein complex (cAMP-CRP) on the positioning of RNA polymerase and on the location of the transcription start point at the Escherichia coli gal and lac operon regulatory regions. In both cases, RNA polymerase can form two alternative complexes which promote transcription from two different start points, S1 and S2: pre-incubation of promoter DNA with cAMP-CRP results in a shift of the transcription start from S2 to S1 and in an increase in the rate of open complex formation. Moreover, the rate of formation of each heparin-resistant complex parallels the establishment of the corresponding footprint, showing that the stable binding corresponds to open complex formation. We show that, in the case of gal, RNA polymerase, which is bound so as to transcribe from S2, cannot be diverted to S1 by subsequent addition of cAMP-CRP. In contrast, in the case of lac, when cAMP-CRP is added after RNA polymerase, complexes which initiate transcription at S2 are rapidly converted to complexes which initiate at S1. Finally, we present data which suggest that protein-protein interactions are essential for CRP-induced activation at both the lac and gal promoters.
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PMID:On the action of the cyclic AMP-cyclic AMP receptor protein complex at the Escherichia coli lactose and galactose promoter regions. 632 69

When isolated HeLa cell nuclei were preincubated under transcription conditions with excess E. coli RNA polymerase, chromatin DNA became relatively resistant to digestion by micrococcal nuclease. Quantitation of the DNA content in nuclei after enzyme digestion revealed that approximately twice as much nuclease was required to give the same levels of release of DNA fragments from transcribed as from untranscribed nuclei. Resistance increased with the amount of polymerase and with the time of preincubation. Since the resistance to nuclease was not observed in the presence of rifampicin or by preincubation without UTP, both RNA chain initiation and elongation were considered to be essential for the manifestation of resistance. However, when DNase 1 was used as a probe, such a change in chromatin DNA was not detected.
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PMID:Transcription renders chromatin resistant to micrococcal nuclease digestion. 635 97

RNA polymerase binds very tightly at a site called Brex in the lambda immunity region, to the left of the rex gene and about 600 nucleotides to the right of PL. The complex formed is resistant to 1 M NaCl in the absence of nucleotide triphosphate. While in vitro little or no transcription is observed from Brex, in vivo, when inserted in a plasmid vector which allows detection of its activity, it acts as an efficient promoter. We have mapped the site protected by RNA polymerase against DNase and determined its sequence which is abnormal compared that of an average promoter.
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PMID:An unusual RNA polymerase binding site in the immunity region of phage lambda. 645 Aug 73

The transcription of the beta-globin genes in mouse erythroleukemia cells has been examined by hybridizing labeled RNA obtained from isolated nuclei after chain elongation in the presence of [alpha-32P]UTP. There is induction of at least 30-fold of beta maj globin transcription after cells are treated with either dimethylsulfoxide or hexamethylene bisacetamide. The induction requires 36 to 48 hours to be maximal, during which time the cells double about three to four times. During this time, a site in the beta maj DNA region becomes hypersensitive to DNase. The development of this hypersensitive site is co-ordinate with the transcriptional increase. The induced transcripts in the beta-globin region are alpha-amanitin-sensitive (and therefore are RNA polymerase II products). An examination of weak transcriptional signals to DNA fragments upstream of the beta maj globin gene in uninduced mouse erythroleukemia cells and in cells that do not make globin is also reported. The low level of hybridization to the upstream regions in uninduced erythroleukemia cells, in L cells (a fibroblast) and in a strain of erythroleukemia cells that no longer make globin are not equally sensitive to alpha-amanitin as in the induced signal. These experiments help define the inducible transcription unit for beta maj globin mRNA production.
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PMID:Induced transcription of the mouse beta-globin transcription unit in erythroleukemia cells. Time-course of induction and of changes in chromatin structure. 658 80

The "killer" plasmid and a larger double-stranded RNA plasmid of yeast exist in intracellular virion particles. Purification of these particles from a diploid killer strain of yeast (grown into stationary growth on ethanol) resulted in co-purification of a DNA-independent RNA polymerase activity. This activity incorporates and requires all four ribonucleoside triphosphates and will not act on deoxyribonucleoside triphosphates. The reaction requires magnesium, is inhibited by sulfhydryl-oxidizing reagents and high concentrations of monovalent cation, but is insensitive to DNase, alpha-amanitin, and actinomycin D. Pyrophosphate inhibits the reaction as does ethidium bromide. Exogenous nucleic acids have no effect on the reaction. The product is mostly single-stranded RNA, some of which is released from the enzymatically active virions.
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PMID:Virion DNA-independent RNA polymerase from Saccharomyces cerevisiae. 700 33


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