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)

DNA polymerase from Micrococcus luteus and RNA polymerase from E. coli catalyze the synthesis of poly(dA) with poly(dT) template, in the presence of ATP and [alpha-32P]dATP. The reaction is completely dependent on poly(A) primer synthesis. Poly(A) chains are covalently extended by DNA polymerase. Primer poly(A) is linked to the product poly(dA) via a 3':5'-phosphodiester bond, and can be specifically removed by ribonuclease H from chick embryos, leaving a 5'-phosphate end of poly(dA). The length of RNA and DNA products appears to be relatively variable. The size of the DNA is less than 3 000 nucleotides.
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PMID:Ribonuclease H from chick embryos cleaves precisely at the junction between the RNA and DNA portion of the hybrid helix. 618 57

Terminal deoxynucleotidyl transferase (TdT) was used to prepare copolymers of dA and 1,N6-ethenodeoxyadenosine (epsilon dA). When used as templates for Escherichia coli DNA polymerase I (Pol I) and compared with poly (dA), normal dTTP incorporation was not significantly affected by the presence of 7% epsilon dA. dGTP misincorporation was only slightly increased and occurred about once for every 500 epsilon dA residues. The error-prone polymerase from avian myeloblastosis virus (AMV reverse transcriptase) increased this error rate 5- to 20-fold to a maximum of 1 dG/25 epsilon dA. No dCTP misincorporation was detected with either polymerase. In transcription with E. coli DNA-dependent RNA polymerase, no errors were revealed by nearest neighbor analysis. Poly (dA) treated with chloroacetaldehyde under conditions producing the same proportion of epsilon dA (without the hydrated form) as the synthesized template behaved in the same manner with a similar low level of misincorporation of dG. Such treatment of alternating poly d(A-T) caused structural changes indicative of crosslinks but did not alter its template properties. Increasing the amount of epsilon dA in either synthesized or modified polymers greatly decreased the template activity without increasing the error rate. It is suggested that epsilon dA generally does not prevent dT incorporation but behaves as a bulky lesion which is bypassed. In contrast to the low mutagenic efficiency of epsilon dA, O4-methyldeoxythymidine (m4dT), in copolymers with dA, directed the misincorporation of 1 dG/12 m4dT with Pol I and 1 dG/3 m4dT with reverse transcriptase. Nearest neighbor analysis of transcripts showed the incorporation of 1 dG/12 m4dT. These data are in agreement with the previous reported mutagenicity of m4dT in alternating poly d(A-T, m4T).
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PMID:Assessment of mutagenic efficiency of two carcinogen-modified nucleosides, 1,N6-ethenodeoxyadenosine and O4-methyldeoxythymidine, using polymerases of varying fidelity. 620 83

An endonuclease, which was originally identified for its RNA polymerase inhibitory activity, was isolated from rat liver endoplasmic reticulum. The enzyme yields on gel chromatography four active fractions of different molecular weights (Mr 5.3 X 10(4), 9 X 10(4), 1.55 X 10(5) and Sephacryl S-200 fraction at V0). Each fraction contains polypeptide chains which give a single band on sodium dodecylsulphate electrophoresis (Mr 5.4 X 10(4). This indicates that the enzyme is an oligomeric protein and each of its subunits exhibits the same or very similar molecular weights. Deoxyribonucleoside and ribonucleoside triphosphates can bind to the endoplasmic reticulum nuclease. Binding is enhanced in the presence of divalent cations particularly Mg2+. The enzyme exhibits mainly RNase activity but can also degrade denatured DNA and DNA . RNA hybrids which contain breaks in one of the two strands. Poly(A) and mainly poly(U) are most susceptible to its nucleolytic activity whereas poly(C) is completely resistant.
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PMID:Endoplasmic reticulum nuclease. Purification and specificity. 627 70

Administration of a single-stranded polynucleotide copolymer containing 9% cytidine residues and 91% 4-thiouridine residues [poly(C,S4U10)], a known potent inhibitor of the virion transcriptase of influenza viruses, suppressed the amount of virus recoverable from the nasal washes of influenza virus-infected hamsters and ferrets. The incidence of sneezing and nasal discharge in infected ferrets was also reduced. In hamsters, poly(C,S4U10) was more effective than amantadine-HCl or Virazole. Polyinosinic acid in combination with poly-5-hydroxy cytidylic acid also had anti-influenza effects. Poly(C,S4U10) annealed to polyadenylic acid was not effective, nor was the double-stranded polymer (polyinosinic acid) . (polycytidylic acid) even when complexed with carboxymethylcellulose and polylysine. No toxic effects of poly(C,S4U10) were apparent in the treated hamsters and ferrets, and high doses (greater than or equal to 2.86 g/kg) administered intraperitoneally to mice produced no adverse effects.
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PMID:Antiviral effects of single-stranded polynucleotide inhibitors of the influenza virion-associated transcriptase against influenza virus infection of hamsters and ferrets. 628 Jun 8

Poly(dC,3- MedC ) has been synthesised and used as a template to compare the miscoding properties of 3-methylcytosine (3-MeC) during DNA and RNA synthesis. Although 3-MeC was promutagenic with the RNA polymerase incorporating both AMP and UMP in the ratio of approximately 5:1 (agreeing with results reported by earlier workers) no non-complementary nucleotide incorporation was observed with DNA polymerase I. The results show that 3-MeC, which is a strong inhibitor of DNA synthesis, is only promutagenic with the less accurate RNA polymerase and that the reported differences in promutagenicity for this modified base with the two nucleotide polymerising enzymes arise from different specificities for the two enzymes.
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PMID:Differences in the promutagenic nature of 3-methylcytosine as revealed by DNA and RNA polymerising enzymes. 637 42

The mechanism of preferential transcription on poly[d(purine)] . poly[d(pyrimidine)] was investigated using RNA polymerase of T. thermophilus HB8. Though the machinery for initiation is lacking, the core enzyme has the latent ability to synthesize poly[r(pyrimidine)] as well as poly[r(purine)]. The holoenzyme can synthesize poly[r(purine)] in the usual manner. Poly[r(pyrimidine)] synthesis by the holoenzyme is, however, forbidden. These results suggest that the sigma factor plays a crucial role in this preferential transcription, and that this preferential transcription may be useful as a model for the sense strand recognition. Various results led us to the hypothesis that the high affinity site for the poly[d(pyrimidine)] strands on the enzyme plays a very important role.
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PMID:The mechanism of preferential synthesis of poly[r(purine)] in the transcription of poly[d(purine)] . poly[d(pyrimidine)] by T. thermophilus RNA polymerase. 694 7

RNA product distribution obtained during the transcription of poly[d(A-T)] by wheat germ RNA polymerase IIA under various experimental conditions was analyzed by high resolution polyacrylamide gel electrophoresis. Poly[r(A-U)] synthesis proceeded as if wheat germ RNA polymerase II was a non-processive enzyme: a ladder of RNA products of increasing lengths was obtained, which apparently, terminated at every other nucleotide. RNA release was not dependent upon nucleoside triphosphate substrate concentrations. A likely explanation would be that ternary complexes enzyme: DNA: RNA were very much unstable; moreover, oligonucleotides released were not re-used for further elongation by the enzyme.
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PMID:Non-processive transcription of poly[d(A-T)] by wheat germ RNA polymerase II. 716 Apr 87

The effects of caps, dinucleotides, oligonucleotides and polynucleotides on influenza virus RNA polymerase activity have been investigated. The results show that both methyl groups in a cap are necessary for optimal stimulation of polymerase activity. Both m7G(5')ppp(5')Am and ApG stimulated the influenza RNA polymerase activity and seemed to interact at different sites. Out of the 16 homopolynucleotides tested, seven inhibited influenza RNA polymerase by 50% at 2-10 micrograms/ml. Poly(G) gave a 90% reduction of influenza virus plaque formation at 10 micrograms/ml. An oligodeoxyribonucleotide complementary to the 12 terminal nucleotides of the 3' end of influenza virus RNA was synthesized. This oligonucleotide did not selectively inhibit influenza RNA polymerase.
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PMID:Functional analysis of influenza RNA polymerase activity by the use of caps, oligonucleotides and polynucleotides. 733 30

We have studied the distribution of poly(A)+ RNA in the mammalian cell nucleus and its transport through nuclear pores by fluorescence and electron microscopic in situ hybridization. Poly(A)+ RNA was detected in the nucleus as a speckled pattern which includes interchromatin granule clusters and perichromatin fibrils. When cells are fractionated by detergent and salt extraction as well as DNase I digestion, the majority of the nuclear poly(A)+ RNA was found to remain associated with the nonchromatin RNP-enriched fraction of the nucleus. After inhibition of RNA polymerase II transcription for 5-10 h, a stable population of poly(A)+ RNA remained in the nucleus and was reorganized into fewer and larger interchromatin granule clusters along with pre-mRNA splicing factors. This stable population of nuclear RNA may play an important role in nuclear function. Furthermore, we have observed that, in actively transcribing cells, the regions of poly(A)+ RNA which reached the nuclear pore complexes appeared as narrow concentrations of RNA suggesting a limited or directed pathway of movement. All of the observed nuclear pores contained poly(A)+ RNA staining suggesting that they are all capable of exporting RNA. In addition, we have directly visualized, for the first time in mammalian cells, the transport of poly(A)+ RNA through the nuclear pore complexes.
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PMID:In vivo analysis of the stability and transport of nuclear poly(A)+ RNA. 751 22

We examined age- and diet-related alterations in RNA poly(A) tail length using high-resolution gel electrophoresis followed by Northern hybridization. The results demonstrate conclusively that there is no age-related decrease in the size of the Poly(A) tail of RNA isolated from the male Fischer 344 rat. In contrast, our results suggest that there is actually a slight age-related increase in the length of the poly(A) tail isolated from the liver and hypothalamus of these rats. Dietary restriction did not affect either poly(A) tail length or its age-related increase. These data demonstrate conclusively that oligo(dT) probes can be used to standardize RNA hybridization experiments between animals of different ages and dietary groups. In addition, these data provide further evidence that the ratio between RNA polymerase I and RNA polymerase II activity does not change with age.
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PMID:Is poly(A) tail length altered by aging or dietary restriction? 769 90


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