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)

Wheat germ RNA polymerase II is able to transcribe polynucleotide templates in the poly-[d(G-C)] family, adopting either the right-handed B or left-handed Z conformations depending on the ionic environment and temperature. Thus, with poly[d(G-C)] either the B state (in MgCl2) or the associated Z* state (in MnCl2) can be established. Poly[d(G-m5C)] adopts the Z form readily in MgCl2, and poly-[d(G-br5C)] can be regarded as being "constitutively" in the Z state. In transcription studies with CpG as a primer and templates in the left-handed conformation, it is found that the rate of productive elongation, i.e., the synthesis of poly[r(G-C)], is depressed, in accordance with the results of previous studies. However, with a single triphosphate substrate, CTP, the rate of formation of the first phosphodiester bond, i.e., the synthesis of CpGpC, is about 4-fold greater with both the Z and Z* templates than with B-DNA. This transcriptional activity is also catalytic in the sense that product concentrations exceed that of the enzyme. The synthesis of CpGpC is reduced in the presence of GTP. However, the apparent Km value for GTP utilization is lower for the trinucleotide synthesis (0.1 microM) than that obtained for productive elongation (0.8 microM), a result that also holds for B-DNA templates. All transcription reactions are specifically inhibited by the fungal toxin alpha-amanitin, and, in the case of the left-handed templates, by monoclonal anti-Z-DNA antibodies. The relative probabilities of single-step addition and productive elongation imply that the major distinction between transcription of templates in the B and Z conformations involves a step following the synthesis of the first phosphodiester bond. As a result, fully competent elongation complexes do not form on the left-handed DNA.
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PMID:Transcription of left-handed Z-DNA templates: increased rate of single-step addition reactions catalyzed by wheat germ RNA polymerase II. 321 41

DNA primase (EC 2.7.7.6) produces an RNA oligomer of approximately 10 bases, which is required by DNA polymerase alpha (EC 2.7.7.7) for the initiation of DNA synthesis. We partially purified DNA primase from acute lymphocytic leukemia cells from patients using several chromatography columns. Poly(dT) and poly(dC), but not poly(dA) or poly(dG), were good templates for ribonucleoside triphosphate (rNTP)-dependent DNA synthesis (i.e., DNA primase activity), and they were used in the study of the effect of natural and arabinofuranosyl nucleoside triphosphates on DNA primase activity. The Km for GTP in the poly(dC) primase assay was approximately 175 microM. All noncomplementary natural rNTPs and deoxyribonucleoside triphosphates (dNTPs) inhibited poly(dC) primase activity to a similar extent (Ki values of ATP and CTP were 610 and 517 microM, respectively). 1-beta-D-Arabinofuranosylcytosine 5'-triphosphate (araCTP) and 9-beta-D-arabinofuranosyladenine 5'-triphosphate (araATP) were more potent inhibitors of poly(dC) primase activity than were CTP and ATP (Ki values were approximately 125 microM). araCTP, araATP, CTP, and ATP inhibited DNA primase activity in a manner competitive with GTP. The concentration required to inhibit poly(dC) DNA primase activity by 50% was determined for a number of arabinofuranosyl nucleoside triphosphate analogs, and the relative potency of inhibition of DNA primase activity was as follows: rNTP = dNTP = 5-aza-dCTP less than ara-5-azaCTP = araTTP = araATP = araCTP less than 2-fluoro-araATP = 2'-azido-2'-deoxy araCTP less than 2'-fluoro-araTTP = 2'-fluoro-5-iodo-araCTP = 2'-fluoro-5-methyl-araCTP. In the poly(dT) primase assay ATP did not follow classic Michaelis-Menten kinetics (ATP exhibited positive cooperativity with a Hill coefficient of 2.0). However, this assay was very sensitive to araCTP (apparent Ki of 25 microM). In summary, these experiments suggested that DNA primase is controlled by the levels of ribonucleoside triphosphates, and that the perturbation of these pools by any agent could lead to the inhibition of DNA primase and thereby inhibit DNA synthesis. Furthermore, aranucleoside triphosphate analogs directly inhibited DNA primase, and it is possible that this effect may contribute to the cytotoxicity of these compounds.
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PMID:Inhibition of DNA primase by nucleoside triphosphates and their arabinofuranosyl analogs. 380 92

Poly(A) polymerase activity is induced during vaccinia virus infection of HeLa cells. The enzyme is maximally induced at 3.5 h postinfection. Partial purification frees the preparation of RNase activity and RNA polymerase activity. ATP is the substrate for poly(A) synthesis. A small amount of poly(A) is produced from added adenosine diphosphate due to the production of ATP by an adenylate kinase present in the preparation. The incorporation of ATP into poly(A) is dependent on divalent cations (Mg(2+) or Mn(2+)) and is not inhibited by UTP, CTP, or GTP. Poly(U) stimulates ATP incorporation; poly(A) and poly(C) have little effect on ATP incorporation, and poly(dT) is extremely inhibitory. RNA prepared from HeLa cells and from the partially purified poly(A) polymerase (the enzyme preparation contains endogenous RNA [Brakel and Kates]) stimulates ATP incorporation by poly(A) polymerase which was subjected to DEAE-cellulose chromatography. RNase's, pancreatic and T(1), inhibit the production of poly(A). DNase has little effect. Poly(U) is able to stimulate poly(A) production in the presence of T(1) RNase.
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PMID:Poly(A) polymerase from vaccinia virus-infected cells. I. Partial purification and characterization. 441 6

1. Various types of nuclear preparations, with different ratios of neuronal to glial nuclei, were isolated from guinea-pig cerebral grey matter and ox cerebral grey matter and white matter. Conditions appropriate for the separate assay of RNA and poly A formation were described. Comparative rates of RNA and poly A formation were studied in cerebral and liver nuclei. 2. RNA polymerase activity per nucleus is higher in neuronal nuclei than in glial nuclei. In liver nuclei, the activity is much lower than in cerebral nuclei. The physical relationship between RNA polymerase and deoxyribonucleoprotein seems to differ in neuronal, glial and liver nuclei. 3. Poly A polymerase activity in liver nuclei is selectively activated by Mn(2+) and inhibited by GTP, CTP and UTP. On a DNA basis, the activity in an aggregate enzyme is the same as in intact nuclei. Poly A polymerase activity per nucleus is much higher in liver nuclei than in neuronal nuclei. Glial nuclei show an intermediate activity. 4. It is suggested that, in neuronal nuclei, the synthesis of RNA is more prominent than that of poly A under conditions where both polymers are formed simultaneously. This contrasts with liver nuclei, where more poly A is made than RNA. 5. In neuronal nuclei, the rate of CTP incorporation is much higher than in glial and liver nuclei. This incorporation is most probably due to poly C synthesis.
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PMID:Studies on ribonucleic acid and homopolyribonucleotide formation in neuronal, glial and liver nuclei. 543 90

Poly(C) and heparin at low concentrations (1 microgram/ml) prevent the RNA synthesis termination protein rho from functioning during the biosynthesis of RNA from bacteriophage T7 DNA catalyzed by Escherichia coli RNA polymerase. Both of these polyanions inhibit the binding of rho to isolated T7 RNA. Heparin also inhibits rho ATPase when isolated RNA transcripts are used as cofactors. It is concluded that the polyanions inhibit termination by binding to the site on rho that is normally used for the initial interaction with a nascent RNA transcript in the rho-mediated release of RNA. Since one of the inhibitors, poly(C), is itself a potent activator for rho ATPase, it is also concluded that the ATP hydrolysis step that is required for rho termination has to be coupled to an action of rho on the RNA molecule to be released from the transcription complex.
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PMID:Inhibition of the action of Escherichia coli transcription termination protein rho by poly(C) and heparin. 611 50

The major 5'-termini of human adenovirus type 2 early gene block 4 mRNA were sequenced. Poly(A+) polyribosomal RNA was isolated from Ad2 early infected cells, the 5'-terminal m7GPPP removed and the 5'-OH of the penultimate 2'-0-methylated nucleotide labeled with [gamma-32P]ATP using polynucleotide kinase. Ad2 E4 mRNA was purified by hybridization to the Ad2 EcoRI-C fragment and was digested with RNase T1. The resulting oligonucleotides were resolved by two dimensional paper electrophoresis-homochromatography. Four major and 3-4 minor 5'-terminal sequences were identified and characterized. The sequence of the 5'-terminal structures of the major four termini are: (1) m7GpppUmU(m)UUACACUGp, (2) m7GpppUmU(m)UACACUGp, (3) m7GpppUmU(m)ACACUGp, and (4) m7Gppp(m6)AmC(m)ACUGp. These major 5'-terminal sequences were aligned with nucleotide 325, 326, 327, and 329 from the righthand end of the known Ad2 DNA sequence (1) in the region mapped as the 5'-terminus of E4 mRNA by electron microscopy (2,3) and S1 nuclease-gel (4) mapping. Two potential ribosomal binding sites and an initiator codon were found at 40 to 65 nucleotides and about 80 nucleotides, respectively, from these heterogenous 5'-termini. Ad2 E4 major mRNA species appear to be unique since mRNA molecules initiate at a pyrimidine, perhaps by RNA polymerase stuttering, or they are products of an unusual type of RNA processing.
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PMID:Nucleotide sequences and mapping of novel heterogenous 5'-termini of adenovirus 2 early region 4 mRNA. 616 92

A subcellular system from mouse L-cells has been used to study RNA synthesis and processing in vitro. The nuclei in this system incorporate nucleoside triphosphates into RNA with high yield for more than 120 min. The capacity for RNA synthesis is stable for extended periods at 4 degrees C. All three RNA polymerases contribute to the overall synthetic activity as shown by differential inhibition with alpha-amanitin. The in vitro labeled RNA contains about 15% of polyadenylated RNA. The non-polyadenylated RNA shows molecules in the range of larger than 20 S down to 4-5 S. The polyadenylated RNA exhibits mainly transcripts around 18 S and below 8 S. Methylation of nucleoside bases and the ribose 2'-OH group including 5'-caps is performed in vitro as well. Base methylation and 5'-cap methylation are partially sensitive to alpha-amanitin. 28% of the methyl groups are found in polyadenylated RNA being distributed throughout molecules of all sizes. The methylated non-polyadenylated RNA shows peaks at 45 S, around 28 S and 18 S, and a very prominent low-molecular weight RNA peak. Addition of the poly(A) tract to RNA molecules in vitro is revealed by the presence of [3H]-uridine-labeled polyadenylated RNA. The poly(A) tract was isolated and analyzed on polyacrylamide gels. Its maximum length coincides with an in vivo poly(A) marker indicating the addition of about 150-200 nucleotides. Poly(A) addition is possible on pre-existing RNA chains, preferably on 3'-oligo(A) tracts. This process is insensitive to alpha-amanitin. In addition, the specificity of polyadenylation may be relaxed since incorporation of [3H]UTP into polyadenylated RNA is only reduced to about 50% under conditions (1 microgram alpha-amanitin/ml) where RNA polymerase II is inhibited. A small fraction of the in vitro labeled RNA binds to polysomes which can be recovered from the cytoplasm adhering to the nuclei. This RNA contains poly(A) and is enriched in base methylations and 5' end caps. It can be dissociated from the polysomes by EDTA. It is likely to be in vitro labeled and maturated mRNA.
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PMID:RNA synthesis and processing reactions in a subcellular system from mouse L cells. 617 4

8006-I is an antibacterial antibiotic with a rather broad spectrum of activity. The minimum inhibitory concentrations for the most sensitive bacteria are in the range of one to ten micrograms/ml. Yeasts are not affected by concentrations up to 100 micrograms/ml. Some filamentous fungi like Fusarium oxysporum and Mucor miehei are inhibited at 100 micrograms/ml. In Ehrlich carcinoma ascitic cells the incorporation of uridine and leucine and to a lesser extent that of thymidine is reduced. In isolated nuclei of these cells the incorporation of UTP into RNA is inhibited. At low concentrations, the incorporation of uracil into trichloroacetic acid-precipitable material is almost completely inhibited in cells of Bacillus subtilis; at higher concentrations all macromolecular syntheses are affected. No reduction of respiration of the cells is observed. The antibiotic exhibits weak hemolytic activity and lytic activity towards bacteria. In vitro an inhibition of both DNA- and RNA polymerase from Escherichia coli is observed. Poly(U)-directed poly(Phe) synthesis is not affected.
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PMID:8006-I, an antibiotic from Amblyosporium spongiosum (Pers.) Hughes sensu Pirozynski. II. Biological properties. 617 18

A goat immunized with poly(A).poly(dT) produced three distinct antibody populations. The major one was specific for RNA-DNA hybrids and was purified from precipitates made with poly(I).poly(dC). It also reacted with hybrids of mixed base composition made with E. coli RNA polymerase. The other populations were purified with poly(A).poly(U) or poly(dT). Three rabbits also produced mainly hybrid-specific antibody in response to poly(A) . poly(dT). A goat immunized with poly(I).poly(dC) formed antibodies reactive with poly(I) and others reactive with poly(dC) but none specific for hybrid structure. Three rabbits did not respond to poly(I).poly(dC). Measurements of reactions with anti-inosine sera, thermal denaturation and sensitivity to S1 nuclease indicated that poly(I).poly(dC) is a less stable helix than poly(A).poly(dT) or poly(I).poly(C). Poly(A).poly(dT) is the more suitable synthetic immunogen for the production of hybrid-specific antibodies.
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PMID:Comparison of poly(A).poly(dT) and poly(I).poly(dC) as immunogens for the induction of antibodies to RNA-DNA hybrids. 617 64

RNA polymerase I and II and poly(ADP-ribosyl) synthetase activities were determined in isolated nuclei prepared from mouse testes at 1, 3, and 8 weeks after birth. RNA polymerase II and poly(ADP-ribosyl) synthetase activities increased with progression of spermatogenesis and age while RNA polymerase I activity decreased. The observed inverse relationship of RNA polymerase I and II parallels the shift in species of RNA, produced during spermatogenesis. Poly(ADP-ribosyl) synthetase activity increased with age, reaching a peak at 8 weeks. These enzymatic activities in aged mouse testis nuclei were equivalent to that of 8-week-old mice. Germ cells from the adult testis were separated by unit gravity velocity sedimentation. The enriched fractions containing pachytene and round spermatids possessed RNA polymerase and poly(ADP-ribosyl) synthetase activities. The present results suggest that transcriptional events during spermatogenesis may be modulated by changes in the activities of variants of RNA polymerase.
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PMID:RNA synthesis and poly(adenosine diphosphoribosyl) synthetase activity in developing mouse testis. 618 Jun 89


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