Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A preliminary analysis of an RNA-directed DNA polymerase was made and a C-type virus-like particle was identified in platelets from 2 patients with the myeloproliferative disorder thrombocythemia (primary, essential, hemorrhagic, or idiopathic thrombocythemia). Platelet homogenates were centrifuged through a sucrose equilibrium density gradient. Both endogenous and exogenous DNA polymerase activity was found at a density of 1.19 g/ml. No activity was seen at comparable densities in control gradients. Electron micrographs of thin sections of these platelets revealed a particle with the morphologic characteristics of a C-type virus; however, the diameter of this particle was about 80 nm, slightly lower than that commonly found for C-type particles. Critical-point dried specimens, from the fractions of the sucrose gradient at which DNA polymerase activity was found, contained particles of the same size and morphology as those in the thin sections.
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PMID:Analysis of platelets from patients with thrombocythemia for reverse transcriptase and virus-like particles. 5 32

Phosphonoacetate was an effective inhibitor of both the Marek's disease herpesvirus- and the herpesvirus of turkey-induced DNA polymerase. Using the herpesvirus of turkey-induced DNA polymerase, phosphonoacetate inhibition studies for the DNA polymerization reaction and for the deoxyribonucleoside triphosphate-pyrophosphate exchange reaction were carried out. The results demonstrated that phosphonoacetate inhibited the polymerase by interacting with it at the pyrophosphate binding site to create an alternate reaction pathway. A detailed mechanism and rate equation for the inhibition were developed. For comparison to phosphonoacetate, pyrophosphate inhibition patterns and apparent inhibition constants were determined. Twelve analogues of phosphonoacetate were tested as inhibitors of the herpesvirus of turkey-induced DNA polymerase. At the concentrations tested, only one, 2-phosphonopropionate, was an inhibitor. The apparent inhibition constant for it was about 50 times greater than the corresponding apparent inhibition constant for phosphonoacetate. DNA polymerase alpha of duck embryo fibroblasts, the host cell for the herpesviruses, was inhibited by phosphonoacetate. The apparent inhibition constants for the alpha polymerase were about 10-20 times greater than the corresponding inhibition constants for the herpesvirus-induced DNA polymerase. Duck DNA polymerase beta, Escherichia coli DNA polymerase I, and avian myeloblastosis virus reverse transcriptase were not inhibited by phosphonoacetate.
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PMID:Mechanism of phosphonoacetate inhibition of herpesvirus-induced DNA polymerase. 5 73

The alpha beta DNA polymerase of avian myeloblastosis virus was treated with dimethyl sulfoxide to dissociate the enzyme subunits. The dimethyl sulfoxide treated enzymes were passed over phosphocellulose to purify and characterize the dissociated subunits as well as to remove the dimethyl sulfoxide. RNA-directed DNA polymerase, RNase H, and nucleic acid-binding activity were monitored, as well as the subunit structure (on sodium dodecyl sulfate-polyacrylamide gels) of the various enzyme species obtained. With 30% dimethyl sulfoxide, the majority of DNA polymerase and RNase H activities as well as the alpha subunit were displaced from the alpha beta DNA polymerase position on phosphocellulose (0.23 M potassium phosphate) to the alpha DNA polymerase position (0.1 M). The association of DNA polymerase and RNase H activities with the alpha subunit suggests that alpha is the enzymatically active subunit in alpha beta. In addition to alpha DNA polymerase, a minor polymerase species eluted from phosphocellulose at 0.4 M potassium phosphate. The dissociated beta subunit eluted from phosphocellulose at a wide range of salt concentrations (0.28 to 0.5 M potassium phosphate). The dissociated beta subunit bound 3H-labeled murine leukemia virus RNA and [3H]poly(dT)-poly(dA) approximately 20-fold more avidly than alpha DNA polymerase alone. In contrast to the results with the alpha subunit, there was no correlation between DNA polymerase and RNase H activity profiles and the elution profile of the beta subunit from phosphocellulose. These observations suggest the beta subunit is either enzymatically inactive or possesses limited DNA polymerase and RNase H activity when compared with the alpha subunit.
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PMID:Dissociation of alpha beta DNA polymerase of avian myeloblastosis virus by dimethyl sulfoxide. 5 61

The RNA-directed DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase EC 2.7.7.7) of avian oncornavirus requires a tryptophan tRNA (tRNATrp) primer molecule located close to the 5' end of the viral RNA genome for the initiation of DNA synthesis in vitro. In this communication we demonstrate that the DNA product, transcribed from avian myeloblastosis virus (AMV) 35S RNA containing only tRNATrp as primer, is located also at the 5' end of the RNA genome. More importantly, we demonstrate that these 5' terminal DNA transcripts contain nucleotide sequences complementary to the 3' end of the genome. We have interpreted these results to mean that the genome. We have interpreted these results to mean that the 3' and 5' termini of the AMV 35S RNA genome become juxtaposed with each other either before or immediately after DNA synthesis has begun. These results are discussed in regard to the mechanism for synthesis of the circular forms of oncornavirus proviral DNA.
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PMID:Evidence for circularization of the avian oncornavirus RNA genome during proviral DNA synthesis from studies of reverse transcription in vitro. 5 20

Cocultivation of cells derived from embryos of golden pheasants or Amherst pheasants with chicken embryo cells infected with Bryan strain of Rous sarcoma virus resulted in the detection of viruses which appear to be endogenous in these pheasant cells. The pheasant viruses (PV) were similar to avian leukosis-sarcoma viruses (ALSV) in their gross morphology, in the size of their RNA, in the presence of a virion-associated RNA-dependent DNA polymerase (DNA nucleotidyltransferase; deoxynucleoside triphosphate: DNA deoxynucleotidyltransferase; EC 2.7.7.7), and in their growth characteristics. PV also serves as a helper for the glycoprotein-defective Rous sarcoma virus. However, PV was shown to be different from both ALSV and reticuloendotheliosis virus in the following properties: (i) PV does not have ALSV group specific antigens; (ii) the protein composition of PV is different from those of the other two groups of viruses; (iii) PV fails to complement the defective polymerase of alpha type Rous sarcoma virus; and (iv) PV RNA shows no detectable homology with nucleic acids of the other two groups of viruses. Thus, PV appears to be a new class of RNA viruses which contain RNA-dependent DNA polymerase.
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PMID:Pheasant virus: new class of ribodeoxyvirus. 5 21

Measurement of DNA polymerase in leukaemic guinea-pig plasms reveals the presence of low levels of sedimentable and non-sedimentable enzymic activities. Since the sedimentable DNA polymerase is ribonuclease sensitive, uses poly(C).oligo(dG) as template, and bands in a sucrose density gradient at 1-17 g/ml it is thought to be the GPLV-associated reverse transcriptase. The soluble DNA polymerase is stimulated by ribonuclease and is probably of cellular origin.
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PMID:DNA polymerase activity in plasma from leukaemic guinea-pigs. 5 90

The induction of erythroid differentiation in the T3-C12 clone of Friend leukemia cells by dimethyl sulfoxide is accompanied by reduction in viral RNA-dependent DNA polymerase activity with increased cellular delta-aminolevulinic acid synthetase activity and hemoglobin synthesis. These cells were treated with a variety of compounds to determine whether other durgs are capable on inducing erythroid differentiation. While several hormones, inhibitors of RNA synthesis, organic solvents, inhibitors of DNA polymerase, sulfhydryl inhibitors, and inducers of delta-aminolevulinic acid synthetase administered singly did not stimulate hemoglobin synthesis like dimethyl sulfoxide, inhibitors of DNA and RNA synthesis such as adriamycin, mitomycin C, and hydroxyurea:mithramycin were synergistic in stimulating erythroid differentiation.
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PMID:Erythroid differentiation in cultured Friend leukemia cells treated with metabolic inhibitors. 5 26

A line of hamster cells transformed by SV40 (TSV5 clone 2) contains different DNA polymerase activities. One of them has the same template specificity as viral reverse transcriptases. Partial isolation of R-type virus-like particles from TSV5 clone 2 shows that a reverse transcriptase activity is associated with these RNA viruses. This reverse transcriptase was partially purified and its biochemical properties are described.
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PMID:Reverse transciptase activity associated with R-type virus-like particles of SV40-transformed hamster cells (TSV5 clone 2). 5 43

We have compared the relative merits of several procedures for the isolation of RNA-directed DNA polymerase (EC 2.7.7.7.) from cells using a reconsituted model system consisting of a mixture of woolly monkey (simian) sarcoma virus and a cultured human lymphoblastoid cell line, NC-37. When the cell-virus mixture was gently disrupted and fractionated by differential centrifugation, most of the added polymerase was recovered associated with a particulate fraction obtained from the post-mitochondrial supernatant. Purification of the polymerase was best achieved starting from this fraction. The particulate fraction itself can be purified by gel filtration through a Sepharose 2 B column. This procedure did not significantly alter the composition of viral and cellular DNA polymerases. Whereas as little as 7.5 - 10(5) viral particles were sufficient for the detection of RNA-directed DNA polymerase activity, a minimum of about 10(11) particles were necessary for the isolation and unequivocal characterization of the enzyme from the cell-virus mixture by subcellular fractionation and chromatographic separation from cellular DNA polymerases. Purified RNA-directed DNA polymerase had the same primer-template characteristics, sedimentation properties, and immunological cross reactivity as the enzyme purified from density gradient-banded virions of simian sarcoma virus. Methods involving total extraction of the cell-virus mixture either by repeated freezing and thawing followed by detergent treatment or by Dounce homogenization and treatment with high salt and detergent failed to provide RNA-directed DNA polymerase free of cellular DNA polymerases. Because of this, low levels of cellular RNA-directed DNA polymerase may be missed when these approaches are used.
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PMID:A comparative evaluation of methods for isolation of RNA-directed DNA polymerase from cells in a reconstituted system. 5 69

The alkoxybenzophenanthridine alkaloids (coralyne acetosulfate, fagaronine chloride, and nitidine chloride) have been reported to possess antileukemic activity in mice. These compounds were tested for inhibition of reverse transcriptase activity of an RNA tumor virus and DNA polymerase, RNA polymerase, and polyadenylic acid polymerase activities of NIH-Swiss mouse embryos. Reverse transcriptase and DNA polymerase activities were strongly inhibited by these antileukemic alkaloids, whereas RNA polymerase and polyadenylic acid polymerase activities were only moderately affected. Viral and cellular DNA polymerase activities were potently diminished by the alkaloids when poly[d(A-T)], poly(dA)-oligo(dT), and poly(rA)-oligo(dT) template primers were used in the reaction mixture; however, no inhibition of enzyme activity was obtained with poly(rC)-oligo(dG) as template primer. These results suggest that alkoxybenzophenanthridine alkaloids inhibit DNA polymerase activity by interaction with A:T base pairs of the template primer.
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PMID:Inhibition of mammalian and oncornavirus nucleic acid polymerase activities by alkoxybenzophenanthridine alkaloids. 5 19


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