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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Equine infectious anemia (EIAV) is shown to have an associated RNA-instructed DNA polymerase similar in its cofactor requirements and reaction conditions to the RNA tumor virus DNA polymerases. Demonstrating this DNA polymerase activity requires a critical concentration of a nonionic detergent, all four deoxyribonucleoside triphosphates, and a divalent metal ion. The reaction is sensitive to RNase, and a substantial fraction of the FNA synthesized is complementary to viral RNA. The detection of a complex of tritium-labeled polymerase product DNA-template RNA, which sedimented at 60S to 70S, provided evidence that EIAV contains high-molecular-weight RNA. These results, obtained with both virus propagated in cell culture and virus from the serum of an experimentally infected horse, indicate that EIAV may properly be considered a member of the family Retroviridae. They may also be pertinent to the mechanism(s) of viral persistence and periodic recrudescence of disease in chronically infected horses.
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PMID:RNA-dependent DNA polymerase associated with equine infectious anemia virus. 6 19

An RNA-directed DNA polymerase was found to be associated with intracytoplasmic A-particles from DBA/2 mouse leukemia cells. The enzyme activity was detected after disrupting the purified particles with 2 M NaCl-20 mM dithiothreitol. The presence of a divalent cation and all four deoxyribonucleoside triphosphates was essential for this enzyme activity. The enzyme had a clear preference for Mg2+ over Mn2+. Cesium sulfate isopycnic gradient centrifugation of the DNA product synthesized in the actinomycin D-containing reaction revealed the presence of DNA-RNA hybrid. Furthermore, the purified DNA product was found to hybridize with RNA isolated from A-particles. These observations strongly indicate that the endogenous A-particle RNA serves as the template for the DNA polymerase.
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PMID:Characterization of an RNA-directed DNA polymerase found in association with murine intracytoplasmic A-particles. 6 24

Radioimmunological techniques were applied to the analysis of reverse transcriptase of mammalian type C RNA viruses. The polymerase of Rauscher mouse leukemia virus was purified by ion exchange and sequential affinity chromatography. Radioimmunoassays that utilized the viral enzyme as a probe detected as little as 1 ng of purified polymerase. No cross-reactivity could be demonstrated between the reverse transcriptase and other known virus-coded proteins. By comparing the immunological reactivity of the purified enzyme with the reactivity of detergent-disrupted virions, Rauscher mouse leukemia virus was shown to contain the antigenic equivalent of 40 molecules of reverse transcriptase. In a homologous competition immunoassay, the Rauscher viral enzyme demonstrated type-specific antigenic determinants, which distinguish it from other mouse type C viral polymerases. In a broadly reactive interspecies immunoassay, the reverse transcriptases of a number of mammalian type C viruses were cross-reactive, indicating their shared antigenic determinants. Various treatments that inhibit or inactivated DNA polymerase activity had little or no effect on the immunological properties of the enzyme. Thus, radioimmunoassays should be useful in the search for type C viral reverse transcriptase as a marker of subviral expression.
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PMID:Radioimmunoassay for mammalian type C viral reverse transcriptase. 6 26

We have previously reported [(Ohno, T., Sweet, R.W., Hu, R., DeJak, D. & Spiegelman, S. (1977) Proc. Natl. Acad. Sci. USA 74, 764-768)] on the purification and characterization of the DNA polymerase from human breast cancer particles. Its preference for certain synthetic templates and its ability to use a viral RNA to fashion a faithful DNA transcript identify it as a reverse transcriptase similar to that found in the mouse mammary tumor virus and in the Mason-Pfizer monkey virus (MPMV). We report here that the human breast cancer enzyme crossreacts immunologically with the reverse transcriptase of MPMV. The crossreactivity was shown both by inhibition of enzyme activity and by complex formation between purified enzyme and isolated IgG against MPMV polymerase. No such interactions were observed with other oncornavirus reverse transcriptases of avian, murine, feline, or simian origin. Further, the IgG failed to neutralize the reverse transcriptases from human mesenchymal neoplasias (leukemias and lymphomas) or the activities of normal cellular DNA polymerases (alpha, beta, gamma).
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PMID:Antigenic relatedness of the DNA polymerase of human breast cancer particles to the enzyme of the Mason-Pfizer monkey virus. 6 75

Northern poke lymphosarcoma DNA polymerase was partially purified from particulate fractions banding at 1.15 to 1.16 g/ml from homogenates prepared from frozen necropsies of tumor-bearing pike. The enzyme behaves as a typical reverse transcriptase, in that it prefers ribotemplates to deoxytemplates. The isoelectric point (pl 5.5) is similar to that of avian myeloblastosis virus polymerase. The pike enzyme elutes from a phosphocellulose column at 0.22 M potassium phosphate, the same as avian myeloblastosis virus DNA polymerase. The enzyme activity is inhibited by pyran, a specific inhibitor of viral DNA polymerases. The most striking difference between the pike lymphoma polymerase and the other viral DNA polymerases tested is the low maximum temperature of 20 degrees, compared to 30 degrees for Rauscher leukemia virus polymerase and 38 degrees for avian myeloblastosis virus and Rous sarcoma virus.
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PMID:Presence of DNA polymerase in lymphosarcoma in northern pike (Esox lucius). 6 92

The initiation of DNA synthesis in vitro by RNA-directed DNA polymerase (deoxynucleosidetriphosphate: DNA deoxynucleotidyltransferase, EC 2.7.7.7) of avian oncornaviruses requires a tRNAtrp primer molecule located close to the 5' end of the viral RNA genome. DNA transcripts, 100 nucleotides in length, initiated on the tRNAtrp primer molecule contain nucleotide sequences complementary to a large (25 nucleotides) RNase T1 oligonucleotide, T-13, located at the 5' terminus of the avian sarcoma virus RNA genome. tRNAtrp-initiated DNA transcripts with a length of about 70 nucleotides contain substantially fewer nucleotide sequences complementary to this 5'-terminal oligonucleotide, suggesting that the tRNAtrp primer associated with the avian sarcoma virus RNA is located approximately 100 nucleotides from the 5' end of the RNA. In addition, we present evidence to demonstrate that DNA transcribed from avian sarcoma virus RNA sequences located at the 3' end, immediately adjacent to the poly(A), contains nucleotide sequences that are complementary to the 5'-terminal T1 oligonucleotide T-13. These data indicate that the 5' end of the viral genome contains nucleotide sequences that are repeated at the 3' end of the genome. We conclude that the avian oncornavirus RNA genome is terminally redundant.
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PMID:Terminally repeated sequences in the avian sarcoma virus RNA genome. 7 37

The extent of binding of various RNA species to the three forms of avian sarcoma virus B77 RNA-dependent DNA polymerase was determined using a sensitive nitrocellulose filter binding technique which was capable of detecting binding reactions with association constants as low as 3 X 10(6) liters X mole-1. All three enzyme forms, alphabeta, beta2, and alpha, bound to all single-stranded RNA species that were tested, including nonviral RNAs. 70 S viral RNA exhibited the highest association constant (about 10(11) liters X mole-1), and a population of virus-derived tRNA molecules from which tRNATrp had been removed, the lowest (about 3000 times lower). The affinity for other RNAs was roughly proportional to their size. The affinity of RNAs for the alphabeta enzyme form always exceeded that for the two others by a factor that depended on the particular RNA, never exceeded 6 and was sometimes as low as 1.2. The association constant of the alphabeta enzyme form with viral 70 S RNA was about 15-fold higher than that with viral 35 S RNA. 35 S RNA annealed to tRNATrp had an association constant that was only 2.5 times higher than that of 35 S RNA alone. This finding suggests that the tertiary structure of 70 S RNA plays a significant role in its affinity for B77 DNA polymerase.
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PMID:The RNA-dependent DNA polymerase of avian sarcoma virus B77. Binding of viral and nonviral ribonucleic acids to the alpha, beta2, and alphabeta forms of the enzyme. 7 Apr 28

Virions produced by cells in the presence of actinomycin D (Act D virions) contain reverse transcriptase but are deficient in 70S genomic RNA. To assess the role of genomic RNA in encapsidation of a functional reverse transcriptase and to study the interaction of the enzyme and its template in the cores of intact virions, the reverse transcriptase enzymes of normal and Act D virions were compared. The enzymes were indistinguishable by column chromatography, sedimentation velocity, or template/primer preferences. In addition, these enzymes showed equal sensitivity to inactivation by antibodies directed against Rauscher murine leukemia virus DNA polymerase. The enzymes from Act D and normal virions had similar thermal decay rates and were both protected against heat denaturation by natural and synthetic template/primers. By these criteria, the DNA polymerase molecules synthesized and assembled into virions in the absence of genomic RNA are identical to those packaged under normal conditions. Additional studies designed to measure protection of reverse transcriptase by genomic RNA were carried out by comparing the thermal lability of the enzyme in intact Act D and normal virions. The thermal decay rate of reverse transcriptase in Act D virions was identical to that in control virions. In contrast to the lability of the virion-associated enzyme, however, genomic RNA in control virions was stable to heat treatment.
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PMID:Interactions of murine leukemia virus core components: characterization of reverse transcriptase packaged in the absence of 70S genomic RNA. 7 60

The nature of transcription of the avian retrovirus RNA genome by the alpha form of the viral RNA-directed DNA polymerase has been investigated. Transcription was most efficient when Mn2+ was provided as the divalent metal ion. The patterns of DNA transcription using 70S RNA, 35S RNA-tRNAtrp, or 35S RNA-oligo(dT)12-18 template-primer complexes by the alpha DNA polymerase were essentially identical to those obtained using the alphabeta form. The alpha DNA polymerase appears to be deficient in the synthesis of true duplex DNA but is able to synthesize hairpin-structured DNA initiated at the 5' terminus of the viral genome on the tRNAtrp primer molecule.
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PMID:In vitro transcription of the avian retrovirus genome by the alpha form of the viral RNA-directed DNA polymerase. 7 62

Poly (2-azaadenylic acid) [(aza2A)n] and poly(2-azainosinic acid [(aza2I)n], two newly synthesized analogues of (A)n and (I)n, in which CH-2 of the purine ring is replaced by a nitrogen atom, have been evaluated in various biological assay systems. (Aza2A) n formed a complex with (U)n and (br5U)n, and (aza2I)n formed a complex with (C)n and (br5C)n, but these complexes were markedly destabilized relative to the corresponding (A)n or (I)n complexes. The (aza2A)n-and (aza2I)n-derived complexes failed to stimulate the production of interferon in primary rabbit kidney cells and human diploid fibroblasts, under conditions (A)n. (U)n, (I)n. (C)n and (I)n. (br5C)n induced high amounts of interferon. both (aza2A)n and (aza2I)n exerted a marked inhibitory effect on the endogenous RNA directed DNA polymerase (reverse transcriptase) activity associated with murine leukemia virus. They caused a relatively mild inhibition of complement activity in an hemolytic assay system.
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PMID:Biologic activities of poly (2-azaadenylic acid) and poly (2-azainosinic acid). 7 66


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