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Query: HUMANGGP:003721 (Poly)
 11,742 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A gamma-like DNA polymerase devoid of DNA polymerase-alpha and -beta activities was prepared from the nuclear fraction of blastulae of the sea urchin, Hemicentrotus pulcherrimus. The enzyme sedimented at the position of an approximate sedimentation coefficient of 3.3 S under high salt conditions by sucrose gradient centrifugation. An isoelectric point was determined to be pH 5.8. The enzyme activity was sensitive to sulfhydryl blocking reagents. Poly(rA) . oligo(dT)12--18 followed by poly(dA) . oligo(dT)12--18 was effectively utilized as a template-primer. From the above results, this polymerase seems to resemble the vertebrate DNA polymerase-gamma.
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PMID:Identification of gamma-like DNA polymerase from sea urchin embryos. 3 10

We have investigated three aspects of RNA turmor virus replication and cell transformation: (1) the properties of the purified avian and mammalian viral RNA-directed DNA polumerase, (2) some characteristics of the viral 60-70S RNA genome, 30-40S RNA subunits and intracellular viral RNA species, and (3) the interaction of the viral DNA polymerase with its RNA template early during infection and cell transformation by the murine sarcoma-leukemia virus (MSV[MLV]). Avian myeloblastosis virus (AMV) contains two forms of RNA-directed DNA polymerase, alpha, consisting of a single polypeptide of molecular weight 65,000, and alphabeta, consisting of two polypeptides of molecular weights 65,000 and 105,000. The alpha and alphabeta forms of AMV DNA polymerase both possess RNase H activity that requires free end termini on the ribopolymer and can degrade the RNA of the RNA-DNA hybrid in the 3' to 5' and 5' to 3' directions. But, alpha and alphabeta possess a different mode of exoribonuclease activity. While alphabeta RNase H is a processive exoribonuclease that degrades the polynucleotide chain to a core residue before attacking a second chain, alpha RNase H is a random exoribonuclease that releases the polynucleotide after each scission. Highly purified Moloney-MSV(MLV) DNA polymerase has both RNase H activity and the ability to read viral 60-70S RNA. These activities comigrate through five different steps of purification and are present at levels comparable to those found in purified AMV DNA polymerase. The MSV(MLV) 60-70S RNA genome and 35S RNA subunits were shown by periodate oxidationtritiated borohydride reduction to contain adenosine as the major 3'-terminal nucleoside. Poly (A) segments were isolated from viral 60-70S and 35S RNA by treatment with RNase A or RNase T1 and purified by afinity chromatography and gel electrophoresis. Viral poly(A) was shown to be present at the 3' terminus as -G(C,U)A190AOH. The similar sequence reported for poly(A) present in mammalian mRNA suggests that similar mechanisma are involved in the transcription and processing of both cellular and viral DNA sequences. Within transformed cells replicating MSV(MLV), viral 35S and 20S RNA were found in membrane-bound polyribosomes, whereas only 35S RNA was detected in free polyribosomes. The origin and function of 20S RNA is unknown. The early events during rapid infection and cell transformation of mouse 3T6 cells by the Harvey strain of MSV(MLV) were studied. By both autoradiographic analysis and molecular hybridization, viral DNA synthesis was detected in the cytoplasm by 1 hour after infection, reached a maximum at 2 hours, and subsequently decreased. Cytological chase experiments produced evidence that cytoplasmic viral DNA was transported to the nucleus. In situ hybridization experiments using radioactive viral DNA product as a probe demonstrated the rapid association of viral DNA sequences with the chromocenters of interphase nuclei and with the centromeric heterochromatin regions of some chromosomes.
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PMID:Properties of oncornavirus RNA-directed DNA polymerase, the RNA template, and the intracellular products formed early during infection and cell transformation. 5 Sep 2

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

The biochemical properties of DNA polymerase purified from Mason-Pfizer monkey virus were studied, with respect to synthetic and natural template-primer utilization. Thes studies revealed the following new information about the Mason-Pfizer monkey virus enzyme: (a) Mason-Pfizer monkey virus polymerase was found to prefer template: primer molar nucleotide ratios of 2.5-5: 1 for optimal rates of synthesis with poly(C) .(dG)12-18 as template-primer. (b) Poly(A)-directed synthesis was stimulated by the addition of low concentrations of inorganic phosphate to the reaction mixture. (c) Poly(2' -O-methyl-cytidylate), poly(rCm), was the only template studied for which Mn2+ proved the preferred divalent cation. Combinations of divalent cations stimulated rather than inhibited poly(rCm)-directed poly(dG) synthesis by the Mason-Pfizer monkey virus enzyme. (d) Heteropolymeric regions of rabbit globin mRNA and avian myeloblastosis virus 70 S RNA could be copied by the Mason-Pfizer monkey virus polymerase with oligo(dT), oligo(U) or in the case of avian myeloblastosis virus RNA, endogenous primers. In all such studies, Mg2+ was the preferred divalent cation and a distinct preference for the DNA primer in the reverse transcription of natural RNAs was observed. These new findings necessitated comparative studies with the DNA polymerases from Rauscher murine leukemia virus and murine mammary tumor virus, as representative type C and type B retroviruses. Although the Mason-Pfizer monkey virus enzyme was found to share some properties in common with both type C and type B mammalian viral enzymes, certain of the above properties rendered it unique among the polymerases examined.
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PMID:Template-specific requirements for DNA synthesis by the Mason-Pfizer monkey virus DNA polymerase: unique aspects. 7 24

Poly (2-methylthioinosinic acid) [poly(ms2I)] was found to markedly inhibit the RNA directed DNA polymerase (reverse transcriptase) activity of murine (Moloney, Rauscher) leukemia virus and murine (Moloney) sarcoma virus, while under the same conditions the unsubstituted parent compound poly(I) showed little, if any, inhibitory effect. Copolymers of inosinic acid (I) and 2-methylthioinosinic acid2(ms2I) showed an intermediary effect, depending on the I:ms2I ratio. Poly(ms2I) also inhibited the transformation of normal cells by murine (Moloney) sarcoma virus, as assessed by an infectious center assay.
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PMID:Inhibition of oncornavirus functions by poly (2-methylthioinosinic acid). 7 96

The activity of a 7.3S-8.3S Drosophila DNA polymerase was characterized in detail using poly dA.p(dT)[unk] and poly rA.p(dT)[unk]. With poly dA.p(dT)[unk], Mg(2+) ion was the preferred divalent cation, and enzyme activity was inhibited by K(+) ion and by spermidine. With poly rA.p(dT)[unk], Mn(2+) ion was the preferred divalent cation and enzyme activity was stimulated by K(+) ion and by spermidine. The dependence of enzyme activity on the concentration of primer-template and on the ratio of primer to template was the same in both reactions. The two enzyme activities were identically inhibited by N-ethylmaleimide. Poly dA was replicated extensively and poly rA was replicated partially. The activation energy for poly dA replication was twice that for poly rA replication. Enzyme activity with poly dA.p(dT)[unk] was more stable to thermal inactivation than was enzyme activity with poly rA.p(dT)[unk]. These studies suggest that the same enzyme responds to both the deoxy- and the ribohomopolymer template but that the mechanisms of replication may be different.
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PMID:Replication of poly dA and poly rA by a drosophila DNA polymerase. 9 38

Three different DNA polymerases have been isolated from rat ascites hepatoma cells [1--3]. The molecular weight of a DNA polymerase (polymerase C) purified from the soluble fraction of the cells was estimated to be 142 000 by sedimentation on a sucrose gradient, while the molecular weights of two DNA polymerases (polymerase P-1 and P-2) purified from nuclear membrane-chromatin fraction were estimated to be 117 000 and 44 000, respectively, by the same method. Under certain conditions, the poly (dT) strand of poly[(dA)-(dT)] was copied well by the polymerases, especially by the nuclear polymerases. Poly (dC) was a good template for the high molecular weight DNA polymerases C and P-1, but poly(dT) and poly(dA) were not effective templates. By addition of complementary oligoribonucleotides, the single-stranded deoxypolymers were copied by the high molecular weight polymerases C and P-1. When single-stranded fd phage DNA was used as template, the polymerization reactions by the high molecular weight polymerases were stimulated by the concomitant synthesis of RNA. This indicates that the oligoribonucleotide acts as a primer in these reactions.
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PMID:Three DNA polymerases of rat ascites hepatoma cells: properties of the enzymes and effect of RNA synthesis on the reactions. 16 56

Poly(2'-fluoro-2'-deoxyuridylic acid) is known to be an effective inhibitor of the deoxyribonucleic acid polymerase found within the oncornaviruses. This synthetic polynucleotide was found to inhibit the replication of vesicular stomatitis virus in mouse L cells. The polymer was shown to be capable of inhibiting the viral ribonucleic acid (RNA)-dependent RNA polymerase, and it is proposed that this is the mechanism of antiviral activity. The following observations support this viewpoint: (i) the polymer is most active when added after virus adsorption; (ii) the antiviral activity is not species specific; and (iii) the polynucleotide is nontoxic to the host cell. Conventional methodologies designed to increase nucleic acid uptake by cultured cells do not show an increase in antiviral potency.
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PMID:Inhibition of vesicular stomatitis virus replication by poly(2'-fluoro-2'-deoxyuridylic acid). 17 88

DNA polymerase from BHK-21/C13 cells were separated into two species, DNA polymerase I corresponding to the heterogeneous enzyme with sedimentation coefficient of 6-8S, and DNA polymerase II, corresponding to the enzyme with sedimentation coefficient of 3.3S. DNA polymerase I was purified 114-fold and DNA polymerase II 154-fold by a simple extraction procedure followed by column chromatography on phosphocellulose and gel filtration through Sephadex G-100. The purified enzymes differed markedly in respect of pH optimum, stimulation and inhibition by K+, Km for the deoxyribonucleoside 5'-triphosphates, stability to heating at 45 degrees C, and inhibition by N-ethylmaleimide. The preferred primer-template for both enzymes was "activated" DNA (DNA submitted to limited degradation by pancreatic deoxyribonuclease); native or thermally denatured DNA templates were relatively very poorly copied. When certain synthetic templates were tested, substantial differences were revealed between the two enzymes. Poly[d(A-T)] was poorly used by polymerase I but was superior to "activated" DNA for polymerase II. Poly[d(A)]-oligo[d(pT)10] was used efficiently by polymerase I but not by polymerase II. Poly(A)-oligo[d(pT)10] was not an effective primer-template although polymerase I could use it to a limited extent when Mn2+ replaced Mg2+ in the polymerase reaction and when the temperature of incubation was lowered from 37 degrees to 30 degrees C. When only one or two or three triphosphates were supplied in the reaction mixture, the activity of polymerase I was more severly diminished than that of polymerase II.
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PMID:Deoxyribonucleic acid polymerases of BHK-21/C13 cells. Partial purification and characterization of the enzymes. 23 80

Purified DNA polymerase beta of calf thymus can utilize poly(rA).oligo(dT) as efficiently as poly(dA).oligo(dT) or activated DNA as a template primer. The poly(rA).oligo(dT)-dependent activity of DNA polymerase beta was found to differ markedly from the DNA-dependent activity of the same enzyme (with either activated calf thymus DNA or poly(dA).(dT)10) in the following respects. 1) Poly(rA)-dependent activity was strongly inhibited by natural DNA from various sources or synthetic deoxypolymer duplexes at very low concentrations (less than 0.5 microgram/ml) at which the DNA-dependent activity was affected to a much smaller extent, if at all. 2) Poly(rA)-dependent activity was inhibited by N-ethylmaleimide more strongly than DNA-dependent activity measured at 37 degrees C, while it was resistant to this reagent at 26 degrees C. 3) The curves of the activity versus substrate concentration were sigmoidal in the poly(rA)-dependent reaction but hyperbolic in the activated DNA-dependent reaction. A kinetic study suggested that the association of beta-enzyme protomers may be required to copy the poly(rA) strand.
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PMID:Novel properties of DNA polymerase beta with poly(rA).oligo(dT) template-primer. 45 38


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