Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.31.1 (micrococcal nuclease)
 2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

More than half of the DNA polymerase beta in mouse ascites cell chromatin was found to be associated with monomeric nucleosomal particles (produced by micrococcal nuclease treatment of chromatin). Almost all nuclear DNA polymerase activity in lymphocytes was found to be associated with nucleosomes. The nucleosome-associated enzyme was mainly DNA polymerase beta in chromatin from resting and mainly DNA polymerase alpha in chromatin from concanavalin-A-stimulated lymphocytes.
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PMID:Association of DNA polymerase with nucleosomes from mammalian cell chromatin. 56 14

The carbocyclic analog of 2'-deoxyguanosine (CdG) is active against herpes simplex virus (HSV), human cytomegalovirus, and human hepatitis-B virus. In order to understand the mechanism of action of this compound against HSV, we have evaluated (a) the incorporation of [3H]CdG into viral and host DNA in HEp-2 cells infected with HSV and (b) the interaction of the 5'-triphosphate of CdG (CdG-TP) with the HSV DNA polymerase and human DNA polymerases alpha, beta, and gamma (EC 2.7.7.7). Incubation of HSV-1-infected HEp-2 cells with [3H]CdG resulted in the incorporation of CdG into both the HSV and the host cell DNA. These results indicated that CdG-TP was used as a substrate for HSV DNA polymerase and for at least one of the cellular DNA polymerases. Degradation of both viral and host DNA with micrococcal nuclease and spleen phosphodiesterase indicated that CdG was incorporated primarily into internal positions in both DNAs. The viral DNA containing CdG sedimented in neutral and alkaline sucrose gradients in the same way as did viral DNA labeled with [3H]thymidine, indicating that the HSV DNA containing CdG was similar in size to untreated HSV DNA. CdG-TP was a competitive inhibitor of the incorporation of dGTP into DNA by the HSV DNA polymerase (Ki of 0.35 microM) and the human DNA polymerase alpha (Ki of 1 microM). CdG-TP was not a potent inhibitor of either DNA polymerase beta or gamma. Using DNA-sequencing technology, CdG-TP was found to be an efficient substrate for HSV DNA polymerase. Incorporation of CdG monophosphate (CdG-MP) into the DNA by HSV DNA polymerase did not interfere with subsequent chain extension. These results suggested that the antiviral activity of CdG was due to its incorporation into the DNA and subsequent disruption of viral functions. In contrast, CdG-TP was not as good as dGTP as a substrate for DNA synthesis by DNA polymerase alpha, and incorporation of CdG-MP by DNA polymerase alpha inhibited further DNA chain elongation.
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PMID:Incorporation of the carbocyclic analog of 2'-deoxyguanosine into the DNA of herpes simplex virus and of HEp-2 cells infected with herpes simplex virus. 131 7

In vivo in mammalian cells, ultraviolet-induced unscheduled DNA synthesis was less sensitive to aphidicolin than was replicative DNA synthesis. Replicative DNA synthesis in HeLa, HEp-2, WI-38 VA-13 and CV-1 cells was inhibited more than 97% by aphidicolin at 10 micrograms/ml, whereas aphidicolin inhibition of DNA synthesis in ultraviolet-irradiated cells varied between 30% and 90% depending on cell types and assay conditions. Aphidicolin inhibition of unscheduled DNA synthesis (UDS) in HeLa cells increased gradually with increasing aphidicolin concentration and reached approximately 90% at 100 micrograms/ml aphidicolin. A significant fraction of UDS in ultraviolet-irradiated HEp-2 cells was resistant to aphidicolin even at 300 micrograms/ml. Considered along with related information reported previously, the present results suggest that both aphidicolin-sensitive and insensitive DNA polymerases, DNA polymerase alpha and a non-alpha DNA polymerase (possibly DNA polymerase beta), are involved in in situ UDS in these ultraviolet-irradiated cells. Comparison of staphylococcal nuclease sensitivity between DNAs repaired in the presence and in the absence of aphidicolin in HEp-2 cells suggested that the involvement of DNA polymerase alpha in UDS favored DNA synthesis in the intranucleosomal region.
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PMID:Differential sensitivity to aphidicolin of replicative DNA synthesis and ultraviolet-induced unscheduled DNA synthesis in vivo in mammalian cells. 643 54

1. Nuclei isolated from regenerating rat liver were digested with micrococcal nuclease and fractionated on glycerol gradients into soluble chromatin fragments and chromatin associated with the nuclear skeleton. 2. Distributions of DNA polymerases alpha and beta in these fractions were different. While beta polymerase followed closely the distribution of the chromatin fragments, alpha polymerase associated preferentially with the skeleton-chromatin complex. 3. At least 20% of total alpha polymerase in the nuclei was shown to be bound to the skeleton. In nuclei extracted with isotonic sucrose buffer containing 50 or 100 mM Tris-Cl the portion of the skeleton associated enzyme was increased to 40-50%. 4. These data show that the skeleton bound alpha polymerase was preferentially retained in the nuclei during salt extraction. 5. Contrary to the replicational DNA polymerase alpha, DNA polymerase beta did not show any affinity to the skeleton.
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PMID:Intranuclear localization of DNA polymerases alpha and beta in regenerating rat liver. 686 93

1-(2-Deoxy-beta-D-erythro-pentofuranosyl)-5-hydroxy-5-methylhydantoin (5-OH-5-Me-dHyd) (3) has been shown to be a major oxidation product of thymidine formed upon exposure of DNA to (*)OH-radical and excited photosensitizers. To investigate the biological and structural significance of the 5-OH-5-Me-dHyd residue to DNA, the latter modified 2'-deoxyribonucleoside was chemically prepared and then site-specifically incorporated into oligodeoxyribonucleotides. This was efficiently achieved using the phosphoramidite approach that involved mild deprotection conditions. The purity and the integrity of the modified synthetic DNA fragments were checked using different complementary techniques such as HPLC and polyacrylamide gel electrophoresis, together with electrospray ionization and MALDI-TOF mass spectrometry. The piperidine test applied to 5-OH-5-Me-dHyd containing oligonucleotides showed a weak instability of hydantoin nucleoside inserted into the oligonucleotide chain. Several enzymatic experiments aimed at determining the biochemical features of such a DNA lesion were carried out. Thus, processing of 5-OH-5-Me-dHyd by nuclease P(1), snake venom phosphodiesterase, and calf spleen phosphodiesterase was investigated. The specificity and the mechanism of excision of the lesion by several bacterial and yeast DNA N-glycosylases, namely, endonuclease III (endo III), endonuclease VIII (endo VIII), formamidopyrimidine DNA N-glycosylase (Fpg), Ntg1 protein (Ntg1), Ntg2 protein (Ntg2), and Ogg1 protein (yOgg1), were also determined. These repair studies clearly showed that all these enzymes, with the exception of the yOgg1 protein, are able to recognize and remove 5-hydroxy-5-methylhydantoin from the double-stranded DNA fragment. Finally, a 22-mer DNA oligomer bearing a 5-OH-5-Me-dHyd residue was used as a template to study the in vitro nucleotide incorporation opposite the damage by the Klenow fragment of Escherichia coli polymerase I, Taq DNA polymerase, and DNA polymerase beta. Thus, it may be concluded that the oxidized thymine residue is a strongly blocking lesion for the three studied DNA polymerases.
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PMID:Repair and coding properties of 5-hydroxy-5-methylhydantoin nucleosides inserted into DNA oligomers. 1089 89