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)

Estradiol (E2) exerts both inhibitory and stimulatory effects on DNA synthesis in the rat uterine luminal epithelium (LE). This inhibitory effect is due to a shift in the time course of DNA synthesis, i.e. in animals receiving a single injection of E2, a peak of DNA synthesis occurs 24 h after treatment, but in animals receiving multiple injections of E2, DNA synthesis is suppressed until 10-12 h after hormone treatment ceases. In these previous studies LE DNA synthesis was assessed by measuring tritiated thymidine incorporation. In the present study, we sought to determine if the molecular basis for this decrease in DNA synthesis was due to a suppression of DNA polymerase activity in LE nuclei. Animals receiving a single injection of E2 exhibit a peak of nuclear DNA polymerase activity 20-24 h later. Animals receiving multiple injections of E2 (0, 12, 15, and 18 h) show more than a 50% decrease in DNA polymerase activity at 20-24 h, due to a shift in the maximum increase in enzyme activity to 32-36 h after the initial treatment. The observed differences between these groups are not due to different levels of DNase activity or different degrees of leakage of the nuclear enzyme. The observed enzyme activity is due to DNA polymerase-alpha, since it requires ATP as well as deoxyribonucleoside triphosphates, and is aphidicolin sensitive. These results indicate that the inhibitory effect of E2 on LE DNA synthesis is due at least in part to a suppression of nuclear DNA polymerase-alpha activity.
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PMID:Regulation of deoxyribonucleic acid polymerase activity in uterine luminal epithelium after multiple doses of estrogen. 312 37

Apurinic and/or apyrimidinic (AP) sites were excised from PM2 phage DNA by two enzymes: an AP endodeoxyribonuclease isolated from rat neocortex chromatin and a rat brain exodeoxyribonuclease, DNase B III. The resulting gap was filled with DNA polymerase beta prepared from rat liver and finally ligated by Escherichia coli DNA ligase.
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PMID:Excision of apurinic and/or apyrimidinic sites from DNA by nucleolytical enzymes from rat brain. 327 4

A minimal mechanism is proposed which describes the transcriptional and translational processes for four phage proteins (RNA polymerase, DNase, primase and DNA polymerase) involved in T3/T7 DNA replication. Phage DNA replication is also included. It is shown how lag times may be incorporated into a kinetic mechanism. The distinct three-stage transport of phage DNA into the bacterial host (E. coli) is considered. DNA transport is assumed to be rate-determining for the transcription of class I and II proteins. Transcriptional and translational lag times have been calculated on the basis of available gene mapping of T7 phages. The kinetic behavior of T7 and T3 phage infection is practically identical. The hydrolysis of bacterial DNA by phage DNase (endonculease and exonuclease) as well as the subsequent phosphorylation to the deoxymononucleoside triphosphates are assumed to be rate-determining in phage DNA replication. Good agreement with experiment is obtained in our computer simulations.
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PMID:Computer simulation of T3/T7 phage infection using lag times. 330 Aug 7

ATP-stimulated DNA polymerase activity involving DNA polymerase I has been found to be present in cell extracts from wild type and recC mutant strains of Escherichia coli, but not in extracts from recB strain. The activity has been separated from recBC DNase by DEAE-cellulose ion exchange. It is suggested that recB-dependent factor is involved in the ATP-stimulation of polymerase. Evidence is provided that this stimulation may be due to the interaction of recB-dependent factor with DNA polymerase I.
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PMID:ATP-stimulated polymerase activity involving DNA polymerase I and a recB-dependent factor in extracts of Escherichia coli cells. 331 95

Monoclonal antibodies which react specifically with the nuclei of interphase cells recognized three nuclear antigens with molecular weights of 110,000 (p110), 85,000 (p85), and 18,000 (p18). p110 and p85 were found in eight tumor cell lines but were not found in resting lymphocytes. p18 was found in resting lymphocytes as well as the tumor cell lines. Protein p85 appeared in phytohemagglutinin-stimulated lymphocytes in the G1 phase and protein p110 appeared in the S phase. p110 and p85 were localized to the extranucleolar chromatin while p18 was distributed throughout the nucleus and was determined by microscopic and DNase digestion studies to be DNA associated. The anti-p110 antibody recognized a component of the DNA polymerase alpha 2 complex. Three novel nuclear proteins were identified using monoclonal antibodies. Two of these proteins (p110 and p85) are proliferating cell nuclear and nucleolar antigen-like while the third (p18) is not cell cycle dependent.
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PMID:Novel cell cycle-related nuclear proteins found in rat and human cells with monoclonal antibodies. 355 71

The majority of the DNA polymerase alpha activity in HeLa cells has been isolated and purified as a multiprotein Mr 640,000 form. The multiprotein form of DNA polymerase alpha corresponds to DNA polymerase alpha 2 that was previously reported by us (Lamothe, P., Baril, B., Chi, A., Lee, L., and Baril, E. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 4723-4727). The highly purified DNA polymerase alpha 2 has in addition to DNA polymerase alpha-associated DNase, primase, and diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A)binding activities and accessory primer recognition proteins C1 and C2. The DNA polymerase alpha and associated activities increase coordinately during the G1/S-phase transition of the cell cycle. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the electrophoretically homogeneous DNA polymerase alpha shows that it is composed of at least eight polypeptides in the molecular weight range of 180,000-15,000. Hydrophobic chromatography on butyl-agarose resolves the DNase and Ap4A-binding protein from a complex of DNA polymerase alpha, primase, and the primer recognition proteins C1 and C2. Hydrophobic chromatography of the latter complex on phenyl-Sepharose resolves the C1 protein from a DNA polymerase alpha-C2 protein-primase complex. Phosphocellulose chromatography of the DNA polymerase-primase-C2 protein complex resolves the C2 protein from a complex of DNA polymerase alpha-primase.
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PMID:A multiprotein form of DNA polymerase alpha from HeLa cells. Resolution of its associated catalytic activities. 370 Apr 10

The nick-translation procedure without external addition of DNase was performed in situ on sections of various rat organs to detect possible DNA single-strand breaks (nicks) in normal tissues. The freshly frozen sections were briefly fixed in ethanol/acetone and nick-translated in the presence of E. coli DNA polymerase I. A significant difference in the amount of nuclear reaction was found among the different cell populations as detected by autoradiography following incorporation of tritiated TTP as well as by histochemical staining following incorporation of biotin-dUTP into nuclei. Such incorporation of triphosphates was localized in the DNA and was entirely dependent on E. coli DNA polymerase I. The nuclei with the highest reactivity were found in skeletal muscle cells, lymphocytes in various lymphatic organs, the proliferative cells in the gastrointestinal tract, stratified squamous epithelial cells, duct epithelial cells of salivary gland and the maturing spermatids in the seminiferous tubules. These results suggest that, under the conditions adopted, the cells in various tissues reveal different chromatin structures resulting in varying rates of nick translation reaction. Such difference(s) in chromatin structure, presumably including that in the number of DNA single-strand breaks or in the level of endogenous nuclease activity, may be associated with the mechanisms involved in cell growth and differentiation.
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PMID:DNA strand breaks in rat tissues as detected by in situ nick translation. 377 92

Protein kinase C (Ca2+/phospholipid-dependent protein kinase) purified from rat brain or endogenous to cell-free extracts from HeLa cells stimulates, by a factor of 2-3, HeLa DNA polymerase alpha but not beta or gamma. Monoclonal antibody to the kinase prevents the stimulation, and monoclonal antibody to human DNA polymerase alpha neutralizes the enhanced activity. Reduced DNA polymerase alpha activity is obtained from noncycling HeLa cells and this activity has lower fidelity when copying synthetic primer-templates than that obtained from log phase cultures. After exposure to the kinase, the fidelities and activities of the polymerase from both sources increase by 2- to 3-fold. This improved accuracy is not accompanied by the appearance of triphosphatase or DNase activities. Exposure to the protein kinase reduces the Km for activated DNA and for poly(dA-dT) but not for dNTPs. Moreover, the Vmax for activated DNA but not for poly(dA-dT) is increased approximately 2- to 3-fold. These alterations suggest a role for protein phosphorylation in modulating DNA polymerase alpha.
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PMID:Exposure of HeLa DNA polymerase alpha to protein kinase C affects its catalytic properties. 381 50

The mechanism of the human placental DNase VII, described previously (Hollis, G. F., and Grossman, L. (1981) J. Biol. Chem. 256, 8074-8079) has been investigated in further detail. The enzyme initiates exonucleolytic hydrolysis from the 3'-end of DNA in a nonprocessive, or distributive, manner, regardless of whether the carbohydrate moiety associated with the 3'-terminal nucleotide contains H or OH at its 2' and 3' positions. DNase VII does not have associated RNase H activity; however, it is capable of removing 3'-terminal ribonucleotides. The enzyme also can hydrolyze DNA containing a terminal nucleotide lacking a purine or pyrimidine as well as termini containing noncomplementary nucleotides. DNase VII activity is product-inhibited by deoxynucleoside 5'-monophosphates. From kinetic studies, the mononucleotide deoxyadenylic acid is a noncompetitive inhibitor with a Ki = 0.3 mM. The resemblance of DNase VII to the 3'----5' exonuclease activity of Escherichia coli DNA polymerase I and its possible role in excision repair and proofreading are discussed.
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PMID:DNase VII of human placenta. Mechanism studies. 388 48

E. coli DNA polymerase I (EC 2.7.7.7) can engage in either DNA- or RNA-directed DNA synthesis with hybrid templates. The choice of the strand to be transcribed depends primarily on the relative lengths of the two strands of the hybrid, the longer strand serving as the template and the shorter as the primer. If a polynucleotide is reduced in size by exposure to an endonuclease before being hybridized to the complementary strand, the template efficiency of the latter increases several-fold. Under properly selected conditions, highly efficient reverse transcription of the all-ribonucleotide template-primers poly(A).oligo(U), poly(C).oligo(I), and poly(I).oligo(C) can be achieved. "f1 RNA," the RNA strand of an f1 DNA.RNA hybrid, can also serve as template for reverse transcription either after "nicking" of the hybrid with DNase, or after separation from the DNA strand and priming by DNase-treated f1 DNA.
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PMID:Reverse transcription by Escherichia coli DNA polymerase I. 412 27


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