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)

The effects of nalidixic acid in vitro on deoxyribonucleic acid (DNA)- polymerase (deoxyribonucleosidetriphosphate: DNA deoxynucleotidyltransferase, EC 2.7.7.7), deoxyribonucleotide kinases (ATP: deoxymono- and diphosphate phosphotransferases), and deoxyribosyl transferase (nucleoside: purine deoxyribosyltransferase, EC 2.4.2.6) were examined employing partially purified and crude extracts of Escherichia coli ATCC 11229 and E. coli 15TAU. Nalidixic acid had no inhibitory effect on the DNA-polymerase of the wild-type strain E. coli ATCC 11229 at concentrations of 1.4 x 10(-3) to 2.8 x 10(-3)m. No inhibition of deoxyribonucleotide kinase activity was observed at concentrations of nalidixic acid ranging from 2 x 10(-3) to 8.6 x 10(-3)m. Nalidixic acid (0.43 x 10(-4) to 0.43 x 10(-3)m) had no inhibitory effect on the deoxyribosyl transferase activity of crude extracts obtained from E. coli ATCC 11229 or E. coli 15TAU. Analytical CsCl density gradient centrifugation demonstrated that the DNA obtained after treatment of E. coli 15TAU with nalidixic acid was not cross-linked. These results suggest that the prevention of DNA synthesis in vivo by nalidixic acid is not attributable to inhibition of DNA polymerase, deoxyribonucleotide kinase, deoxyribosyl transferase, or to cross-linking of the DNA of treated cells.
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PMID:Mechanism of action of nalidixic acid on Escherichia coli. Vi. Cell-free studies. 488 14

Human placental extracts contain a specific inhibitor of mammalian retroviral RNA-directed DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) activity. This inhibitor copurifies with retrovirus-like particles in human placental extracts. The inhibitor can be removed from these particles by salt extraction, which leads to the recovery of the polymerase activity. Thus, the inhibitor does not irreversibly inactivate the particle-associated RNA-directed DNA polymerase activity. The inhibitory preparation contained no nuclease, protease, or phosphatase activity. Because its inhibitory action can be eliminated by the addition of more virus to the reaction, nonspecific inactivation of enzyme substrate has been ruled out. A partial characterization of the inhibitor indicates that it is (i) insensitive to ether, trypsin, and phospholipase C; (ii) stable to heat and pH 2-12; and (iii) nondialyzable.
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PMID:Human placentas contain a specific inhibitor of RNA-directed DNA polymerase. 616 15

A novel form of DNA polymerase I (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, DNA nucleotidyltransferase, EC 2.7.7.7) activity has been isolated from Escherichia coli cells that had been activated for expression of the DNA damage-inducible genes. Induction was by treatment of normal cells or cells carrying the spr-51 and tif-1 mutations with nalidixic acid. This activity, DNA polymerase I, seems to be a form of DNA polymerase I because it is insensitive to N-ethylmaleimide, is inhibited by antibody to DNA polymerase I, and does not appear in a polA1 strain. DNA polymerase I activity sediments through sucrose gradients as a broad peak with s20.w = 6.6--10.5, compared with an s20,w = 4.8--5.5 for DNA polymerase I. The fidelity during polymerization reactions of DNA polymerase I is relatively low with a variety of synthetic templates and deoxynucleoside triphosphates, although the enzyme appears to have a normal level of 3' greater than 5' exonuclease. Polymerase I has properties that might implicate it in some form of mutagenic DNA repair.
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PMID:Isolation of an altered form of DNA polymerase I from Escherichia coli cells induced for recA/lexA functions. 628 65

Several triphosphates of 5-substituted deoxyuridine (dU), such as 5-ethyl-, 5-n-propyl-, 5-n-hexyl- and 5-isopropyldeoxyuridine triphosphates and 5-trifluorothymidine triphosphate are substrates for HeLa cell DNA polymerase beta (2'-deoxynucleoside-5'-triphosphate:DNA-deoxynucleotidyltransferase, EC 2.7.7.7) and for a DNA polymerase isolated from HeLa cells infected with herpes simplex virus type 2 (HSV-2) strain 75. At the concentration tested (50 microM), all these analogues were incorporated more readily into DNA by the virus-coded enzyme than by DNA polymerase beta from the host cell. The DNA polymerase coded by HSV-2 showed an affinity for deoxythymidine triphosphate (dTTP) and the analogues studied higher than that of DNA polymerase beta. Analogues are preferential substrates for the viral enzyme, since they readily substitute for dTTP during synthesis in vitro. In contrast, arabinosylthymine-5'-triphosphate was readily incorporated into DNA by the host cell DNA polymerase beta, but inhibited the DNA polymerase specified by HSV-2.
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PMID:Differential substrate specificity of DNA polymerase beta and of a DNA polymerase induced by herpes simplex virus type 2 towards thymidine triphosphate analogues. 632 35

A monoclonal antibody against purified calf DNA polymerase alpha (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) was used to immunoprecipitate proteins from a crude soluble extract of growing monkey BSC-1 cells. Immunoprecipitates contained familiar DNA polymerase alpha catalytic polypeptides of Mrs approximately equal to 115,000 and 70,000 and also a Mr 40,000 catalytic polypeptide; the major component in the immunoprecipitates, however, was a polypeptide of Mr approximately equal to 190,000 not previously identified as a DNA polymerase. This protein was capable of DNA polymerase activity after electroelution from NaDodSO4/polyacrylamide gels and renaturation. The highly purified enzyme so obtained was active with poly(dT).oligo(rA) as template.primer, resistant to dideoxy TTP (ddTTP), and inhibited by aphidicolin and butylphenyldeoxyguanosine 5'-triphosphate, thus identifying it as a DNA polymerase alpha. The results indicate that a polypeptide of Mr approximately equal to 190,000 is an abundant component among DNA polymerase alpha catalytic polypeptides in growing monkey cells.
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PMID:Identification of a higher molecular weight DNA polymerase alpha catalytic polypeptide in monkey cells by monoclonal antibody. 639 27

The gene 4 protein of bacteriophage T7 recognizes specific sequences on single-stranded DNA and then catalyzes the synthesis of tetraribonucleotide primers complementary to the template. With phi X174 DNA as a template, the gene 4 protein enables T7 DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) to initiate DNA synthesis at 13 major sites. DNA sequence analysis of the 5' termini of the newly synthesized DNA shows the predominant recognition sequences for the gene 4 protein to be 3'-C-T-G-G-G-5' or 3'-C-T-G-G-T-5'; the products of synthesis at these sites are RNA primers having the sequences pppA-C-C-C or pppA-C-C-A. The gene 4 protein can also synthesize primers at the sequences 3'-C-T-G-G-AC-5' and 3'-C-T-G-T-N-5', although these sites are used less than 10% as frequently as the predominant sites. Comparison of the utilization of primer sites suggests that the gene 4 protein binds randomly to single-stranded DNA and then translocates along the DNA in a unidirectional 5'-to-3' direction with regard to the DNA strand in search of recognition sequences. Models are presented for the role of the gene 4 protein in the initiation of lagging-strand synthesis and in the initiation of DNA replication at the origin.
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PMID:Template recognition sequence for RNA primer synthesis by gene 4 protein of bacteriophage T7. 645 35

DNA from the am16 mutant of bacteriophage phi X174 may be replicated in vitro and expressed in vivo to give five classes of revertants. Each class may be specifically induced by the appropriate biasing of the concentrations of deoxynucleoside triphosphates in a predictable manner. The frequency of each reversion follows a kinetic rate equation relating it to the concentrations of the triphosphates involved in the substitution. The reversions corresponding to TAG leads to GAG, AAG, CAG, TGG, and TCG are calculated to occur with frequencies of 5 X 10(-7), 4 X 10(-7), 4 X 10(-7), approximately 2 X 10(-7), and approximately 5 X 10(-9), respectively, at the concentration of triphosphates found in vivo. The frequencies are in the range found for the reversion of the phage in vivo and so are consistent with errors in nucleotide selection by DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) III being largely responsible for the rate of spontaneous mutation in vivo. The relative frequency of mispairing leading to misincorporation is: purine.purine approximately purine.pyrimidine much greater than pyrimidine.pyrimidine, confirming predictions from model-building studies that transversions arise through purine.purine mismatches.
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PMID:DNA polymerase accuracy and spontaneous mutation rates: frequencies of purine.purine, purine.pyrimidine, and pyrimidine.pyrimidine mismatches during DNA replication. 645 1

In the extract of mature sperm of the sea urchin, Hemicentrotus pulcherrimus, two species of DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7.) activity were detected. One of them was eluted from a hydroxyapatite column at 0.08 M phosphate buffer and was insensitive to both N-ethylmaleimide and aphidicolin. The sedimentation coefficient was 3.3 S and the isoelectric point was pH 8.6. This activity corresponds to the DNA polymerase-beta activity. The other was eluted from the hydroxyapatite column at 0.14 M phosphate buffer and was inhibited by N-ethylmaleimide but not by aphidicolin. The sedimentation coefficient was 3.3 S and 6.0 S and the isoelectric point was pH 4.8. The template primer preference of this enzyme was coincident with DNA polymerase-gamma. The DNA polymerase-alpha activity was not detected in the extract of mature sperm.
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PMID:Characterization of DNA polymerases in mature sperm of the sea urchin. 677 24

Aphidicolin, a tetracyclic diterpenoid antibiotic, is a specific inhibitor of DNA synthesis in vivo and DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) alpha of eukaryotic organisms. After ethyl methanesulfonate mutagenesis, we have recovered mutants of Drosophila melanogaster Schneider cell line no. 2 that grow at concentrations of aphidicolin that completely inhibit wild-type cells. The DNA polymerase alpha from one of these mutants, aph-10, is much more resistant to inhibition by the drug; the apparent Ki of the wild-type enzyme is 12 nM aphidicolin, whereas the apparent Ki of the aph-10 polymerase is more than 100 nM. (The apparent Km for dCTP is the same for both enzymes.) Another mutant, aph-13, overproduces DNA polymerase alpha at least 8-fold. The DNA polymerase of this mutant has the same apparent Km and Ki for dNTPs and aphidicolin as does wild-type polymerase.
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PMID:DNA polymerase alpha mutants from a Drosophila melanogaster cell line. 678 18

The purified high molecular weight form of HeLa cell DNA polymerase alpha (deoxynucleosidetriphosphate: DNA deoxynucleotidyltransferase, EC 2.7.7.7) was shown to associate tightly with several aminoacyl-tRNA synthetase activities. Fractionation of the high molecular weight enzyme on hexylagarose followed by gel filtration, chromatography on phosphocellulose, or polyacrylamide gel electrophoresis under nondenaturing conditions demonstrated copurification of only tryptophanyl-tRNA synthetase [L-tryptophan:tRNATrp ligase (AMP-forming), EC 6.1.1.2] along with DNA polymerase alpha. The high molecular weight (660,000) and low molecular weight (145,000) forms of DNA polymerase alpha were shown to possess a highly specific, noncovalent, diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) binding activity. The dissociation constants were determined to be 16 and 22 microM, respectively, by utilization of a charcoal adsorption procedure. No high-affinity binding of ATP could be detected. These findings suggest a link between the amino acid activation process and DNA replication in mammalian cells.
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PMID:HeLa cell DNA polymerase alpha is tightly associated with tryptophanyl-tRNA synthetase and diadenosine 5',5"'-P1,P4-tetraphosphate binding activities. 694 Jan 51


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