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)

Protein extracts were prepared at various times after serum stimulation of growth-arrested mouse 3T3 fibroblasts. The extracts were fractionated by sucrose gradient centrifugation and used to determine the activities of DNA polymerase alpha and DNA primase. We found that polymerase and primase appeared in close association in one homogeneous 8.2-S peak. Neither polymerase, free of associated primase, nor primase, free of polymerase, could be detected at any time after serum stimulation. The activities of both enzymes started to increase concomitantly at the beginning of the DNA replication phase of the cell cycle. We found five to six times more DNA primase activity in replicating than in resting 3T3 cells. Besides DNA primase, a second additional priming activity could be detected. This activity sedimented at 12.5 S and corresponded most probably to RNA polymerase I.
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PMID:Cell-cycle-dependent expression of DNA primase activity. 383 Jan 83

The shoulder of the UV fluence-survival curve of exponentially growing Escherichia coli B/r WP2 trpE65 was expanded by chloramphenicol pretreatment and an exponential segment with intermediate slope appeared between the shoulder and the final exponential segment. These changes were dependent on DNA replication. The transitions with UV exposure to increased slopes were ascribed to UV inactivation of qualitatively different repair systems, each dependent upon the accumulation in each bacterium of multiple DNA-containing redundant repair components, which must be inactivated before the respective transitions to decreased resistance occur. Rifampin, which blocks DNA-dependent RNA polymerase function, limited drastically expansion of the shoulder and development of the intermediate exponential slope. Bacteria defective in DNA polymerase I (polA) showed only a slight expansion of the shoulder with pretreatment with chloramphenicol. Since certain bacterial plasmids require RNA primer formation for initiation of replication and are not maintained in a polA strain, it is proposed that the chloramphenicol-promoted increase in resistance depends on the formation of multiple numbers of specific resistance episomes (called repairons in view of their role in DNA repair).
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PMID:Modification of survival after ultraviolet light exposure in a wild-type and a polA strain of Escherichia coli B/r by preirradiation treatment with chloramphenicol or rifampin. 390 85

Two high molecular weight DNA polymerases, which we have designated delta I and delta II, have been purified from calf thymus tissue. Using Bio Rex-70, DEAE-Sephadex A-25, and DNA affinity resin chromatography followed by sucrose gradient sedimentation, we purified DNA polymerase delta I 1400-fold to a specific activity of 10 000 nmol of nucleotide incorporated h-1 mg-1, and DNA polymerase delta II was purified 4100-fold to a final specific activity of 30 000 nmol of nucleotide incorporated h-1 mg-1. The native molecular weights of DNA polymerase delta I and DNA polymerase delta II are 240 000 and 290 000, respectively. Both enzymes have similarities to other purified delta-polymerases previously reported in their ability to degrade single-stranded DNA in a 3' to 5' direction, affinity for an AMP-hexane-agarose matrix, high activity on poly(dA) X oligo(dT) template, and relative resistance to the polymerase alpha inhibitors N2-(p-n-butylphenyl)dATP and N2-(p-n-butylphenyl)dGTP. These two forms of DNA polymerase delta also share several common features with alpha-type DNA polymerases. Both calf DNA polymerase delta I and DNA polymerase delta II are similar to calf DNA polymerase alpha in molecular weight, are inhibited by the alpha-polymerase inhibitors N-ethylmaleimide and aphidicolin, contain an active DNA-dependent RNA polymerase or primase activity, display a similar extent of processive DNA synthesis, and are stimulated by millimolar concentrations of ATP. We propose that calf DNA polymerase delta I, which also has a template specificity essentially identical with that of calf DNA polymerase alpha, could be an exonuclease-containing form of a DNA replicative enzyme.
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PMID:Purification and characterization of two new high molecular weight forms of DNA polymerase delta. 395 90

Blood samples containing antibodies to DNA were obtained from patients with systemic lupus erythematosus (SLE) and rabbits immunized with denatured DNA complexed to methylated bovine serum albumin. The immunoglobulin fractions from these sources did not decrease the over-all template activity of singlestranded DNA with DNA polymerase or DNA-dependent RNA polymerase. In competition studies, both DNA polymerase and DNA-dependent RNA polymerase inhibited the binding of DNA antibodies to single-stranded DNA, as evidenced by inhibition of micro-complement fixation. These findings suggest that antibodies to DNA fail to decrease denatured DNA template activity because the enzymes which use a single-stranded DNA template can displace or block the antibodies from the denatured DNA as a result of greater binding affinity to the denatured DNA. The anti-DNA antibodies associated with SLE, therefore, may not be involved in the pathogenesis of the intracellular abnormalities associated with the disease.
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PMID:In vitro effect of antibodies to DNA on the template activity of DNA. 417 49

The effect of the antitumor antibiotic illudin S on bacterial macromolecular synthesis was investigated. Illudin S was found to be inhibitory to in vivo deoxyribonucleic acid (DNA) synthesis from thymidine. Ribonucleic acid (RNA) synthesis was inhibited only at a concentration of illudin S 10 times that which inhibited DNA synthesis. The rate of protein synthesis remained the same except for a brief initial inhibition. When thymidine triphosphate was used for in vitro DNA synthesis, inhibition by illudin S did not occur, as tested with partially purified DNA polymerase II from Escherichia coli pol A(1) (-), with E. coli DNA-dependent RNA polymerase, with E. coli pol A(1) (-) spheroplasts, and with frozen and thawed Bacillus subtilis cells. A protein fraction isolated from B. subtilis capable of forming thymidine mono-, di-, and triphosphates from thymidine was not inhibited by illudin S. Furthermore, (14)C-illudin S taken up by B. subtilis cells was reisolated unchanged, making an intracellular activation of illudin S unlikely. Therefore, an attractive hypothesis is that illudin S inhibits DNA synthesis from thymidine which does not proceed through deoxyribonucleoside triphosphates, the generally accepted substrates for DNA synthesis.
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PMID:Mode of action illudin S. 420 86

Two of the adenovirus capsid proteins, the fiber and the hexon, complexed with either KB cell or type 5 adenovirus deoxyribonucleic acid (DNA). Maximal binding occurred at 0.01 m NaCl; increasing the ionic strength of the reaction mixture to 0.2 m NaCl resulted in a decrease in the association of either antigen to DNA. Variations of pH between 6.3 and 8.4 did not affect the binding of fiber antigen to DNA. Below pH 7.5, however, there was a small decrease in the ability of the hexon to bind nucleic acid. The association between the adenovirus structural proteins and DNA was reversible and was independent of whether the DNA was native or denatured. The fiber or hexon protein inhibited the DNA-dependent ribonucleic acid (RNA) polymerase and the DNA polymerase from KB cells. On a weight basis, the fiber protein inhibited enzymatic activity to a greater extent than the hexon. Increasing the template DNA concentration decreased this inhibition. The inhibition of the DNA-dependent RNA polymerase activity by either antigen could be reversed by increasing the ionic strength of the reaction mixture. After infection of KB cells with type 5 adenovirus, the levels of DNA and RNA polymerases remained unchanged for 15 to 20 hr. Thereafter, the specific activity of both enzymes decreased. By 30 hr postinfection, the polymerase activities were only about 30% of the enzyme activities in uninfected cells.
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PMID:Role of adenovirus structural proteins in the cessation of host-cell biosynthetic functions. 430 13

The influence of ribonucleic acid (RNA) and protein synthesis on the replication of the cloacinogenic factor Clo DF13 was studied in Escherichia coli cells and minicells. In chromosomeless minicells harboring the Clo DF13 factor, Clo DF13 deoxyribonucleic acid (DNA) synthesis is slightly stimulated after inhibition of protein synthesis by chloramphenicol or puromycin and continues for more than 8 h. When minicells were treated with rifampin, a specific inhibitor of DNA-dependent RNA polymerase, Clo DF13 RNA and DNA synthesis appeared to stop abruptly. In cells, the Clo DF13 factor continues to replicate during treatment with chloramphenicol long after chromosomal DNA synthesis ceases. When rifampin was included during chloramphenicol treatment of cells, synthesis of Clo DF13 plasmid DNA was blocked completely. Isolated, supercoiled Clo DF13 DNA, synthesized in cells or minicells in the presence of chloramphenicol, appeared to be sensitive to ribonuclease and alkali treatment. These treatments convert a relatively large portion of the covalently closed Clo DF13 DNA to the open circular form, whereas supercoiled Clo DF13 DNA, isolated from non-chloramphenicol-treated cells or minicells, is not significantly affected by these treatments. These results indicate that RNA synthesis and specifically Clo DF13 RNA synthesis are involved in Clo DF13 DNA replication and that the covalently closed Clo DF13 DNA, synthesized in the presence of chloramphenicol, contains one or more RNA sequences. De novo synthesis of chromosomal and Clo DF13-specific proteins is not required for the replication of the Clo DF13 factor. Supercoiled Clo DF13 DNA, isolated from a polA107 (Clo DF13) strain which lacks the 5' --> 3' exonucleolytic activity of DNA polymerase I, is insensitive to ribonuclease or alkali treatment, indicating that in this mutant the RNA sequences are still removed from the RNA-DNA hybrid.
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PMID:Influence of protein and ribonucleic acid synthesis on the replication of the bacteriocinogenic factor Clo DF13 in Escherichia coli cells and minicells. 459 94

The effect of rifampin, an inhibitor of bacterial DNA-dependent RNA polymerase, was studied in Chlamydomonas reinhardi. It was shown, in vivo and in vitro, that chloroplast-located, but not nuclear, DNA-dependent RNA polymerase is inhibited by this drug. The inhibition of chloroplast RNA polymerase results in the inhibition of chloroplast rRNA synthesis, and thus in the loss of chloroplast ribosomes. The ability to carry out photosynthesis is also lost after prolonged heterotrophic growth in the presence of rifampin, but cell division and chloroplast replication are not affected. It is proposed that chloroplast DNA contains information for chloroplast rRNA, but this DNA does not have the information for chloroplast DNA polymerase. Moreover, the DNA polymerase is not synthesized on chloroplast ribosomes.
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PMID:Genetic functions of the chloroplast of Chlamydomonas reinhardi: effect of rifampin on chloroplast DNA-dependent RNA polymerase. 526 Sep 35

Terminal deoxynucleotidyl transferase (TdT) was used to prepare copolymers of dA and 1,N6-ethenodeoxyadenosine (epsilon dA). When used as templates for Escherichia coli DNA polymerase I (Pol I) and compared with poly (dA), normal dTTP incorporation was not significantly affected by the presence of 7% epsilon dA. dGTP misincorporation was only slightly increased and occurred about once for every 500 epsilon dA residues. The error-prone polymerase from avian myeloblastosis virus (AMV reverse transcriptase) increased this error rate 5- to 20-fold to a maximum of 1 dG/25 epsilon dA. No dCTP misincorporation was detected with either polymerase. In transcription with E. coli DNA-dependent RNA polymerase, no errors were revealed by nearest neighbor analysis. Poly (dA) treated with chloroacetaldehyde under conditions producing the same proportion of epsilon dA (without the hydrated form) as the synthesized template behaved in the same manner with a similar low level of misincorporation of dG. Such treatment of alternating poly d(A-T) caused structural changes indicative of crosslinks but did not alter its template properties. Increasing the amount of epsilon dA in either synthesized or modified polymers greatly decreased the template activity without increasing the error rate. It is suggested that epsilon dA generally does not prevent dT incorporation but behaves as a bulky lesion which is bypassed. In contrast to the low mutagenic efficiency of epsilon dA, O4-methyldeoxythymidine (m4dT), in copolymers with dA, directed the misincorporation of 1 dG/12 m4dT with Pol I and 1 dG/3 m4dT with reverse transcriptase. Nearest neighbor analysis of transcripts showed the incorporation of 1 dG/12 m4dT. These data are in agreement with the previous reported mutagenicity of m4dT in alternating poly d(A-T, m4T).
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PMID:Assessment of mutagenic efficiency of two carcinogen-modified nucleosides, 1,N6-ethenodeoxyadenosine and O4-methyldeoxythymidine, using polymerases of varying fidelity. 620 83

A series of cyano- and carboxyborane adducts of cyclohexylamines and toluidines were shown to be cytotoxic towards suspended single cell tumors. The carboxyborane adducts of cyclohexylamine were more potent than the cyanoborane adducts of cyclohexylamine or any of the toluidine derivatives. A number of the compounds were active at 8 mg/kg/day i.p. in the Ehrlich ascites carcinoma screen in vivo. The mode of action study with N-methylcyclohexylaminecyanoborane 10 in L-1210 lymphoid leukemia cells showed that RNA synthesis was markedly reduced followed by DNA synthesis. Purine de novo synthesis was suppressed at PRPP-amido transferase, IMP dehydrogenase, and dihydrofolate reductase enzyme sites. The agent also interfered with DNA template activity causing reduction of DNA polymerase alpha, and RNA polymerase I, II and III activities. The d[NTP] pools were marginally reduced while DNA viscosity was reduced and DNA fragmentation occurred.
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PMID:Synthesis and cytotoxicity of amine-borane adducts of cyclohexylamines and toluidines. 858 54


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