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)

A new DNA polymerase and DNase activity were identified from cells infected with human B-lymphotropic herpesvirus (HBLV). DNA polymerase associated with HBLV infection was similar in its sensitivity to inhibition by ppi analogs as other herpesvirus-specific DNA polymerases but was dissimilar in its inhibition by certain nucleoside triphosphates.
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PMID:Identification and some properties of a unique DNA polymerase from cells infected with human B-lymphotropic virus. 278 39

PM2 duplex DNA substrates containing small gaps were utilized to study DNA repair reactions of extensively purified HeLa DNase V (a bidirectional double strand DNA exonuclease) and DNA polymerases beta, gamma (mitochondrial and extramitochondrial), and alpha holoenzyme, and delta as a function of ionic strength. At 50 mM NaCl, DNase V carried out extensive exonucleolytic degradation, and beta-polymerase exhibited strand displacement synthesis. However, at 150 mM NaCl, the DNase appeared only to remove damaged nucleotides from DNA termini while beta-polymerase catalyzed only gap-filling synthesis. When present in equimolar amounts, beta-polymerase and DNase V (which can be isolated as a 1:1 complex) catalyzed more degradation than synthesis at 50 mM NaCl; however, at 150 mM NaCl a coupled very limited nick translation reaction ensued. At physiological ionic strength DNA polymerase alpha holoenzyme was not active upon these substrates. In 15 mM KCl it could fill small gaps and carry out limited nick translation with undamaged DNA, but it could not create a ligatable substrate from UV-irradiated DNA incised with T4 UV endonuclease. Mitochondrial DNA polymerase gamma was more active at 150 mM NaCl than at lower ionic strengths. It readily filled small gaps but was only marginally capable of strand-displacement synthesis. The extramitochondrial form of gamma-polymerase, conversely, was less sensitive to ionic strength; it too easily filled small gaps but was not effective in catalyzing strand displacement synthesis. Finally, DNA polymerase delta was able to fill gaps of several to 20 nucleotides in 0.05 M NaCl, but at higher NaCl concentrations there was little activity. DNA polymerases delta did not demonstrate strand displacement synthesis. Therefore, at physiological ionic strength, it appears that either DNA polymerase beta or extramitochondrial DNA polymerase gamma might aid in short patch DNA repair of nuclear (or transfecting) DNAs, whereas mitochondrial gamma-polymerase might fill small gaps in mitochondrial DNA.
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PMID:DNA-repair reactions by purified HeLa DNA polymerases and exonucleases. 284 25

In an attempt to examine further the association between active Epstein-Barr virus (EBV) infection and the chronic fatigue syndrome (chronic EBV syndrome, or chronic or atypical mononucleosis), antibodies acting against EBV-specific DNase and DNA polymerase, which are expressed only during virus replication, were assayed. Serum samples from 25 healthy EBV-seropositive individuals neutralized 3.5 +/- 5.1 U (mean +/- SD) of DNase activity and 14.7 +/- 8.5 U of DNA polymerase activity. From these values were selected upper limits of anti-EBV enzyme activity of 17.9 and 31.3 U neutralized in normal individuals, respectively (representing the 95% confidence limit). Serum samples from six groups of subjects representing a variety of EBV-related illnesses were then studied. Only patients with notably elevated anti-EBV antibody titers to viral capsid antigen (VCA) (greater than 10,000) had elevated levels of anti-EBV DNase (38 to 56 U neutralized) and anti-EBV DNA polymerase (72 to 106 U neutralized). Three additional patients and two geriatric controls with average anti-EBV early antigen/VCA titers had slightly elevated levels of antibody to EBV DNA polymerase. IgA anti-VCA, anti-early antigen antibodies, or both, were also detected in the same patients who had high EBV DNase and polymerase antibody levels. These antibody profiles are similar to those in patients with nasopharyngeal carcinoma. Since three of the six patients with elevated anti-EBV enzyme antibody levels developed fatal lymphomas, patients with chronic EBV and this antibody profile might be in another illness category at risk for malignant disease.
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PMID:Antibodies to Epstein-Barr virus-specific DNase and DNA polymerase in the chronic fatigue syndrome. 284 38

The DNase that is associated with a multiprotein form of HeLa cell DNA polymerase alpha (polymerase alpha 2) has two distinct exonuclease activities: the major activity initiates hydrolysis from the 3' terminus and the other from the 5' terminus of single-stranded DNA. The two exonuclease activities show identical rates of thermal inactivation and coincidental migration during chromatofocusing, glycerol gradient centrifugation, and nondenaturing polyacrylamide gel electrophoresis of the DNase. Moreover, the purified DNase shows a single protein band of Mr 69,000 following nondenaturing polyacrylamide and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The 3'----5' exonuclease activity hydrolyzes only single-stranded DNA substrates and the products are 5' mononucleotides. This activity recognizes and excizes mismatched bases at the 3' terminus of double-stranded DNA substrates. The 3'----5' exonuclease does not hydrolyze 3' phosphoryl terminated single-stranded DNA substrates. The 5'----3' exonuclease activity also only hydrolyzes single-stranded DNA substrates. The rate of hydrolysis, however is only about 1/25th the rate of the 3'----5' exonuclease. This exonuclease activity requires a 5' single-stranded terminus in order to initiate hydrolysis and does not proceed into double-stranded regions. The products of hydrolysis by 5'----3' exonuclease are also 5' nucleoside monophosphates.
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PMID:Exonuclease activity associated with a multiprotein form of HeLa cell DNA polymerase alpha. Purification and properties of the exonuclease. 300 66

Epstein-Barr virus (EBV) has been found to be associated with nasopharyngeal carcinoma (NPC), and antibodies with high frequency and titer to EBV proteins have been found in sera from NPC patients. Raji cells, an EBV genome-carrying nonproducer cell line, treated with 12-O-tetradecanoylphorbol-13-acetate and n-butyrate induced a unique EBV DNA polymerase which has properties similar to the EBV DNA polymerase induced by 12-O-tetradecanoylphorbol-13-acetate in P3HR-1 cells, an EBV producer cell line. The possible presence of antibodies to this EBV DNA polymerase in NPC patient serum was examined. The mean number of EBV DNA polymerase units neutralized was 380 +/- 168 units/ml serum (mean +/- SD) in 48 sera from patients with NPC, whereas that in the sera from 52 healthy donors was 62 +/- 56 units/ml (p less than 0.01). The EBV DNA polymerase antibody was found to be associated with the immunoglobulin G but not the immunoglobulin A fraction, and its titer was not correlated with the titers against EBV DNase or virus capsid antigen-immunoglobulin A. Whether the EBV DNA polymerase antibody is against the EBV DNA polymerase core protein or its stimulating protein is still being investigated. This study demonstrated the high frequency and high titer of antibody against EBV DNA polymerase in serum from NPC patients and suggested the potential of utilizing this antibody titer to complement other methods for the early diagnosis or prognosis of NPC.
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PMID:Demonstration of Epstein-Barr virus-specific DNA polymerase in chemically induced Raji cells and its antibody in serum from patients with nasopharyngeal carcinoma. 301 19

The localization of ICP 4, ICP 8, DNA polymerase and alkaline exonuclease within herpes simplex virus type 1 (HSV)-infected cells has been examined by immunofluorescence using specific antibodies to these proteins. Cells were simultaneously counterstained with the DNA-binding fluorochrome 4,6-diamidino-2-phenylindole (DAPI) to reveal the intranuclear distribution of DNA. These studies showed that in the absence of virus DNA replication ICP 4, ICP 8 and DNA polymerase were diffusely distributed throughout the nucleus but during virus DNA replication these proteins accumulated at specific foci within the nucleus. Initially these foci were near the nuclear membrane but with continuing virus DNA replication they increased in size until the whole of the nucleus became affected. The increase in size of these foci was coincident with a redistribution of nuclear DNA and margination of chromatin at the nuclear membrane, as revealed by DAPI staining. The number of foci initially present in an infected cell was dependent on the multiplicity of infection. The distribution of ICP 4, ICP 8 and DNA polymerase within the nucleus was altered by treating the cells with DNase. The majority of alkaline exonuclease was diffusely distributed throughout the nucleus during virus DNA replication and did not localize at specific foci within the nucleus. Autoradiographic examination of the incorporation of [3H]thymidine in cells infected with HSV showed that viral DNA replication occurred in restricted areas within the nucleus that were similar, in terms of number, location and size, to the foci where ICP 4, ICP 8 and DNA polymerase accumulated. Furthermore, in cells blocked in mitosis following infection with HSV, ICP 4, ICP 8 and DNA polymerase, but not alkaline exonuclease, localized in areas outside the condensed chromatin structures. DAPI staining revealed the presence of DNA in these areas and, as such structures were never seen when uninfected cells had entered mitosis, it is suggested that this extrachromosomal DNA is of viral origin. These studies therefore suggest that ICP 4 is associated with progeny virus DNA and that while its intranuclear localization is initially at non-viral sites, as DNA replication proceeds so ICP 4 is recruited into areas of virus DNA transcription and replication.
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PMID:Intranuclear localization of herpes simplex virus immediate-early and delayed-early proteins: evidence that ICP 4 is associated with progeny virus DNA. 302 Jan 58

A tumor-derived factor that inhibits cellular DNA synthesis was identified. The factor was extractable from a small-cell lung carcinoma cell line grown in either chemically defined medium or nu/nu mice and inhibited tritiated thymidine ([3H]dThd) incorporation by tumor cell lines of autologous, allogeneic, and xenogeneic origins. The viability of nonproliferating cells from normal tissue was not affected. Tumor extract inhibitory activity was trypsin labile but was resistant to other proteases, neuraminidase, lipase, DNase, RNase, glucosidase, extremes of pH-temperature, and reducing conditions. Inhibitory activity was reversibly bound to helix pomatia lectin but not to lentil, wheat germ, or concanavalin A lectins. Purification by size-exclusion high-performance liquid chromatography yielded a bioactive unimodal 12-kilodalton (kd) peak. The bioactive 12-kd moiety could be eluted from sodium dodecyl sulfate-polyacrylamide gels. Redosing of populations of the T-lymphoblastoid cell line CEM achieved an early (24 hr) sustained depression of pulse [3H]dThd incorporation and ultimately led to decreased population density of factor-treated populations. DNA histogram analysis demonstrated no change in cell cycle phase distribution after factor treatment. 5-Bromo-2'-deoxyuridine (BrdUrd) vs. propidium iodide with the two-parameter Fluorescence-Activated Cell Sorter analysis showed relative inhibition of non-S-phase BrdUrd uptake at 24 hours. A cell-free DNA polymerase assay demonstrated significant inhibition of non-alpha-polymerase-associated DNA synthesis in factor-treated cells. These studies suggest that this tumor-derived inhibitor of DNA synthesis represents a class of cellular products involved in the autoregulation of growth by regulation of DNA synthetic activity.
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PMID:Inhibition of DNA synthesis by a small-cell lung carcinoma-derived protein. 302 Mar 1

A procedure was developed for cloning and characterizing genes that encode proteins with nuclease activity in the Streptococcus pneumoniae [pLS1] host/vector system. Clones are screened for nuclease activity by a DNase colony assay and the nucleases that they produce are characterized by detection of enzyme activity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The method was used to clone the gene encoding a DNA polymerase (Pol)-exonuclease of S. pneumoniae. The activity of this enzyme, the predominant DNA Pol of S. pneumoniae, is tenfold greater in cells carrying the multicopy recombinant plasmid than in cells without the plasmid. The enzyme corresponds to a 100-kDa polypeptide, and its properties are similar to PolI of Escherichia coli. A restriction map of the pSM22 plasmid containing the pneumococcal polA gene was obtained. The gene was transferred into Bacillus subtilis and E. coli, and it was expressed in both species. Its direction of transcription was determined by placement of the gene in both orientations in an E. coli hyperexpression plasmid. In one of the orientations the pneumococcal PolI enzyme was produced at a level 50-fold greater than normally found in S. pneumoniae, and it comprised 5% of the total protein.
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PMID:Cloning of a gene encoding a DNA polymerase-exonuclease of Streptococcus pneumoniae. 302 92

Nutrient-depleted conditions, which induced an inhibited state in uninfected cell monolayers, rendered the cells nonpermissive for vaccinia virus, while not affecting their ability to support propagation of an unrelated mengovirus. When the inhibited state was reversed, the ability to propagate vaccinia virus was restored. The inhibited cells retained the ability to support some early-induced events (thymidine kinase synthesis and its arrest, which are DNA synthesis-independent functions in a mouse cell host), but lost the ability to support some others (sensitization of input viral DNA to DNase, induction of DNA polymerase synthesis, and virus-induced CPE). The data are consistent with involvement of a host factor(s) in induction of early vaccinia virus-induced events in infected cells.
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PMID:Host involvement in vaccinia virus replication. 303 43

Phorbol esters and n-butyrate (SB) together could induce Epstein-Barr virus (EBV) DNA polymerase and DNase activities in Raji cells (virus nonproducer). Neither 12-O-tetradecanoylphorbol-13-acetate (TPA) nor SB alone could induce these EBV enzyme activities, transcription of the EcoRI C-region or other EBV proteins in Raji cells. The enzyme induction caused by exposure of Raji cells to TPA-SB was the result of the synthesis of virus-specified RNA, and the increase of linear EBV DNA content in Raji cells caused by TPA alone was not sufficient for induction of EBV-enzyme activities. Temporal characteristics of the TPA-SB induction process, but not the phorbol 12,13-dibutyrate-SB induction process, in Raji cells were observed; a critical phase (10-24 h) postphorbol ester treatment in phorbol 12,13-dibutyrate-SB-treated Raji cells which was responsible for the synthesis of virus RNA and enzymes was found. Phospholipase C, which increases intracellular diacylglycerols (and subsequently activates protein kinase C) was able to partially substitute for TPA in the TPA-SB induction for EBV polymerase and DNase activities. Sphingosine, a protein kinase C inhibitor, partially prevented the induction of virus enzyme activities in Raji cells treated with phorbol 12,13-dibutyrate and SB. No apparent changes in the methylation state of EBV DNA (EcoRI C region) were observed when Raji cells were treated with SB and TPA, alone or in combination. These results suggest that induction of EBV polymerase and DNase activities by TPA-SB may involve protein kinase C activation and another factor triggered by SB which together increase transcription of EBV DNA.
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PMID:Induction of virus enzymes by phorbol esters and n-butyrate in Epstein-Barr virus genome-carrying Raji cells. 303 11


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