Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.25 (triphosphatase)
 1,529 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The gene 4 protein of bacteriophage T7 is both a primase and a helicase. In this paper, we present a detailed description of a third activity, single-stranded DNA-dependent nucleoside 5'-triphosphate hydrolysis, and show that this activity is coupled to the unidirectional translocation of the gene 4 protein on single-stranded DNA (Tabor, S., and Richardson, C.C. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 205-209). The competitive inhibitor of NTP hydrolysis, beta, gamma-methylene dTTP, is also a potent inhibitor of gene 4 protein-dependent, RNA-primed DNA synthesis; inhibition is not due to a direct inhibition of T7 DNA polymerase or RNA primer synthesis. We conclude that the energy derived from the hydrolysis of NTPs by the gene 4 protein is required for translocation of the protein to primase recognition sites. Measurement of the rates of hydrolysis of NTPs using a variety of DNAs of known structure and length support the unidirectional translocation of the gene 4 protein on single-stranded DNA. Duplex DNA, RNA, and single-stranded DNA coated with single-stranded DNA-binding protein do not serve as effectors for the nucleoside triphosphatase of the gene 4 protein. Kinetic data suggest that the gene 4 protein does not remain bound to newly synthesized oligoribonucleotide primers but continues to search for other primase recognition sites. Although all the predominant naturally occurring NTPs except rCTP are hydrolyzed by the gene 4 protein, the enzyme shows specificity for dTTP with a Km of 0.4 mM. In the accompanying paper (Matson, S.W., Tabor, S., and Richardson, C.C. (1983) J. Biol. Chem. 258, 14017-14024), we show that the hydrolysis of NTPs is also required for the protein to function as a helicase in duplex regions of DNA.
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PMID:DNA-dependent nucleoside 5'-triphosphatase activity of the gene 4 protein of bacteriophage T7. 613 75

The complete hepatitis B virus (Dane particle) contains a circular doublestranded DNA with single stranded regions and an endogenous DNA polymerase. The HBV associated DNA polymerase closes the single stranded regions of the HBV-DNA in the presence of triphosphatase and a detergent. The DNA polymerase reaction can be inhibition by antiviral substances that exhibit different mode of actions: intercalating agents, phosphonoformiate and the triphosphates of arabinofuranosyladenine and arabinofuranosylcytosine. The value of these in vitro test for the therapy of HBsAg positive chronic liver disease is limited by the fact that is remains so far unclear whether the HBV associated DNA polymerase is a virus- or a host-coded enzyme, and whether virus- or host-coded enzymes are involved in HBV-DNA synthesis in vivo.
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PMID:[Inhibition of hepatitis B virus associated DNA polymerase by antiviral agents: in vitro studies with clinical implications (author's transl)]. 645 51

Nuclei isolated from Yoshida sarcoma cells had activity for conversion of dGTP dependent on DNA synthesis. The ratio of nucleotide generation/generation + incorporation was 0.4 +/0- 0.1, indicating that approx. 40% of the incorporated dGMP was excised. Two lines of evidence indicated the dependence of this activity on DNA synthesis. (1) The activity was observed only in the presence of ATP, which is essential for nuclear DNA synthesis. (2) Inhibitors of DNA synthesis, such as N-ethylmaleimide, aphidicolin, spermine and KCl, also inhibited ATP- or DNA synthesis-dependent dGMP generation. Although nuclei contain nucleoside triphosphatase (N-nucleotidase), this enzyme was not involved appreciably in DNA synthesis-dependent dGMP generation. The reason for this was explained by the following findings. (a) Inhibitors did not decrease dGMP production in the complete absence of DNA synthesis. (b) Inhibitors did not inactivate N-nucleotidase to the same degree as they inhibited DNA synthesis-dependent dGMP generation. (c) Addition of ATP reduced dGMP hydrolysis catalyzed by N-nucleotidase. (d) GDP has no appreciable effect on DNA synthesis-dependent dGMP generation, but had a diluting effect on dGMP production catalyzed by N-nucleotidase. These results show that the pathway of dGMP generation in isolated nuclei was switched on addition of ATP from a N-nucleotidase-catalyzed one to a DNA polymerase-exonuclease-catalyzed one.
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PMID:Conversion of dNTP to dNMP dependent on DNA synthesis in isolated Yoshida sarcoma nuclei. 706 29

The herpes simplex virus type 1 (HSV) UL5, UL8, and UL52 proteins form a helicase-primase complex in infected cells. Several laboratories have demonstrated that helicase and nucleoside triphosphatase activities of the heterotrimer (UL5/8/52) are indistinguishable from that of a subassembly of UL5 and UL52 (UL5/52). Although the UL5/52 subassembly functions in coupled primase-polymerase assays on homopolymeric templates, its activity on natural DNA templates has been reported to require UL8. To determine the role of UL8 in primase assays, the activity of the UL5/52 subassembly was compared to that of the heterotrimer reconstituted by adding UL8 to UL5/52. We detected significant activity of the UL5/52 subassembly in coupled primase-polymerase and oligoribonucleotide primer synthesis assays on phi X174 and M13 virion DNAs. However the addition of UL8 to UL5/52 stimulated this activity in a dose-dependent manner. We demonstrate that stimulation occurred at the level of primer synthesis. UL8 did not affect the amount or size of primers annealed to template, their utilization by DNA polymerase, or the use of specific initiation sites within the template. In kinetic studies, the rate of primer synthesis was increased by UL8 but the Km for phi X174 DNA template was unchanged. These results suggest that a function of the UL8 component of the HSV helicase-primase complex is to increase the efficiency of primer synthesis by UL5/52.
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PMID:The UL8 component of the herpes simplex virus helicase-primase complex stimulates primer synthesis by a subassembly of the UL5 and UL52 components. 810 78

The nucleotide sequence of the genome of Chilo iridescent virus (CIV) between the genome coordinates 0.974 and 0.101 comprising 27,079 bp was determined. Computer-assisted analysis of the DNA sequence of this particular region of the CIV genome revealed the presence of 42 potential open reading frames (ORFs) with coding capacities for polypeptides ranging from 50 to 1,273 amino acid residues. The analysis of the amino acid sequences deduced from the individual ORFs resulted in the identification of 10 potential viral genes that show significant homology to functionally characterized proteins of other species. A cluster of five viral genes that encode enzymes involved in the viral DNA replication was identified including the DNA topoisomerase II (A039L,1,132 amino acids (aa)), the DNA polymerase (ORF A031L,1,273 aa), a helicase (ORF A027L, 530 aa), a nucleoside triphosphatase I (ORF A025L, 1,171 aa), and an exonuclease II (ORF A019L, 624aa), all ORFs possessing the same genomic orientation. The DNA polymerase of CIV showed the highest homology (24.8% identity) to the DNA polymerase of lymphocystis disease virus lymphocystis disease virus 1 (LCDV-1), a member of the family Iridoviridae, indicating the close relatedness of the two viruses. In addition, four putative gene products were found to be significantly homologous to previously identified hypothetical proteins of CIV.
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PMID:Identification of a gene cluster within the genome of Chilo iridescent virus encoding enzymes involved in viral DNA replication and processing. 1045 93

Cytoplasmic replication of poxviruses dictates the encoding of most, if not all, of the trans-acting factors required for faithful genome duplication. Several of these proteins have been identified through genetic and biochemical evaluation, including the catalytic DNA polymerase (E9), an essential and stoichiometric component of the processive polymerase (A20), a single-strand DNA-binding protein (I3), a type I topoisomerase (H6), the uracil DNA glycosylase (D4), a nucleic acid-independent nucleoside triphosphatase (D5), a serine/threonine protein kinase (B1), and a Holliday Junction resolvase (A22). All of these factors work in concert to faithfully duplicate the viral genome. Although a replication origin has not been defined for the poxviruses, cis-acting sequences found within the telomeric 200 bp have been implicated as necessary and sufficient for minichromosome replication. Replication occurs within cytoplasmic foci from approx 3 to 12 h postinfection. This chapter includes several methodologies to assay and quantitate replication in vivo, visualize replication foci microscopically, and test the integrity of central replication enzymes in vitro.
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PMID:Methods for analysis of poxvirus DNA replication. 1511 16