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)

(S)-1-[3-Hydroxy-2-(phosphonylmethoxy)propyl]cytosine (HPMPC) is an antiviral phosphonate nucleotide analogue that displays activity against a range of herpesviruses. Anion exchange high performance liquid chromatography analysis of the 60% methanol extract from [14C]HPMPC-treated cells reveals the formation of three major metabolites. Two of these were identified as phosphorylated forms of HPMPC, HPMPC phosphate, and HPMPC diphosphate, by liberation of HPMPC upon acid digestion and coelution with synthetic standards on high performance liquid chromatography. The third metabolite, which is resistant to alkaline phosphatase cleavage but sensitive to phosphodiesterase, is proposed to be an HPMPC phosphate adduct. In herpes simplex virus-1-infected cells the same three metabolites are detected, at concentrations comparable to those in uninfected cells. When HPMPC is removed from the medium, the concentrations of the metabolites in cells decrease slowly, with half-lives of approximately 6, 17, and 48 hr for HPMPC phosphate, HPMPC diphosphate, and the HPMPC phosphate adduct, respectively. HPMPC diphosphate inhibits herpes simplex virus-1 and -2 DNA polymerases with a lower Ki than that for DNA polymerase alpha, and enzyme inhibition is competitive in each case. The formation and the persistence of HPMPC phosphates in cells and the selective inhibition of viral DNA polymerases by HPMPC diphosphate can explain why cells pretreated with HPMPC remain refractory to viral infection even long after HPMPC is removed from the medium.
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PMID:Intracellular metabolism of the antiherpes agent (S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl]cytosine. 131 Jan 43

Three independently isolated mutants of human cytomegalovirus strain AD169 were found to be resistant to ganciclovir at a 50% effective dose of 200 microM. Phosphorylation of ganciclovir was reduced 10-fold in mutant-infected cells compared with AD169-infected cells. All three mutants were also determined to be resistant to the nucleotide analogs (S)-1-[(3-hydroxy-2- phosphonylmethoxy)propyl]adenine (HPMPA) and (S)-1-[(3-hydroxy-2-phosphonylmethoxy)propyl]cytosine (HPMPC) and hypersensitive to thymine-1-D-arabinofuranoside (AraT). Single base changes resulting in amino acid substitutions were demonstrated in the nucleotide sequence of the DNA polymerase gene of each mutant. The polymerase mutation contained in one of the mutants was transferred to the wild-type AD169 background. Ganciclovir phosphorylation in cells infected with the recombinant virus produced by this transfer was found to be equivalent to that of AD169-infected cells. The ganciclovir resistance of the recombinant was reduced fourfold compared with that of the parental mutant; however, the recombinant remained resistant to HPMPA and HPMPC and hypersensitive to AraT. The ganciclovir resistance of the mutants therefore appears to result from mutations in two genes: (i) a kinase which phosphorylates ganciclovir and (ii) the viral DNA polymerase.
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PMID:Point mutations in the DNA polymerase gene of human cytomegalovirus that result in resistance to antiviral agents. 133 15

Cytomegalovirus strains with reduced in vitro susceptibilities to ganciclovir have been recovered from patients who failed long-term ganciclovir therapy. The ganciclovir-resistant clinical isolates in this study were unable to induce ganciclovir phosphorylation in virus-infected cells. The viral DNA polymerase function appeared unaltered in one genetically pure ganciclovir-resistant strain, compared with that of its wild-type ganciclovir-sensitive counterpart. All nine of the ganciclovir-resistant strains were susceptible to foscarnet. Moreover, these strains were sensitive to inhibition both by vidarabine and 1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine (FIAC), antiviral agents that are activated by cellular enzymes, and by (S)-1(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), which is a monophosphate nucleoside analog. The in vitro resistance to ganciclovir of the ganciclovir-resistant clinical isolates studied was attributed to the inability of the cells infected with these isolates to phosphorylate ganciclovir; the virally encoded DNA polymerase did not appear to play a role in this ganciclovir resistance.
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PMID:Ganciclovir-resistant cytomegalovirus clinical isolates: mode of resistance to ganciclovir. 166 92

The acyclic nucleoside phosphonate analogues (HPMPA, HPMPC, PMEA, FPMPA) show great promise for the treatment of infections with such important human pathogens as adeno, pox (vaccinia) and hepadna (hepatitis B) viruses (HPMPA), herpes (herpes simplex, varicella-zoster, cytomegalo, Epstein-Barr) viruses (HPMPC), and retro (human immunodeficiency) viruses (PMEA, FPMPA). All these compounds seem to be targeted at the viral DNA polymerase, with which they interact, as either competitive inhibitors or alternative substrates (or chain terminators), following their intracellular phosphorylation to the diphosphoryl derivatives. Of particular interest is the prolonged anti-viral action, lasting for several days or even weeks, that has been noted both in vitro and in vivo after a single administration of the acyclic nucleoside phosphonates.
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PMID:Chemotherapy of the acquired immune deficiency syndrome (AIDS): acyclic nucleoside phosphonate analogues. 182 10

Resistance of human cytomegalovirus to approved antiviral drugs is becoming a problem of increasing concern. In order to further study drug resistance in a related virus, strains of murine cytomegalovirus (MCMV) have been prepared in vitro by extensive adaptation of the virus to increasingly higher concentrations of either ganciclovir, foscarnet, or (S)-9-(3-hydroxy-2-[phosphonylmethoxy]propyl)cytosine (HPMPC). Plaque reduction 50% effective concentrations (EC50) for the above inhibitors increased 9-, 7-, and 23-fold, respectively (against the corresponding virus), compared to wild-type MCMV. Each virus was then evaluated against other known anti-MCMV agents to determine cross-resistance patterns. These compounds included 3-hydroxy-phosphonylmethoxypropyl derivatives of adenine (HPMPA) and guanine (HPMPG), 2-phosphonylmethoxyethyl derivatives of adenine (PMEA) and 2,6-diaminopurine (PMEDAP), cyclobutylguanine, acyclovir, and the methylene phosphonate derivatives of acyclovir (SR3722) and ganciclovir (SR3773). The ganciclovir-resistant MCMV was cross-resistant to foscarnet, HPMPA, HPMPC, HPMPG, SR3722, and SR3773. The foscarnet-resistant virus was also resistant to acyclovir, PMEA, PMEDAP, SR3722, and SR3773. The HPMPC-resistant MCMV was cross-resistant to HPMPA, HPMPG, and SR3773. Changes in susceptibility were from 3- to 22-fold relative to the wild-type virus. Virus yield reduction data correlated with the plaque assay results. Only cyclobutylguanine was approximately equally active against wild-type and the three drug-resistant MCMVs. The patterns of cross-resistance correlated with resistance seen in human cytomegalovirus strains expressing altered DNA polymerase function. The GCV-resistant and HPMPC-resistant viruses were markedly attenuated in their ability to kill severe combined immunodeficient mice.
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PMID:Antiviral activities of nucleosides and nucleotides against wild-type and drug-resistant strains of murine cytomegalovirus. 774 17

The inhibitory effects of the diphosphate of (S)-1-(3-hydroxy-2-phosphonylmethoxy-propyl)cytosine (HPMPCpp) toward human DNA polymerases beta and gamma were studied. The Ki values of HPMPCpp were compared with the Ki values of the triphosphates of 3'-azidothymidine (AZTTP), 2',3'-dideoxycytidine (ddCTP) and 5-iodo-2'-fluoroarabinosyluridine (FIAUTP). The Ki values toward DNA polymerase beta in increasing order were 1.32, 1.43, 140, and 520 microM for ddCTP, FIAUTP, AZTTP and HPMPCpp, respectively. The Ki values toward DNA polymerase gamma in increasing order were 0.034, 0.031, 18.3 and 299 microM for ddCTP, FIAUTP, AZTTP and HPMPCpp, respectively. Therefore, HPMPC would be expected to have less inhibitory effects on DNA repair (DNA polymerase beta) and mitochondrial DNA synthesis (DNA polymerase gamma) than ddC, FIAU or AZT.
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PMID:Kinetic analysis of the interaction between the diphosphate of (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine, ddCTP, AZTTP, and FIAUTP with human DNA polymerases beta and gamma. 798 13

Foremost among the acyclic nucleoside phosphonates currently pursued for their potential in the treatment of herpes and retrovirus infections are (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC) and 9-(2-phosphonylmethoxyethyl)adenine (PMEA). These compounds are as such taken up by the cells and then phosphorylated by cellular enzymes to their diphosphoryl derivatives HPMPCpp and PMEApp. The main target for the antiviral action of HPMPCpp and PMEApp is the viral DNA polymerase. Whereas PMEApp has been shown to interact as a DNA chain terminator with both retro- and herpes viruses, the mechanism by which HPMPCpp inhibits herpes viral DNA synthesis remains the subject of further study.
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PMID:Mechanism of action of acyclic nucleoside phosphonates against herpes virus replication. 831 44

Three human cytomegalovirus (HCMV) strains (VR4760, VR4955, and VR5120) showing double resistance to ganciclovir (GCV) and foscarnet (PFA) were isolated from three patients with AIDS who underwent multiple sequential courses of therapy with GCV and PFA (A. Sarasini, F. Baldanti, M. Furione, E. Percivalle, R. Brerra, M. Barbi, and G. Gerna, J. Med. Virol., 47:237-244, 1995). We previously demonstrated that the three strains were genetically unrelated and that each of them was present as a single viral population in vivo. Thus, in each of the three cases, a single viral strain was resistant to both GCV and PFA. In the present paper, we report the characterization of the molecular bases of the double resistance and demonstrate that the PFA resistance is associated with a slower replication of HCMV strains in cell cultures. Sequencing of the UL97 and UL54 genes, GCV anabolism assays, and marker transfer experiments showed that GCV resistance was due to single amino acid changes in the UL97 gene product (VR4760, Met-460 --> Ile; VR4955, Ala-594 --> Val; VR5120, Leu595 --> Ser), while single amino acid changes in domain II of the DNA polymerase (VR4760 and VR5120, Val-715 --> Met; VR4955, Thr-700 --> Ala) were responsible for both the PFA resistance and the slow-growth phenotype. Thus, in these three cases, double resistance to GCV and PFA was not due to a single mutation conferring cross-resistance or to the presence of a mixture of strains with different drug susceptibilities. The HCMV DNA polymerase recombinant strains carrying the mutations conferring PFA resistance were sensitive to GCV and (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC). In addition, the same UL54 mutations were responsible for the slow growth of the clinical isolates, since the recombinant strains showed a marked delay in immediate-early antigen plaque formation and a reduction of infectious virus yield compared with AD169, from which they were derived. These results may have some important implications for the successful isolation, propagation, and characterization of PFA-resistant strains from clinical samples containing mixed viral populations.
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PMID:Single amino acid changes in the DNA polymerase confer foscarnet resistance and slow-growth phenotype, while mutations in the UL97-encoded phosphotransferase confer ganciclovir resistance in three double-resistant human cytomegalovirus strains recovered from patients with AIDS. 862 55

Cidofovir [CDV,(S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine, HPMPC] is an acyclic cytosine nucleoside phosphonate analog with potent in vitro and in vivo activity against a broad spectrum of herpesviruses. CDV diphosphate (CDVpp), the putative antiviral metabolite of CDV, is a competitive inhibitor of dCTP and an alternate substrate for human cytomegalovirus (HCMV) DNA polymerase. HCMV DNA polymerase used a synthetic DNA primer-template with a Km value of 90 +/- 8 nM and incorporated dCTP approximately 42 times more efficiently than CDVpp. HCMV DNA polymerase also utilized a synthetic DNA primer containing a single molecule of CDV at the 3'-terminus. The Km value for this DNA primer-template was 165 +/- 42 nM and incorporation of dCTP was approximately 17 times more efficient than that of CDVpp. The slower rate of incorporation of CDVpp was due mostly to the higher Km value of CDVpp toward the enzyme-primer-template complexes. These data demonstrate that incorporation of a single CDV into DNA by HCMV DNA polymerase does not lead to chain termination.
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PMID:Kinetic analysis of the interaction of cidofovir diphosphate with human cytomegalovirus DNA polymerase. 863 98

(S)-1-(3-Hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC, Cidofovir, Vistide) is an acyclic nucleoside phosphonate with broad-spectrum activity against a wide variety of DNA viruses including herpesviruses [Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus type 6 (HHV-6) and equine and bovine herpesviruses], papovaviruses [human polyoma virus and human papilloma virus (HPV)], adeno-, irido-, hepadna-, and poxviruses. HPMPC has proved effective against these viruses in different cell culture systems and/or animal models. The mechanism of action of HPMPC is based upon the interaction of its active intracellular metabolite, the diphosphorylated HPMPC derivative HPMPCpp, with the viral DNA polymerase. HPMPCpp has been shown to block CMV DNA synthesis by DNA chain termination following incorporation of two consecutive HPMPC molecules at the 3'-end of the DNA chain. HPMPC confers a prolonged antiviral action, which lasts for several days or weeks, thus allowing infrequent dosing (i.e. every week or every two weeks). This prolonged antiviral action is probably due to the very long intracellular half-life of the HPMPC metabolites, particularly the HPMPCp-choline adduct. In clinical studies, HPMPC has proved efficacious in the treatment of CMV retinitis, following both intravenous injection (3 or 5 mg/kg, every other week) and intravitreal injection (single dose of 20 micrograms per eye). Initial clinical trials also point to the efficacy of both systemic (intravenous) and topical HPMPC (1% ointment) in the treatment of acyclovir-resistant HSV infections, and of topical HPMPC (ointment or injection) in the treatment of pharyngeal, laryngeal and anogenital HPV infections. HPMPC is now being pursued in the topical and/or systemic (intravenous) treatment of various infections due to CMV, HSV, VZV, EBV, HPV, polyoma-, adeno- and poxviruses.
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PMID:Therapeutic potential of Cidofovir (HPMPC, Vistide) for the treatment of DNA virus (i.e. herpes-, papova-, pox- and adenovirus) infections. 870


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