Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “HIV Reverse Transcriptase”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60Linked to original sources
PubMed1995

[Substrate properties of dioxolane analogs of 3'-deoxythymidine-5'-triphosphate in DNA synthesis reactions, catalyzed by various DNA polymerases].

The substrate properties of 3'-deoxythymidine 5'-triphosphate analogs prepared on the basis of 2,4-disubstituted 1,3-dioxolanes were investigated in reactions of the DNA synthesis catalyzed by various DNA polymerases. The 4'-triphosphates of (+/-)-cis-4-hydroxymethyl-2-(1-thyminylmethyl)-1,3-dioxolane and the corresponding (+/-)-trans-isomer were shown to be terminating substrates of terminal deoxynucleotidyl transferase. 4'-Triphosphate of (+/-)-cis-4-hydroxymethyl-2-(1-thyminylmethyl)- 1,3-dioxolane terminates the DNA synthesis catalyzed by HIV reverse transcriptase, whereas 2'-triphosphate of (+/-)-cis-2-hydromethyl-4-(1-thyminylmethyl)-1,3-dioxolane is a terminator in the DNA synthesis catalyzed by HIV reverse transcriptase and the Klenow fragment of DNA polymerase I.

Base Sequence↗
PubMed1992

Synthesis and evaluation of 2-pyridinone derivatives as HIV-1 specific reverse transcriptase inhibitors. 1. Phthalimidoalkyl and -alkylamino analogues.

A potent (IC50 = 30 nM), specific nonnucleoside HIV-1 reverse transcriptase (RT) inhibitor 3-[N-(phthalimidomethyl)amino]-5-ethyl-6-methylpyridin-2(1H) -one (1), was discovered through an in vitro screening program. This compound did not inhibit (IC50 > 300 microns) other DNA and RNA polymerases, including HIV-2 RT and SIV-RT. Unfortunately, hydrolytic instability of this (aminomethyl)phthalimide precluded use as an antiviral agent. In the first paper of this series, preliminary development efforts are described which produced ethylphthalimide 20, a hydrolytically stable compound with reduced (100-fold) HIV-1 RT inhibitory activity and weak (CIC95 = 40 microM) antiviral activity in H9 cells. Structure-activity studies demonstrated the importance of the 5-ethyl, 6-methyl substituent pattern on the pyridinone ring and the need for a flexible two-atom linker between the pyridinone and phthalimide heterocycles. These leads, 1 and 20, provided a basis for the further development of this structural class of inhibitors from which several compounds, the subject of accompanying reports, were selected for clinical evaluation.

Antiviral Agents↗
PubMed2001

Chiral resolution and molecular modeling investigation of rac-2-cyclopentylthio-6-[1-(2,6-difluorophenyl)ethyl]-3,4-dihydro-5-methylpyrimidin-4(3H)-one (MC-1047), a potent anti-HIV-1 reverse transcriptase agent of the DABO class.

rac-2-Cyclopentylthio-6-[1-(2,6-difluorophenyl)ethyl]-3,4-dihydro-5-methylpyrimidin-4(3H)-one (MC-1047) is a potent inhibitor of HIV-1 multiplication in acutely infected cells. MC-1047 racemate has been resolved by chiral HPLC using, as chiral stationary phase (CSP), a commercially available (R,R)-Whelk-01 column. The optical purity and the circular dichroism (CD) of the two resolved enantiomers were determined and their biological activities tested in in vitro assays. Molecular modeling inspection of the binding of (R) and (S) enantiomers to the non-nucleoside binding site (NNBS) of reverse transcriptase (RT) using the defined model of F(2)-S-DABO/RT complex indicates the (R) enantiomer as the more active isomer.

Anti-HIV Agents↗
PubMed1992

Synthesis and evaluation of 2-pyridinone derivatives as HIV-1-specific reverse transcriptase inhibitors. 2. Analogues of 3-aminopyridin-2(1H)-one.

A series of nonnucleoside 3-aminopyridin-2(1H)-one derivatives was synthesized and evaluated for HIV-1 RT inhibitory properties. Several analogs proved to be potent and highly selective antagonists with in vitro IC50 values as low as 19 nM in the enzyme assay using rC.dG as template-primer. Two compounds from this series, 3-[[(4,7-dimethylbenzoxazol-2-yl)methyl]-amino]-5-ethyl-6-methy lpyridin-2(1H)-one (34, L-697,639) and the corresponding 4,7-dichloro analogue (37, L-697,661) inhibited the spread of HIV-1 IIIb infection by 95% in MT4 cell culture at concentrations of 25-50 nM and were selected for clinical trials as antiviral agents.

Aminopyridines↗
PubMedDate not supplied

3D-quantitative structure-activity relationships of HEPT derivatives as HIV-1 reverse transcriptase inhibitors, based on Ab initio calculations.

Comparative molecular field analysis (CoMFA) has been applied to a large set of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) analogues. The starting geometry of HEPT was obtained from crystallographic data of HEPT/HIV-1 reverse transcriptase (RT) complexes. The structures of 101 HEPT derivatives were considered and fully optimized by ab initio molecular orbital calculations at the HF/3-21G level. The best CoMFA model is satisfactory in both statistical significance and predictive ability. It shows excellent, high predictive ability as r2cv = 0.858. The derived model indicates the importance of steric contributions (64.4%) as well as electrostatic interactions for the HIV-1 RT inhibition. In addition, steric and electrostatic contour maps from this analysis agree well with the experimentally observed trend that there are steric interactions between the side chain of HEPT and an aromatic ring of Tyr181. It is concluded that a moderately sized group at C5 enhances contact with Tyr181 enough to push it into a position which renders the protein nonfunctional, but a smaller group has insufficient steric requirements to do this and a larger group renders the ligand too large for the cavity. The mutation-induced resistance of reverse transcriptase is explained by this analysis. The obtained results not only lead to a better understanding of structural requirements of this set of compounds for the inhibition but also enable the suggestions for new and more potent drugs.

Algorithms↗
PubMedDate not supplied

[Nucleotide-dependent degradation of nucleic acids by DNA and RNA polymerases].

In this review we summarize the current knowledge about recently discovered reactions of nucleotide-dependent nucleic acid degradation catalyzed by DNA and RNA polymerases. These reactions consist in the excision of the 3'-nucleotide of nascent DNA or RNA chain in the presence of non-complementary r/dNTPs. In the case of DNA polymerases the dinucleoside-5',5"-tetraphosphate as a product of the reaction is formed. In contrast, in the case of RNA polymerases non-complementary r/dNTPs stimulate 3'-->5' exonuclease degradation of RNA transcript. The possible role of these reactions in fidelity of DNA and RNA synthesis, in resistance of HIV reverse transcriptase towards nucleoside inhibitors is discussed.

Catalysis↗
PubMed1993

Human immunodeficiency virus reverse transcriptase. A kinetic analysis of RNA-dependent and DNA-dependent DNA polymerization.

A minimal kinetic mechanism for HIV reverse transcriptase (RT)-catalyzed RNA-dependent and DNA-dependent DNA polymerization was determined by pre-steady-state kinetic methods to be: [formula: see text] where E, TP, dNTP, and PPi are RT, template-primer, 2'-deoxynucleoside 5'-triphosphate, and inorganic pyrophosphate, respectively. Defined sequence template-primers that encode for incorporation of dTTP were prepared by annealing either a 44-mer RNA template or a 44-mer DNA template (of the same sequence) to a 21-mer DNA primer (r44:d21-mer and d44:d21-mer, respectively). The values of the above kinetic constants were determined for dTMP and 3'-azido-3'-deoxythymidine 5'-monophosphate (AZTMP) incorporation into both template primers. The kcat and Km values calculated from these kinetic constants were similar to the values directly determined from steady-state experiments. Further, the net rate constants for processive incorporation of three successive nucleotides into the r44:d21-mer were similar indicating that a rate-determining step did not follow catalysis. A 20-fold difference in the rate constants (kp) for incorporation of dTMP into the r44:d21-mer versus the d44:d21-mer was largely responsible for the difference in the calculated processivity numbers of 340 and 5, respectively. Finally, the rate constant for pyrophosphorolysis of the 3'-AZTMP-terminated r44:d21-mer (kpyro) was similar to the rate constant for dissociation of the chain-terminated template primer from the enzyme (koff) indicating that millimolar concentrations of intracellular inorganic pyrophosphate would be required for pyrophosphorolysis of AZTMP-terminated retroviral genomes.

Base Sequence↗
PubMed2001

Inhibitors of human immunodeficiency virus type 1 reverse transcriptase target distinct phases of early reverse transcription.

Early HIV-1 reverse transcription can be separated into initiation and elongation phases. Here we show, using PCR analysis of negative-strand strong-stop DNA [(-)ssDNA] synthesis in intact virus, that different reverse transcriptase (RT) inhibitors affect distinct phases of early natural endogenous reverse transcription (NERT). The effects of nevirapine on NERT were consistent with a mechanism of action including both specific and nonspecific binding events. The nonspecific component of this inhibition targeted the elongation reaction, whereas the specific effect seemed principally to be directed at very early events (initiation or the initiation-elongation switch). In contrast, foscarnet and the nucleoside analog ddATP inhibited both early and late (-)ssDNA synthesis in a similar manner. We also examined compounds that targeted other viral proteins and found that Ro24-7429 (a Tat antagonist) and rosmarinic acid (an integrase inhibitor) also directly inhibited RT. Our results indicate that NERT can be used to identify and evaluate compounds that directly target the reverse transcription complex.

Anti-HIV Agents↗
PubMed1992

Extension of base mispairs by Taq DNA polymerase: implications for single nucleotide discrimination in PCR.

Thermus aquaticus (Taq) DNA polymerase was used to measure the extension efficiency for all configurations of matched and mismatched base pairs at template-primer 3'-termini. The transition mispairs, A(primer).C, C.A, G.T, and T.G were extended 10(-3) to 10(-4)-fold less efficiently than their correctly paired counterparts. Relative efficiencies for extending transversion mispairs were 10(-4) to 10(-5) for T.C and T.T, about 10(-6) for A.A, and less than 10(-6) for G.A, A.G, G.G and C.C. The transversion mispair C(primer).T was extended with high efficiency, about 10(-2) compared to a correct A.T basepair. The unexpected ease of extending the C.T mismatch was not likely to have been caused by primer-template misalignment. Taq polymerase was observed to bind with similar affinities to each of the correctly paired and mispaired primer-template 3'-ends. Thus, the failure of Taq polymerase to extend mismatches efficiently appears to be an intrinsic property of the enzyme and not due to an inability to bind to 3'-terminal mispairs. For almost all of the mispairs, C.T being the exception, Taq polymerase exhibits about 100 to 1000-fold greater discrimination against mismatch extension compared to avian myeloblastosis reverse transcriptase and HIV-1 reverse transcriptase which extend most mismatched basepairs permissively. Relative mismatch extension efficiencies for Taq polymerase were measured at 45 degrees C, 55 degrees C and 70 degrees C and found to be independent of temperature. The mispair extension data should be important in designing experiments using PCR to distinguish between sequences that vary by a single nucleotide.

Base Composition↗
PubMed1995

Inhibition of human immunodeficiency virus type 1 wild-type and mutant reverse transcriptases by the phenyl ethyl thiazolyl thiourea derivatives trovirdine and MSC-127.

A new class of very potent and selective non-nucleoside inhibitors of HIV reverse transcriptase (RT) has recently been identified. The prototype compound trovirdine (LY 300046 HCl) and one analogue, MSC-127, have been studied with respect to inhibition of wild-type HIV-1 RT and RT with various mutations known to give rise to resistance to other non-nucleoside RT inhibitors, namely Leu100-->Ile (Ile100), Glu138-->Arg (Arg138), Tyr181-->Cys (Cys181) and Tyr188-->His (His188). The inhibition of HIV-1 RT by trovirdine and MSC-127 was reversible and template dependent. Trovirdine inhibited HIV-1 RT with an IC50 of 0.007 microM when employing heteropolymeric primer/template (oligo-DNA/ribosomal RNA) and dGTP as substrate. Enzyme kinetic studies showed that inhibition of RT by trovirdine was non-competitive with regard to deoxynucleoside triphosphates and uncompetitive with respect to varied primer/template under steady-state conditions. The amino acid changes Leu100, Tyr181 and Tyr188 gave rise to 25-, 147- and 12-fold decrease in inhibition by trovirdine. Enzyme-kinetic studies on trovirdine have been carried out using various RT mutants and compared to the properties of the earlier reported non-nucleoside RT inhibitors 9-Cl-TIBO, nevirapine and L-697,661.

Antiviral Agents↗
PubMed2001

Hypogin, a novel antifungal peptide from peanuts with sequence similarity to peanut allergen.

A protein designated hypogin, with a prominent suppressive action on the growth of the fungi Mycosphaerella arachidicola, Fusarium oxysporum and Coprinus comatus, was isolated from seeds of the peanut Arachis hypogaea. The protein inhibited human immunodeficiency virus (HIV) reverse transcriptase and enzymes associated with HIV infection including alpha-glucosidase and beta-glucosidase. The proliferative response of mouse splenocytes was attenuated in the presence of the protein. The protein exhibited a molecular mass of 7.2 kDa in tricine gel electrophoresis and gel filtration on Superdex 75 and an N-terminal sequence resembling peanut allergen Ara H1. The isolation procedure involved affinity chromatography on Affi-gel blue gel and ion-exchange chromatography on CM-Sepharose. The protein was adsorbed in both chromatographic media.

Allergens↗
PubMed2001

Inhibitory effects of Korean plants on HIV-1 activities.

In the search for novel anti-human immunodeficiency virus type 1 (anti-HIV-1) agents from natural sources, 49 MeOH extracts of Korean plants were screened for their inhibitory effects against RNA-dependent DNA polymerase (RT) and ribonuclease H (RNase H) activities of HIV-1 reverse transcriptase and HIV-1 protease, and anti-HIV-1 activity. Regarding the HIV-1 reverse transcriptase, Agrimonia pilosa (whole plant), Cornus kousa (stem and leaf), Limonium tetragonum (root) and Mallotus japonicus (stem) showed significant inhibitory activity on RT activity with 50% inhibitory activity (IC(50)) of 8.9, 6.3, 7.5 and 11.9 microg/mL, respectively, whereas Agrimonia pilosa was also active against RNase H activity (IC(50) = 98.4 microg/mL). Four plants, namely Agrimonia pilosa (whole plant), Atractylodes japonica (root), Clematis heracleifolia (whole plant) and Syneilesis palmata (whole plant), were appreciably active (<35%) against recombinant HIV-1 protease at a concentration of 100 microg/mL. Crinum asiaticum var. japonicum (root) showed significant anti-HIV-1 activity (ED(50) = 12.5 microg/mL) with a favourable SI value of 16.

Anti-HIV Agents↗
PubMed2001

HIV protease and reverse transcriptase variation and therapy outcome in antiretroviral-naive individuals from a large North American cohort.

OBJECTIVE: To assess the effect of baseline HIV reverse transcriptase (RT) and protease sequence variation on virologic outcomes in a large cohort of antiretroviral-naive patients in British Columbia, Canada. METHODS: Population sequencing of RT and protease was performed on baseline viral RNA of all antiretroviral-naive patients first seeking treatment in British Columbia between June 1997 and August 1998 (n = 479). Relative risks of virological failure associated with genotypic differences from a 'standard' HIV strain (HXB2) were assessed for up to 18 months. RESULTS: The prevalence of key baseline mutations known to confer resistance to RT and protease inhibitors (PI) was 3.4 and 3.8%, respectively. No statistically significant impact on virologic outcomes could be established for these patients. However, the data suggest that some individuals (harboring a M184V mutation in RT or a V82I in protease) may have benefited from pre-therapy resistance tests. 'Secondary' mutations in the protease associated with resistance (e.g. codons 10, 36 or 63) were common, but the presence of these secondary mutations, either alone or in combination, did not appear to result in early loss of therapeutic virological suppression. Preliminary analyses suggest that an amino acid change at codon 35 in the protease may be associated with early treatment failure. CONCLUSIONS: The results suggest that routine genotyping of naive patients about to start antiretroviral therapy would be of benefit to a relatively small proportion of the population. Secondary mutations associated with resistance to PI alone were not found to affect virologic outcomes significantly.

Anti-HIV Agents↗
PubMed1991

[Polymerase and immunologic activity of reverse transcriptase of the HIV-1 virus, isolated from Escherichia coli].

The recombinant reverse transcriptase of HIV-1 virus has been isolated from Escherichia coli cells transformed by the plasmid pRT40 DNA. The 103 Kd protein produced by these cells is shown to be processed to proteins with lower molecular masses by the reverse transcriptases own protease activity as well as Escherichia coli proteases. The resulting 103-66 Kd proteins possess the polymerase activity while 51 Kd and smaller proteins are lacking the activity. The 66 and 51 Kd reverse transcriptase fragments demonstrate the positive immunological reaction with the human blood serum from the people possessing antibodies to HIV-1 virus. The recombinant reverse transcriptase of HIV-1 produced by Escherichia coli cells is shown to be useful in AIDS diagnosis in humans.

Acquired Immunodeficiency Syndrome↗
PubMed2005

The role of breast cancer resistance protein (BCRP/ABCG2) in cellular resistance to HIV-1 nucleoside reverse transcriptase inhibitors.

Treatment of HIV-1-infected patients with anti-retroviral agents is not always successful due to the emergence of resistant HIV-1 mutants with reduced susceptibility to the agents. However, factors other than viral mutation may also contribute to treatment failure. It has been demonstrated that the ATP-binding cassette (ABC) transporter P-glycoprotein (P-gp/ABCB1) is a key determinant of oral bioavailability of HIV-1 protease inhibitors and their penetration of the central nervous system. More recently, we have found that the expression of breast cancer resistance protein (BCRP/ABCG2) in a CD4+ T-cell line confers cellular resistance to nucleoside reverse transcriptase inhibitors (NRTIs). The anti-HIV-1 activity of the NRTI zidovudine (AZT) was significantly diminished through the reduction of its metabolite levels in MT-4 cells which express high levels of BCRP. Moreover, the BCRP-specific inhibitor fumitremorgin C could completely restore the cytotoxicity of AZT and intracellular levels of its metabolites in BCRP-expressing cells. Thus, BCRP is considered to be a cellular factor that modulates the anti-HIV-1 activity of NRTIs.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed1995

HIV-1 RNA serum-load and resistant viral genotypes during early zidovudine therapy.

The response of HIV-1 to initial zidovudine (ZDV) treatment was assessed in 11 patients with severe HIV disease. We quantified serum HIV-1 concentrations and mutations associated with ZDV resistance by culture-independent methods. There was a prompt fall in serum HIV-1 RNA within 1-2 days of treatment with maximum suppression by seven days, which was paralleled by changes in serum p24 antigen (p24 Ag). Serum RNA started to return to pretreatment levels within weeks. The HIV reverse transcriptase (RT) gene in most patients developed mutations associated with drug resistance within months and as early as 25 days on therapy in one patient. The codon changes were not sufficient to explain the early return of serum HIV-1 RNA levels and their patterns continued to evolve after patients stopped taking ZDV. The significance of these findings is discussed in relation to the limited long-term efficacy of ZDV. The dynamic time course of viral load and RT responses to ZDV is of particular importance in short-term interventions such as pregnancy.

Adult↗