Gene/Protein
Disease
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Enzyme
Compound
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Target Concepts:
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Query: EC:3.1.26.4 (
RNase H
)
2,751
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
HIV-1 reverse transcriptase (RT) is multifunctional, with RNA-dependent DNA polymerase (RDDP), DNA-dependent DNA polymerase (DDDP), and
ribonuclease H
(
RNase H
) activities. N-(4-tert-Butylbenzoyl)-
2-hydroxy-1-naphthaldehyde
hydrazone (BBNH) inhibited both the polymerase and the
RNase H
activities of HIV-1 RT in vitro. IC50 values for inhibition of RDDP were 0.8-3.4 microM, depending on the template/primer (T/P) used in the assay. The IC50 for DDDP inhibition was about 12 microM, while that for inhibition of
RNase H
was 3.5 microM. EC50 for inhibition of HIV-1 replication in cord blood mononuclear cells was 1.5 microM. BBNH inhibition of
RNase H
in vitro was time-dependent, whereas inhibition of RT polymerase activities was immediate. BBNH was a linear mixed-type inhibitor of RT RDDP activity with respect to both T/P and to dNTP, whereas BBNH inhibition of RT
RNase H
activity was linear competitive. Protection experiments using an azidonevirapine photolabel showed that BBNH binds to the non-nucleoside RT inhibitor (NNRTI) binding pocket. Importantly, the compound inhibited recombinant RT containing mutations associated with high-level resistance to other NNRTI. While BBNH did not inhibit the DNA polymerase activities of other retroviral reverse transcriptases and DNA polymerases, the compound inhibited Escherichia coli RNase HI and the
RNase H
activity of murine leukemia virus RT. BBNH also inhibited HIV-1 RT
RNase H
in the presence of high concentrations of other non-nucleoside inhibitors with higher affinities for the NNRTI binding pocket, and of RT in which the NNRTI binding pocket had been irreversibly blocked by the azidonevirapine photolabel. We conclude that BBNH may therefore bind to two sites on HIV-1 RT. One site is the polymerase non-nucleoside inhibitor binding site and the second may be located in the
RNase H
domain. BBNH is therefore a promising lead compound for the development of multisite inhibitors of HIV-1 RT.
...
PMID:Inhibition of the ribonuclease H and DNA polymerase activities of HIV-1 reverse transcriptase by N-(4-tert-butylbenzoyl)-2-hydroxy-1-naphthaldehyde hydrazone. 911 94
N-(4-tert-butylbenzoyl)-
2-hydroxy-1-naphthaldehyde
hydrazone (BBNH) inhibits both the DNA polymerase and
ribonuclease H
(
RNase H
) activities of the human immunodeficiency virus type 1 reverse transcriptase. In this study, we show that BBNH binding impacts on the stability of the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) heterodimer. The Gibbs free energy of dimer dissociation of HIV-1 RT is decreased in the presence of increasing concentrations of BBNH, resulting in a loss in stability of 3.8 kcal mol(-1). To evaluate whether this observed phenomenon was mediated by BBNH binding to one or more sites in RT, we synthesized a variety of BBNH analogs and identified (4-t-butylbenzoyl)-2-hydroxy-1-salicylyl hydrazone (BBSH) and (4,N,N-dimethylaminobenzoyl)-2-hydroxy-1-naphthyl hydrazone as specific inhibitors of RT DNA polymerase or RT
RNase H
activity, respectively. Interestingly, only BBSH provided significant destabilization of the HIV-1 RT dimer. The identification of these specific inhibitors, in combination with other biochemical data, suggests a model in which two molecules of BBNH bind per RT heterodimer. In this regard, only the binding of hydrazone molecules in the DNA polymerase domain activity elicits the observed destabilization of the HIV-1 RT heterodimer.
...
PMID:Destabilization of the HIV-1 reverse transcriptase dimer upon interaction with N-acyl hydrazone inhibitors. 1213 Jun 93
