Inhibition of the ribonuclease H activity of HIV-1 reverse transcriptase by GSK5750 correlates with slow enzyme-inhibitor dissociation.
J Biol Chem
; 289(23): 16270-7, 2014 Jun 06.
Article
em En
| MEDLINE
| ID: mdl-24719329
ABSTRACT
Compounds that efficiently inhibit the ribonuclease (RNase) H activity of the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) have yet to be developed. Here, we demonstrate that GSK5750, a 1-hydroxy-pyridopyrimidinone analog, binds to the enzyme with an equilibrium dissociation constant (K(d)) of ~400 nM. Inhibition of HIV-1 RNase H is specific, as DNA synthesis is not affected. Moreover, GSK5750 does not inhibit the activity of Escherichia coli RNase H. Order-of-addition experiments show that GSK5750 binds to the free enzyme in an Mg(2+)-dependent fashion. However, as reported for other active site inhibitors, binding of GSK5750 to a preformed enzyme-substrate complex is severely compromised. The bound nucleic acid prevents access to the RNase H active site, which represents a possible biochemical hurdle in the development of potent RNase H inhibitors. Previous studies suggested that formation of a complex with the prototypic RNase H inhibitor ß-thujaplicinol is slow, and, once formed, it dissociates rapidly. This unfavorable kinetic behavior can limit the potency of RNase H active site inhibitors. Although the association kinetics of GSK5750 remains slow, our data show that this compound forms a long lasting complex with HIV-1 RT. We conclude that slow dissociation of the inhibitor and HIV-1 RT improves RNase H active site inhibitors and may circumvent the obstacle posed by the inability of these compounds to bind to a preformed enzyme-substrate complex.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Piridinas
/
Pirimidinonas
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Ribonuclease H
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Inibidores da Transcriptase Reversa
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Transcriptase Reversa do HIV
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article