A novel, dipyridodiazepinone inhibitor of HIV-1 reverse transcriptase acts through a nonsubstrate binding site

Abstract

A novel dipyridodiazepinone, 6,11-dihydro-11-cyclopropyl-4-methyldipyrido[2,3-b:2',3'-e]- [1,4]diazepin-6-one (BI-RG-587), is a selective noncompetitive inhibitor of HIV-1 reverse transcriptase (RT-1). An azido photoaffinity analogue of BI-RG-587 was synthesized and found to irreversibly inhibit the enzyme upon UV irradiation. BI-RG-587 and close structural analogues competitively protected RT-1 from inactivation by the photoaffinity label. A thiobenzimidazolone (TIBO) derivative, a nonnucleoside inhibitor of RT-1, also protected the enzyme from photoinactivation, which suggests a common binding site for these compounds. Substrates dGTP, template-primer, and tRNA afforded no protection from enzyme inactivation. A tritiated photoaffinity probe was found to stoichiometrically and selectively label p66 such that 1 mol of probe inactivates 1 mol of RT-1.

Development of a New Methodology for Screening of Human Immunodeficiency Virus Type 1 Microbicides Based on Real-Time PCR Quantification

“…3B) were 0.05 M and 10 nM, respectively. The IC 50 s are in agreement with those reported in the literature (34,35). Importantly, the two assays showed similar effects of NNRTI inhibition on viral infectivity and in NERT assays, demonstrating good correlation between the two strategies.…”

Mechanism of resistance to U‐90152S and sensitization to L‐697,661 by a proline to leucine change at residue 236 of human immunodeficiency virus type 1 (HIV‐1) reverse transcriptase

“…When HIV-1 was grown in the presence of L-697,661, viral variants were resistant to all these three classes of nonnucleosides [15]. These [14,15] and other studies [1,7,[16][17][18][19][20][21] suggest that most classes of NNRTIs appear to share the same binding pocket on the enzyme [10].…”

Function and Structure Relationships in DNA Polymerases

“…In the p66-pSI heterodimer, only the p66 subunit has polymerase activity, as shown by the observation that mutations of essential active-site residues eliminate polymerase activity only when present on the p66 subunit (30,31). The p66 subunit also contains the single binding site for non-nucleoside inhibitors such as Nevirapine (32). The heterodimer, but not the isolated subunits, interacts in I: I stoichiometry with the tRNA primer (33).…”