Conformational inhibitors of the HIV-1 Rev response element identified through a FRET-based screening approach

The complex formed between the HIV-1 protein Rev and the Rev Response Element (RRE) in the genomic RNA of the virus represents an attractive target for antiretroviral therapy. To date, however, there are no RRE-Rev inhibitors in clinical use. In this study we have applied a fluorescence resonance energy transfer (FRET) assay based on placing Cy3- and Cy5-labeled oligomeric probes at distal domain locations within the RRE to identify small-molecule compounds capable of perturbing the spatial organization of RRE domains and disrupting the association of Rev monomers. After screening a library of bioactive compounds and approved drugs, we identified two molecules, myricetin and raloxifene, that recognize the RRE and inhibit the RRE-Rev interaction in vitro and in cellulo. Both compounds exhibited antiretroviral activity with favorable selectivity indexes, and further analyses involving RRE mutants suggested that myricetin modulated the conformation of the RRE through binding to a four-helix intersection. Collectively, these findings provide proof of concept for targeting the RRE-Rev complex and identify myricetin and raloxifene as promising starting points for the development of novel anti-HIV agents.