A Flexible Approach to Inhibiting HIV NCp7

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 DESCRIPTION (provided by applicant): The extensive use of antiviral drugs has resulted in the emergence of mutant viral strains that are resistant to the currently available nucleoside therapeutics. Using a combination of drugs that target different viral enzymes (termed highly active anti-retroviral therapy or HAART) has helped, however undesirable side effects and toxicity are often prevalent and reports of multidrug resistance are increasing. As a result, the need for new viral enzymatic targets is critical. In that regard, the nucleocapsid protein of HIV offers forth an attractive target. NCp7 is a small zinc-binding protein that has been shown to be critical in both the early and late stages of the HIV-1 replication process. NCp7 (and the NCp7 domain of the Gag precursor polyprotein) has several key roles in HIV replication, including direct participation in RNA genome recognition and packaging, promoting annealing of the tRNA primer to initiate reverse transcription, and facilitating strand transfer during reverse transcription. NCp7 contains two CCHC-type zinc finger domains that play critical RNA-binding roles during replication, and single-atom Cys-to-Ser mutations that disrupt zinc coordination are sufficient to completely block viral replication. Several approaches to designing inhibitors have been tried, most commonly, use of zinc-ejectors, however to date these have exhibited significant toxicity and poor specificity. A problem that has hindered the identification of viable inhibitors is the inherent flexibility of the protein itself. As such, flexible nucleosides, known s "fleximers" designed and developed in the Seley-Radtke laboratory may provide a solution. In that regard, a series of flexible nucleobase ("flexbase") inhibitors of NCp7 have been identified by means of a virtual screening process. The flexbase analogues are in excellent alignment with the central guanosine residue known to be critical to the biologically relevant conformations of NCp7, thus form the basis for this application. Notably, the flexbases should not result in zinc ejection thereby overcoming the problems associated with other approaches.