Structure, biological functions and inhibition of the HIV-1 proteins Vpr and NCp7

The Gag-encoded nucleocapsid protein NCp7 (72 amino acids) from HIV-1, the regulatory protein, Vpr (96 amino acids) and a numerous derivatives have been synthesized by solid phase method and their structures determined by 2D NMR. In NCp7, the two highly folded zinc fingers of the Cx(z)Cx(4)Hx(4)C type are in close spacial proximity and the replacement of H by C in the first zinc finger or P by L in the short interdigital domain led to structural modifications evidenced by NMR. In vivo, these point mutations induced a complete loss of viral infectivity by interrupting critical step(s) of the retroviral life cycle. To account for these findings, a model of the complex between NCp7 and d (ACGCC) has been proposed from NMR data, showing the intercalation of Trp(37) in the oligonucleotide. This model could also explain the role of NCp7 in the formation of viral particles and agrees with the modifications in morphology of the virions containing mutations in the NCp7 zinc fingers. Vpr is essentially constituted by two long helical domains at its N-and C-terminals and the side chains of Leu(60) and Leu(67) participate in a leucine-zipper mode of intramolecular interaction. The results obtained have been used to try to develop new antiviral agents inhibiting NCp7 functions and thus possibly devoid of the resistance effects found with inhibitors of HIV enzymes (reverse transcriptase and protease).