Inhibition of HIV-1 Replication by a Bis-Thiadiazolbenzene-1,2-Diamine That Chelates Zinc Ions from Retroviral Nucleocapsid Zinc Fingers

Abstract

The human immunodeficiency virus type 1 (HIV-1) nucleocapsid p7 (NCp7) protein holds two highly conserved "CCHC" zinc finger domains that are required for several phases of viral replication. Basic residues flank the zinc fingers, and both determinants are required for high-affinity binding to RNA. Several compounds were previously found to target NCp7 by reacting with the sulfhydryl group of cysteine residues from the zinc fingers. Here, we have identified an N,N-bis(1,2,3-thiadiazol-5-yl)benzene-1,2-diamine (NV038) that efficiently blocks the replication of a wide spectrum of HIV-1, HIV-2, and simian immunodeficiency virus (SIV) strains. Time-of-addition experiments indicate that NV038 interferes with a step of the viral replication cycle following the viral entry but preceding or coinciding with the early reverse transcription reaction, pointing toward an interaction with the nucleocapsid protein p7. In fact, in vitro, NV038 efficiently depletes zinc from NCp7, which is paralleled by the inhibition of the NCp7-induced destabilization of cTAR (complementary DNA sequence of TAR). A chemical model suggests that the two carbonyl oxygens of the esters in this compound are involved in the chelation of the Zn 2؉ ion. This compound thus acts via a different mechanism than the previously reported zinc ejectors, as its structural features do not allow an acyl transfer to Cys or a thiol-disulfide interchange. This new lead and the mechanistic study presented provide insight into the design of a future generation of anti-NCp7 compounds.

Advances in targeting nucleocapsid–nucleic acid interactions in HIV-1 therapy

“…Another relatively recently reported category of zinc ejectors are the thiadiazaole derivatives that act by zinc chelation (Fig 3) (Pannecouque et al, 2010; Vercruysse et al, 2012). Unlike the thioesters, thiadiazaole derivatives do not form covalent bonds with the NC protein.…”

Reactions of Malonothioamide Derivatives with Azides*

“…A broad spectrum of biological activity is also characteristic of 1,2,3-thiadiazole derivatives. Most interesting from the practical standpoint are substances having antiviral, herbicidal, and fungicidal activity and agents for the protection and growth regulation of plants [6,9,15,16].…”

Zinc finger function of HIV-1 nucleocapsid protein is required for removal of 5′-terminal genomic RNA fragments: A paradigm for RNA removal reactions in HIV-1 reverse transcription

“…The existence of this common mechanism suggests its evolutionary importance and underscores its significance as a determinant of successful viral replication and thus, viral fitness. Finally, these results emphasize the promise of novel anti-retroviral agents that are being developed to specifically target the ZFs of the HIV-1 NC protein and its associated helix destabilizing activity (Avilov et al, 2012; Breuer et al, 2012; Grigorov et al, 2011; Pannecouque et al, 2010; Shvadchak et al, 2009). …”