Inhibition of HIV-1 infectivity by zinc-ejecting aromatic C-nitroso compounds

Abstract

Retroviral nucleocapsid and gag-precursor proteins from all known strains of retroviruses contain one or two copies of an invariant sequence, Cys-X2-Cys-X4-His-X4-Cys, that is populated with zinc in mature particles. Modification of cysteine or histidine residues results in defective packaging of genomic viral RNA and formation of non-infectious particles, making these structures potentially attractive targets for antiviral therapy. We recently reported that aromatic C-nitroso ligands of poly(ADP-ribose) polymerase preferentially destabilize one of the two (Cys-X2-Cys-X28-His-X2-Cys) zinc-fingers with concomitant loss of enzymatic activity, coincidental with selective cytocidal action of the C-nitroso substituted ligands on cancer cells. Based on the occurrence of (3Cys, 1His) zinc-binding sites in both retroviral nucleocapsid and gag proteins and in poly(ADP-ribose) polymerase, we reasoned that the C-nitroso compounds may also have antiretroviral effects. We show here that two such compounds, 3-nitrosobenzamide and 6-nitroso-1,2-benzopyrone, inhibit infection of human immunodeficiency virus HIV-1 in human lymphocytes and also eject zinc from isoalted HIV-1 nucleocapsid zinc fingers and from intact HIV-1 virions. Thus the design of zinc-ejecting agents that target retroviral zinc fingers represents a new approach to the chemotherapy of AIDS.

The yeast Ty3 retrotransposon contains a 5'-3' bipartite primer-binding site and encodes nucleocapsid protein NCp9 functionally homologous to HIV-1 NCp7

“…In support of this, preliminary experiments have shown that Ty3 reverse transcription can be inhibited by anti-NCp7 compounds (Rice et al, 1993), raising the possibility that the Ty3 genetic system might be used to screen potential inhibitors of HIV replication.…”

Identification of the Zn2+ binding region in calreticulin

“…These locations are also known to contain calreticulin [5]. Zn z+ plays an important role in the regulation of gene expression, action of some metaloenzymes [1,2], and the capsid formation of human immunodeficiency virus (HIV) [33]. Zn 2+ has also been shown to block Ca 2+ influx in some cells [34] and induce apoptosis in peripheral blood lymphocytes [35].…”

Inhibition of the replication of native and 3′‐azido‐2′,3′‐dideoxy‐thymidine (AZT)‐resistant simian immunodeficiency virus (SIV) by 3‐nitrosobenzamide

“…The direct anti-SIV action of NOBA was also assayed with human peripheral lymphocytes that were stimulated by phytohaemagglutinin (PHA-PBL) as described earlier for HIV [6]. This experiment represents a direct comparison between SIV and HIV in the same test system.…”

“…pounds, 6-nitroso-l,2-benzopyrone (NOBP) and 3-nitrosobenzamide (NOBA), induce zinc ejection from isolated zinc fingers of p7 or from HIV-1 virions and inhibit HIV-1 replication in human lymphocytes [6]. Since NOBA was more effective in suppressing HIV-1 propagation than NOBP and was well tolerated by uninfected lymphocytes [6], this drug appeared to be the agent of choice for further studies.…”

“…Since NOBA was more effective in suppressing HIV-1 propagation than NOBP and was well tolerated by uninfected lymphocytes [6], this drug appeared to be the agent of choice for further studies. SIV in terms of genetics and CD4 cell tropism is by far the closest animal retrovirus to HIV [7].…”