Studies of the interaction of HIV-1 nucleocapsid protein NCp7 with zinc-ejecting compounds by nuclear magnetic resonance spectroscopy

Abstract

The highly conserved and mutationally intolerant retroviral zinc finger motif of the HIV-1 nucleocapsid protein is an attractive target for drug therapy due to its participation in multiple stages of the viral replication cycle. A literature search identified cystamine, thiamine disulfide, azodicarbonamide, and disulfiram as compounds that have been shown to inhibit HIV-1 replication by poorly defined mechanisms and that have functional groups that might electrophilically attack the metal-chealating sulfur atoms of the retroviral zinc fingers. 1H-NMR studies with the nucleocapsid protein and analogous synthetic peptides showed that all of the compounds mentioned above have zinc-ejecting capabilities. The reduced forms of disulfiram and cystamine, diethyldithiocarbamate and cysteamine, were also studied, and found to be ineffective at zinc-ejection, however cystamine formed a transient complex with the zinc fingers. The N-terminal zinc finger and the intact protein were noted to accelerate the oxidation of cysteamine to cystamine. The disulfide compounds and their thiols were also evaluated by our collaborators in vitro to determine their potential as antiviral agents. Azodicarbonamide, cystamine and cysteamine had significant antiviral properties at non-toxic concentrations, which warrant their pursuance as therapeutically useful anti-HIV agents.