Inhibition of HIV Maturation via Selective Unfolding and Cross-Linking of Gag Polyprotein by a Mercaptobenzamide Acetylator

Abstract

For HIV to become infectious, any new virion produced from an infected cell must undergo a maturation process that involves the assembly of viral polyproteins Gag and Gag-Pol at the membrane surface. The self-assembly of these viral proteins drives formation of a new viral particle as well as the activation of HIV protease, which is needed to cleave the polyproteins so that the final core structure of the virus will properly form. Molecules that interfere with HIV maturation will prevent any new virions from infecting additional cells. In this manuscript, we characterize the unique mechanism by which a mercaptobenzamide thioester small molecule (SAMT-247) interferes with HIV maturation via a series of selective acetylations at highly conserved cysteine and lysine residues in Gag and Gag-Pol polyproteins. The results provide the first insights into how acetylation can be utilized to perturb the process of HIV maturation and reveal a new strategy to limit the infectivity of HIV.

Investigation of the Low-Populated Excited States of the HIV-1 Nucleocapsid Domain

“…This dynamic behavior of p1 seems, therefore, to favor the zinc de-coordinated forms of the nucleocapsid domain. These results agree with the fact that the mercaptobenzamide thio-esters, which have been shown to target specifically the minor forms of NCp7 [ 33 ], are also able to target Gag with a similar mechanism [ 47 ]. Our work also shows that the observations of these forms are a temperature-dependent phenomenon, the minor forms being not visible at 10 °C but easily observed at 35 °C, near the physiological temperature.…”

An SAMT-247 Microbicide Provides Potent Protection against Intravaginal Simian Immunodeficiency Virus Infection of Rhesus Macaques, whereas an Added Vaccine Component Elicits Mixed Outcomes

“…It is formed by the basic gagpolyprotein domain, which contains two copies of the retroviral zinc finger motif C-X 2 -C-X 4 -H-X 4 -C delimited by highly conserved residues within HIV-1 subtypes (17,18). Anti-HIV compounds known as 2-mercaptobenzamide thioesters (SAMTs) can cause zinc ejection that inactivates the nucleocapsid and leads to production of immature viral particles (19). SAMTs have been shown to retain efficacy in the presence of cervical mucus and to lack toxicity to human cervical tissue, expanding their potential clinical applicability (20).…”

Prodrug Strategy Extends the Use of Anti-HIV Sulfanylbenzamides for Application In Vivo

“…The cross-linked Gag/Gag-Pol blocks Gag-Pol dimerization and prevents the activation of HIV protease, ultimately producing noninfectious viral particles. 26 The formation of disulfide cross-links between different Gag/Gag-Pol proteins may happen spontaneously but could also be promoted by mixed disulfides 3 and benzisothiazolinone 4 which are formed in situ by oxidation of thiol 2. 19 Previously, our group investigated the pharmacokinetic and antiviral activities of the sulfanylbenzamide esterase-sensitive prodrug 5 (Figure 2), 24 as well as substitutions on both the aromatic ring and side chain of 5 to examine the effects on antiviral activity.…”

“…Destabilization of NCp7 triggers the exposure of cysteine sulfhydryls, which undergo oxidative disulfide formation, resulting in Gag/Gag-Pol cross-linking. The cross-linked Gag/Gag-Pol blocks Gag-Pol dimerization and prevents the activation of HIV protease, ultimately producing noninfectious viral particles . The formation of disulfide cross-links between different Gag/Gag-Pol proteins may happen spontaneously but could also be promoted by mixed disulfides 3 and benzisothiazolinone 4 which are formed in situ by oxidation of thiol 2 …”