Abstract
Small molecules targeting the PF74 binding site of the HIV-1 capsid protein (CA) confer potent and mechanistically unique antiviral activities. Structural modifications of PF74 could further the understanding of ligand binding modes, diversify ligand chemical classes, and allow identification of new variants with balanced antiviral activity and metabolic stability. In the current work, we designed and synthesized three series of PF74-like analogs featuring conformational constraints at the aniline terminus or the phenylalanine carboxamide moiety, and characterized them using a biophysical thermal shift assay (TSA), cell-based antiviral and cytotoxicity assays, and in vitro metabolic stability assays in human and mouse liver microsomes. These studies showed that the two series with the phenylalanine carboxamide moiety replaced by a pyridine or imidazole ring can provide viable hits. Subsequent SAR identified an improved analog 15 which effectively inhibited HIV-1 (EC50 = 0.31 μM), strongly stabilized CA hexamer (ΔTm = 8.7 °C), and exhibited substantially enhanced metabolic stability (t1/2 = 27 min for 15 vs. 0.7 min for PF74). Metabolic profiles from the microsomal stability assay also indicate that blocking the C5 position of the indole ring could lead to increased resistance to oxidative metabolism.
Highlights
The capsid protein (CA) of human immunodeficiency virus type 1 (HIV-1), expressed as part of the viral Gag polyprotein, plays a critical role in multiple steps of the viral replication cycle [1]
CA-mediated post-entry events [1] up to the completion of integration, including uncoating, cytoplasmic trafficking, reverse transcription, nuclear import, and integration site targeting. These events typically involve CA binding by host proteins, such as nucleoporin 153 (NUP153) [3] and cleavage and polyadenylation specificity factor 6 (CPSF6) [4,5], both of which are required for the nuclear import of HIV-1 pre-integration complexes (PICs)
Analogs synthesized for each series were first tested in a biophysical thermal shift assay (TSA), which measures how compounds affect the stability of covalently crosslinked
Summary
The capsid protein (CA) of human immunodeficiency virus type 1 (HIV-1), expressed as part of the viral Gag polyprotein, plays a critical role in multiple steps of the viral replication cycle [1]. CA–CA interactions drive the assembly of Gag polyproteins, and the reassembly of released CAs, toward immature and mature viral capsids, respectively [2]. CA-mediated post-entry events [1] up to the completion of integration, including uncoating, cytoplasmic trafficking, reverse transcription, nuclear import, and integration site targeting. These events typically involve CA binding by host proteins, such as nucleoporin 153. (NUP153) [3] and cleavage and polyadenylation specificity factor 6 (CPSF6) [4,5], both of which are required for the nuclear import of HIV-1 pre-integration complexes (PICs).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
