AUTHOR=Singh Kamal , Gallazzi Fabio , Hill Kyle J. , Burke Donald H. , Lange Margaret J. , Quinn Thomas P. , Neogi Ujjwal , Sönnerborg Anders TITLE=GS-CA Compounds: First-In-Class HIV-1 Capsid Inhibitors Covering Multiple Grounds JOURNAL=Frontiers in Microbiology VOLUME=10 YEAR=2019 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01227 DOI=10.3389/fmicb.2019.01227 ISSN=1664-302X ABSTRACT=

Recently reported HIV-1 capsid (CA) inhibitors GS-CA1 and GS-6207 (an analog of GS-CA1) are first-in-class compounds with long-acting potential. Reportedly, both compounds have greater potency than currently approved anti-HIV drugs. Due to the limited access to experimental data and the compounds themselves, a detailed mechanism of their inhibition is yet to be delineated. Using crystal structures of capsid-hexamers bound to well-studied capsid inhibitor PF74 and molecular modeling, we predict that GS-CA compounds bind in the pocket that is shared by previously reported CA inhibitors and host factors. Additionally, comparative modeling suggests that GS-CA compounds have unique structural features contributing to interactions with capsid. To test their proposed binding mode, we also report the design of a cyclic peptide combining structural units from GS-CA compounds, host factors, and previously reported capsid inhibitors. This peptide (Pep-1) binds CA-hexamer with a docking score comparable to GS-CA compounds. Affinity determination by MicroScale thermophoresis (MST) assays showed that CA binds Pep-1 with a ~7-fold better affinity than well-studied capsid inhibitor PF74, suggesting that it can be developed as a possible CA inhibitor.