Structure-function Analyses Reveal Key Molecular Determinants of HIV-1 CRF01_AE Resistance to the Entry Inhibitor Temsavir

Abstract

The HIV-1 entry inhibitor temsavir prevents CD4 from interacting with the envelope glycoprotein (Env) and blocks its conformational changes. To do this temsavir relies on the presence of a residue with small side chain at position 375 in Env and is unable to neutralize viral strains like CRF01_AE carrying His375. Here we investigate the mechanism of temsavir-resistance and show that residue 375 is not the sole determinant of resistance. At least six additional residues within the gp120 inner domain layers, including five distant from the drug-binding pocket, contribute to resistance. A detailed structure-function analysis using engineered viruses and soluble trimer variants reveal that the molecular basis of resistance is mediated by crosstalk between His375 and the inner domain layers. Furthermore, our data confirm that temsavir can adjust its binding mode to accommodate changes in Env conformation, a property that likely contributes to its broad-antiviral activity.

Temsavir Modulates HIV-1 Envelope Conformation by Decreasing Its Proteolytic Cleavage

“…Accordingly, a cleavage-deficient Env was resistant to temsavir, as highlighted by an absence of a decrease in recognition by bNAbs, whereas recognition by the CD4-Ig ligand was decreased, likely due to competition with the small molecule. This was consistent with recent structural studies revealing that temsavir engages gp120 in a pocket under the β20-β21 loop, sequestering three key CD4 contact residues, N425, M426, and W427 [15,16]. Altogether, these results suggest that temsavir mostly modifies Env conformation by altering its cleavage.…”

“…Among them, temsavir (BMS-626529 and GSK2616713), a small molecule entry inhibitor administrated as a prodrug for fostemsavir (BMS-663068, GSK3684934, and RUKOBIA), was recently approved for the treatment of patients who have limited therapeutic options [ 13 , 14 ]. Temsavir is known to bind a conserved pocket in gp120 under its β20–β21 loop, thereby preventing CD4 interaction [ 15 , 16 ]. This molecule also stabilizes the “closed” State 1 Env conformation, which is preferentially recognized by bNAbs [ 5 , 7 ].…”