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. 2017 Feb 14;91(5):e02219-16. doi: 10.1128/JVI.02219-16

FIG 8.

FIG 8

(A) Model for modulation of HIV-1 sensitivity to gp120-directed inhibitors by changes in the gp41 ectodomain. (A) In the unliganded conformation, the envelope glycoproteins of primary HIV-1 mostly sample state 1. The proposed effects of the indicated Env changes on Env conformation are shown. The A582T change in gp41 is proposed to stabilize state 1 (indicated by a green arrow), whereas the L587A change in gp41 is suggested to destabilize state 2 (indicated by a red arrow). The H66A change in gp120 decreases CD4 binding by increasing the off rate of the gp120-CD4 interaction (26, 51, 61) (red arrow). All three changes (A582T, L587A, and H66A) act in different ways to predispose Env to assume a state 1 conformation. (B) Sequences of the gp41 ectodomain in primate immunodeficiency virus Envs. Primary sequence alignment of gp41 HR1 region residues from representative HIV-1 B (GenBank accession number K03455), HIV-1 C (accession number U46016), simian immunodeficiency virus strain cpz (SIVcpz) (accession number DQ373064), HIV-2 (accession number AF082339), SIVmac/smm (accession number M33262), SIVtan (accession number U58991), SIVagm (accession number M30931), and SIVsyk (accession number L06042) isolates (7, 25). The shading highlights residues that are conserved in all primate immunodeficiency virus lineages (85). Heptad repeat positions are shown in lowercase letters on top of the amino acid sequence alignment.