Structure of HIV-1 gp120 V1/V2 domain with broadly neutralizing antibody PG9.
Variable regions 1 and 2 (V1/V2) of human immunodeficiency virus-1 (HIV-1) gp120 envelope glycoprotein are critical for viral evasion of antibody neutralization, and are themselves protected by extraordinary sequence diversity and N-linked glycosylation. Human antibodies such as PG9 nonetheless engage V1/V2 and neutralize 80% of HIV-1 isolates. Here we report the structure of V1/V2 in complex with PG9. V1/V2 forms a four-stranded β-sheet domain, in which sequence diversity and glycosylation are largely segregated to strand-connecting loops. PG9 recognition involves electrostatic, sequence-independent and glycan interactions: the latter account for over half the interactive surface but are of sufficiently weak affinity to avoid autoreactivity. The structures of V1/V2-directed antibodies CH04 and PGT145 indicate that they share a common mode of glycan penetration by extended anionic loops. In addition to structurally defining V1/V2, the results thus identify a paradigm of antibody recognition for highly glycosylated antigens, which-with PG9-involves a site of vulnerability comprising just two glycans and a strand.
McLellan, JS; Pancera, M; Carrico, C; Gorman, J; Julien, J-P; Khayat, R; Louder, R; Pejchal, R; Sastry, M; Dai, K; O'Dell, S; Patel, N; Shahzad-ul-Hussan, S; Yang, Y; Zhang, B; Zhou, T; Zhu, J; Boyington, JC; Chuang, G-Y; Diwanji, D; Georgiev, I; Kwon, YD; Lee, D; Louder, MK; Moquin, S; Schmidt, SD; Yang, Z-Y; Bonsignori, M; Crump, JA; Kapiga, SH; Sam, NE; Haynes, BF; Burton, DR; Koff, WC; Walker, LM; Phogat, S; Wyatt, R; Orwenyo, J; Wang, L-X; Arthos, J; Bewley, CA; Mascola, JR; Nabel, GJ; Schief, WR; Ward, AB; Wilson, IA; Kwong, PD
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