Targeting the Late Stage of HIV-1 Entry for Antibody-Dependent Cellular Cytotoxicity: Structural Basis for Env Epitopes in the C11 Region.
Structure 2017;
25:1719-1731.e4. [PMID:
29056481 PMCID:
PMC5677539 DOI:
10.1016/j.str.2017.09.009]
[Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/28/2017] [Accepted: 09/18/2017] [Indexed: 01/14/2023]
Abstract
Antibodies can have an impact on HIV-1 infection in multiple ways, including antibody-dependent cellular cytotoxicity (ADCC), a correlate of protection observed in the RV144 vaccine trial. One of the most potent ADCC-inducing epitopes on HIV-1 Env is recognized by the C11 antibody. Here, we present the crystal structure, at 2.9 Å resolution, of the C11-like antibody N12-i3, in a quaternary complex with the HIV-1 gp120, a CD4-mimicking peptide M48U1, and an A32-like antibody, N5-i5. Antibody N12-i3 recognizes an epitope centered on the N-terminal "eighth strand" of a critical β sandwich, which our analysis indicates to be emblematic of a late-entry state, after the gp120 detachment. In prior entry states, this sandwich comprises only seven strands, with the eighth strand instead pairing with a portion of the gp120 C terminus. The conformational gymnastics of HIV-1 gp120 thus includes altered β-strand pairing, possibly to reduce immunogenicity, although nevertheless still recognized by the human immune system.
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