2esx

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The structure of the V3 region within gp120 of JR-FL HIV-1 strain (minimized average structure)

Overview

HIV-1 coreceptor usage plays a critical role in virus tropism and, pathogenesis. A switch from CCR5- to CXCR4-using viruses occurs during the, course of HIV-1 infection and correlates with subsequent disease, progression. A single mutation at position 322 within the V3 loop of the, HIV-1 envelope glycoprotein gp120, from a negatively to a positively, charged residue, was found to be sufficient to switch an R5 virus to an X4, virus. In this study, the NMR structure of the V3 region of an R5 strain, HIV-1(JR-FL), in complex with an HIV-1-neutralizing antibody was, determined. Positively charged and negatively charged residues at, positions 304 and 322, respectively, oppose each other in the beta-hairpin, structure, enabling a favorable electrostatic interaction that stabilizes, the postulated R5 conformation. Comparison of the R5 conformation with the, postulated X4 conformation of the V3 region (positively charged residue at, position 322) reveals that electrostatic repulsion between residues 304, and 322 in X4 strains triggers the observed one register shift in the, N-terminal strand of the V3 region. We posit that electrostatic, interactions at the base of the V3 beta-hairpin can modulate the, conformation and thereby influence the phenotype switch. In addition, we, suggest that interstrand cation-pi interactions between positively charged, and aromatic residues induce the switch to the X4 conformation as a result, of the S306R mutation. The existence of three pairs of identical (or very, similar) amino acids in the V3 C-terminal strand facilitates the switch, between the R5 and X4 conformations.

About this Structure

2ESX is a Single protein structure of sequence from Human immunodeficiency virus 1. Full crystallographic information is available from OCA.

Reference

Molecular switch for alternative conformations of the HIV-1 V3 region: implications for phenotype conversion., Rosen O, Sharon M, Quadt-Akabayov SR, Anglister J, Proc Natl Acad Sci U S A. 2006 Sep 19;103(38):13950-5. Epub 2006 Sep 11. PMID:16966601

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