A dynamic three-step mechanism drives the HIV-1 pre-fusion reaction

Nat Struct Mol Biol. 2018 Sep;25(9):814-822. doi: 10.1038/s41594-018-0113-x. Epub 2018 Aug 27.

Abstract

Little is known about the intermolecular dynamics and stoichiometry of the interactions of the human immunodeficiency virus type 1 (HIV-1) envelope (Env) protein with its receptors and co-receptors on the host cell surface. Here we analyze time-resolved HIV-1 Env interactions with T-cell surface glycoprotein CD4 (CD4) and C-C chemokine receptor type 5 (CCR5) or C-X-C chemokine receptor type 4 (CXCR4) on the surface of cells, by combining multicolor super-resolution localization microscopy (direct stochastic optical reconstruction microscopy) with fluorescence fluctuation spectroscopy imaging. Utilizing the primary isolate JR-FL and laboratory HXB2 strains, we reveal the time-resolved stoichiometry of CD4 and CCR5 or CXCR4 in the pre-fusion complex with HIV-1 Env. The HIV-1 Env pre-fusion dynamics for both R5- and X4-tropic strains consists of a three-step mechanism, which seems to differ in stoichiometry. Analyses with the monoclonal HIV-1-neutralizing antibody b12 indicate that the mechanism of inhibition differs between JR-FL and HXB2 Env. The molecular insights obtained here identify assemblies of HIV-1 Env with receptors and co-receptors as potential novel targets for inhibitor design.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD4 Antigens / metabolism
  • COS Cells
  • Chlorocebus aethiops
  • HEK293 Cells
  • HIV-1 / metabolism*
  • Humans
  • Membrane Fusion*
  • Microscopy / methods
  • Receptors, CCR5 / metabolism
  • Receptors, CXCR4 / metabolism
  • Spectrometry, Fluorescence / methods
  • Viral Envelope Proteins / metabolism*

Substances

  • CCR5 protein, human
  • CD4 Antigens
  • CXCR4 protein, human
  • Receptors, CCR5
  • Receptors, CXCR4
  • Viral Envelope Proteins