Cyclophilin A stabilizes the HIV-1 capsid through a novel non-canonical binding site

Nat Commun. 2016 Mar 4:7:10714. doi: 10.1038/ncomms10714.

Abstract

The host cell factor cyclophilin A (CypA) interacts directly with the HIV-1 capsid and regulates viral infectivity. Although the crystal structure of CypA in complex with the N-terminal domain of the HIV-1 capsid protein (CA) has been known for nearly two decades, how CypA interacts with the viral capsid and modulates HIV-1 infectivity remains unclear. We determined the cryoEM structure of CypA in complex with the assembled HIV-1 capsid at 8-Å resolution. The structure exhibits a distinct CypA-binding pattern in which CypA selectively bridges the two CA hexamers along the direction of highest curvature. EM-guided all-atom molecular dynamics simulations and solid-state NMR further reveal that the CypA-binding pattern is achieved by single-CypA molecules simultaneously interacting with two CA subunits, in different hexamers, through a previously uncharacterized non-canonical interface. These results provide new insights into how CypA stabilizes the HIV-1 capsid and is recruited to facilitate HIV-1 infection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Capsid Proteins / metabolism*
  • Catalytic Domain
  • Computer Simulation
  • Cyclophilin A / pharmacology*
  • Escherichia coli / metabolism
  • Gene Expression Regulation, Viral / physiology*
  • HIV-1
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Protein Binding
  • Protein Conformation
  • Virus Assembly

Substances

  • Capsid Proteins
  • Cyclophilin A