Sequential conformational rearrangements in flavivirus membrane fusion

Elife. 2014 Dec 5;3:e04389. doi: 10.7554/eLife.04389.

Abstract

The West Nile Virus (WNV) envelope protein, E, promotes membrane fusion during viral cell entry by undergoing a low-pH triggered conformational reorganization. We have examined the mechanism of WNV fusion and sought evidence for potential intermediates during the conformational transition by following hemifusion of WNV virus-like particles (VLPs) in a single particle format. We have introduced specific mutations into E, to relate their influence on fusion kinetics to structural features of the protein. At the level of individual E subunits, trimer formation and membrane engagement of the threefold clustered fusion loops are rate-limiting. Hemifusion requires at least two adjacent trimers. Simulation of the kinetics indicates that availability of competent monomers within the contact zone between virus and target membrane makes trimerization a bottleneck in hemifusion. We discuss the implications of the model we have derived for mechanisms of membrane fusion in other contexts.

Keywords: West Nile virus; biophysics; conformational change; flavivirus; kinetics; membrane fusion; single particle; structural biology; viruses.

Publication types

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

MeSH terms

  • Aedes
  • Animals
  • Cell Line
  • Computer Simulation
  • Epithelial Cells / metabolism
  • Epithelial Cells / virology
  • Gene Expression
  • HEK293 Cells
  • Humans
  • Hydrogen-Ion Concentration
  • Kinetics
  • Membrane Fusion / genetics*
  • Models, Chemical
  • Mutagenesis, Site-Directed
  • Protein Multimerization
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Viral Envelope Proteins / chemistry*
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / metabolism
  • Virion / chemistry*
  • Virion / genetics
  • Virion / metabolism
  • Virus Internalization*
  • West Nile virus / chemistry*
  • West Nile virus / genetics
  • West Nile virus / metabolism

Substances

  • Viral Envelope Proteins