1. Structural Biology and Molecular Biophysics

Sequential conformational rearrangements in flavivirus membrane fusion

  1. Luke H Chao
  2. Daryl E Klein
  3. Aaron G Schmidt
  4. Jennifer M Peña
  5. Stephen C Harrison  Is a corresponding author
  1. Harvard Medical School, United States
https://doi.org/10.7554/eLife.04389
Share this article
Cite this article
  1. Luke H Chao
  2. Daryl E Klein
  3. Aaron G Schmidt
  4. Jennifer M Peña
  5. Stephen C Harrison
(2014)
Sequential conformational rearrangements in flavivirus membrane fusion
eLife 3:e04389.
https://doi.org/10.7554/eLife.04389
  2. Download BibTeX
  3. Download .RIS

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.

Article and author information

Author details

  1. Luke H Chao

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.

  2. Daryl E Klein

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.

  3. Aaron G Schmidt

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.

  4. Jennifer M Peña

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.

  5. Stephen C Harrison

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    For correspondence
    harrison@crystal.harvard.edu
    Competing interests
    Stephen C Harrison, Reviewing editor, eLife.

Reviewing Editor

  1. Reinhard Jahn, Max Planck Institute for Biophysical Chemistry, Germany

Version history

  1. Received: August 18, 2014
  2. Accepted: December 4, 2014
  3. Accepted Manuscript published: December 5, 2014 (version 1)
  4. Version of Record published: January 15, 2015 (version 2)

Copyright

© 2014, Chao et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 4,588
    views
  • 645
    downloads
  • 70
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Luke H Chao
  2. Daryl E Klein
  3. Aaron G Schmidt
  4. Jennifer M Peña
  5. Stephen C Harrison
(2014)
Sequential conformational rearrangements in flavivirus membrane fusion
eLife 3:e04389.
https://doi.org/10.7554/eLife.04389

Share this article

https://doi.org/10.7554/eLife.04389

Categories and tags

Research organism

Further reading

    1. Structural Biology and Molecular Biophysics

    How small-molecule inhibitors of dengue-virus infection interfere with viral membrane fusion

    Luke H Chao, Jaebong Jang ... Stephen C Harrison
    Research Advance Updated

    Dengue virus (DV) is a compact, icosahedrally symmetric, enveloped particle, covered by 90 dimers of envelope protein (E), which mediates viral attachment and membrane fusion. Fusion requires a dimer-to-trimer transition and membrane engagement of hydrophobic ‘fusion loops’. We previously characterized the steps in membrane fusion for the related West Nile virus (WNV), using recombinant, WNV virus-like particles (VLPs) for single-particle experiments (Chao et al., 2014). Trimerization and membrane engagement are rate-limiting; fusion requires at least two adjacent trimers; availability of competent monomers within the contact zone between virus and target membrane creates a trimerization bottleneck. We now report an extension of that work to dengue VLPs, from all four serotypes, finding an essentially similar mechanism. Small-molecule inhibitors of dengue virus infection that target E block its fusion-inducing conformational change. We show that ~12–14 bound molecules per particle (~20–25% occupancy) completely prevent fusion, consistent with the proposed mechanism.

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics

    Caenorhabditis elegans Dicer acts with the RIG-I-like helicase DRH-1 and RDE-4 to cleave dsRNA

    Claudia D Consalvo, Adedeji M Aderounmu ... Brenda L Bass
    Research Article

    Invertebrates use the endoribonuclease Dicer to cleave viral dsRNA during antiviral defense, while vertebrates use RIG-I-like Receptors (RLRs), which bind viral dsRNA to trigger an interferon response. While some invertebrate Dicers act alone during antiviral defense, Caenorhabditis elegans Dicer acts in a complex with a dsRNA binding protein called RDE-4, and an RLR ortholog called DRH-1. We used biochemical and structural techniques to provide mechanistic insight into how these proteins function together. We found RDE-4 is important for ATP-independent and ATP-dependent cleavage reactions, while helicase domains of both DCR-1 and DRH-1 contribute to ATP-dependent cleavage. DRH-1 plays the dominant role in ATP hydrolysis, and like mammalian RLRs, has an N-terminal domain that functions in autoinhibition. A cryo-EM structure indicates DRH-1 interacts with DCR-1’s helicase domain, suggesting this interaction relieves autoinhibition. Our study unravels the mechanistic basis of the collaboration between two helicases from typically distinct innate immune defense pathways.