Structure of the low pH conformation of Chandipura virus G reveals important features in the evolution of the vesiculovirus glycoprotein

PLoS Pathog. 2015 Mar 24;11(3):e1004756. doi: 10.1371/journal.ppat.1004756. eCollection 2015 Mar.

Abstract

Chandipura virus (CHAV), a member of the vesiculovirus genus, is an emerging human pathogen. As for other rhabdoviruses, CHAV entry into susceptible cells is mediated by its single envelope glycoprotein G which is both involved in receptor recognition and fusion of viral and cellular membranes. Here, we have characterized the fusion properties of CHAV-G. As for vesicular stomatitis virus (VSV, the prototype of the genus) G, fusion is triggered at low pH below 6.5. We have also analyzed the biochemical properties of a soluble form of CHAV-G ectodomain (CHAV-Gth, generated by thermolysin limited-proteolysis of recombinant VSV particles in which the G gene was replaced by that of CHAV). The overall behavior of CHAV-Gth is similar to that previously reported for VSV-Gth. Particularly, CHAV-Gth pre-fusion trimer is not stable in solution and low-pH-induced membrane association of CHAV-Gth is reversible. Furthermore, CHAV-Gth was crystallized in its low pH post-fusion conformation and its structure was determined at 3.6Å resolution. An overall comparison of this structure with the previously reported VSV-Gth post-fusion conformation, shows a high structural similarity as expected from the comparison of primary structure. Among the three domains of G, the pleckstrin homology domain (PHD) appears to be the most divergent and the largest differences are confined to the secondary structure of the major antigenic site of rhabdoviruses. Finally, local differences indicate that CHAV has evolved alternate structural solutions in hinge regions between PH and fusion domains but also distinct pH sensitive switches. Globally the comparison between the post fusion conformation of CHAV and VSV-G highlights several features essential for the protein's function. It also reveals the remarkable plasticity of G in terms of local structures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Evolution, Molecular*
  • Humans
  • Hydrogen-Ion Concentration
  • Nucleocapsid / chemistry*
  • Nucleocapsid / genetics
  • Nucleocapsid / metabolism
  • Protein Structure, Tertiary
  • Vesiculovirus / chemistry*
  • Vesiculovirus / genetics
  • Vesiculovirus / metabolism
  • Viral Fusion Proteins / chemistry*
  • Viral Fusion Proteins / genetics
  • Viral Fusion Proteins / metabolism

Substances

  • Viral Fusion Proteins

Associated data

  • PDB/4D6W

Grant support

This work was supported by the EU through the Marie Curie ITN VIRUS ENTRY (Project 582 reference 235649) (PhD grants for EB), grant from Agence Nationale de la Recherche 583 (ANR-11-BSV8-002) (Post-doctoral grant for EB) and from the Fondation pour la Recherche Médicale (FRM DEQ20120323711). The platforms are supported by the French Infrastructure for Integrated Structural Biology (FRISBI) [ANR-10-INSB-05-01]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.