Cryo-EM Structure of Chikungunya Virus in Complex with the Mxra8 Receptor

Cell. 2019 Jun 13;177(7):1725-1737.e16. doi: 10.1016/j.cell.2019.04.006. Epub 2019 May 9.


Mxra8 is a receptor for multiple arthritogenic alphaviruses that cause debilitating acute and chronic musculoskeletal disease in humans. Herein, we present a 2.2 Å resolution X-ray crystal structure of Mxra8 and 4 to 5 Å resolution cryo-electron microscopy reconstructions of Mxra8 bound to chikungunya (CHIKV) virus-like particles and infectious virus. The Mxra8 ectodomain contains two strand-swapped Ig-like domains oriented in a unique disulfide-linked head-to-head arrangement. Mxra8 binds by wedging into a cleft created by two adjacent CHIKV E2-E1 heterodimers in one trimeric spike and engaging a neighboring spike. Two binding modes are observed with the fully mature VLP, with one Mxra8 binding with unique contacts. Only the high-affinity binding mode was observed in the complex with infectious CHIKV, as viral maturation and E3 occupancy appear to influence receptor binding-site usage. Our studies provide insight into how Mxra8 binds CHIKV and creates a path for developing alphavirus entry inhibitors.

Keywords: HDX mass spectrometry; alphavirus; cryo-electron microscopy; infection; protein crystallography; surface plasmon resonance; virus receptor.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Chikungunya virus / chemistry*
  • Chikungunya virus / metabolism
  • Chikungunya virus / ultrastructure
  • Cryoelectron Microscopy
  • HEK293 Cells
  • Humans
  • Membrane Proteins / chemistry*
  • Membrane Proteins / metabolism
  • Protein Domains
  • Viral Envelope Proteins / chemistry*
  • Viral Envelope Proteins / metabolism


  • Membrane Proteins
  • Viral Envelope Proteins