Structural basis for assembly of vertical single β-barrel viruses

Nat Commun. 2019 Mar 12;10(1):1184. doi: 10.1038/s41467-019-08927-2.


The vertical double β-barrel major capsid protein (MCP) fold, fingerprint of the PRD1-adeno viral lineage, is widespread in many viruses infecting organisms across the three domains of life. The discovery of PRD1-like viruses with two MCPs challenged the known assembly principles. Here, we present the cryo-electron microscopy (cryo-EM) structures of the archaeal, halophilic, internal membrane-containing Haloarcula californiae icosahedral virus 1 (HCIV-1) and Haloarcula hispanica icosahedral virus 2 (HHIV-2) at 3.7 and 3.8 Å resolution, respectively. Our structures reveal proteins located beneath the morphologically distinct two- and three-tower capsomers and homopentameric membrane proteins at the vertices that orchestrate the positioning of pre-formed vertical single β-barrel MCP heterodimers. The cryo-EM based structures together with the proteomics data provide insights into the assembly mechanism of this type of viruses and into those with membrane-less double β-barrel MCPs.

Publication types

  • Research Support, Non-U.S. Gov't
  • Video-Audio Media

MeSH terms

  • Archaeal Viruses / physiology*
  • Capsid Proteins / chemistry
  • Capsid Proteins / metabolism
  • Capsid Proteins / ultrastructure*
  • Cryoelectron Microscopy
  • DNA Viruses / physiology*
  • Haloarcula / virology*
  • Models, Molecular
  • Protein Conformation, beta-Strand
  • Protein Multimerization
  • Virion / ultrastructure
  • Virus Assembly*


  • Capsid Proteins