Human Picobirnavirus Ht-CP VLP

Experimental Data Snapshot

  • Resolution: 2.80 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

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Cryo-electron Microscopy Structure, Assembly, and Mechanics Show Morphogenesis and Evolution of Human Picobirnavirus.

Ortega-Esteban, A.Mata, C.P.Rodriguez-Espinosa, M.J.Luque, D.Irigoyen, N.Rodriguez, J.M.de Pablo, P.J.Caston, J.R.

(2020) J Virol 94

  • DOI: https://doi.org/10.1128/JVI.01542-20
  • Primary Citation of Related Structures:  
    6Z8D, 6Z8E, 6Z8F

  • PubMed Abstract: 

    Despite their diversity, most double-stranded-RNA (dsRNA) viruses share a specialized T=1 capsid built from dimers of a single protein that provides a platform for genome transcription and replication. This ubiquitous capsid remains structurally undisturbed throughout the viral cycle, isolating the genome to avoid triggering host defense mechanisms. Human picobirnavirus (hPBV) is a dsRNA virus frequently associated with gastroenteritis, although its pathogenicity is yet undefined. Here, we report the cryo-electron microscopy (cryo-EM) structure of hPBV at 2.6-Å resolution. The capsid protein (CP) is arranged in a single-shelled, ∼380-Å-diameter T=1 capsid with a rough outer surface similar to that of dsRNA mycoviruses. The hPBV capsid is built of 60 quasisymmetric CP dimers (A and B) stabilized by domain swapping, and only the CP-A N-terminal basic region interacts with the packaged nucleic acids. hPBV CP has an α-helical domain with a fold similar to that of fungal partitivirus CP, with many domain insertions in its C-terminal half. In contrast to dsRNA mycoviruses, hPBV has an extracellular life cycle phase like complex reoviruses, which indicates that its own CP probably participates in cell entry. Using an in vitro reversible assembly/disassembly system of hPBV, we isolated tetramers as possible assembly intermediates. We used atomic force microscopy to characterize the biophysical properties of hPBV capsids with different cargos (host nucleic acids or proteins) and found that the CP N-terminal segment not only is involved in nucleic acid interaction/packaging but also modulates the mechanical behavior of the capsid in conjunction with the cargo. IMPORTANCE Despite intensive study, human virus sampling is still sparse, especially for viruses that cause mild or asymptomatic disease. Human picobirnavirus (hPBV) is a double-stranded-RNA virus, broadly dispersed in the human population, but its pathogenicity is uncertain. Here, we report the hPBV structure derived from cryo-electron microscopy (cryo-EM) and reconstruction methods using three capsid protein variants (of different lengths and N-terminal amino acid compositions) that assemble as virus-like particles with distinct properties. The hPBV near-atomic structure reveals a quasisymmetric dimer as the structural subunit and tetramers as possible assembly intermediates that coassemble with nucleic acids. Our structural studies and atomic force microscopy analyses indicate that hPBV capsids are potentially excellent nanocages for gene therapy and targeted drug delivery in humans.

  • Organizational Affiliation

    Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Capsid protein precursor
A, B
588Human picobirnavirusMutation(s): 0 
Gene Names: Segment-1ORF2
Find proteins for Q50LE5 (Human picobirnavirus (strain Human/Thailand/Hy005102/-))
Explore Q50LE5 
Go to UniProtKB:  Q50LE5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ50LE5
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.80 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 
EM Software:
TaskSoftware PackageVersion

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Spanish Ministry of Economy and CompetitivenessSpainBFU2017-88736-R

Revision History  (Full details and data files)

  • Version 1.0: 2020-09-23
    Type: Initial release
  • Version 1.1: 2020-10-21
    Changes: Database references
  • Version 1.2: 2020-12-02
    Changes: Database references