Fig. 8: Multimer interactions of the Acheta domesticus segmented densovirus (AdSDV) capsid.

a Cross-section view of the fivefold channel in case of the vpORF1 virus-like particles (VLPs), both empty capsid (EC) populations and the full, genome-filled particles (FC). The electron density is radially colored from the map center and is shown as a mash at ơ = 2. Each map is fitted with its corresponding atomic model as ribbon diagrams as well as with the ribbon diagram of the FC structure. The orange arrow indicates the FC N-terminus. b Top-down view of the opening of the fivefold channel, the fivefold pore, with the electron density rendered at ơ=2. The atomic model fitted shows the ribbon diagram as well as the sidechains of the corresponding residues. Note the drastic conformation change of the five DE loops in opening up the channel from the closed conformation of the empty capsids (EC) vs. the open conformation of the genome-filled FC population. Note the difference between the hydrophobic plug covering the channel in case of the vpORF1 VLPs, as opposed to the actual N-terminus externalization observed in the FC capsids. c Ribbon diagrams of the AdSDV FC trimer (left panel), displaying the opening of the β-annulus, typical of densoviruses. The middle panel shows the hydrophobic and positively-charged sidechains, highlighted in cyan, occupying the annulus, and the right panel shows an example of the threefold axis architecture of vertebrate-infecting parvoviruses of the Parvovirinae, represented by canine parvovirus. d Ribbon diagrams of the AdSDV dimer inner surface, interior in comparison with the three other types of dimer assembly strategy, described in the Parvoviridae thus far. Symmetry axes are labeled by a pentagon (fivefold axis), a triangle (threefold axis) and an ellipse (twofold axis). The N-terminus of each subunit is marked by the green arrow. Note the differences between the vertebrate-infecting parvoviruses, represented here by canine parvovirus (CPV) in comparison to the domain swapping conformation of the invertebrate-infecting members of the family, represented by Galleria mellonella densovirus (GmDV) and Penaeus monodon metallodensovirus (PmMDV).