Fig. 3: ^NRTD architecture does not limit stoichiometry in the context of the mature virion.

a Domain connectivity in TBSV capsid proteins. Unstructured linker that connects the C-terminus of the S domain (light blue) to the N-terminus of the P domain (dark blue) highlighted in yellow. b Arrangement of TBSV capsid proteins at the two-fold symmetry axis (dashed arrow) in the assembled virion (see Fig. S2) shown in two orientations. S and P domains associated with individual monomers are colored orange and olive (monomer A) and slate and dark blue (monomer B). c Predicted connectivity in TuYV capsid proteins based on structural modeling. Dashed yellow line denotes the predicted trajectory linking the C-terminus of the TuYV CP (light blue, PDB: 6RTK) to the N-terminus of the TuYV ^NRTD (dark blue). d Composite model of the polerovirus RTP built from the crystallized TuYV ^NRTD dimer and CP monomers taken from the cryo-EM reconstruction of modified TuYV virion devoid of the readthrough domain (PDB: 6RTK). RTP dimer is organized around two-fold symmetry axis analogous to the arrangement in (b) (see Fig. S2). e View of subunit associations in (b, d) looking down the two-fold axis of symmetry in the direction of the dashed arrow in (b). f Side (left) and top down (right) views of TuYV RTP modeled at the two-fold symmetry axis of the icosahedral virion. Two-, three-, and five-fold symmetry axes are marked with a yellow ellipse, yellow triangles, and yellow pentagons, respectively. RTP is colored as in (d) with the rest of the capsid subunits colored wheat. g Model illustrating the feasible positioning of ^NRTD dimers (olive and dark blue) around icosahedral asymmetric unit of TuYV VLP assuming the structural organization of the RTP in (d). Associated CP monomers are colored orange and slate with the rest of the capsid surface colored wheat.