FIG. 5.

(a) Cross-sectional views of the particle envelopes of MGNNV (left) and PaV (right) defined by the cryoEM density. The refined TBSV model is superimposed with the MGNNV density and the X-ray atomic model of PaV with the PaV density. In both panels, two icosahedral asymmetric units are shown. Subunits A, B, and C are colored blue, red, and green, respectively, and the RNA duplex in the PaV model is colored yellow. (b) Comparison of one subunit of TBSV (left) that was fitted into the MGNNV density in panel a with the equivalent PaV subunit (right). The lack of connectivity between the two domains of TBSV reflects the lack of obvious density connecting the domains in the cryoEM map of MGNNV, suggesting that the connection is made by a single, extended polypeptide. (c) A view down the two-fold axis of the MGNNV density with the TBSV model superimposed. The view emphasizes the strong trimer association of the protruding domains around the quasi-three-fold axes. The C termini of subunits are indicated by stars, and the positions of icosahedral three- and five-fold axes are indicated by 3 and 5, respectively. (d) Cross section of the TBSV model superimposed on the cryoEM density of the full particle of MGNNV viewed down the five-fold axis.