FIG. 9.

How the structure of the uridylylation complex might affect biological function. Large ovals represent the viral protein domains; wavy lines represent polypeptide chains. The cre RNA is predicted to have a stem-loop structure and is shown in gray. The purple and yellow rectangles represent the D-D and D-C interfaces, respectively, as they are seen in the 3CD crystal structure. Aggregation of 3CD may compete with the formation of the uridylylation complex (top panel). 3CD might dissociate either intact or after it has been cleaved (middle panel). Interfaces D-D and D-C can coexist with interface I (red rectangle, bottom panel, left); however, the formation of interface D-C′ (white rectangle) would be in steric conflict with interface I (bottom panel, right). Interface II (not shown) would conflict with interface D-C.