FIG. 4.

Three-dimensional locations of residues conserved among A-VP1, B-VP1, and C-VP1. (A) Surface representation of the A-VP1 crystal structure (PDB no. 2R7R). Domains and subdomains are colored as in Fig. 1. Template entry and dsRNA/RNA exit tunnels are labeled for reference. The 3′CS of group A +RNA (UGUGACC) is shown (green element sticks) in the template entry tunnel, and a GTP (red element sticks) is shown in the putative cap-binding site. (B) Same image as panel A with conserved (red) and nonconserved (gray) amino acids shown. (C and D) Same image as in panels A and B but rotated 180° to the right. The NTP and template entry tunnels are shown for reference. Conserved residues (red) are shown around an unstructured loop that extends from Q346 to D357 (purple). (E and F) Same image as in panels A and B but rotated 90° to the left and shown in sagittal cutaway. All four tunnels are labeled, and free NTPs (yellow element sticks) are modeled near the active site. Conserved residues (red) are shown decorating the catalytic center and NTP and template entry tunnels.