FIG 5.

Structure of ARV RdRp VP2 with bound RNA and comparison of RdRp bracelet domains in ARV and CPV. (A to D) Ribbon diagrams of the atomic model of ARV RdRp VP2 with domains shown together (A) or separated. The RdRp core domain (B), comprising the finger, palm, and thumb subdomains, is sandwiched between the N-terminal domain (C) and the C-terminal bracelet domain (D). (E and F) The segment blocking the template exit in the CPV RdRp bracelet domain undergoes large conformational changes between the quiescent (E) and transcribing (F) states (13). The equivalent segment in ARV RdRp is similarly colored in panel D. (G and H) Cartoons showing the hand metaphor of polymerase core structure, with color coding following that in panel A. The polygons represent N- and C-terminal domains. (G) Four channels intersecting at the active site are labeled. (H) The N-terminal domain and bracelet are displayed on back and front planes, respectively.