FIG. 5.

Model for the initiation complex of DENV RdRp, inspired by the Φ6 polymerase quaternary complex (10) and the HCV complex with ribonucleotides (8). (A) Ribbon representation with the priming base stacking to Trp-795 making Watson-Crick interactions with the template base. (B) Representation of the electrostatic surface of the DENV 3 RdRp viewed from the back (compared to Fig. 2A). Positive electrostatic potentials are colored blue, and negative potentials are colored red. The view illustrates a ssRNA template and provides a model for the initiation complex. The RNA template traverses the tunnel formed between the thumb and fingers subdomains, entering from the top of the figure. The NTP entry channel is at the interface between the thumb and palm subdomains, indicated by an arrow. The ssRNA template and the tP moiety are shown as sticks (the base and sugar moieties were modeled). Residues discussed in the text that play an important functional role are labeled.