Modeling of the Ad5:FX interaction to identify FX contact points in the hexon protein. Models of the interaction between hexon and FX were used to determine candidate contact residues in the Ad5 hexon. (A) An atomic resolution representation of one such model is shown in top view (ie, viewed from the virion exterior). Hexon is shown in blue. FX is shown in purple. (B) Polypeptide chains within the trimeric capsomere are named and colored (A, red; B, yellow; and C, purple) relative to the orientation of FX. Missing regions in the crystal structure of hexon are represented with blue sticks and highlighted with black arrows. (C-E) Contact residues are shown for each of the 3 models calculated and named/colored according to their chain assignment relative to FX. Amino acids targeted for mutagenesis have labels that are colored according to regions identified in panel F. In each panel, hexon is represented such that FX is in approximately the same orientation as in panel C. (F) Amino acid alignment of Ad5 and Ad26 hexon HVR sequences to highlight domains (HVR5, red box; HVR7, blue box) and amino acids targeted for mutagenesis studies (point mutations highlighted by *).