Movie S2.

The transition from α-helix (dark green) in the hexon to β-strand (orange) in the penton for residues 189–198. The movie shows the morphing of a pair of adjacent molecules from the hexon to the penton by superimposition according to the molecule in red. The two molecules are colored blue and red, respectively. Residues 182–206 are in green. Side chains of residues W146 (magenta), W173 (cyan), and W196 (gold) as well as surrounding hydrophobic residues (gray) are shown as stick models. Included are two views related by 90° about the horizontal axis.