Fig. 6.

Modeling HAP-1-induced assembly. A fragment from a hexagonal lattice modeled by minimizing an AB dimer from the crystal structure (16) in plane group p3 with unit cell dimensions of a = b = 95 Å. (A and B) Dimer is viewed down the spike (A) or from the side (B). Modest changes in the C terminus (residues 128-142) and at the dimer interface are demonstrated in the overlay of the starting (A, red; B, yellow) and minimized (A, indigo; B, cyan) dimers. Note that C termini in both A and B show similar changes, consistent with the quasi-sixfold nature of the p3 threefold. (C) A schematic of Cp assembly products without and with HAP. Small amounts of HAP-1 were tolerated in capsids with apparently normal morphology. Larger amounts of HAP-1 led to aberrant structures that contained larger fractions of hexameric capsomers. Dimers without HAP-1 are filled with gray and black; dimers with bound HAP-1 are white.