FIG 4.

Atomic models of the A/B subunit pairs for the apo (A) and GCDCA (B) MNV complexes. In these images, the A and B subunits are colored blue and tan, respectively. (A) Structure of the apo form of MNV. While the resolution of the shell domain was of sufficient quality to build an atomic model, a previously published crystal structure of the P domain (11) was used for modeling. (B) The P domain rotates by nearly 90° and drops down onto the shell in the presence of bile salts. The bound GCDCA is highlighted in yellow and red spheres. (C) Interactions between the P domains in the MNV/GCDCA complex when the capsid collapses in the presence of bile salts. The A, B, and C subunits are shown in blue, green, and red, respectively. Also shown in gray is the electron density of bound GCDCA.