Fig 4.
Location and binding environment of putative zinc ion. (A) The putative zinc ion (mauve sphere) binding site is located at the icosahedral 3-fold axes. The three icosahedrally related subunits are colored yellow, pink, and green. The view is from the exterior of the capsid looking into the 3-fold axis. The ligating residue H62 and the location of the P73 mutation for defective transmission are also noted. (B) Side-on view of the putative zinc binding site. The black mesh represents the Fo-Fc map contoured at 4σ. The two partially occupied zinc atoms are shown along with distance between one of the two bound zinc atoms and the closest ε2 nitrogen atom of the two alternative histidine side chain conformations.