Structure of the human adenovirus serotype 2 fiber head domain at 1.5 angstrom resolution

Adenovirus binds to its receptor via the head domain of its fiber protein. We have crystallized the adenovirus serotype 2 (subgroup C) receptor bindin g domain and solved the structure at 1.5 Angstrom resolution by the molecul ar replacement technique using the known adenovirus type 5 head structure. Included in the high-resolution model are 306 water molecules, five alterna tive side chain conformations, and individual anisotropic temperature facto rs for each atom. The overall structure of the serotype 2 head is very simi lar to its serotype 5 homologue, apart from differences in some of the flex ible loops. All but subgroup B adenoviruses are believed to use the recentl y identified protein CAR (Coxsackievirus and adenovirus receptor) as recept or. By comparison of the two structures and sequence alignment of CAR bindi ng and non-CAR binding serotype fiber heads, we discuss possible receptor b inding sites and propose a receptor binding site in a crevice between two m onomers on the side of the trimer. The structural basis of the extraordinar y stability of the fiber bead trimer is also discussed. (C) 1999 Academic P ress.