Crystallographic data and statistics.

aNumbers in parentheses correspond to the highest resolution shell.bRsym = Σ|Ii−〈I〉|/ΣIi, where Ii is the intensity of the ith observation, and 〈I〉 is the mean intensity of reflection.cRcryst = Σ∥Fo|−|Fc∥/Σ|Fo|, calculated with the working reflection set. Rfree is the same as Rcryst but calculated with the reserved reflection set.dProgram PROCHECK [28], portions of the protein residues in most favored/additional allowed/generously allowed regions.