(A) Coat protein subunits depicted as ribbon diagrams around a quasi three-fold axis Dec-binding site. Three coat subunits directly surrounding a quasi three-fold axis are shown in light grey, and three neighboring coat proteins are shown in black. Residues selected for mutagenesis are shown as spheres. (B) Normalized binding data of the ratio of variant coat protein bound to WT Dec, color-coded to match the corresponding residues in panel A. (C) Portions of Dec highlighting the OB-fold (residues 10–77) shown as ribbons, with each monomer a different shade of blue. Residues selected for mutagenesis are shown as spheres. (D) Enlarged side view of the Dec cryo-EM density with the OB-fold (residues 10–77) from one monomer shown as a ribbon, with the two different capsid-binding sites indicated. (E) Normalized binding data of the ratio of WT coat protein bound to variant Dec, and color-coded to match the corresponding residues in panels C and D.