Figure 2. Fab binding sites on ZIKV surface.

The E proteins are represented in three colours—blue (chains A, A′ and A″), red (chains C, C′ and C″) and green (chains E, E′ and E″). Chains A and A′ are arranged in a dimer around the icosahedral two-fold axis (blue oval with black outline), while chains C and E are arranged in a general dimer around a quasi two-fold axis (yellow oval with black outline). The icosahedral and general dimers are related by an axis of quasi two-fold symmetry (orange oval with black outline). Residues Asp67 (red), Gln89 (green) and Lys118 (blue), which were mapped to the Fab binding site by mutagenesis, are shown as spheres. The footprints of the Fab bound at the 2f and 3f sites are represented as light and dark grey ovals with broken outlines. The black stars mark the position of the fusion peptides. The steric hindrance on the 5f site due to the orientation of DIII of chain A″ is highlighted by black arrows. For reference, two asymmetric units are shown as triangles in solid and broken dashed lines. The icosahedral five- and three-fold axes are marked with a pentagon and two triangles receptively.