Figure 3.

Comparisons of the DPP4 Binding Site with the Epitopes of MERS-4 and MERS-4V2, and Conformational Change of the RBD β5-β6 Loop in the Antibody-Bound State

(A) Structural superimposition showing that the epitopes of MERS-4 and MERS-4V2 (right) are distinct from the DPP4 binding site. A significant conformational difference was found in the RBD β5-β6 loop between antibody-bound and DPP4-bound states.

(B) Zoom-in view of the aligned RBD β5-β6 loops in unbound (4KQZ: blue; 4L3N: magenta; 4ZPW: wheat) and DPP4-bound (4L72: cyan; 4KR0: yellow) with either the MERS-4-bound (green) or MERS-4V2-bound (green) (right) states.

(C) Patch 2 of the RBD/DPP4 binding interface in which residues Leu506, Asp510, and Glu513 from the RBD β5-β6 loop are critical for DPP4 binding.

(D) The steric clashes in the red circle between the β5-β6 loop of the RBD and the DPP4 receptor upon antibody binding.

See also Figure S3.