Structural Bases of Coronavirus Attachment to Host Aminopeptidase N and Its Inhibition by Neutralizing Antibodies
Figure 5
Structure of the RBD of TGEV and conformation of the receptor-binding edge in Alphacoronavirus.
A. Ribbon diagram of RBD protein structure with β-strands in light or dark blue, coils in orange, and helix in red. A β-bulge at β-strand 5 is shown in magenta. N- and C-terminal ends on the terminal side of the structure are indicated in lowercase letters. The Asn residues at glycosylation sites and the attached glycans defined in the structure are shown as a ball-and-stick model, with carbons in yellow. Cysteine residues and disulfide bonds are shown as green cylinders. Side chains of the pAPN-binding Tyr and Trp residues in the loops at the β-barrel domain tip are shown in red in panels A to C. B. Stereo view of superimposed Alphacoronavirus RBD structures. The pAPN-binding RBD of TGEV is in blue and the ACE2-binding RBD of HCoV-NL63 (PDB ID 3KBH) is in orange. C. Surface representation of the TGEV and HCoV-NL63 RBD structures in B, with receptor-binding residues in pink or red. D. Structure-based sequence alignment of Alphacoronavirus RBD structures shown in C. β-strands are marked (bars) above or beneath their sequences. TGEV sequence is numbered. ACE2 receptor-binding residues reported for HCoV-NL63 [11], as well as pAPN receptor-binding residues for TGEV (Supplementary Table S2) are colored as in C. Residues absent in the RBD structures are in grey, and the thrombin recognition sequence at the end of the TGEV RBD is in lowercase letters.