Fig. 4

Comparison of secondary and tertiary structures of MERS-like CoV RBD. a Predicted 3D MMS of the core and external subdomains of HKU4 RBD and human DPP4 (right and left lateral view). The two deletions observed in IT Bat CoVs RBD are evidenced in green. b Structure –based sequence alignment . The secondary structure elements are defined based on an ESPript algorithm and are labeled as in a previous report on the MERS RBD structure [24]. Spiral lines indicate helices, while arrows represent β strands. The external subdomain is highlighted by enclosure in a blue box. The two deletions found in IT Bat CoVs and HKU5 RBD are marked with blue lines. The Arabic numerals 1–4 indicate cysteine residues that pair to form disulfide bonds