Fig 1.

Crystal structure of the MERS-CoV S1 C-domain. (A) Domain structure of MERS-CoV S1 subunit that contains an N-terminal domain (NTD) and a C-domain. The boundaries of the C-domain and proposed receptor-binding motif (RBM) of MERS-CoV were determined by sequence and structural comparisons with the SARS-CoV S1 subunit (see Fig. 2). (B) Sequence and secondary structure of the MERS-CoV C-domain. Helices are drawn as cylinders, and strands are drawn as arrows. The disordered region is shown as a dashed line. (C) Crystal structure of the MERS-CoV C-domain. The core structure is in cyan, and the proposed RBM region is in red.