Supplementary Material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmicb.2020.00298/full#supplementary-material
FIGURE S1  Structures of SARS-CoV and MERS-CoV S proteins, RBDs, and their complexes with respective receptor. Trimeric S proteins of SARS-CoV (PDB: 5×5b) (A) and MERS-CoV (PDB: 5×5f) (C) are colored differently for each monomer. Two conformations of the RBD in each trimeric S protein are labeled as standing and lying states. The RBDs of each S protein are shown as light blue on the right panel. ACE2 and DPP4 receptors are respectively modeled to the trimeric S proteins by match-alignment of SARS-CoV RBD-ACE2 complex (PDB: 2AJF) to SARS-CoV S trimer (B) or MERS-CoV RBD-DPP4 complex (PDB: 4kr0) to MERS-CoV S trimer (D). Each of the RBD-receptor complexes is shown on the right panel. ACE2, angiotensin-converting enzyme 2; DPP4, dipeptidyl peptidase 4; RBD, receptor-binding domain; S, spike.
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