Figure 3.

RBD amino acids in 3D structure of the bound ACE2 and schematic representation of mutations in the RBD

(A) Overall 3D structure of the RBD-ACE2 interaction. The RBD is colored in green, the receptor-binding motif (RBM) of the RBD is in dark blue, and ACE2 is in dark cyan. C361 is in the bottom middle of the overall structure in the RBD core section and is not depicted in the following illustrations. (B) Enlarged view of the overall structure depicting the RBD target mutation sites in stick representation, colored in magenta. (C–E) Stick representation of target mutation sites at the contact site of two molecules. Dotted lines connect the mutant amino acids (aa) to their contacting amino acids in ACE2. The structure is from PDB: 6M0J. (F) Illustration of the amino acid changes used to examine the RBD in this study. (G) Immunoblot of LgBiT-RBD mutant expression from the cell lysates of transfected HEK293T cells. β-actin and total protein loading are shown as controls. (H) Bioreporter assay with LgBiT-RBD mutants demonstrating altered binding affinity of various mutants.