Fig. 1

Interaction between lectin griffithsin (GRFT) (PDB ID: 2NU5) that was homodimer (A and B chain) with N-acetylglucosamine (GlcNAc) as ligand. a The interacting domains of the lectin with GlcNAc, depicted by BIOVIA Discovery Studio Visualizer, are shown. In the figure, the lectin is shown schematically in blue, while ligands are shown in scaled ball-and-stick style in red. b–d Residues and atoms participating in the interaction between B chain of the lectin and three residues of ligand (GlcNAc 122, 123 and 124), depicted by using the LigPlot⁺ v.2.2 program [15]. The bonds shown by dashed lines in olive-green color represent hydrogenic bonds, while the bonds shown by radius lines in brick-red color represent hydrophobic bonds. The numbers on the hydrogen bond show bond distances. Note: Two carbohydrates of N-acetylglucosamine and mannose are contained in SARS-CoV-2 surface glycan, and the residues are exposed to the innate immune system [16]. So, the crystal structure of complexes of antiviral lectin GRFT with glucose and N-acetylglucosamine were solved and refined at high resolution. In both complexes, all six monosaccharide-binding sites of GRFT were occupied, and the mode of binding was similar to that of mannose [17]. Therefore, as an example of multiple lectins, the interaction pattern of GRFT with GlcNAc is selected to be shown in the figure