Crystal structures of the complex between human AGO2 MID domain and modified nucleoside monophosphates. (A) 8-Br AMP electron density and its interactions with Ago2-MID (PDB ID: 7D7U). The 8-Br AMP molecule is shown as a ball-and-stick model with its carbon atoms in gold. The main chain structure of Ago2-MID is shown as a ribbon model, while the amino acid residues and water molecules incorporated in the interactions are shown as simple stick models and red balls, respectively. The hydrogen bonds are indicated by pink dashed lines, and the ligand-omitted Fo − Fc electron density map at the 3.0 σ level is represented as a green mesh. (B) Superimposed AMP in the AGO2-MID/8-Br AMP complex. 8-Br AMP and AMP molecules are shown as ball-and-stick models with their carbon atoms in gold and pale green, respectively. The protein structure of the AGO2-MID/8-Br AMP complex is illustrated as a ribbon model. (C) Chemical structure of 6-mCEPh-purine. (D) 6-mCEPh-purine electron density and its interactions with AGO2-MID (PDB ID: 7C6B). 6-mCEPh-purine molecule is shown as a ball-and-stick model with its carbon atoms in moss green. The main chain structure of AGO2-MID is shown as a ribbon model, while the amino acid residues and water molecules incorporated in the interactions are represented as simple stick models and red balls, respectively. The hydrogen bonds are indicated by pink dashed lines, and the ligand-omitted Fo − Fc electron density map at the 3.0 σ level is represented as a green mesh.
