Figure 5

Comparison of the charged surface and the residues on loop 1 and loop 7 surrounding the Zn-active site center of A3H, A3A (PDB: 4XXO), and A3B-CD2 (PDB: 5CQI). (A) The charge distribution around the Zn-active site, showing that the Zn-center of A3H and A3A, but not of A3B-CD2, is surrounded by positively charged surface. The surface electrostatic potential colored according to calculated electrostatic potential of accessible surface area from −5 kT/e (red) to 5 kT/e (blue). (B) Five arginine residues on loop 1 of A3H that affect deaminase activity and mC selectivity. (C) Position of A28 (blue dotted sphere) at the Zn-active center pocket, located on the side of the modeled target C in the pocket. The space that would be occupied by a larger T/S at the same position in other APOBECs is represented by red dotted sphere that may pack tighter with the target C. (D) The residues on loop 7, H114 and W115 are shown in sticks. The side chain of W115 was modeled based on the monomer structure.