Figure 3.

Predicted Mg²⁺ binding site at the P4–P5 interface of the Mg²⁺ riboswitch. (A) Crystallographic electron density at the interface (gray surface) with residues ligating the crystallographic assigned water molecule labeled. (B) GFE maps (cyan mesh) and predicted Mg²⁺ binding sites (green spheres) at this site. (C) Three “core” Mg²⁺ binding regions of the M-box Mg²⁺ riboswitch according to Wakeman et al.²⁹ are indicated. The GCMC sampling box is mapped onto the structure.