Figure 1

Overall structure of cnCka1-AMPPNP-Mg²⁺. cnCka1 is shown in magenta and AMPPNP in green. The coordinating Mg²⁺ ion is shown as a green sphere. (a) Structure of cnCka1-AMPPNP-Mg²⁺ consisting of an ATP-binding site, N-terminal β-sheets, a critical αC helix as well as C-terminal α-helices. (b) Electrostatic potential map depicting the hydrophobic ATP-binding cleft where AMPPNP-Mg²⁺ lies. Basic regions are shown in blue, acidic regions in red and hydrophobic regions in white. (c) 2Fo-Fc map showing the binding of AMPPNP-Mg²⁺ at the ATP-binding site contoured at 2.0 σ. (d) Interaction between cnCka1 residues and AMPPNP-Mg²⁺. Hydrogen bonds are depicted as brown dashed lines. Blue dashed lines depict the coordination of the Mg²⁺ ion by the β- and γ-phosphates of AMPPNP and Asp174.