On the Importance of Polar Interactions for Complexes Containing Intrinsically Disordered Proteins
Figure 6
Box plots of electrostatic components of the binding free energy.
(a) Electrostatic contribution to the desolvation free energy of binding. (b) Coulombic interaction energy of binding. (c) Total electrostatic free energy of binding. Asterisks identify distributions that are significantly different (p values<0.05; Wilcoxon test). Electrostatic contributions to binding are shown for ID complexes and 3D complexes in red and grey, respectively. (d–f) Nup50/importin-α2 is an example of a complex that involves burial of extensive polar surfaces (PDB: 2C1M [81]). The surface of importin-α2 was generated using a probe radius of 1.5 Å. The surface is colored using the electrostatic potential map of importin-α2 that was generated by Delphi. The ID segment, Nup50, is represented by the cartoon ribbon structure with ARG, LYS, and HIS residues colored in blue and GLU and ASP residues colored in red. (d) The full view of the interacting region of the Nup50/importin-α2 complex. (e) Nup50 (37–46) contains a high concentration of positively charged residues that bind to an acidic region of importin-α2. (f) The positively charged residues of the N-terminus of Nup50 are complementary to an acidic surface on its binding partner.