Fig. 3

Global structural changes observed in cN-II hyperactive mutants. a Structural changes in the R367Q mutant revealed by its superposition with the wild-type cN-II (PDB ID 2XCX). The subunits of cN-II tetramer are represented as a light gray surface or dark gray ribbons. The residues with altered positions of C_α atoms are shaded according to the calculated RMSD values. The active site and mutated residues are highlighted as blue and green spheres, respectively, in one of the protein subunits. b Altered intersubunit interactions in the R367Q mutant. Cartoon representations (colored in light blue) illustrate altered intersubunit contacts in the mutant protein, i.e., loss of contact (highlighted as green spheres), formation of a compensatory interaction between subunits (red spheres), and residues with altered binding partners (orange spheres). c Detail of interface B within the wild type and the R367Q mutant. Each subunit is shown in a different color: light and dark gray (wild type) or yellow and orange (R367Q). Residues involved in altered intersubunit contacts are shown as sticks. The beta-sheet structure observed only in the mutants is highlighted. d Segments with the highest RMSD values located within interface A of the R367Q mutant. These regions are shown in cartoon representation, with subunits in different colors. The interhelical loop spanning residues 405–416 was not found in the crystal structure and was modeled using the ModLoop server for illustration. e Structural changes observed in the R238W (PDB ID 5L4Z) and L375F mutants as revealed by a superposition with the wild-type structure (surface representation) and by analysis of polar intersubunit contacts (cartoon representation). Coloring is identical as for the R367Q mutant (panels a and b). f Superposition of the structures obtained for the studied mutants with the ATP-bound wild-type cN-II structure (PDB ID 2XCW). The coloring is identical as for the structures in panels a, b, and e