Figure 6:

In the wild-type complex, both residues K416 and R418 are located at the interface between A and C subunits and form specific hydrogen bonds with sidechains of residues in subunit C (a). We reconstructed the sidechains of mutated residues R418W and K416E at the interface between A subunits and C (b). Residue-based simulation shows that the double mutants almost totally prevent the association between subunit A and C (c). Furthermore, RB simulations suggest that comparing with the wild-type, the B-C interactions in the mutant dramatically decrease and their fluctuations are distinctively enhanced, although the mutations at subunit A do not directly interfere with the binding interface between subunit B and C (d).