An in silico method for designing thermostable variant of a dimeric mesophilic protein based on its 3D structure

Abstract

Designing proteins with enhanced thermostability has been a major interest of protein engineering because of its potential industrial applications. Here, we have presented a computational method for designing dimeric thermostable protein based on rational mutations on a mesophilic protein. Experimental and structural data indicate that the surface stability of a protein is a major factor controlling denaturation of a protein and ion-pairs are most efficient in enhancing the stability of the surfaces of the monomers and the interface between them. Our mutation based strategy is to first identify several polar or charged residues on the protein surface, interacting weakly with the rest of the protein and then replacing the side-chains of suitable neighboring residues to increase the interaction between these two residues. In stabilizing the interface, mutation is done in the interface for forming an ion pairs between the monomers. Application of this design strategy to a homo-dimeric protein and a hetero-dimeric protein as examples has produced excellent results. In both the cases the designed mutated proteins including the individual monomers and the interfaces were found to be considerably more stable than the respective mesophilic proteins as judged by self-energies and residue-wise interaction patterns. This method is easily applicable to any multi-meric proteins.