Effect of the Lys62Ala Mutation on the Thermal Stability of <i>Bst</i>HPr Protein by Molecular Dynamics

Abstract

We analyzed the thermal stability of the BstHPr protein through the site-directed point mutation Lys62 replaced by Ala residue using molecular dynamics simulations at five different temperatures: 298, 333, 362, 400, and 450 K, for periods of 1 μs and in triplicate. The results from the mutant thermophilic BstHPrm protein were compared with those of the wild-type thermophilic BstHPr protein and the mesophilic BsHPr protein. Structural and molecular interaction analyses show that proteins lose stability as temperature increases. Mutant and wild-type proteins behave similarly up to 362 K. However, at 400 K the mutant protein shows greater structural instability, losing more buried hydrogen bonds and exposing more of its non-polar residues to the solvent. Therefore, in this study, we confirmed that the salt bridge network of the Glu3–Lys62–Glu36 triad, made up of the Glu3–Lys62 and Glu36–Lys62 ion pairs, provides thermal stability to the thermophilic BstHPr protein.

Keywords

• <i>Bst</i>HPr protein
• wild type
• mutant
• thermal stability
• molecular dynamics
• salt bridge network