The effect of L۸۱۳N|A۸۱۴R double mutations on Taq polymerase structure

Thermus aquaticus DNA polymerase I (Taq polymerase), similar to family A DNA polymerase other members, possess polymerization and ۵’-۳’ exonuclease activities. This enzyme plays a role in DNA repair and Okazaki fragments ejection during DNA replication and the lack of ۳’-۵’ exonuclease activity causes its high error rate. Taq polymerases, due to their thermostability properties, have a wide application in biotechnology techniques, namely PCR. There are several studies in order to create improved enzymes, including hot start enzymes, chimeric enzymes with ۳’-۵’ exonuclease activity and additional thermostability. Here, we studied the e↵ect of L۸۱۳N| A۸۱۴R double mutations on Taq polymerase structural stability using MD simulation methods. The comparison of three iterated simulations on wild-type and mutant enzymes demonstrated that the enzymes did not show any significant di↵erence in RMSF, SASA, and protein-protein hydrogen bonds analysis. However, the number of protein-solvent hydrogen bonds increased in mutant ones (with seven more bonds). Substitution of aliphatic residues (L and A) with polar ones (N and R) enhances the possibility of hydrogen bond formation, which improves protein structure stability. In our case, due to the presence of ۸۱۳ and ۸۱۴ residues on the protein surface, this increase in the bonds was observed between protein and solvent. Therefore, it is proposed that L۸۱۳N| A۸۱۴R double mutations are able to raise Taq polymerase structural stability.

کلیدواژه ها:

Taq Polymerase ، Thermus aquaticus ، DNA polymerase ، structural stability ، MD simulation