| Calcineurin and PP1, which both belong to serine/threonine protein phosphatase, play important roles in the process of dephosphorylation.We can use molecular mechanics method and classical molecular dynamics to study CN and PP1, which can reveal their relationship between structure and function in atomic level. Because of the lack of related parameters of transition metals in current force field, we decided to carry out parmeter fitting to the active site of CN and PP1. In this study, we performed quantum chemical calculations to the active site of CN and PP1 and got the Hessian matrix related transition metals. We finally obtained the force constant through unit conversion. We compared the results with the values reported in published reference and found out that the results of parameters were reasonable. Calcineurin B subunit (CNB), as a regulatory subunit of the calcineurin, is a member of EF-hand calcium-binding proteins. In this study, Molecular dynamics simulations were performed to simulate Calcium-induced conformational change of CNB. Simulations of the fully Ca2+-saturated state of CNB (Holo-CNB) and the Ca2+-free state (Apo-CNB) were performed in solution for 20ns starting from the X-ray crystal structure of Holo-CNB binding with Calcineurin A subunit (CNA). Based on the trajectories of MD, we found that there was no drastic change between Holo-CNB and Apo-CNB. The modest difference mainly exists in the interhelical angles of four EF-hand motifs and solvent accessible surface area of hydrophobic groove, whereas both Holo-CNB and Apo-CNB hold an integrated hydrophobic groove, which implies that CNB, regardless of binding with Ca2+ or not, has the potential to bind with CNA, although distinguished in the affinity. We can set up the relationship between the exposure degree of the hydrophobic groove and the affinity between CNB and CNA according to the previous work done by our lab. This may reveal the structure reason for the CNB's regulating function.. Calcineurin B subunit (CNB), as a regulatory subunit of the calcineurin, is a member of EF-hand calcium-binding proteins. Its hydrophobic domain, which is composed of four EF-hands, is an important structural basis of the regulating function. The crystal structure shows that the main site locates in the place where immunosuppressive agent FK506 interacts with CN. The mutant experiment on the hydrophobic domain showed that the activity of CN decrease, general 10% as compared to the wildtype CNB. The same tendency also occurred in the ANS fluorescence spectroscopy and the survival rate of mice-injected-protein against H22, especially in the M118 mutant serials. In this study, Molecular dynamics simulations were performed to simulate wildtype CNB, M118E-CNB in which the Met118 was mutanted to Glu118 and M118K-CNB in which the Met118 was mutanted to Lys118. Based on the trajectories of MD, we found that the mutant to M118 indeed destoried the hydrophobic domain of C-Terminal, which became fragmented and less hydrophobic residues exposured to solvent. This may block the activation of congenital immune system in which CNB participates and decrease the anticancer activity of CNB. |
