Background:
The Murine Double Minute 2 (MDM2) protein is a well-studied primary negative regulator of the tumor suppressor p53 molecule. Therefore, nowadays, many research studies have focused on the inhibition of MDM2 with potent inhibitors. Idasanutlin (RG7388) is a well-studied small molecule, the antagonist of MDM2 with potential antineoplastic activity. Nevertheless, the highly significant information about the free energy profile, intermediates, and the association of receptor and ligand components in the MDM2-idasanutlin complex remains unclear.
Objective:
To study the free energy profile of the MDM2-idasanutlin complex in terms of the Potential of Mean Force (PMF) method.
Method:
We have used the PMF method coupled with umbrella sampling simulations to generate the free energy profile for the association of N-Terminal Domain (NTD) of MDM2 and idasanutlin and a specific reaction coordinate for identifying transition states, intermediates as well as the relative stabilities of the endpoints. We have also determined the binding characteristics and interacting residues at the interface of the MDM2-idasanutlin complex from the Binding Free Energy (BFE) and Per Residue Energy Decomposition (PRED) analyses.
Results:
The PMF minima for the MDM2-idasanutlin complex was observed at a center of mass (CoM) distance of separation of 11 Å with dissociation energy of 17.5 kcal mol-1. As a function of the distance of separation of MDM2 from idasanutlin. We also studied the conformational dynamics and stability of the NTD of MDM2. We found a high binding affinity between MDM2 and idasanutlin (∆Grinding = -3.19 kcal mol-1). We found that in MDM2, the residues MET54, VAL67, and LEU58 provide the highest energy input for the interaction between MDM2 and idasanutlin.
Conclusion:
Our results in this study illustrate the significant structural and binding features of the MDM2-idasanutlin complex that may be useful in developing potent inhibitors of MDM2.
Exact Relation between Potential of Mean Force and Free-Energy Profile
