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Updated: Jan 29, 2026
Purification of Ubiquitinated p53 Proteins from Mammalian Cells
Published on: March 21, 2022
Insight Into the Binding Mechanism of p53/pDIQ-MDMX/MDM2 With the Interaction Entropy Method
Mengxin Li1, Yalong Cong1, Yuchen Li1
1School of Physics and Electronics, Shandong Normal University, Jinan, China.
Abstract:
The study of the p53-MDMX/MDM2 binding sites is a research hotspot for tumor drug design. The inhibition of p53-targeted MDMX/MDM2 has become an effective approach in anti-tumor drug development. In this paper, a theoretically rigorous and computationally accurate method, namely, the interaction entropy (IE) method, combined with the polarized protein-specific charge (PPC) force field, is used to explore the difference in the binding mechanism between p53-MDMX and p53-MDM2. The interaction of a 12mer peptide inhibitor (pDIQ), which is similar to p53 in structure, with MDMX/MDM2 is also studied. The results demonstrate that p53/pDIQ with MDM2 generates a stronger interaction than with MDMX. Compared to p53, pDIQ has larger binding free energies with MDMX and MDM2. According to the calculated binding free energies, the differences in the binding free energy among the four complexes that are obtained from the combination of PPC and IE are more consistent with the experimental values than with the results from the combination of the non-polarizable AMBER force field and IE. In addition, according to the decomposition of the binding free energy, the van der Waals (vdW) interactions are the main driving force for the binding of the four complexes. They are also the main source of the weaker binding affinity of p53/pDIQ-MDMX relative to p53/pDIQ-MDM2. Compared with p53-MDMX/MDM2, according to the analysis of the residue decomposition, the predicated total residue contributions are higher in pDIQ-MDMX/MDM2 than in p53-MDMX/MDM2, which explains why pDIQ has higher binding affinity than p53 with MDMX/MDM2. The current study provides theoretical guidance for understanding the binding mechanisms and designing a potent dual inhibitor that is targeted to MDMX/MDM2.
Insights
The interaction entropy (IE) method with polarized protein-specific charge (PPC) force fields reveals MDM2 binds stronger than MDMX to p53 and peptide inhibitors. Van der Waals interactions drive binding, guiding potent dual inhibitor design for cancer therapy.
Area of Science:
- Computational chemistry and molecular modeling
- Drug discovery and design
- Cancer biology and therapeutics
Background:
- The p53-MDMX/MDM2 binding sites are crucial targets in cancer drug development.
- Inhibiting p53-targeted MDMX/MDM2 is a promising anti-tumor strategy.
Purpose of the Study:
- To investigate the differential binding mechanisms between p53 and its peptide inhibitor (pDIQ) with MDMX and MDM2.
- To evaluate the accuracy of the interaction entropy (IE) method combined with the polarized protein-specific charge (PPC) force field for predicting binding affinities.
- To provide theoretical insights for designing potent dual inhibitors targeting MDMX/MDM2.
Main Methods:
- Utilized the interaction entropy (IE) method coupled with the polarized protein-specific charge (PPC) force field.
- Calculated and compared binding free energies for p53-MDMX, p53-MDM2, pDIQ-MDMX, and pDIQ-MDM2 complexes.
- Analyzed binding free energy decomposition and residue contributions to understand interaction drivers.
Main Results:
- MDM2 exhibited stronger binding interactions with both p53 and the pDIQ peptide compared to MDMX.
- The PPC-IE combination provided binding free energy predictions more consistent with experimental data than the AMBER force field-IE combination.
- Van der Waals interactions were identified as the primary driving force for the binding of all studied complexes.
Conclusions:
- The pDIQ peptide demonstrates higher binding affinity to both MDMX and MDM2 than the native p53.
- The PPC-IE method is a reliable computational tool for studying protein-ligand interactions in drug design.
- Understanding these binding mechanisms and forces can guide the development of effective dual MDMX/MDM2 inhibitors for cancer treatment.
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