Molecular dynamics simulations of p53 DNA-binding domain

Area of Science:

• Structural biology
• Computational biophysics
• Molecular dynamics simulations

Background:

• The p53 protein plays a crucial role in tumor suppression.
• Understanding the structural dynamics of the p53 DNA-binding domain is essential for comprehending its function and the impact of mutations.

Purpose of the Study:

• To investigate the room-temperature structural and dynamic properties of the p53 DNA-binding domain.
• To compare these properties in both DNA-bound and DNA-free states.
• To correlate native contacts with the inactivation mechanisms of tumor mutations.

Main Methods:

• Performed extensive explicit solvent molecular dynamics simulations (55 ns cumulative).
• Utilized particle mesh Ewald treatment for electrostatics.
• Analyzed structural deviations, backbone root-mean-square deviations (RMSD), and B-factors.

Main Results:

• Simulated mean structures closely matched crystal structures (RMSD 1.6-2.0 Å).
• Observed minor structural deviations primarily in loop L6, more pronounced in the DNA-free state.
• Found minimal backbone structural changes between DNA-bound and DNA-free states, except at the DNA-binding interface.
• Identified specific tumor mutations potentially weakening key interactions, leading to loss of local structure and protein stability.

Conclusions:

• The p53 DNA-binding domain exhibits remarkable structural stability regardless of DNA binding.
• Tumorigenic mutations likely inactivate p53 by disrupting critical interactions at the DNA-binding interface, compromising protein stability.
• Specific residue interactions (e.g., R175/S183) are identified as crucial for DNA binding.