Microsecond MD Simulations to Explore the Structural and Energetic Differences between the Human RXRα-PPARγ vs....

Area of Science:

• Molecular biology
• Structural biology
• Computational chemistry

Background:

• The RXRα-PPARγ heterodimer is crucial for lipid metabolism, regulating gene expression via DNA binding.
• Previous studies elucidated the complex's conformation but lacked energetic insights into interactions.

Purpose of the Study:

• To investigate the structural and energetic mechanisms of the RXRα-PPARγ heterodimer, with and without DNA and ligands.
• To understand how DNA binding influences receptor-ligand and protein-protein interactions.

Main Methods:

• Microsecond molecular dynamics (MD) simulations.
• Binding free energy calculations (MM/GBSA).
• Principal component analysis (PCA) and free energy landscape analysis.

Main Results:

• DNA binding modifies correlated motions and conformational flexibility within the RXRα-PPARγ system.
• Intradomain correlated motions are enhanced in the DNA-bound complex, particularly near ligand-binding sites.
• PPARγ plays a more significant role in regulating both free and DNA-bound states.

Conclusions:

• DNA binding modulates the RXRα-PPARγ complex's dynamics, affecting dimerization and ligand binding affinity.
• Understanding these energetic shifts provides deeper insights into transcriptional regulation of lipid metabolism.