Molecular-Scale Investigations Reveal the Effect of Natural Polyphenols on BAX/Bcl-2 Interactions

Area of Science:

• Molecular Biology
• Biophysics
• Cell Biology

Background:

• Apoptosis, or programmed cell death, is regulated by protein-protein interactions (PPIs) between B-cell lymphoma 2-associated x protein (BAX) and B-cell lymphoma 2 protein (Bcl-2).
• The balance between BAX and Bcl-2 activity kinetics is crucial for proper apoptosis signaling.
• Natural polyphenols present a potential avenue for modulating these critical PPIs, but the underlying mechanisms require detailed investigation.

Purpose of the Study:

• To investigate the molecular mechanisms by which various natural polyphenols affect the binding dynamics of BAX and Bcl-2.
• To quantify the impact of polyphenols on the forces, kinetics, thermodynamics, and structural characteristics of BAX/Bcl-2 complex formation.

Main Methods:

• Atomic Force Microscopy (AFM) was employed to probe the molecular interactions between BAX and Bcl-2 in the presence of polyphenols.
• Surface free energy measurements and molecular docking simulations were utilized to complement AFM data.

Main Results:

• Polyphenols were found to quantitatively influence the interaction forces, kinetics, thermodynamics, and structural properties of BAX/Bcl-2 complex formation at the molecular scale.
• Specific polyphenols, including rutin, epigallocatechin gallate, and baicalin, significantly reduced the binding affinity between BAX and Bcl-2 by approximately one order of magnitude.
• Analysis revealed that polyphenols modulate PPIs through hydrogen bonding, hydrophobic interactions, and van der Waals forces, influencing the orientation freedom of the complex.

Conclusions:

• This study demonstrates that natural polyphenols can effectively tune the PPIs of BAX/Bcl-2, thereby modulating apoptosis signaling.
• The findings provide a molecular-level understanding of how polyphenols interact with and alter the BAX/Bcl-2 complex, offering insights for therapeutic strategies targeting cell death.
• The research highlights the potential of using small molecules like polyphenols to precisely control protein-protein interactions and their functional outcomes.