Probing the Epidermal Growth Factor Receptor under Piconewton Mechanical Compressive Force Manipulations

Area of Science:

• Biophysics
• Molecular Biology
• Structural Biology

Background:

• Research on protein dynamics under external forces primarily focuses on pulling forces, leaving compressive force effects underexplored.
• Understanding protein conformational changes under compression is vital for cell signaling mechanisms.

Purpose of the Study:

• To investigate the response of epidermal growth factor receptor (EGFR) monomers and dimers to external compressive forces.
• To uncover novel protein behaviors and conformational changes induced by compression.

Main Methods:

• Utilized a modified Atomic Force Microscopy (AFM) setup with an ultrasoft tip to apply controlled compressive forces.
• Developed a kinetic model to analyze force transmission and internal tension within proteins.
• Employed molecular dynamics (MD) simulations, including Steered MD (SMD) and Umbrella Sampling (US), to study protein dynamics.

Main Results:

• Observed spontaneous tertiary structural rupture in both ligand-bound and unbound EGFR under piconewton-level compressive forces.
• Determined threshold compressive forces in the tens to hundreds of piconewtons, relevant to biological systems.
• Quantified that 45-65% of the applied compressive force contributes to internal tension causing pseudopulling forces before rupture.

Conclusions:

• EGFR proteins exhibit significant conformational changes and structural rupture under compressive forces, a previously unrecognized behavior.
• The findings suggest a new mechanism of protein regulation and signaling influenced by mechanical compression.
• MD simulations provide detailed insights into the flexibilities and unfolding pathways of EGFR under compressive stress.