Transitions to catalytically inactive conformations in EGFR kinase

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• The epidermal growth factor receptor (EGFR) kinase domain is a critical target for small-molecule drugs due to its role in cellular signaling.
• Understanding the conformational transitions between active and inactive states of EGFR kinase is crucial for drug development.
• Experimental characterization of these dynamic transitions has been challenging.

Purpose of the Study:

• To investigate the dynamic conformational transitions of EGFR kinase using molecular dynamics simulations.
• To identify and characterize intermediate states during the transition from active to inactive EGFR kinase conformations.
• To correlate simulation findings with experimental data and explore implications for drug discovery.

Main Methods:

• Unbiased, all-atom molecular dynamics simulations of EGFR kinase.
• Simulations of transitions to both "Src-like inactive" and "Asp-Phe-Gly-out" (DFG-out) inactive conformations.
• Hydrogen-deuterium (H/D) exchange measurements to validate simulation results.

Main Results:

• EGFR kinase spontaneously transitioned from active to inactive states through novel intermediate conformations, including locally disordered and "extended" states.
• The "extended" intermediate conformations are characterized by the opening of the ATP-binding site.
• Simulated intermediate conformations showed better correlation with H/D exchange data than existing crystal structures.
• Local unfolding, or "cracking," was identified as a key element in the simulated transitions.

Conclusions:

• Molecular dynamics simulations reveal previously undescribed intermediate conformations during EGFR kinase activation/inactivation.
• These intermediate states, validated by H/D exchange, differ significantly from static crystal structures.
• The identified intermediate conformations present new opportunities for structure-based drug discovery targeting EGFR kinase.