How Electrostatic Coupling Enables Conformational Plasticity in a Tyrosine Kinase.

Area of Science:

• Biochemistry
• Structural Biology
• Computational Biology

Background:

• Protein kinases are crucial in cell signaling and disease, exhibiting complex conformational flexibility.
• Understanding kinase conformational dynamics is vital for developing targeted therapies.
• Current drug discovery methods face challenges due to this inherent plasticity.

Purpose of the Study:

• To explore the conformational landscape of c-Src kinase using molecular dynamics.
• To investigate the role of protonation states in kinase conformational changes.
• To identify novel intermediate states for drug design.

Main Methods:

• Proton-coupled molecular dynamics simulations were performed on c-Src kinase.
• Simulations explored conformational states without predefined targets, mutations, or biases.
• Key residue protonation states and their impact on conformation were analyzed.

Main Results:

• All major kinase conformational states were captured, including inactive and active forms.
• Protonation states of key residues (DFG-Asp, αC-Glu, HRD-Asp) were found to be conformation-dependent.
• A novel DFG-out/α-C intermediate state was identified, involving a salt bridge with catalytic Lys.

Conclusions:

• Proton coupling is a critical mechanism underlying kinase conformational plasticity.
• The identified intermediate states offer new opportunities for selective inhibitor design.
• Considering proton-coupled dynamics could revolutionize computational kinase studies and drug discovery.