Structure-kinetic relationship reveals the mechanism of selectivity of FAK inhibitors over PYK2.

There is increasing evidence of a significant correlation between prolonged drug-target residence time and increased drug efficacy. Here, we report a structural rationale for kinetic selectivity between two closely related kinases: focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (PYK2). We found that slowly dissociating FAK inhibitors induce helical structure at the DFG motif of FAK but not PYK2. Binding kinetic data, high-resolution structures and mutagenesis data support the role of hydrophobic interactions of inhibitors with the DFG-helical region, providing a structural rationale for slow dissociation rates from FAK and kinetic selectivity over PYK2. Our experimental data correlate well with computed relative residence times from molecular simulations, supporting a feasible strategy for rationally optimizing ligand residence times. We suggest that the interplay between the protein structural mobility and ligand-induced effects is a key regulator of the kinetic selectivity of inhibitors of FAK versus PYK2.
Competing Interests: Declaration of interests M.F., J.B., and T.H. are employees of Merck KGaA, Darmstadt, Germany. M.A. was an employee of Merck KGaA, Darmstadt, Germany at the time of experimental procedures and is now an employee of Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany. Other authors have no conflict of interest to declare.
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