A biophysical framework for double-drugging kinases

Area of Science:

• Biochemistry
• Structural Biology
• Pharmacology

Background:

• Selective kinase inhibition is difficult due to conserved active sites and resistance mutations.
• Simultaneous targeting of orthosteric and allosteric sites ('double-drugging') shows promise for overcoming resistance.
• The cooperative mechanisms underlying kinase double-drugging require detailed biophysical characterization.

Purpose of the Study:

• To develop a quantitative framework for characterizing kinase double-drugging.
• To investigate the cooperative effects between orthosteric and allosteric modulators on Aurora A kinase (AurA) and Abelson kinase (Abl).
• To elucidate the structural and mechanistic basis of synergistic kinase inhibition.

Main Methods:

• Isothermal titration calorimetry (ITC)
• Förster resonance energy transfer (FRET)
• Coupled-enzyme assays
• X-ray crystallography

Main Results:

• Identified positive and negative cooperativity between orthosteric and allosteric modulators for AurA and Abl.
• Demonstrated that conformational equilibrium shifts govern cooperativity.
• Observed synergistic reduction in drug dosages for clinically relevant inhibition levels.
• Determined X-ray crystal structures of double-drugged kinase complexes, revealing molecular mechanisms.
• Reported a fully closed Abl conformation induced by positively cooperative modulators.

Conclusions:

• Double-drugging provides a synergistic strategy for kinase inhibition, reducing drug dosage requirements.
• Conformational equilibrium shifts are key to understanding cooperativity in double-drugging.
• Mechanistic and structural insights support the rational design of double-drugging therapies.