Covalent Lipid Pocket Ligands Targeting p38α MAPK Mutants

A chemical genetic approach is presented to covalently target a unique lipid binding pocket in the protein kinase p38α, whose function is not yet known. Based on a series of cocrystal structures, a library of 2‐arylquinazolines that were decorated with electrophiles were designed and synthesized to covalently target tailored p38α mutants containing artificially introduced cysteine residues. Matching protein–ligand pairs were identified by MS analysis and further validated by MS/MS studies and protein crystallography. The covalent ligands that emerged from this approach showed excellent selectivity towards a single p38α mutant and will be applicable as suitable probes in future studies of biological systems to dissect the function of the lipid pocket by means of pharmacological perturbations. Pocket picking: Electrophile‐modified quinazolines have been developed as covalent ligands of a lipid binding pocket in p38α, the biological function of which is as yet unknown. Their binding to tailor‐made kinase mutants was validated by mass spectrometry and protein X‐ray crystallography. This chemical genetic approach led to the identification of specific protein–ligand pairs suitable for application in future studies.