Temperature vaulting: A method for screening of slow- and tight-binding inhibitors that selectively target kinases in their non-native state

A polypeptide folds into its protein tertiary structure in the native state through a folding intermediate in the non-native state. The transition between these states is thermodynamically driven. A folding intermediate of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) autophosphorylates intramolecularly, whereas DYRK1A in the native state no longer catalyzes this reaction. The alteration in substrate specificity suggests a conformational transition of DYRK1A during its folding process. Consistent with this hypothesis, we identified FINDY ( 1 ), which inhibits the intramolecular autophosphorylation but not the intermolecular phosphorylation, suggesting that the folding intermediate possesses an alternative inhibitor-binding site. Meanwhile, it remains an issue that the methods for approaching the alternative binding site require an intricate assay tailored to the individual target. Here we show a method, designated as “temperature vaulting,” for screening the non-native-state-targeted inhibitors of DYRK1A. Transient heating of recombinant DYRK1A protein drove the reversible transition between the native state and the non-native state targeted by FINDY ( 1 ). At physiological temperature, FINDY ( 1 ) slowly bound to the DYRK1A protein. These results indicate that transient heating accelerates the slow-binding process by assisting the protein to overcome the high-energy barrier leading to the target non-native state. The energy barrier also slowed down the dissociation process, resulting in tight binding between DYRK1A and FINDY ( 1 ). Furthermore, this study suggests that the dissociation rate underlies the inhibition selectivity of FINDY ( 1 ) between DYRK1A and its family kinase DYRK1B. This method enables the identification of slow- and tight-binding inhibitors that have been missed in conventional assays.