Allosteric Modulation of JNK Docking Site Interactions with ATP-Competitive Inhibitors.

The c-Jun N-terminal kinases (JNKs) play a wide variety of roles in cellular signaling processes, dictating important, and even divergent, cellular fates. These essential kinases possess docking surfaces distal to their active sites that interact with diverse binding partners, including upstream activators, downstream substrates, and protein scaffolds. Prior studies have suggested that the interactions of certain protein-binding partners with one such JNK docking surface, termed the D-recruitment site (DRS), can allosterically influence the conformational state of the ATP-binding pocket of JNKs. To further explore the allosteric relationship between the ATP-binding pockets and DRSs of JNKs, we investigated how the interactions of the scaffolding protein JIP1, as well as the upstream activators MKK4 and MKK7, are allosterically influenced by the ATP-binding site occupancy of the JNKs. We show that the affinity of the JNKs for JIP1 can be divergently modulated with ATP-competitive inhibitors, with a >50-fold difference in dissociation constant observed between the lowest- and highest-affinity JNK1-inhibitor complexes. Furthermore, we found that we could promote or attenuate phosphorylation of JNK1's activation loop by MKK4 and MKK7, by varying the ATP-binding site occupancy. Given that JIP1, MKK4, and MKK7 all interact with JNK DRSs, these results demonstrate that there is functional allostery between the ATP-binding sites and DRSs of these kinases. Furthermore, our studies suggest that ATP-competitive inhibitors can allosterically influence the intracellular binding partners of the JNKs.