Structural and dynamic insights into the allosteric activation of p38α MAP kinase via specific docking interactions.

Mitogen-activated protein kinases (MAPKs) bind their cognate activating kinases, inactivating phosphatases, substrates and scaffold proteins through docking interactions. Hematopoietic tyrosine phosphatase (HePTP) can remove phosphate from pTyr of activated p38α and ERK2 to generate partially active, mono-phosphorylated MAPKs (p38α/pT and ERK2/pT). Here, we reported that the enzymatic activity of p38α/pT, but not ERK2/pT, can be significantly increased through its interaction with the kinase interaction motif (KIM) of HePTP. To understand the allosteric activation of p38α/pT, we solved the crystal structure of inactive p38α complexed with a KIM peptide derived from HePTP (pepHePTPm). This study provides for the first time a high resolution structural comparison of the interactions for p38α and ERK2 with the same KIM peptide, and reveals a previously unrecognized interaction mode between MAPK and KIM peptide. Binding of pepHePTPm to the p38α C-lobe induces a distinct conformational change in the kinase hinge region which might influence binding of ATP to the active site. The molecular dynamics (MD) simulations further show that the KIM peptide binding increases the dynamic flexibility of the hinge region, facilitating ATP binding. Our results provide new insights into the regulation of MAPK signaling, highlighting the role of docking-induced allosteric changes in modulating kinase activity.