In‐silico identification of Tyr232 in AMPKα2 as a dephosphorylation site for the protein tyrosine phosphatase PTP‐PEST

Abstract

AbstractThe AMP‐activated protein kinase (AMPK) is known to be activated by the protein tyrosine phosphatase non‐receptor type 12 (PTP‐PEST) under hypoxic conditions. This activation is mediated by tyrosine dephosphorylation of the AMPKα subunit. However, the identity of the phosphotyrosine residues that PTP‐PEST dephosphorylates remains unknown. In this study, we first predicted the structure of the complex of the AMPKα2 subunit and PTP‐PEST catalytic domain using bioinformatics tools and further confirmed the stability of the complex using molecular dynamics simulations. Evaluation of the protein–protein interfaces indicated that residue Tyr232 is the most likely dephosphorylation site on AMPKα2. In addition, we explored the effect of phosphorylation of PTP‐PEST residue Tyr64 on the stability of the complex. Phosphorylation of the highly conserved Tyr64, an interface residue, enhances the stability of the complex via the rearrangement of a network of electrostatic interactions in conjunction with conformational changes in the catalytic WPD loop. We generated a phosphomimetic (PTP‐PEST‐Y64D) mutant and used co‐immunoprecipitation to study the effect of PTP‐PEST phosphorylation on AMPKα2 binding. The mutant exhibited an increased affinity for AMPKα2 and corroborated the in‐silico predictions. Together, our findings present a plausible structural basis of AMPK regulation by PTP‐PEST and show how phosphorylation of PTP‐PEST affects its interaction with AMPKα2.