Molecular dynamics analysis of T567 phosphorylation-induced conformational changes in ezrin

Ezrin, a key member of the ERM (Ezrin-Radixin-Moesin) family, links the plasma membrane to the actin cytoskeleton and is regulated by a conformational switch between closed and open states. Although phosphatidylinositol 4,5-bisphosphate binding and phosphorylation at Thr567 are known to promote Ezrin activation, the associated conformational mechanism remains incompletely understood. Here, we combined Martini coarse-grained molecular dynamics simulations with enhanced sampling, all-atom molecular dynamics simulations, and MM/PBSA calculations to compare wild-type Ezrin with the phosphomimetic T567D mutant. The simulations indicate that T567 phosphorylation destabilizes the FERM/C-ERMAD interface, promotes domain separation, and facilitates exposure of membrane- and actin-binding sites. Computational analysis of binding free energies further demonstrates that the interaction between FERM and C-ERMAD is attenuated due to the phosphorylation of T567. Finally, a stepwise dissociation mechanism for the C-ERMAD α-helices is proposed. These results support a model in which T567 phosphorylation primarily promotes the initial transition toward an open conformation, whereas complete unfolding and full activation likely require additional events, including PIP2 binding, recruitment of partner proteins, and interaction with actin filaments.