Phosphorylation modulates estrogen receptor disorder by altering long-range hydrophobic interactions

Protein intrinsic disorder is coupled to a range of biological phenomena, from gene regulation to cancer progression. Phosphorylation of the estrogen receptor (ER) at Ser118 through its disordered N-terminal domain (NTD) activates its transcriptional function, but it is challenging to rationalize how this modification regulates ER activity. Using biophysical approaches of small-angle X-ray scattering and nuclear magnetic resonance spectroscopy, we demonstrate that Ser118 phosphorylation triggers long-range conformational changes in ER-NTD, particularly between two hydrophobic clusters of residual structures. Alanine substitution of hydrophobic amino acids near Ser118 produces similar conformational alterations and rescues impaired ER activity caused by a phosphorylation-deficient mutant. These findings establish a direct link between phosphorylation-induced conformational changes and the activation function of this disordered protein as a promising avenue to block ER transcriptional activation.