Phosphorylation-Dependent Conformations of the Disordered Carboxyl-Terminus Domain in the Epidermal Growth Factor Receptor

Abstract

The epidermal growth factor receptor (EGFR), a receptor tyrosine kinase, regulates basic cellular functions and is a major target for anticancer therapeutics. The carboxylterminus domain is a disordered region of EGFR that contains the tyrosine residues, which undergo autophosphorylation followed by docking of signaling proteins. Local phosphorylationdependent secondary structure has been identified and is thought to be associated with the signaling cascade. Deciphering and distinguishing the overall conformations, however, have been challenging because of the disordered nature of the carboxyl-terminus domain and resultant lack of well-defined three-dimensional structure for most of the domain. We investigated the overall conformational states of the isolated EGFR carboxyl-terminus domain using single-molecule Forster resonance energy transfer and coarse-grained simulations. Our results suggest that electrostatic interactions between charged residues emerge within the disordered domain upon phosphorylation, producing a looplike conformation. This conformation may enable binding of downstream signaling proteins and potentially reflect a general mechanism in which electrostatics transiently generate functional architectures in disordered regions of a well-folded protein.

Using molecular dynamics simulation to study the polarization response of the liquid water interface to surface charge heterogeneity

“…The transient dynamics of salt bridge formation and deformation are thus relayed to the surrounding liquid via changes in water's interfacial polarization response. These changes may play a role in modulating the water-mediated effects that drive conformational changes (38)(39)(40) or the nascent stages of protein-protein (41) or protein-ligand binding (2).…”

Expanding the Disorder-Function Paradigm in the C-Terminal Tails of Erbbs

“…Moreover, full description of the tail conformation should include phosphorylated states, which are, to our knowledge, not well described in terms of multiplicity and heterogeneity, and difficult to reproduce. The phosphorylated states structurally described so far are therefore either phosphomimetics [28], synthetic monophosphorylations [29], or in vitro autophosphorylation products which were shown to have, on average, one phosphate per tail, which may not be physiologically relevant [34,35].…”

“…IDPs are therefore ideal candidates to participate in signal transduction [24,25]. Recent studies have explicitly confirmed that CT-ErbBs are disordered [26][27][28][29][30]. For a long time, the conformational properties of these tails were not included in studies, and they were treated as mere "strings" attaching the tyrosine phosphorylation sites to the rest of the receptor.…”

“…For a long time, the conformational properties of these tails were not included in studies, and they were treated as mere "strings" attaching the tyrosine phosphorylation sites to the rest of the receptor. However, the growing evidence that the CTs have roles in kinase activity regulation [31][32][33], and that the conformational modulation by phosphorylation may have functional impacts [28,29,34,35] calls for a better structural description.…”

Consistent Force Field Captures Homolog Resolved HP1 Phase Separation

“…The maximum entropy optimization algorithm was developed for parameterizing transferable IDP force fields using biasing energies derived from experimental constraints. 44,45 Energy gap maximization, on the other hand, has been a successful strategy for deriving force fields of folded proteins. [46][47][48][49] The resulting force field, MOFF, indeed provides a more balanced set of interactions that can predict the radii of gyration of both ordered and disordered proteins.…”