Interactions of the EphA2 Kinase Domain with PIPs in Membranes: Implications for Receptor Function

Matthieu Chavent,Dimple Karia,Antreas C Kalli,Jan Domański,Anna L Duncan,George Hedger,Phillip J Stansfeld,Elena Seiradake,E Yvonne Jones,Mark S.P Sansom

doi:10.1016/j.str.2018.05.003

Abstract

SummaryEphA2 is a member of the receptor tyrosine kinase family. Interactions of the cytoplasmic region of EphA2 with the cell membrane are functionally important and yet remain incompletely characterized. Molecular dynamics simulations combined with biochemical studies reveal the interactions of the transmembrane, juxtamembrane (JM), and kinase domains with the membrane. We describe how the kinase domain is oriented relative to the membrane and how the JM region can modulate this interaction. We highlight the role of phosphatidylinositol phosphates (PIPs) in mediating the interaction of the kinase domain with the membrane and, conversely, how positively charged patches at the kinase surface and in the JM region induce the formation of nanoclusters of PIP molecules in the membrane. Integration of these results with those from previous studies enable computational reconstitution of a near complete EphA2 receptor within a membrane, suggesting a role for receptor-lipid interactions in modulation of EphA2.

Highlights

The ephrin receptors (Ephs) are key members of the family of receptor tyrosine kinases (RTKs)
Interaction of the EphA2 Kinase Domain with Model Cell Membranes Inspection of the location of basic residues both within the JM region and on the surface of the kinase domain suggest that the components of the JM + kinase region are likely to interact with anionic lipids at the cytoplasmic surface of the cell membrane
We have demonstrated the contribution of PIP2-mediated interactions between the JM + kinase domains and the membrane in determining the overall configuration of the EphA2 receptor within cell membranes

Summary

Introduction

The ephrin receptors (Ephs) are key members of the family of receptor tyrosine kinases (RTKs). They have critical roles in developmental processes and have been implicated in a number of cancers (Herbert and Stainier, 2011; Lai and Ip, 2009; Pasquale, 2010). Class A Ephs bind preferentially to ephrinA ligands, which are membrane-tethered through a glycosylphosphatidylinositol (GPI) anchor. Class B Ephs preferentially bind ephrinBs, which are attached to the membrane via a transmembrane (TM) helix (Kullander and Klein, 2002). All Eph receptors share a common domain architecture, whereby the N-terminal ectodomain is made up of a ligand binding domain (LBD), which interacts with ephrin ligands, a Sushi domain, an epidermal growth factor (EGF)-like domain, and two fibronectin type III domains (FN1 and FN2). Recent combined simulation and biochemical studies (Chavent et al, 2016) suggest the ectodomain may be oriented relative to the cell membrane via FN2 domain interactions with lipids in the extracellular leaflet

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Conclusion