Biochemical and NMR characterization of the interactions of Vav2–SH2 domain with lipids and the EphA2 juxtamembrane region on membrane

Abstract

Vav2 is a ubiquitous guanine nucleotide exchange factor (GEF) for Rho family GTPases that is involved in regulating a wide range of biological processes. It interacts with several tyrosine-phosphorylated cell surface receptors, including the Eph family receptors, through its SH2 domain. The interaction of Vav2 with EphA2 is crucial for EphA2-mediated tumor angiogenesis. Here we show that Vav2–SH2 domain is a lipid-binding module that can recognize PI(4,5)P2 and PI(3,4,5)P3 lipids weakly but specifically. The specific lipid-binding site in Vav2–SH2 domain was identified by NMR chemical shift perturbation experiments using the head groups of PI(4,5)P2 and PI(3,4,5)P3, both of which bind to Vav2–SH2 with millimolar binding affinities. In addition, the interaction between Vav2–SH2 and the phosphorylated juxtamembrane region (JM) of EphA2 (Y594 phosphorylated) was investigated using NMR techniques. Furthermore, by using a nickel–lipid containing peptide-based nanodiscs system, we studied the binding of Vav2–SH2 to the phosphorylated JM region of EphA2 on lipid membrane and uncovered a role of membrane environment in modulating this protein–protein recognition.