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

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.

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