Understanding Periperal Membrane Protein Interactions | BPS Thematic Meeting

Understanding Peripheral Membrane Protein Interactions: Structure, Dynamics, Function and Therapy

Monday Speaker Abstracts

by a Membrane Ligand Activates the EphA2 Receptor.” J Mol Biol. 433:167144. Zhang, L.*, & Buck, M.* (2017) Molecular Dynamics Simulations Reveal Isoform Specific Contact Dynamics Between the Plexin Rho GTPase Binding Domain (RBD) and Small Rho GTPases Rac1 and Rnd1. J Phys Chem B. 121:1485-1498.

SPRY2 INTERACTS WITH ACTIVE RAS TO MODULATE ITS MEMBRANE ORGANIZATION Daniel Abankwa 1 ; 1 University of Luxembourg, Department of Life Sciences and Medicine, Esch-sur-Alzette, Luxembourg K-Ras is regulated and active in nanoscale proteo-lipid domains of the plasma membrane. Only few regulators of K-Ras membrane organisation have been identified so far. We here combined a primary TurboID based proximal proteome screen with a secondary BRET-screen to identify eight novel bona fide interactors of the K-Ras G-domain that would modulate its membrane organisation. We focused our hit characterisation on one novel candidate, APLP2, and SPRY2, which was previously implicated as negative regulator of MAPK-signalling. While APLP2 appeared to indirectly bind to K-Ras via C-Raf, SPRY2 displayed characteristics of a new effector protein. We show by co-immunoprecipitation and BRET-experiments that the C terminal fragment of SPRY2 comprising residues 161-315 interacts more with K-RasG12V than the full-length protein. Both full length and C-terminal fragment localized to the membrane. SPRY2 plasma membrane localization was blocked if K-Ras membrane anchorage was inhibited. Likewise, binding to oncogenic K-Ras was disrupted by K-Ras-inhibitors. Mutations at the predicted interface of the K-Ras effector binding region and the C-terminal fragment of SPRY2 modulated the interaction. Our data further suggest that SPRY2 operates as homo- or hetero-di/oligomer with SPRY4. Both full length SPRY2 and its C-terminal fragment promote differentiation of muscle C2C12 cells, which requires inhibition of MAPK-signalling. We propose a model, wherein active K-Ras recruits SPRY-dimers via the C-terminus of SPRY2 to the plasma membrane where they bind directly to Ras and block access of effectors.

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