Investigating EnB1-Induced Membrane Remodeling via Contrast-Variation Neutron Scattering

Cellular membranes exhibit complex three-dimensional architectures essential for numerous biological processes. Membrane-binding proteins contribute to shaping these structures by inducing curvature and remodeling lipid bilayers into tubules and vesicles. Among them, proteins from the Bin/Amphiphysin/Rvs167 (BAR) domain superfamily are key players. These peripheral dimers possess a conserved coiled-coil domain that forms a banana-shaped BAR domain capable of sensing and generating curvature. N-BAR proteins, a subclass, also contain N-terminal amphipathic helices that insert into membranes to enhance curvature. Endophilin B1 (EnB1), an N-BAR protein, participates in oncogenesis-related pathways, including autophagy and apoptosis. Its amphipathic regions mediate membrane association and tubule formation. Cryo-EM has shown EnB1 decorates lipid vesicles and binds nanodiscs as dimers, but these structures do not fully resolve lipid bilayer rearrangements. To address this, we propose using contrast variation small-angle neutron scattering (SANS), which enables selective visualization of sample components by modulating the D₂O/H₂O ratio. Unlike X-rays, neutrons scatter based on nuclear scattering length density, allowing specific masking of components such as protein, lipid tails, or headgroups. This approach will enable detailed analysis of lipid bilayer remodeling induced by EnB1.