Curvature Sensing and Membrane Remodeling of the VPS37A N-terminal Domain during Autophagy

VPS37A, a component of ESCRT-I, is essential for recruiting a subset of ESCRT proteins that seal the phagophore during autophagosome biogenesis. In this study, we uncover two hydrophobic motifs in the VPS37A N-terminal 148 amino acids (VPS37A ^1-148 ) that selectively interact with highly curved membranes. Mutations in these motifs nearly abolish VPS37A membrane binding in vitro and compromise its localization to the phagophore and autophagic flux in vivo . We also determined the solution structure of residues 21 to 131 and demonstrated that it is the UEVL (ubiquitin E2 variant-like) domain. Intriguingly, this domain remodels highly curved liposomes to high-order structures. We suggest that the specific interactions between VPS37A ^1-148 and the curved membrane may facilitate the recruitment of VPS37A to the phagophore and its subsequent closure. Our results support the premise that the distinct membrane architecture of the cup-like phagophore spatiotemporally regulates autophagosome biogenesis.