Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Medicine, New York, NY, 10065, USA.
Department of Anesthesiology, Weill Cornell Medicine, New York, NY, 10065, USA.
Nat Commun. 2022 Apr 21;13(1):2174. doi: 10.1038/s41467-022-29850-z.
Endosomal Sorting Complex Required for Transport III (ESCRT-III) is a conserved protein system involved in many cellular processes resulting in membrane deformation and scission, topologically away from the cytoplasm. However, little is known about the transition of the planar membrane-associated protein assembly into a 3D structure. High-speed atomic force microscopy (HS-AFM) provided insights into assembly, structural dynamics and turnover of Snf7, the major ESCRT-III component, on planar supported lipid bilayers. Here, we develop HS-AFM experiments that remove the constraints of membrane planarity, crowdedness, and support rigidity. On non-planar membranes, Snf7 monomers are curvature insensitive, but Snf7-spirals selectively adapt their conformation to membrane geometry. In a non-crowded system, Snf7-spirals reach a critical radius, and remodel to minimize internal stress. On non-rigid supports, Snf7-spirals compact and buckle, deforming the underlying bilayer. These experiments provide direct evidence that Snf7 is sufficient to mediate topological transitions, in agreement with the loaded spiral spring model.
内体分选复合物需要运输 III（ESCRT-III）是一种保守的蛋白质系统，参与许多细胞过程，导致膜变形和分裂，拓扑上远离细胞质。然而，对于平面膜相关蛋白组装体转变为 3D 结构的过程知之甚少。高速原子力显微镜（HS-AFM）提供了有关平面支持脂质双层上 Snf7，主要 ESCRT-III 成分的组装、结构动力学和周转的见解。在这里，我们开发了 HS-AFM 实验，以消除膜平面、拥挤和支撑刚性的限制。在非平面膜上，Snf7 单体对曲率不敏感，但 Snf7-螺旋选择性地适应膜几何形状。在非拥挤的系统中，Snf7-螺旋达到临界半径，并进行重构以最小化内部应力。在非刚性支撑下，Snf7-螺旋压缩和弯曲，使底层双层变形。这些实验提供了直接的证据，证明 Snf7 足以介导拓扑转变，与加载的螺旋弹簧模型一致。
