Abstract
The Endosomal Sorting Complexes Required for Transport (ESCRT) machinery is a vital cellular system orchestrating diverse membrane remodeling events, including multivesicular body (MVB) biogenesis, cytokinesis, viral budding, and plasma membrane repair [9, 8, 23, 26]. This intricate process involves the sequential recruitment and assembly of ESCRT-0, -I, -II, and -III complexes, culminating in membrane scission, followed by the ATP-dependent disassembly of ESCRT-III polymers by the Vps4 ATPase [9]. Understanding the dynamic structural transformations underpinning ESCRT function has been a significant challenge due to the transient and polymorphic nature of its protein assemblies. This article reviews the transformative impact of cryo-electron microscopy (cryo-EM) on elucidating the molecular mechanisms of ESCRT machinery assembly and disassembly. Recent cryo-EM studies have provided unprecedented near-atomic resolution insights into the architecture of ESCRT-III helical filaments, revealing how these polymers induce membrane constriction and curvature [24, 29]. Furthermore, cryo-EM has clarified the structural basis of Vps4-mediated ESCRT-III disassembly, detailing the conformational changes of Vps4 hexamers and their interaction with ESCRT-III subunits during ATP hydrolysis [22, 25]. These structural revelations have significantly advanced our comprehension of how ESCRT complexes orchestrate membrane topology changes. Future cryo-EM applications, particularly cryo-electron tomography, promise to further unravel the full ESCRT cascade in situ, offering deeper mechanistic understanding with implications for understanding cellular pathologies associated with ESCRT dysfunction [2, 20].