Cellular Membrane Remodeling

Cells are constantly severing, fusing and reshaping their membranes. One of the most important cellular membrane remodeling systems is the ESCRT (Endosomal Sorting Complexes Required for Transport) pathway, whose cellular functions include endosomal membrane remodeling, membrane repair, enveloped virus budding, closure of the nuclear envelope, and cytokinetic abscission. Subunits of the ESCRT-III complex perform key roles in these processes by forming membrane-bound filaments. To understand how these filaments shape membranes, Frost, Sundquist and colleagues used cryo-EM to determine the first high resolution structure of an ESCRT-III filament. The structure showed how ESCRT-III subunits open up and interlock in an elaborate domain-swapped filament architecture, unexpectedly revealed that ESCRT-III filaments contain two ESCRT-III strands, and suggested how analogous ESCRT-III filament architectures can curve and constrict membranes to different degrees and in different directions.