Cellular Membrane Remodeling

ESCRT-III filaments constricting a membrane. (Janet Iwasa)

Cells are continually severing, fusing, and reshaping their membranes. One of the essential 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 vital 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 revealed how ESCRT-III subunits open and interlock in an elaborate domain-swapped filament architecture. Unexpectedly, the results showed that ESCRT-III filaments contain two ESCRT-III strands and that analogous ESCRT-III filament architectures can curve and constrict membranes to different degrees and directions.


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Structure and membrane remodeling activity of ESCRT-III helical polymers. McCullough J, Clippinger AK, Talledge N, Skowyra ML, Saunders MG, Naismith TV, Colf LA, Afonine P, Arthur C, Sundquist WI, Hanson PI, Frost A. Science. 2015 Dec;350(6267):1548.

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