Structural basis of CHMP2A-CHMP3 ESCRT-III polymer assembly and membrane cleavage

Abstract

The endosomal sorting complex required for transport (ESCRT) is a highly conserved protein machinery that drives a divers set of physiological and pathological membrane remodeling processes. However, the structural basis of ESCRT-III polymers stabilizing, constricting and cleaving negatively curved membranes is yet unknown. Here we present cryo electron microscopy structures of membrane-coated CHMP2A-CHMP3 filaments of two different diameters at 3.3 and 3.6 Å resolution. The structures reveal helical filaments assembled by CHMP2A-CHMP3 heterodimers in the open ESCRT-III conformation, which generates a partially positive charged membrane interaction surface, positions short N-terminal motifs for membrane interaction and the C-terminal VPS4 target sequence towards the tube interior. Inter-filament interactions are electrostatic, which facilitate filament sliding upon VPS4-mediated polymer remodeling. Fluorescence microscopy as well as high speed atomic force microscopy imaging corroborate that CHMP2A-CHMP3 polymers and VPS4 can constrict and cleave narrow membrane tubes, thus acting as a minimal membrane fission machinery.

Predicting cell type-specific extracellular vesicle biology using an organism-wide single cell transcriptomic atlas – insights from theTabula Muris

“…ESCRT-II (Vps25, Vps22 and Vps36) sorts proteins within the membrane region forming the endosome [13,14] and assembles ESCRT-III [15]. ESCRT-III is a filament (polymer) of charged multivesicular body proteins (Chmps) including Chmp1a, Chmp1b, Chmp2a, Chmp2b, Chmp4a, Chmp4b and Chmp4c, which wrap around the inward curving region of the membrane [16,17]. Other Chmp family members with putative roles in ESCRTdependent processing include Chmp3, Chmp5, Chmp6, Chmp7, Chmp8 and Ist1 [18].…”

The Calpain-7 protease functions together with the ESCRT-III protein IST1 within the midbody to regulate the timing and completion of abscission

“…Humans express 12 distinct ESCRT-III proteins that are recruited to membrane fission sites throughout the cell, including to midbodies that connect dividing cells during cytokinesis. Within the midbody, ESCRT-III proteins copolymerize into filaments that constrict the membrane to the fission point ( Guizetti et al, 2011 ; Elia et al, 2011 ; Mierzwa et al, 2017 ; Nguyen et al, 2020 ; Pfitzner et al, 2021 ; Azad et al, 2022 ). ESCRT-III filaments also recruit a variety of cofactors, including the VPS4 AAA+ ATPases, which dynamically remodel the filaments to drive midbody constriction ( Elia et al, 2012 ; Mierzwa et al, 2017 ; Pfitzner et al, 2020 ; Pfitzner et al, 2021 ).…”