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

Abstract

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An inducible ESCRT-III inhibition tool to control HIV-1 budding

“…In contrast, CHMP3-NS3-FP does not affect VPS4 activity, suggesting that its structure is compatible with VPS4 function. Blocking auto-cleavage of CHMP4B and CHMP2A by NS3 with Glecaprevir does not fully inhibit VLP release and notably blocking auto-cleavage of CHMP3-NS3-FP has no effect on VLP release, but enhances the effect of CHMP2A-NS3-FP, in agreement with the reported synergy of CHMP2A-CHMP3 on HIV-1 budding [53] and CHM2A-CHMP3 heteropolymer formation in vitro [34]. Interestingly, a VPS4B mutant that was previously shown to slow down the kinetics of ESCRT-III disassembly in vitro [64] shows a similar reduction in VLP release as inhibition of CHMP4B and CHMP2A auto-cleavage.…”

“…VPS4 was suggested to constantly remodel ESCRT-III in vivo [47] consistent with VPS4-catalyzed ESCRT-III filament remodeling in vitro [48, 49]. Notably CHMP2A-CHMP3 filament remodeling into dome-like end-caps was suggested to constrict membrane necks from fixed diameters of 45 to 55 nm down to the point of fission [34, 48, 50].…”

“…Mammalian cells express eight different ESCRT-III proteins, CHMP1 to 8, with CHMP1, CHMP2 and CHMP4 present in two and three isoforms, respectively [23]. ESCRT-III proteins shuttle between an inactive autoinhibited closed conformation [26,27] and an activated state [28][29][30] that polymerizes in the open ESCRT-III conformation [31][32][33][34] assembling into loose filaments or tight helical structures in vitro [27,[35][36][37][38][39][40] and in vivo [41][42][43][44][45]. Most ESCRT-III proteins contain MIT-domain interacting motifs (MIMs) present within their C-termini recruiting VPS4 [46].…”

The patterned assembly and stepwise Vps4-mediated disassembly of composite ESCRT-III polymers drives archaeal cell division

“…S3D). This suggests that ESCRT-III proteins in S. acidocaldarius form layered composite structures, not heteropolymers like their eukaryotic counterparts Vps2 and Vps24 ( 43 ). CdvB1 consistently formed two rings flanking CdvB2, while CdvB2 was found either assembled into a single diffuse structure overlying the central CdvB ring or into two flanking rings that are too close to easily resolve using STED.…”

Brominated lipid probes expose structural asymmetries in constricted membranes

“…When exposed to model membranes in vitro, ESCRT-III proteins can shape membranes into structures with zero 31,32 , positive 22,29,[33][34][35][36] or negative curvature 31,32,[37][38][39] . We recently demonstrated how a pair of human ESCRT-III proteins, CHMP1B and IST1, assemble into helical filaments that act in sequence to remodel membranes into high-curvature nanotubes with an inner diameter of only roughly Supplementary Information for full details).…”