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Structure. 2008 Sep 10;16(9):1345-56. doi: 10.1016/j.str.2008.06.010.

Structure and disassembly of filaments formed by the ESCRT-III subunit Vps24.

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1
MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.

Abstract

The ESCRT machinery mediates sorting of ubiquitinated transmembrane proteins to lysosomes via multivesicular bodies (MVBs) and also has roles in cytokinesis and viral budding. The ESCRT-III subunits are metastable monomers that transiently assemble on membranes. However, the nature of these assemblies is unknown. Among the core yeast ESCRT-III subunits, Snf7 and Vps24 spontaneously form ordered polymers in vitro. Single-particle EM reconstruction of helical Vps24 filaments shows both parallel and head-to-head subunit arrangements. Mutations of regions involved in intermolecular assembly in vitro result in cargo-sorting defects in vivo, suggesting that these homopolymers mimic interactions formed by ESCRT-III heteropolymers during MVB biogenesis. The C terminus of Vps24 is at the surface of the filaments and is not required for filament assembly. When this region is replaced by the MIT-interacting motif from the Vps2 subunit of ESCRT-III, the AAA-ATPase Vps4 can both bundle and disassemble the chimeric filaments in a nucleotide-dependent fashion.

PMID:
18786397
DOI:
10.1016/j.str.2008.06.010
[Indexed for MEDLINE]
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