Structure and disassembly of filaments formed by the ESCRT-III subunit Vps24.
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.
Ghazi-Tabatabai
Sara
S
MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.
Saksena
Suraj
S
Short
Judith M
JM
Pobbati
Ajaybabu V
AV
Veprintsev
Dmitry B
DB
Crowther
R Anthony
RA
Emr
Scott D
SD
Egelman
Edward H
EH
Williams
Roger L
RL
D000251:Adenosine Triphosphatases / Q000378:metabolism; D003599:Cytoskeleton / Q000737:chemistry* / Q000378:metabolism; D019281:Dimerization; D056827:Endosomal Sorting Complexes Required for Transport; D008954:Models, Biological; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense / Q000502:physiology; D011108:Polymers / Q000378:metabolism; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary / Q000502:physiology; D021122:Protein Subunits / Q000737:chemistry; D021381:Protein Transport / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D056827:Endosomal Sorting Complexes Required for Transport; D018832:Molecular Chaperones; D011108:Polymers; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; C533340:Vps24 protein, S cerevisiae; D000251:Adenosine Triphosphatases