Ordered assembly of the ESCRT-III complex on endosomes is required to sequester cargo during MVB formation.
The sequential action of the Vps27/HRS complex, ESCRT-I, -II, and -III is required to sort ubiquitinated transmembrane proteins to the lumen of lysosomes via the multivesicular body (MVB) pathway. While Vps27/HRS, ESCRT-I, and -II are recruited to endosomes as preformed complexes, the ESCRT-III subunits Vps20, Snf7, Vps24, and Vps2 only assemble into a complex on endosomes. We have addressed the pathway and the regulation for ESCRT-III assembly. Our findings indicate the ordered assembly of a transient 450 kDa ESCRT-III complex on endosomes. Despite biochemical and structural similarity, each subunit contributes a specific function. Vps20 nucleates transient oligomerization of Snf7, which appears to sequester MVB cargo. Vps24 terminates Snf7 oligomerization by recruiting Vps2, which subsequently engages the AAA-ATPase Vps4 to dissociate ESCRT-III. We propose that the ordered assembly and disassembly of ESCRT-III delineates an MVB sorting domain to sequester cargo and complete the last steps of MVB sorting.
Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.
David
D
Teis
Suraj
S
Saksena
Scott D
SD
Emr
D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000737:chemistry / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000378:metabolism*; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D022161:Transport Vesicles / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D056827:Endosomal Sorting Complexes Required for Transport; D009687:Nuclear Proteins; C083890:SNF7 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C119627:VPS27 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D049452:Green Fluorescent Proteins