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PDBsum entry 4lcb
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Protein transport
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PDB id
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4lcb
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DOI no:
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J Mol Biol
426:510-525
(2014)
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PubMed id:
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The oligomeric state of the active Vps4 AAA ATPase.
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N.Monroe,
H.Han,
M.D.Gonciarz,
D.M.Eckert,
M.A.Karren,
F.G.Whitby,
W.I.Sundquist,
C.P.Hill.
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ABSTRACT
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The cellular ESCRT (endosomal sorting complexes required for transport) pathway
drives membrane constriction toward the cytosol and effects membrane fission
during cytokinesis, endosomal sorting, and the release of many enveloped
viruses, including the human immunodeficiency virus. A component of this
pathway, the AAA ATPase Vps4, provides energy for pathway progression. Although
it is established that Vps4 functions as an oligomer, subunit stoichiometry and
other fundamental features of the functional enzyme are unclear. Here, we report
that although some mutant Vps4 proteins form dodecameric assemblies, active
wild-type Saccharomyces cerevisiae and Sulfolobus solfataricus Vps4 enzymes can
form hexamers in the presence of ATP and ADP, as assayed by size-exclusion
chromatography and equilibrium analytical ultracentrifugation. The Vta1p
activator binds hexameric yeast Vps4p without changing the oligomeric state of
Vps4p, implying that the active Vta1p-Vps4p complex also contains a single
hexameric ring. Additionally, we report crystal structures of two different
archaeal Vps4 homologs, whose structures and lattice interactions suggest a
conserved mode of oligomerization. Disruption of the proposed hexamerization
interface by mutagenesis abolished the ATPase activity of archaeal Vps4 proteins
and blocked Vps4p function in S. cerevisiae. These data challenge the prevailing
model that active Vps4 is a double-ring dodecamer, and argue that, like other
type I AAA ATPases, Vps4 functions as a single ring with six subunits.
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');
}
}
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