Activation of human VPS4A by ESCRT-III proteins reveals ability of substrates to relieve enzyme autoinhibition

Samuel A. Merrill, Phyllis I. Hanson

Research output: Contribution to journalArticlepeer-review

Abstract

VPS4 proteins are AAA+ ATPases required to form multive-sicular bodies, release viral particles, and complete cytokinesis. They act by disassembling ESCRT-III heteropolymers during or after their proposed function in membrane scission. Here we show that purified human VPS4A is essentially inactive but can be stimulated to hydrolyze ATP by ESCRT-III proteins in a reaction that requires both their previously defined MIT interacting motifs and ∼50 amino acids of the adjacent sequence. Importantly, C-terminal fragments of all ESCRT-III proteins tested, including CHMP2A, CHMP1B, CHMP3, CHMP4A, CHMP6, and CHMP5, activated VPS4A suggesting that it disassembles ESCRT-III heteropolymers by affecting each component protein. VPS4A is thought to act as a ring-shaped cylindrical oligomer like other AAA+ ATPases, but this has been difficult to directly demonstrate. We found that concentrating His 6-VPS4A on liposomes containing Ni2+-nitrilotriacetic acid-tagged lipid increased ATP hydrolysis, confirming the importance of inter-subunit interactions for activity. We also found that mutating pore loops expected to line the center of a cylindrical oligomer changed the response of VPS4A to ESCRT-III proteins. Based on these data, we propose that ESCRT-III proteins facilitate assembly of functional but transient VPS4A oligomers and interact with sequences inside the pore of the assembled enzyme. Deleting the N-terminal MIT domain and adjacent linker from VPS4A increased both basal and liposome-enhanced ATPase activity, indicating that these elements play a role in autoinhibiting VPS4A until it encounters ESCRT-III proteins. These findings reveal new ways in which VPS4 activity is regulated and specifically directed to ESCRT-III polymers.

Original languageEnglish (US)
Pages (from-to)35428-35438
Number of pages11
JournalJournal of Biological Chemistry
Volume285
Issue number46
DOIs
StatePublished - Nov 12 2010

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Activation of human VPS4A by ESCRT-III proteins reveals ability of substrates to relieve enzyme autoinhibition'. Together they form a unique fingerprint.

Cite this