Phosphatidylinositol and phosphatidylinositol-3-phosphate activate HOPS to catalyze SNARE assembly, allowing small headgroup lipids to support the terminal steps of membrane fusion.
Mol Biol Cell
; 32(21): ar19, 2021 11 01.
Article
em En
| MEDLINE
| ID: mdl-34495682
ABSTRACT
Intracellular membrane fusion requires Rab GTPases, tethers, SNAREs of the R, Qa, Qb, and Qc families, and SNARE chaperones of the Sec17 (SNAP), Sec18 (NSF), and SM (Sec1/Munc18) families. The vacuolar HOPS complex combines the functions of membrane tethering and SM catalysis of SNARE assembly. HOPS is activated for this catalysis by binding to the vacuolar lipids and Rab. Of the eight major vacuolar lipids, we now report that phosphatidylinositol and phosphatidylinositol-3-phosphate are required to activate HOPS for SNARE complex assembly. These lipids plus ergosterol also allow full trans-SNARE complex assembly, yet do not support fusion, which is reliant on either phosphatidylethanolamine (PE) or on phosphatidic acid (PA), phosphatidylserine (PS), and diacylglycerol (DAG). Fusion with a synthetic tether and without HOPS, or even without SNAREs, still relies on either PE or on PS, PA, and DAG. These lipids are thus required for the terminal bilayer rearrangement step of fusion, distinct from the lipid requirements for the earlier step of activating HOPS for trans-SNARE assembly.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfatidilinositóis
/
Fosfatos de Fosfatidilinositol
/
Proteínas SNARE
Idioma:
En
Revista:
Mol Biol Cell
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
2021
Tipo de documento:
Article