A guanine nucleotide exchange factor (GEF) limits Rab GTPase-driven membrane fusion.
The identity of organelles in the endomembrane system of any eukaryotic cell critically depends on the correctly localized Rab GTPase, which binds effectors and thus promotes membrane remodeling or fusion. However, it is still unresolved which factors are required and therefore define the localization of the correct fusion machinery. Using ... SNARE-decorated proteoliposomes that cannot fuse on their own, we now demonstrate that full fusion activity can be achieved by just four soluble factors: a soluble SNARE (Vam7), a guanine nucleotide exchange factor (GEF, Mon1-Ccz1), a Rab-GDP dissociation inhibitor (GDI) complex (prenylated Ypt7-GDI), and a Rab effector complex (HOPS). Our findings reveal that the GEF Mon1-Ccz1 is necessary and sufficient for stabilizing prenylated Ypt7 on membranes. HOPS binding to Ypt7-GTP then drives SNARE-mediated fusion, which is fully GTP-dependent. We conclude that an entire fusion cascade can be controlled by a GEF.
Mesh Terms:
Endosomes, Guanine Nucleotide Dissociation Inhibitors, Guanine Nucleotide Exchange Factors, Lysosomes, Membrane Fusion, Prenylation, Protein Binding, Protein Transport, Proteolipids, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Synaptosomal-Associated Protein 25, Vesicular Transport Proteins, rab GTP-Binding Proteins
Endosomes, Guanine Nucleotide Dissociation Inhibitors, Guanine Nucleotide Exchange Factors, Lysosomes, Membrane Fusion, Prenylation, Protein Binding, Protein Transport, Proteolipids, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Synaptosomal-Associated Protein 25, Vesicular Transport Proteins, rab GTP-Binding Proteins
J. Biol. Chem.
Date: Dec. 12, 2017
PubMed ID: 29184002
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