Class C Vps Protein Complex Regulates Vacuolar SNARE Pairing and Is Required for Vesicle Docking/Fusion

• Published in: Molecular cell Vol. 6; no. 3; pp. 661 - 671
• Main Authors: Sato, Trey K., Rehling, Peter, Peterson, Michael R., Emr, Scott D.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2000
• Subjects: Adaptor Proteins, Vesicular Transport; Carrier Proteins; Cytoplasmic Vesicles - metabolism; Escherichia coli; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Expression - physiology; Golgi Apparatus - metabolism; Membrane Fusion - physiology; Membrane Proteins - genetics; Membrane Proteins - metabolism; Munc18 Proteins; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Protein Transport - physiology; Qa-SNARE Proteins; Saccharomyces cerevisiae Proteins; SNARE protein; SNARE Proteins; Synaptosomal-Associated Protein 25; Vacuoles - metabolism; Vesicular Transport Proteins; Vps protein; Yeasts
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/S1097-2765(00)00064-2

In yeast, the Class C Vps protein complex (C-Vps complex), composed of Vps11, Vps16, Vps18, and Vps33, functions in Golgi-to-vacuole protein transport. In this study, we characterized and purified this complex and identified its interaction with the syntaxin homolog Vam3. Vam3 pairs with the SNAP-25 homolog Vam7 and VAMP homolog Vti1 to form SNARE complexes during vesicle docking/fusion with the vacuole. The C-Vps complex does not bind to Vam3-Vti1-Vam7 paired SNARE complexes but instead binds to unpaired Vam3. Antibodies to a component of this complex inhibited in vitro vacuole-to-vacuole fusion. Furthermore, temperature-conditional mutations in the Class C VPS genes destabilized Vam3-Vti1-Vam7 pairing. Therefore, we propose that the C-Vps complex associates with unpaired (activated) Vam3 to mediate the assembly of trans-SNARE complexes during both vesicle docking/fusion and vacuole-to-vacuole fusion.