Class C Vps protein complex regulates vacuolar SNARE pairing and is required for vesicle docking/fusion.
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.
Sato
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TK
Division of Cellular and Molecular Medicine and Howard Hughes Medical Institute, University of California at San Diego School of Medicine, La Jolla 92093, USA.
Rehling
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Peterson
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Emr
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SD
D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D004926:Escherichia coli; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000502:physiology; D006056:Golgi Apparatus / Q000378:metabolism; D008561:Membrane Fusion / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D050765:Qa-SNARE Proteins; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D050825:Synaptosomal-Associated Protein 25; D014617:Vacuoles / Q000378:metabolism*; D033921:Vesicular Transport Proteins; D015003:Yeasts
D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; C071657:PEP3 protein, S cerevisiae; C065710:PEP5 protein, S cerevisiae; D050765:Qa-SNARE Proteins; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D050825:Synaptosomal-Associated Protein 25; C107706:VAM3 protein, S cerevisiae; C080045:VPS16 protein, S cerevisiae; C065454:VPS33 protein, S cerevisiae; D033921:Vesicular Transport Proteins