A direct role for the Sec1/Munc18-family protein Vps33 as a template for SNARE assembly.
Fusion of intracellular transport vesicles requires soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and Sec1/Munc18-family (SM) proteins. Membrane-bridging SNARE complexes are critical for fusion, but their spontaneous assembly is inefficient and may require SM proteins in vivo. We report x-ray structures of Vps33, the SM subunit of the yeast homotypic fusion and vacuole protein-sorting (HOPS) complex, bound to two individual SNAREs. The two SNAREs, one from each membrane, are held in the correct orientation and register for subsequent complex assembly. Vps33 and potentially other SM proteins could thus act as templates for generating partially zipped SNARE assembly intermediates. HOPS was essential to mediate SNARE complex assembly at physiological SNARE concentrations. Thus, Vps33 appears to catalyze SNARE complex assembly through specific SNARE motif recognition.
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Richard W
RW
Baker
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Philip D
PD
Jeffrey
Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
Michael
M
Zick
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Ben P
BP
Phillips
Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
William T
WT
Wickner
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA. hughson@princeton.edu.
Frederick M
FM
Hughson
D018360:Crystallography, X-Ray; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D051938:Munc18 Proteins / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D050765:Qa-SNARE Proteins / Q000378:metabolism*; D050683:R-SNARE Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D050825:Synaptosomal-Associated Protein 25 / Q000737:chemistry / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure
D008565:Membrane Proteins; D051938:Munc18 Proteins; C500806:Nyv1 protein, S cerevisiae; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D050825:Synaptosomal-Associated Protein 25; C494205:VAM7 protein, S cerevisiae; C065454:VPS33 protein, S cerevisiae; D033921:Vesicular Transport Proteins