HOPS recognizes each SNARE, assembling ternary trans -complexes for rapid fusion upon engagement with the 4th SNARE

• Published in: eLife Vol. 9
• Main Authors: Song, Hongki, Orr, Amy S, Lee, Miriam, Harner, Max E, Wickner, William T
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 21-01-2020; eLife Sciences Publications Ltd; eLife Sciences Publications, Ltd
• Subjects: Binding sites; Biochemistry and Chemical Biology; HOPS; Intermediates; Intracellular Membranes - metabolism; Lipids; Membrane Fusion; Membranes; Protein Binding; Proteins; Questions and answers; R-SNARE Proteins - metabolism; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - metabolism; SNAP receptors; SNARE; Vacuoles - metabolism; yeast vacuoles; Canada; yeast vacuoles; chemical biology; biochemistry; HOPS; S. cerevisiae; SNARE; membrane fusion
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.53559

Yeast vacuole fusion requires R-SNARE, Q-SNAREs, and HOPS. A HOPS SM-family subunit binds the R- and Qa-SNAREs. We now report that HOPS binds each of the four SNAREs. HOPS catalyzes fusion when the Q-SNAREs are not pre-assembled, ushering them into a functional complex. Co-incubation of HOPS, proteoliposomes bearing R-SNARE, and proteoliposomes with any two Q-SNAREs yields a rapid-fusion complex with 3 SNAREs in a
-assembly. The missing Q-SNARE then induces sudden fusion. HOPS can 'template' SNARE complex assembly through SM recognition of R- and Qa-SNAREs. Though the Qa-SNARE is essential for spontaneous SNARE assembly, HOPS also assembles a rapid-fusion complex between R- and QbQc-SNARE proteoliposomes in the absence of Qa-SNARE, awaiting Qa for fusion. HOPS-dependent fusion is saturable at low concentrations of each Q-SNARE, showing binding site functionality. HOPS thus tethers membranes and recognizes each SNARE, assembling R+Qa or R+QbQc rapid fusion intermediates.