Sec18p and Vam7p remodel trans-SNARE complexes to permit a lipid-anchored R-SNARE to support yeast vacuole fusion

作者：Jun Youngsoo; Xu Hao; Thorngren Naomi; Wickner William^*

来源：The EMBO Journal, 2007, 26(24): 4935-4945.

DOI：10.1038/sj.emboj.7601915

• membrane fusion
• Nyv1p
• R-SNARE
• trans-SNARE complex
• yeast vacuole

Intracellular membrane fusion requires SNARE proteins in a trans-complex, anchored to apposed membranes. Proteoliposome studies have suggested that SNAREs drive fusion by stressing the lipid bilayer via their transmembrane domains (TMDs), and that SNARE complexes require a TMD in each docked membrane to promote fusion. Yeast vacuole fusion is believed to require three Q-SNAREs from one vacuole and the R-SNARE Nyv1p from its fusion partner. In accord with this model, we find that fusion is abolished when the TMD of Nyv1p is replaced by lipid anchors, even though lipid-anchored Nyv1p assembles into trans-SNARE complexes. However, normal fusion is restored by the addition of both Sec18p and the soluble SNARE Vam7p. In restoring fusion, Sec18p promotes the disassembly of trans-SNARE complexes, and Vam7p enhances their assembly. Thus, either the TMD of this R-SNARE is not essential for fusion, and TMD-mediated membrane stress is not the only mode of trans-SNARE complex action, or these SNAREs have more flexibility than heretofore appreciated to form alternate functional complexes that violate the 3Q:1R rule.

• 出版日期2007-12-12