Journal Article

Reconstituted membrane fusion requires regulatory lipids, SNAREs and synergistic SNARE chaperones

Mima, Joji, Xu, Hao, Wickner, William, Hickey, Christopher M, Jun, Youngsoo

2008

Overview

The homotypic fusion of yeast vacuoles, each with 3Q‐ and 1R‐SNARE, requires SNARE chaperones (Sec17p/Sec18p and HOPS) and regulatory lipids (sterol, diacylglycerol and phosphoinositides). Pairs of liposomes of phosphatidylcholine/phosphatidylserine, bearing three vacuolar Q‐SNAREs on one and the R‐SNARE on the other, undergo slow lipid mixing, but this is unaffected by HOPS and inhibited by Sec17p/Sec18p. To study these essential fusion components, we reconstituted proteoliposomes of a more physiological composition, bearing vacuolar lipids and all four vacuolar SNAREs. Their fusion requires Sec17p/Sec18p and HOPS, and each regulatory lipid is important for rapid fusion. Although SNAREs can cause both fusion and lysis, fusion of these proteoliposomes with Sec17p/Sec18p and HOPS is not accompanied by lysis. Sec17p/Sec18p, which disassemble SNARE complexes, and HOPS, which promotes and proofreads SNARE assembly, act synergistically to form fusion‐competent SNARE complexes, and this synergy requires phosphoinositides. This is the first chemically defined model of the physiological interactions of these conserved fusion catalysts.

• Publisher: John Wiley & Sons, Ltd,Nature Publishing Group UK,Springer Nature B.V,Nature Publishing Group
• Subject: Adenosine Triphosphatases - chemistry / Adenosine Triphosphatases - metabolism / Catalysts / EMBO20 / Genes, Fungal / Lipids / Lipids - chemistry / Lipids - physiology / Liposomes / membrane fusion / Membrane Fusion - physiology / Membranes / Molecular biology / Molecular Chaperones - chemistry / Molecular Chaperones - physiology / Phosphatidylcholines - chemistry / Phosphatidylserines - chemistry / Physiology / Protein Binding / Protein Transport / Qa-SNARE Proteins - chemistry / Qa-SNARE Proteins - physiology / Qb-SNARE Proteins - chemistry / Qb-SNARE Proteins - physiology / Qc-SNARE Proteins - chemistry / Qc-SNARE Proteins - physiology / R-SNARE Proteins - chemistry / R-SNARE Proteins - physiology / reconstitution / regulatory lipids / Saccharomyces cerevisiae - metabolism / Saccharomyces cerevisiae Proteins - chemistry / Saccharomyces cerevisiae Proteins - metabolism / SNARE chaperones / SNARE Proteins - physiology / Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins - chemistry / Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins - metabolism / Vesicular Transport Proteins - chemistry / Vesicular Transport Proteins - metabolism / Yeast / Yeasts