title: A lipid-anchored SNARE supports membrane fusion.
abstract: Intracellular membrane fusion requires R-SNAREs and Q-SNAREs to assemble into a four-helical parallel coiled-coil, with their hydrophobic anchors spanning the two apposed membranes. Based on the fusion properties of chemically defined SNARE- proteoliposomes, it has been proposed that the assembly of this helical bundle transduces force through the entire bilayer via the transmembrane SNARE anchor domains to drive fusion. However, an R-SNARE, Nyv1p, with a genetically engineered lipid anchor that spans half of the bilayer suffices for the fusion of isolated vacuoles, although this organelle has other R-SNAREs. To demonstrate unequivocally the fusion activity of lipid-anchored Nyv1p, we reconstituted proteoliposomes with purified lipid-anchored Nyv1p as the only protein. When these proteoliposomes were incubated with those bearing cognate Q-SNAREs, there was trans-SNARE complex assembly but, in accord with prior studies of the neuronal SNAREs, little lipid mixing. However, the addition of physiological fusion accessory proteins (HOPS, Sec17p, and Sec18p) allows lipid-anchored Nyv1p to support fusion, suggesting that trans-SNARE complex function is not limited to force transduction across the bilayers through the transmembrane domains.
authors: Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755-3844, USA.
authors: Hao
authors: H
authors: Xu
authors: Michael
authors: M
authors: Zick
authors: William T
authors: WT
authors: Wickner
authors: Youngsoo
authors: Y
authors: Jun
mesh_terms: D058635:Lipid-Linked Proteins / Q000737:chemistry / Q000502:physiology; D008561:Membrane Fusion / Q000502:physiology*; D008565:Membrane Proteins / Q000737:chemistry / Q000502:physiology; D055503:Protein Multimerization; D011510:Proteolipids / Q000737:chemistry / Q000502:physiology; D050682:Q-SNARE Proteins / Q000737:chemistry / Q000502:physiology; D050683:R-SNARE Proteins / Q000737:chemistry / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry; D050600:SNARE Proteins / Q000737:chemistry / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000502:physiology; D014617:Vacuoles / Q000737:chemistry / Q000502:physiology
chemical_list: D058635:Lipid-Linked Proteins; D008565:Membrane Proteins; C500806:Nyv1 protein, S cerevisiae; D011510:Proteolipids; D050682:Q-SNARE Proteins; D050683:R-SNARE Proteins; D011994:Recombinant Proteins; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; C020485:proteoliposomes