title: Multiple and distinct strategies of yeast SNAREs to confer the specificity of membrane fusion.
abstract: Trans-QabcR-SNARE pairing on opposing membranes is crucial for eukaryotic membrane fusion, but how selective pairs of Qabc- and R-SNARE proteins regulate membrane fusion specificity remains elusive. Here, we studied 14 purified full-length SNAREs that function in yeast endoplasmic reticulum (ER)-Golgi, intra-Golgi, endosomal, and vacuolar transport by comprehensively testing cis-QabcR-SNARE assembly and fusogenicity of reconstituted SNARE proteoliposomes. Strikingly, the cognate ER-Golgi and intra-Golgi SNARE-complex assemblies were highly stringent, whereas endosomal and vacuolar SNAREs assembled rather promiscuously into the non-cognate mixed complexes. However, these patterns of cis-SNARE assemblies cannot solely explain their potency to be fusogenic via trans-SNARE pairing: Only the vacuolar 3Q-SNARE combination is fusogenic in the absence of additional components; endosomal SNARE-dependent fusogenicity requires membrane-tethering factors; and ER-Golgi SNAREs can be fusogenic by synergistic actions of tethering factors and the cognate Sec1/Munc18-family protein Sly1p. Thus, our findings uncover multiple and distinct strategies of SNAREs to directly mediate fusion specificity.
authors.affiliation: Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Furukawa
authors.affiliation: Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
authors.forename: Joji
authors.initials: J
authors.lastname: Mima
mesh_terms: D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D050356:Lipid Metabolism; D008561:Membrane Fusion; D046912:Multiprotein Complexes / Q000378:metabolism; D014176:Protein Biosynthesis; D050600:SNARE Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D022161:Transport Vesicles / Q000378:metabolism; D015003:Yeasts / Q000378:metabolism*
chemical_list: D046912:Multiprotein Complexes; D050600:SNARE Proteins