title: α-SNAP Enhances SNARE Zippering by Stabilizing the SNARE Four-Helix Bundle.
abstract: Intracellular membrane fusion is mediated by dynamic assembly and disassembly of soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (SNAP) receptors (SNAREs). α-SNAP guides NSF to disassemble SNARE complexes after membrane fusion. Recent experiments showed that α-SNAP also dramatically enhances SNARE assembly and membrane fusion. How α-SNAP is involved in these opposing activities is not known. Here, we examine the effect of α-SNAP on the stepwise assembly of the synaptic SNARE complex using optical tweezers. We found that α-SNAP destabilized the linker domain (LD) of the SNARE complex but stabilized its C-terminal domain (CTD) through a conformational selection mechanism. In contrast, α-SNAP minimally affected assembly of the SNARE N-terminal domain (NTD), indicating that α-SNAP barely bound the partially assembled trans-SNARE complex. Thus, α-SNAP recognizes the folded CTD for SNARE disassembly with NSF and subtly modulates membrane fusion by altering the stabilities of the SNARE CTD and LD.
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Ma
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Yuhao
authors.initials: Y
authors.lastname: Kang
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA; Integrated Graduate Program in Physical and Engineering Biology, New Haven, CT 06520, USA.
authors.forename: Junyi
authors.initials: J
authors.lastname: Jiao
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA; Integrated Graduate Program in Physical and Engineering Biology, New Haven, CT 06520, USA; Department of Physics, Yale University, New Haven, CT 06511, USA.
authors.forename: Aleksander A
authors.initials: AA
authors.lastname: Rebane
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Hyo Keun
authors.initials: HK
authors.lastname: Cha
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Zhiqun
authors.initials: Z
authors.lastname: Xi
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Qu
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA. Electronic address: yongli.zhang@yale.edu.
authors.forename: Yongli
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D007700:Kinetics; D011485:Protein Binding; D000072417:Protein Domains; D017510:Protein Folding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D051381:Rats; D050600:SNARE Proteins / Q000737:chemistry* / Q000378:metabolism*; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / Q000378:metabolism*
chemical_list: D050600:SNARE Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins