Homotetrameric structure of the SNAP-23 N-terminal coiled-coil domain

Steven J. Freedman, Hyun Kyu Song, Yingwu Xu, Zhen Yu J. Sun, Michael J. Eck

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

SNARE proteins mediate intracellular membrane fusion by forming a coiled-coil complex to merge opposing membranes. A "fusion-active" neuronal SNARE complex is a parallel four-helix bundle containing two coiled-coil domains from SNAP-25 and one coiled-coil domain each from syntaxin-la and VAMP-2. "Prefusion" assembly intermediate complexes can also form from these SNAREs. We studied the N-terminal coiled-coil domain of SNAP-23 (SNAP-23N), a non-neuronal homologue of SNAP-25, and its interaction with other coiled-coil domains. SNAP-23N can assemble spontaneously with the coiled-coil domains from SNAP-23C, syntaxin-4, and VAMP-3 to form a heterotetrameric complex. Unexpectedly, pure SNAP-23N crystallizes as a coiled-coil homotetrameric complex. The four helices have a parallel orientation and are symmetrical about the long axis. The complex is stabilized through the interaction of conserved hydrophobic residues comprising the a and d positions of the coiled-coil heptad repeats. In addition, a central, highly conserved glutamine residue (Gln-48) is buried within the interface by hydrogen bonding between glutamine side chains derived from adjacent subunits and to solvent molecules. A comparison of the SNAP-23N structure to other SNARE complex structures reveals how a simple coiled-coil motif can form diverse SNARE complexes.

Original languageEnglish
Pages (from-to)13462-13467
Number of pages6
JournalJournal of Biological Chemistry
Volume278
Issue number15
DOIs
Publication statusPublished - 2003 Apr 11

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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