The C-terminal transmembrane region of synaptobrevin binds synaptophysin from adult synaptic vesicles

Sowmya V. Yelamanchili, Clemens Reisinger, Anja Becher, Stefan Sikorra, Hans Bigalke, Thomas Binz, Gudrun Ahnert-Hilger

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Synaptophysin and synaptobrevin are abundant membrane proteins of neuronal small synaptic vesicles. In mature, differentiated neurons they form the synaptophysin/synaptobrevin (Syp/Syb) complex. Synaptobrevin also interacts with the plasma membrane-associated proteins syntaxin and SNAP25, thereby forming the SNARE complex necessary for exocytotic membrane fusion. The two complexes are mutually exclusive. Synaptobrevin is a C-terminally membrane-anchored protein with one transmembrane domain. While its interaction with its SNARE partners is mediated exclusively by its N-terminal cytosolic region it has been unclear so far how binding to synaptophysin is accomplished. Here, we show that synaptobrevin can be cleaved in its synaptophysin-bound form by tetanus toxin and botulinum neurotoxin B, or by botulinum neurotoxin D, leaving shorter or longer C-terminal peptide chains bound to synaptophysin, respectively. A recombinant, C-terminally His-tagged synaptobrevin fragment bound to nickel beads specifically bound synaptophysin, syntaxin and SNAP25 from vesicular detergent extracts. After cleavage by tetanus toxin or botulinum toxin D light chain, the remaining C-terminal fragment no longer interacted with syntaxin or SNAP 25. In contrast, synaptophysin was still able to bind to the residual C-terminal synaptobrevin cleavage product. In addition, the His-tagged C-terminal synaptobrevin peptide 68-116 was also able to bind synaptophysin in detergent extracts from adult brain membranes. These data suggest that synaptophysin interacts with the C-terminal transmembrane part of synaptobrevin, thereby allowing the N-terminal cytosolic chain to interact freely with the plasma membrane-associated SNARE proteins. Thus, by binding synaptobrevin, synaptophysin may positively modulate neurotransmission.

Original languageEnglish (US)
Pages (from-to)467-475
Number of pages9
JournalEuropean Journal of Cell Biology
Volume84
Issue number4
DOIs
StatePublished - Apr 22 2005
Externally publishedYes

Keywords

  • Clostridial neurotoxins
  • SNARE complex
  • Synaptobrevin
  • Synaptophysin
  • Syp/Syb complex

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology

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