SYNAPTOBREVIN VESICLE-ASSOCIATED MEMBRANE-PROTEIN (VAMP) OF APLYSIA-CALIFORNICA - STRUCTURE AND PROTEOLYSIS BY TETANUS TOXIN AND BOTULINAL NEUROTOXINS TYPE-D AND TYPE-F
S. Yamasaki et al., SYNAPTOBREVIN VESICLE-ASSOCIATED MEMBRANE-PROTEIN (VAMP) OF APLYSIA-CALIFORNICA - STRUCTURE AND PROTEOLYSIS BY TETANUS TOXIN AND BOTULINAL NEUROTOXINS TYPE-D AND TYPE-F, Proceedings of the National Academy of Sciences of the United Statesof America, 91(11), 1994, pp. 4688-4692
Synaptobrevin/vesicle-associated membrane protein (VAMP) and syntaxin
are potential vesicle donor and target membrane receptors of a docking
complex that requires N-ethylmaleimide-sensitive factor (NSF) and sol
uble NSF-attachment proteins as soluble factors for vesicle fusion wit
h target membranes. Members of this docking complex are the target of
clostridial neurotoxins that act as zinc-dependent proteases. Molecula
r cloning of the Aplysia californica synaptobrevin cDNA revealed a 180
-residue polypeptide (M(r), 19,745) with a central transmembrane regio
n and an atypically large C-terminal intravesicular domain. This polyp
eptide integrates into membranes at both the co- and posttranslational
level, as shown by modification of an artificially introduced N-glyco
sylation site. The soluble and membrane-anchored forms of synaptobrevi
n are cleaved by the light chains of the botulinal toxins type D and F
and by tetanus toxin involving the peptide bonds Lys(49)-Ile(50), Gln
(48)-Lys(49), and Gln(66)-Phe(67), respectively. The active center of
the tetanus toxin light chain was identified by site-specific mutagene
sis. His(233), His(237), Glu(234), and Glu(270/271) are essential to t
his proteolytic activity. Modification of histidine residues resulted
in loss of zinc binding, whereas a replacement of Glu(234) only slight
ly reduced the zinc content.