BOTULINUM NEUROTOXINS SEROTYPE-A AND SEROTYPE-E CLEAVE SNAP-25 AT DISTINCT COOH-TERMINAL PEPTIDE-BONDS

SNAP-25, a membrane-associated protein of the nerve terminal, is specifically cleaved by botulinum neurotoxins serotypes A and E, which cause human and animal botulism by blocking neurotransmitter release at the neuromuscular junction. Here we show that these two metallo-endopeptidase toxins cleave SNAP-25 at two distinct carboxyl-terminal sites. Serotype A catalyses the hydrolysis of the Gln(197)-Arg(198) peptide bond, while serotype E cleaves the Arg(180)-Ile(181) peptide linkage. These results indicate that the carboxyl-terminal region of SNAP-25 plays a crucial role in the multi-protein complex that mediates vesicle docking and fusion at the nerve terminal.