Substrate recognition mechanism of VAMP/synaptobrevin cleaving clostridial neurotoxins. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Biological Chemistry Année : 2008

Substrate recognition mechanism of VAMP/synaptobrevin cleaving clostridial neurotoxins.

Thierry Galli

Résumé

Botulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT) inhibit neurotransmitter release by proteolyzing a single peptide bond in one of the three soluble N-ethylmaleimide sensitive factor attachment protein receptors SNAP-25, syntaxin, and vesicle associated membrane protein (VAMP)/synaptobrevin. TeNT and BoNT/B, D, F and G of the seven known BoNTs cleave the synaptic vesicle protein VAMP/synaptobrevin. Except for BoNT/B and TeNT they cleave unique peptide bonds and prior work suggested that different substrate segments are required for the interaction of each toxin. Whereas the mode of SNAP-25 cleavage by BoNT/A and E has recently been studied in detail, the mechanism of VAMP/synaptobrevin proteolysis is fragmentary. Here, we report the determination of all substrate residues that are involved in the interaction with BoNT/B, D, F, and TeNT by means of systematic mutagenesis of VAMP/synaptobrevin. For each of the toxins three or more residues clustered at an N terminal site remote to the respective scissile bond are identified that affect solely substrate binding. These exosites exhibit different sizes and distances to the scissile peptide bonds for each neurotoxin. Substrate segments C-terminal of the cleavage site (P4-P4') do not play a role in the catalytic process. Mutation of residues in the proximity of the scissile bond exclusively affects the turnover number, however, the importance of individual positions at the cleavage sites varied for each toxin. The data evidence that similar to the SNAP-25 proteolyzing BoNT/A and E, VAMP/synaptobrevin specific CNTs also initiate substrate interaction employing an exosite located N terminal of the scissile peptide bond.

Dates et versions

hal-00284772 , version 1 (03-06-2008)

Identifiants

Citer

Stefan Sikorra, Tina Henke, Thierry Galli, Thomas Binz. Substrate recognition mechanism of VAMP/synaptobrevin cleaving clostridial neurotoxins.. Journal of Biological Chemistry, 2008, epub ahead of print. ⟨10.1074/jbc.M800610200⟩. ⟨hal-00284772⟩
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