Botulinum neurotoxin A selectively cleaves the synaptic protein SNAP-25.
Neurotransmitter release is potently blocked by a group of structurally related toxin proteins produced by Clostridium botulinum. Botulinum neurotoxin type B (BoNT/B) and tetanus toxin (TeTx) are zinc-dependent proteases that specifically cleave synaptobrevin (VAMP), a membrane protein of synaptic vesicles. Here we report that inhibition of transmitter release from synaptosomes caused by botulinum neurotoxin A (BoNT/A) is associated with the selective proteolysis of the synaptic protein SNAP-25. Furthermore, isolated or recombinant L chain of BoNT/A cleaves SNAP-25 in vitro. Cleavage occurred near the carboxyterminus and was sensitive to divalent cation chelators. In addition, a glutamate residue in the BoNT/A L chain, presumably required to stabilize a water molecule in the zinc-containing catalytic centre, was required for proteolytic activity. These findings demonstrate that BoNT/A acts as a zinc-dependent protease that selectively cleaves SNAP-25. Thus, a second component of the putative fusion complex mediating synaptic vesicle exocytosis is targeted by a clostridial neurotoxin.
Blasi
J
J
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
Chapman
E R
ER
Link
E
E
Binz
T
T
Yamasaki
S
S
De Camilli
P
P
Südhof
T C
TC
Niemann
H
H
Jahn
R
R
D001905:Botulinum Toxins / Q000494:pharmacology*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D066298:In Vitro Techniques; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism; D013570:Synaptic Membranes / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25; D013574:Synaptosomes / Q000378:metabolism; D013744:Tetanus Toxin / Q000494:pharmacology
D005971:Glutamates; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; D050825:Synaptosomal-Associated Protein 25; D013744:Tetanus Toxin; D018698:Glutamic Acid; D001905:Botulinum Toxins