New Understanding of the Toxic Effects of Botulism Toxin


The physical structure of a complex of the protease part of botulism toxin (botulinum neurotoxin A protease (BoNT/A)) bound to a protein (SNAP-25) has been determined, providing information about how the toxin causes paralysis. SNAP-25 is part of a protein complex that enables release of neurotransmitters that carry signals between successive cells in a nerve. BoNT/A leads to the breakdown of SNAP-25 reducing the ability of cells to release neurotransmitters resulting in paralysis. X-ray diffraction studies of crystals of the complex identified the precise interactions of BoNT/A as it interfaces with SNAP-25. This new information may lead to design of molecules that could inhibit the adverse effects of the botulism neurotoxin. Structures were determined at the Stanford Synchrotron Radiation Laboratory and the Advanced Light Source at the Lawrence Berkeley National Laboratory. The results are described in a paper published in Nature on December 16 (Nature 432, 925-929, 2004) by Stanford University scientists Mark A. Breidenbach and Axel Brunger.