Abstract
Botulinum neurotoxins (BoNTs) are among the most potent toxins known and are also used to treat an increasing number of medical disorders. There are seven well-established serotypes (BoNT/A-G), which all act as zinc-dependent endopeptidases targeting specific members of the SNARE proteins required for synaptic vesicle exocytosis in neurons. A new toxin serotype, BoNT/X, was recently identified. It cleaves not only the canonical targets, vesicle associated membrane proteins (VAMP) 1/2/3 at a unique site, but also has the unique ability to cleave VAMP4/5 and Ykt6. Here we report the 1.35 Å X-ray crystal structure of the light chain of BoNT/X (LC/X). LC/X shares the core fold common to all other BoNTs, demonstrating that LC/X is a bona fide member of BoNT-LCs. We found that access to the catalytic pocket of LC/X is more restricted, and the regions lining the catalytic pocket are not conserved compared to other BoNTs. Kinetic studies revealed that LC/X cleaves VAMP1 with a ten times higher efficiency than BoNT/B and the tetanus neurotoxin. The structural information provides a molecular basis to understand the convergence/divergence between BoNT/X and other BoNTs, to develop effective LC inhibitors, and to engineer new scientific tools and therapeutic toxins targeting distinct SNARE proteins in cells.
Original language | English |
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Article number | 4518 |
Journal | Scientific Reports |
Volume | 8 |
Issue number | 1 |
DOIs | |
Publication status | Published - 14 Mar 2018 |
Funding
We thank the scientists at stations I02 of the Diamond Light Source (UK) and PXI of the Swiss Light Source (Switzerland) for their support during X-ray data collection. This study was partially supported by NIH grants (NS080833 and AI132387) to M.D.; the Swedish Research Council (2014–5667), the Wenner-Gren Foundation, and the Swedish Cancer Society (to P.S.). M.D. acknowledges support by the NIH-funded Harvard Digestive Disease Center (P30DK034854) and Boston Children’s Hospital Intellectual and Developmental Disabilities Research Center (P30HD18655). M.D. holds the Investigator in the Pathogenesis of Infectious Disease award from the Burroughs Wellcome Fund.
ASJC Scopus subject areas
- General