Identification and characterization of a novel botulinum neurotoxin

Nat Commun. 2017 Aug 3:8:14130. doi: 10.1038/ncomms14130.


Botulinum neurotoxins are known to have seven serotypes (BoNT/A-G). Here we report a new BoNT serotype, tentatively named BoNT/X, which has the lowest sequence identity with other BoNTs and is not recognized by antisera against known BoNTs. Similar to BoNT/B/D/F/G, BoNT/X cleaves vesicle-associated membrane proteins (VAMP) 1, 2 and 3, but at a novel site (Arg66-Ala67 in VAMP2). Remarkably, BoNT/X is the only toxin that also cleaves non-canonical substrates VAMP4, VAMP5 and Ykt6. To validate its activity, a small amount of full-length BoNT/X was assembled by linking two non-toxic fragments using a transpeptidase (sortase). Assembled BoNT/X cleaves VAMP2 and VAMP4 in cultured neurons and causes flaccid paralysis in mice. Thus, BoNT/X is a novel BoNT with a unique substrate profile. Its discovery posts a challenge to develop effective countermeasures, provides a novel tool for studying intracellular membrane trafficking, and presents a new potential therapeutic toxin for modulating secretions in cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Botulinum Toxins / chemistry
  • Botulinum Toxins / genetics
  • Botulinum Toxins / metabolism*
  • Botulinum Toxins / toxicity
  • Botulism / genetics
  • Botulism / metabolism
  • Botulism / microbiology*
  • Clostridium botulinum / enzymology*
  • Clostridium botulinum / genetics
  • Humans
  • Mice
  • Models, Molecular
  • Neurotoxins / chemistry
  • Neurotoxins / genetics
  • Neurotoxins / metabolism*
  • Neurotoxins / toxicity
  • R-SNARE Proteins / chemistry
  • R-SNARE Proteins / genetics
  • R-SNARE Proteins / metabolism
  • Sequence Alignment
  • Vesicle-Associated Membrane Protein 2 / chemistry
  • Vesicle-Associated Membrane Protein 2 / genetics
  • Vesicle-Associated Membrane Protein 2 / metabolism


  • Neurotoxins
  • R-SNARE Proteins
  • Vamp4 protein, mouse
  • Vesicle-Associated Membrane Protein 2
  • Botulinum Toxins