Targeting botulinum neurotoxin persistence by the ubiquitin-proteasome system

Proc Natl Acad Sci U S A. 2010 Sep 21;107(38):16554-9. doi: 10.1073/pnas.1008302107. Epub 2010 Sep 7.

Abstract

Botulinum neurotoxins (BoNTs) are the most potent natural toxins known. The effects of BoNT serotype A (BoNT/A) can last several months, whereas the effects of BoNT serotype E (BoNT/E), which shares the same synaptic target, synaptosomal-associated protein 25 (SNAP25), last only several weeks. The long-lasting effects or persistence of BoNT/A, although desirable for therapeutic applications, presents a challenge for medical treatment of BoNT intoxication. Although the mechanisms for BoNT toxicity are well known, little is known about the mechanisms that govern the persistence of the toxins. We show that the recombinant catalytic light chain (LC) of BoNT/E is ubiquitylated and rapidly degraded in cells. In contrast, BoNT/A LC is considerably more stable. Differential susceptibility of the catalytic LCs to ubiquitin-dependent proteolysis therefore might explain the differential persistence of BoNT serotypes. In this regard we show that TRAF2, a RING finger protein implicated in ubiquitylation, selectively associates with BoNT/E LC and promotes its proteasomal degradation. Given these data, we asked whether BoNT/A LC could be targeted for rapid proteasomal degradation by redirecting it to characterized ubiquitin ligase domains. We describe chimeric SNAP25-based ubiquitin ligases that target BoNT/A LC for degradation, reducing its duration in a cellular model for toxin persistence.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Botulinum Toxins / genetics
  • Botulinum Toxins / metabolism*
  • Botulinum Toxins / toxicity*
  • Botulinum Toxins, Type A / genetics
  • Botulinum Toxins, Type A / metabolism*
  • Botulinum Toxins, Type A / toxicity*
  • Cell Line
  • Clostridium botulinum type A / genetics
  • Clostridium botulinum type A / pathogenicity*
  • Clostridium botulinum type A / physiology*
  • Clostridium botulinum type E / genetics
  • Clostridium botulinum type E / pathogenicity*
  • Clostridium botulinum type E / physiology*
  • Genes, Bacterial
  • Humans
  • Mice
  • Molecular Sequence Data
  • Neurons / drug effects
  • Neurons / metabolism
  • Proteasome Endopeptidase Complex / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Synaptosomal-Associated Protein 25 / genetics
  • Synaptosomal-Associated Protein 25 / metabolism
  • Ubiquitin / metabolism*

Substances

  • Recombinant Fusion Proteins
  • Snap25 protein, mouse
  • Synaptosomal-Associated Protein 25
  • Ubiquitin
  • Botulinum Toxins
  • Botulinum Toxins, Type A
  • Proteasome Endopeptidase Complex
  • botulinum toxin type E