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Keywords:

  • Clostridium botulinum ;
  • botulinum neurotoxin;
  • nontoxic nonhemagglutinin;
  • intestinal epithelial cell;
  • β-trefoil;
  • QXW motif

Abstract

Botulinum neurotoxin (BoNT) associates with nontoxic nonhemagglutinin (NTNHA) yielding a complex in culture. BoNT and NTNHA have similar domain organizations, implying that they share common functions, although this remains unclear. Here, we examined cell monolayer transport of serotype D NTNHA in the rat intestinal epithelial cell line IEC-6. NTNHA and BoNT both bound to the cell and were transported across the cell layer. NTNHA contains a QXW motif and a β-trefoil fold, both common in sugar chain–recognizing proteins, whereas the QXW motif is absent in all BoNT serotypes. This could explain the distinct sugar chain–recognizing properties of NTNHA and BoNT.