Clostridium botulinum type E toxins bind to Caco-2 cells by a different mechanism from that of type A toxins.
Cultured Clostridium botulinum strains produce progenitor toxins designated as 12S, 16S, and 19S toxins. The 12S toxin consists of a neurotoxin (NTX, 7S) and a non-toxic non-hemagglutinin (NTNH). The 16S and 19S toxins are formed by conjugation of the 12S toxin with hemagglutinin (HA), and the 19S toxin is a dimer of the 16S toxin. Type A cultures produce all 3 of these progenitor toxins, while type E produces only the 12S toxin. The 7S toxin is cleaved into heavy (H) and light (L) chains by a protease(s) in some strains, and the H chain has 2 domains, the N-terminus (Hn) and C-terminus (Hc). It has been reported that type A toxins bind to the intestinal cells or cultured cells via either HA or Hc. In this study, we investigated the binding of type A and E toxins to Caco-2 cells using Western blot analysis. Both the type E 7S and 12S toxins bound to the cells, with the 7S toxin binding more strongly, whereas, in the type A strain, only the 16S/19S toxins showed obvious binding. Pre-incubation of the type E 7S toxin with IgG against recombinant type E Hc significantly inhibited the 7S toxin binding, indicating that Hc might be a main binding domain of the type E toxin.
Department of Bacteriology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan.
Kai
K
Zhang
Yumiko
Y
Yamamoto
Tomonori
T
Suzuki
Kenji
K
Yokota
Shaobo
S
Ma
Ni Nengah Dwi Fatmawati
Keiji
K
Oguma
D015153:Blotting, Western; D001905:Botulinum Toxins / Q000302:isolation & purification / Q000378:metabolism*; D019274:Botulinum Toxins, Type A / Q000302:isolation & purification / Q000378:metabolism*; D018938:Caco-2 Cells; D006801:Humans
D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A; C096326:botulinum toxin type E