Open AccessHA‐33 facilitates transport of the serotype D botulinum toxin across a rat intestinal epithelial cell monolayer
Author(s) -
Ito Hiroaki,
Sagane Yoshimasa,
Miyata Keita,
Inui Ken,
Matsuo Tomohito,
Horiuchi Ryohta,
Ikeda Toshihiko,
Suzuki Tomonori,
Hasegawa Kimiko,
Kouguchi Hirokazu,
Oguma Keiji,
Niwa Koichi,
Ohyama Tohru,
Watanabe Toshihiro
Publication year - 2011
Publication title -
fems immunology & medical microbiology
Language(s) - English
Resource type - Journals
eISSN - 1574-695X
pISSN - 0928-8244
DOI - 10.1111/j.1574-695x.2011.00779.x
Subject(s) - toxin , biology , clostridium botulinum , neurotoxin , clostridium difficile toxin a , cell culture , caco 2 , cell , microbiology and biotechnology , botulinum toxin , sialic acid , biochemistry , antibiotics , genetics , neuroscience , clostridium difficile
A large size botulinum toxin complex (L‐TC) is composed of a single neurotoxin (BoNT), a single nontoxic nonhaemagglutinin (NTNHA) and a haemagglutinin (HA) complex. The HA complex is comprised of three HA‐70 molecules and three arm structures of HA‐33/HA‐17 that consist of two HA‐33 and a single HA‐17. In addition to the mature L‐TC, smaller TCs are present in cultures: M‐TC (BoNT/NTNHA), M‐TC/HA‐70 and immature L‐TCs with fewer HA‐33/HA‐17 arms than mature L‐TC. Because L‐TC displays higher oral toxicity than pure BoNT, it was presumed that nontoxic proteins are critical for food poisoning. In this study, the absorption of TCs across intestinal epithelial cells was assessed by examining the cell binding and monolayer transport of serotype D toxins in the rat intestinal epithelial cell line IEC‐6. All TCs, including pure BoNT, displayed binding and transport, with mature L‐TC showing the greatest potency. Inhibition experiments using antibodies revealed that BoNT, HA‐70 and HA‐33 could be responsible for the binding and transport. The findings here indicate that all TCs can transport across the cell layer via a sialic acid‐dependent process. Nonetheless, binding and transport markedly increased with number of HA‐33/HA‐17 arms in the TC. We therefore conclude that the HA‐33/HA‐17 arm is not necessarily required for, but facilitates, transport of botulinum toxin complexes.