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Clostridium perfringens iota toxin: binding studies and characterization of cell surface receptor by
B G Stiles1, M L Hale, J C Marvaud
1Department of Immunology, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702-5011, USA. bradley.stiles@det.amedd.army.mil
Insights
Clostridium perfringens iota toxin
Area of Science:
- Microbiology
- Toxicology
- Cell Biology
Background:
- Clostridium perfringens produces binary enterotoxins, including iota toxin.
- Iota toxin is implicated in gastrointestinal diseases.
Purpose of the Study:
- To investigate the cell binding characteristics of iota toxin's components.
- To understand the mechanism of iota toxin interaction with host cells.
Main Methods:
- Fluorescence-activated cytometry was used to study toxin binding.
- Cell surface binding assays were performed at different temperatures.
- Western blot analysis was employed to detect toxin components.
Main Results:
- The binding component, iota b (Ib), binds to various cell types.
- Pronase treatment inhibited Ib binding, suggesting protein-protein interactions.
- Trypsinization of iota b protomer was required for iota a component docking.
- Both iota a and iota b showed diminished surface levels over time, indicating internalization or embedment.
Conclusions:
- Iota toxin binding is specific and involves protein-protein interactions.
- The sequential binding and internalization of iota toxin components are crucial for its cellular activity.
Abstract:
The binding characteristics of iota toxin, a binary enterotoxin produced by Clostridium perfringens type E, were studied by fluorescence-activated cytometry. The proteolytically activated binding component of iota toxin, iota b (Ib), bound to various cell types when incubated at 4, 25, or 37 degrees C for 10 min. The binding of Ib was inhibited by antisera against C. perfringens type E or Clostridium spiroforme culture supernatants, but not C. perfringens types C or D. Pretreatment of Vero cells with glycosidases or lectins did not affect Ib interactions, while pronase effectively prevented Ib binding to the cell surface. The Ib protomer (Ibp) bound to the cell surface, but trypsinization of Ibp was necessary for docking of the ADP-ribosylating component, iota a (Ia). Ia attached to cell-bound Ib within 10 min at 37 degrees C, but surface levels of Ia decreased 90% after 30 min and were undetectable by 60 min. Detectable surface levels of Ib also diminished over time, and Western blot analysis suggested internalization or embedment of Ib into the membrane.
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