BPB Reports

Paper Details

BPB Reports
Vol. 3 No. 4 p.146-149 2020
The Inhibitory Effect of Cholera Toxin B Subunit on Clostridium Perfringens Iota-Toxin-Induced Cytotoxicity
  • Masahiro Nagahama (Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University / nagahama@ph.bunri-u.ac.jp)
Masahiro Nagahama , Keiko Kobayashi , Masaya Takehara
Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University
Received: July 27, 2020;   Accepted: August 18, 2020;   Released: August 22, 2020
Keywords: Clostridium perfringens iota-toxin, cholera toxin B subunit, cytotoxicity

Clostridium perfringens iota-toxin consists of an enzymatic Ia component and binding Ib component. Ib binds to membrane receptors, forms heptamers in lipid rafts, and associates with Ia. The toxin complex is internalized into cells. In this study, we evaluated the inhibitory effects of cholera toxin B subunit (CTB), which binds to lipid rafts, on iota-toxin-mediated cytotoxicity. We examined the effect of CTB on iota-toxin-induced cell rounding activity against MDCK (Madin-Darby canine kidney) cells and Ib-induced cell death in A431 (human epithelial) cells. The presence of CTB inhibited both the cell rounding activity of iota-toxin (MDCK cells) and Ib-induced cell death (A431 cells). Moreover, CTB blocked binding of the Ib monomer to both cells at 4°C. We found by immunofluorescence microscopy that, after loading with Ib and CTB at 4°C, Ib and CTB bound to distinct regions in the plasma membranes. In MDCK cells at 37°C, Ib internalized and partially coexisted with CTB in cytoplasmic vesicles. These findings demonstrated that CTB blocks the binding of iota-toxin to target cells. CTB may provide a protective effect against infection.