title: Intracellular trafficking of Clostridium perfringens iota-toxin b.
abstract: Clostridium perfringens iota-toxin is composed of an enzymatic component (Ia) and a binding component (Ib). Ib binds to a cell surface receptor, undergoes oligomerization in lipid rafts, and binds Ia. The resulting complex is then endocytosed. Here, we show the intracellular trafficking of iota-toxin. After the binding of the Ib monomer with cells at 4°C, oligomers of Ib formed at 37°C and later disappeared. Immunofluorescence staining of Ib revealed that the internalized Ib was transported to early endosomes. Some Ib was returned to the plasma membrane through recycling endosomes, whereas the rest was transported to late endosomes and lysosomes for degradation. Degraded Ib was delivered to the plasma membrane by an increase in the intracellular Ca(2+) concentration caused by Ib. Bafilomycin A1, an endosomal acidification inhibitor, caused the accumulation of Ib in endosomes, and both nocodazole and colchicine, microtubule-disrupting agents, restricted Ib's movement in the cytosol. These results indicated that an internalized Ia and Ib complex was delivered to early endosomes and that subsequent delivery of Ia to the cytoplasm occurs mainly in early endosomes. Ib was either sent back to the plasma membranes through recycling endosomes or transported to late endosomes and lysosomes for degradation. Degraded Ib was transported to plasma membranes.
authors: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan.
authors: Masahiro
authors: M
authors: Nagahama
authors: Mariko
authors: M
authors: Umezaki
authors: Ryo
authors: R
authors: Tashiro
authors: Masataka
authors: M
authors: Oda
authors: Keiko
authors: K
authors: Kobayashi
authors: Masahiro
authors: M
authors: Shibutani
authors: Teruhisa
authors: T
authors: Takagishi
authors: Kazumi
authors: K
authors: Ishidoh
authors: Mitsunori
authors: M
authors: Fukuda
authors: Jun
authors: J
authors: Sakurai
mesh_terms: D036002:ADP Ribose Transferases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001427:Bacterial Toxins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D003016:Clostridium perfringens / Q000235:genetics / Q000378:metabolism*; D004285:Dogs; D011992:Endosomes / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015151:Immunoblotting; D018942:Macrolides; D011485:Protein Binding; D021381:Protein Transport / Q000502:physiology*
chemical_list: D001427:Bacterial Toxins; D018942:Macrolides; C050737:iota toxin, Clostridium perfringens; C040929:bafilomycin A1; D036002:ADP Ribose Transferases; D002118:Calcium