title: Intracellular trafficking of Clostridium botulinum C2 toxin.
abstract: Clostridium botulinum C2 toxin is a binary toxin composed of an enzymatic component (C2I) and binding component (C2II). The activated binding component (C2IIa) forms heptamers and the oligomer with C2I is taken up by receptor-mediated endocytosis. We investigated the intracellular trafficking of C2 toxin. When MDCK cells were incubated with C2I and C2IIa at 37 °C, C2I colocalized with C2IIa in cytoplasmic vesicles at 5 min, and C2I then disappeared (15 min incubation and later), and C2IIa was observed in the vesicles. Internalized C2I and C2IIa were transported to early endosomes. Some of both components were returned to the plasma membrane through recycling endosomes, whereas the rest of C2IIa was transported to late endosomes and lysosomes for degradation. Bafilomycin A1, an endosomal acidification inhibitor, caused the accumulation of C2IIa in endosomes, and both nocodazole and colchicine, microtubule-disrupting agents, restricted C2IIa's movement in the cytosol. These results indicated that an internalized C2I and C2IIa complex was delivered to early endosomes, and that subsequent delivery of C2I to the cytoplasm occurred in early endosomes. C2IIa was either sent back to the plasma membranes through recycling endosomes or transported to late endosomes and lysosomes for degradation.
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan. Electronic address: nagahama@ph.bunri-u.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nagahama
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Takahashi
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Aoyanagi
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Tashiro
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Interdisciplinary Research Organization, Miyazaki University, Miyazaki 889-2192, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Sakaguchi
authors.affiliation: Division of Molecular Biology, Institute for Health Sciences, Tokushima Bunri University, Yamashiro, Tokushima 770-8514, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Ishidoh
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Sakurai
mesh_terms: D000818:Animals; D001905:Botulinum Toxins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000633:toxicity; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism; D004285:Dogs; D004705:Endocytosis / Q000187:drug effects; D011992:Endosomes / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D018942:Macrolides; D011994:Recombinant Proteins; C040929:bafilomycin A1; D001905:Botulinum Toxins; C096324:botulinum toxin type C
keywords: Clostridium botulinum C2 toxin; Early endosomes; Endocytosis; Late endosomes; Recycling endosomes