title: Clostridium perfringens alpha-toxin recognizes the GM1a-TrkA complex.
abstract: Clostridium perfringens alpha-toxin is the major virulence factor in the pathogenesis of gas gangrene. Alpha-toxin is a 43-kDa protein with two structural domains; the N-domain contains the catalytic site and coordinates the divalent metal ions, and the C-domain is a membrane-binding site. The role of the exposed loop region (72-93 residues) in the N-domain, however, has been unclear. Here we show that this loop contains a ganglioside binding motif (H … SXWY … G) that is the same motif seen in botulinum neurotoxin and directly binds to a specific conformation of the ganglioside Neu5Acα2-3(Galβ1-3GalNAcβ1-4)Galβ1-4Glcβ1Cer (GM1a) through a carbohydrate moiety. Confocal microscopy analysis using fluorescently labeled BODIPY-GM1a revealed that the toxin colocalized with GM1a and induced clustering of GM1a on the cell membranes. Alpha-toxin was only slightly toxic in β1,4-N-acetylgalactosaminyltransferase knock-out mice, which lack the a-series gangliosides that contain GM1a, but was highly toxic in α2,8-sialyltransferase knock-out mice, which lack both b-series and c-series gangliosides, similar to the control mice. Moreover, experiments with site-directed mutants indicated that Trp-84 and Tyr-85 in the exposed alpha-toxin loop play an important role in the interaction with GM1a and subsequent activation of TrkA. These results suggest that binding of alpha-toxin to GM1a facilitates the activation of the TrkA receptor and induces a signal transduction cascade that promotes the release of chemokines. Therefore, we conclude that GM1a is the primary cellular receptor for alpha-toxin, which can be a potential target for drug developed against this pathogen.
authors: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan. masa@ph.bunri-u.ac.jp
authors: Masataka
authors: M
authors: Oda
authors: Michiko
authors: M
authors: Kabura
authors: Teruhisa
authors: T
authors: Takagishi
authors: Ayaka
authors: A
authors: Suzue
authors: Kaori
authors: K
authors: Tominaga
authors: Shiori
authors: S
authors: Urano
authors: Masahiro
authors: M
authors: Nagahama
authors: Keiko
authors: K
authors: Kobayashi
authors: Keiko
authors: K
authors: Furukawa
authors: Koichi
authors: K
authors: Furukawa
authors: Jun
authors: J
authors: Sakurai
mesh_terms: D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D000818:Animals; D001427:Bacterial Toxins; D002135:Calcium-Binding Proteins; D002460:Cell Line; D018925:Chemokines / Q000235:genetics / Q000378:metabolism; D003016:Clostridium perfringens; D005677:G(M1) Ganglioside / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020917:Receptor, trkA / Q000235:genetics / Q000378:metabolism*; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism; D010738:Type C Phospholipases; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
chemical_list: D001427:Bacterial Toxins; D002135:Calcium-Binding Proteins; D018925:Chemokines; C502266:ganglioside GM1alpha; D005677:G(M1) Ganglioside; D017350:N-Acetylgalactosaminyltransferases; C023220:(N-acetylneuraminyl)-galactosylglucosylceramide N-acetylgalactosaminyltransferase; D012799:Sialyltransferases; D020917:Receptor, trkA; D010738:Type C Phospholipases; C040649:alpha toxin, Clostridium perfringens; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase