title: Hemolysis induced by Bacillus cereus sphingomyelinase.
abstract: Bacillus cereus sphingomyelinase (Bc-SMase) induces hemolysis of sheep erythrocytes which contain large amounts of sphingomyelin. We investigated the mechanism of this hemolysis in comparison to that induced by Clostridium perfringens alpha-toxin. Pertussis toxin, a Gi-specific inhibitor, N-oleoylethernolamine, a ceramidase inhibitor, and dihydrosphingosine, a sphingosine kinase inhibitor, did not inhibit the hemolysis by Bc-SMase, but did inhibit that by alpha-toxin. Bc-SMase broadly bound to whole membranes, and alpha-toxin specifically bound to the detergent-resistant membrane fractions, lipid rafts. The level of ceramide production induced by Bc-SMase in sheep erythrocytes was 6- to 15-fold that induced by alpha-toxin, when the extent of the hemolysis by Bc-SMase was the same as that by the toxin. However, the level of ceramide production induced by Bc-SMase in SM-liposomes was equal to that triggered by the toxin, when the carboxyl fluorescein-release from liposomes induced by Bc-SMase was the same as that induced by alpha-toxin. Confocal laser microscopy showed that treatment of the cells with Bc-SMase resulted in the formation of ceramide-rich domains. A photobleaching analysis suggested that treatment of the cells with Bc-SMase leads to a reduction in membrane fluidity. These results show that Bc-SMase-induced hemolysis of sheep erythrocytes is related to the formation of interface between ceramide-rich domains and ceramide-poor domains through production of ceramide from SM.
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima, Japan 770-8514.
authors.forename: Masataka
authors.initials: M
authors.lastname: Oda
authors.forename: Masaya
authors.initials: M
authors.lastname: Takahashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsuno
authors.forename: Kana
authors.initials: K
authors.lastname: Uoo
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nagahama
authors.forename: Jun
authors.initials: J
authors.lastname: Sakurai
mesh_terms: D000818:Animals; D001409:Bacillus cereus / Q000201:enzymology* / Q000235:genetics; D001427:Bacterial Toxins / Q000737:chemistry; D002135:Calcium-Binding Proteins / Q000737:chemistry; D002518:Ceramides / Q000737:chemistry; D004910:Erythrocyte Membrane / Q000737:chemistry*; D006461:Hemolysis; D008560:Membrane Fluidity; D021962:Membrane Microdomains / Q000737:chemistry*; D037342:Pertussis Toxin / Q000737:chemistry; D012756:Sheep; D013108:Sphingomyelin Phosphodiesterase / Q000737:chemistry* / Q000235:genetics; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000737:chemistry; D010738:Type C Phospholipases / Q000737:chemistry
chemical_list: D001427:Bacterial Toxins; D002135:Calcium-Binding Proteins; D002518:Ceramides; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D013108:Sphingomyelin Phosphodiesterase; C040649:alpha toxin, Clostridium perfringens; D013110:Sphingosine; C005682:safingol