Relationship between Clostridium septicum alpha-toxin activity and binding to erythrocyte membranes

The activity of Clostridium septicum alpha-toxin was determined in erythrocytes of various animals, with sensitivities observed in the order of mouse, rat, canine, equine, rabbit, chicken, bovine, swine and ovine. Temperature and protease treatment affected the sensitivity of erythrocytes to alpha-toxin. Proteinase K treatment decreased the sensitivity of murine, canine, equine and bovine erythrocytes, but ovine erythrocytes did not change the sensitivity to alpha-toxin activity. On the other hand, the activity of alpha-toxin on swine erythrocytes increased after treatment with proteinase K, trypsin, chymotrypsin or lysyl endopeptidase. Toxin overlay assay showed that alpha-toxin bound to erythrocyte membrane proteins with a molecular mass of 30 to 45-kDa in mouse, equine, bovine, swine and chicken, whereas in rat erythrocyte membranes the toxin reacted with 100-kDa protein. The treatment of murine and swine erythrocyte membranes with phosphatidylinositol-specific phospholipase C resulted in liberation of the toxin-binding protein from the individual membranes in a native state. These results show that alpha-toxin associates with specific erythrocyte membrane proteins in any animal species, and are subsets of glycosylphosphatidylinositol-anchored proteins in various animal species. These results may reflect distinct characteristics of the hemolytic activity of alpha-toxin in response to various erythrocytes.