Identification of residues critical for toxicity in Clostridium perfringens phospholipase C, the key toxin in gas gangrene
Alape Girón, Alberto
Flores Díaz, Marietta
Naylor, Claire E.
Rucavado Romero, Alexandra
Basak, Ajit K.
Gutiérrez, José María
Cole, Steward T.
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Clostridium perfringens phospholipase C (PLC), also called α-toxin, is the major virulence factor in the pathogenesis of gas gangrene. The toxic activities of genetically engineered α-toxin variants harboring single amino-acid substitutions in three loops of its C-terminal domain were studied. The substitutions were made in aspartic acid residues which bind calcium, and tyrosine residues of the putative membrane-interacting region. The variants D269N and D336N had less than 20% of the hemolytic activity and displayed a cytotoxic potency 103-fold lower than that of the wild-type toxin. The variants in which Tyr275, Tyr307, and Tyr331 were substituted by Asn, Phe, or Leu had 11–73% of the hemolytic activity and exhibited a cytotoxic potency 102- to 105-fold lower than that of the wild-type toxin. The results demonstrated that the sphingomyelinase activity and the C-terminal domain are required for myotoxicity in vivo and that the variants D269N, D336N, Y275N, Y307F, and Y331L had less than 12% of the myotoxic activity displayed by the wild-type toxin. This work therefore identifies residues critical for the toxic activities of C. perfringens PLC and provides new insights toward understanding the mechanism of action of this toxin at a molecular level.
Enlace externo al ítem10.1046/j.1432-1327.2000.01588.x
- Microbiología