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Threonine-74 is a key site for the activity of Clostridium perfringens alpha-toxin

M Nagahama1, J Sakurai

  • 1Department of Microbiology, Tokushima Bunri University, Japan.

Microbiology and Immunology
|January 1, 1996
PubMed

Insights

Researchers created a mutant Clostridium perfringens alpha-toxin with significantly reduced hemolytic activity. The T-74 residue was identified as crucial for the toxin

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Clostridium perfringens alpha-toxin is a key virulence factor.
  • Its hemolytic, phospholipase C, and sphingomyelinase activities are critical for pathogenesis.
  • Understanding the structure-function relationship is essential for developing inhibitors.

Purpose of the Study:

  • To identify key residues responsible for the biological activities of Clostridium perfringens alpha-toxin.
  • To characterize a mutant toxin with significantly reduced hemolytic activity.

Main Methods:

  • Random polymerase chain reaction (PCR) mutagenesis was used to generate mutant alpha-toxin genes.
  • Site-directed mutagenesis was employed to create specific amino acid substitutions.
  • Hemolytic, phospholipase C, and sphingomyelinase activities were measured.
  • Zinc binding assays were performed using [65Zn]2+.

Main Results:

  • A mutant toxin (MT) with nearly 99% loss of hemolytic activity was generated.
  • Substitution of Threonine (T)-74 with Isoleucine (I) abolished hemolytic, phospholipase C, and sphingomyelinase activities.
  • Mutations at Tyrosine (Y)-62 and Isoleucine (I)-345 did not significantly affect toxin activities.
  • The T74I mutant retained wild-type binding to erythrocyte membranes and zinc ion binding.

Conclusions:

  • The Threonine (T)-74 residue is critical for the hemolytic, phospholipase C, and sphingomyelinase activities of Clostridium perfringens alpha-toxin.
  • The T-74 residue's role in zinc binding and membrane interaction is essential for toxin function.
  • Targeting the T-74 residue could lead to novel therapeutic strategies against C. perfringens infections.

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