Activation and mechanism of Clostridium septicum alpha toxin |
| |
| Authors: | J Ballard Y Sokolov W-L Yuan B L Kagan R K Tweten |
| |
| Institution: | Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA.;Department of Psychiatry, UCLA Neuropsychiatric Institute and the West Los Angeles Department of Veterans Affairs Medical Center, Los Angeles, California 90024, USA. |
| |
| Abstract: | Clostridium septicum produces a single lethal factor, alpha toxin (AT), which is a cytolytic protein with a molecular mass of approximately 48kDa. The 48kDa toxin was found to be an inactive protoxin (ATpro) which could be activated via a carboxy-terminal cleavage with trypsin. The cleavage site was located approximately 4kDa from the carboxy-terminus. Proteolytically activated ATpro had a specific activity of approximately 1.5 × 106 haemolytic units mg-1. The trypsin-activated toxin (ATact) was haemolytic, stimulated a prelytic release of potassium ions from erythrocytes which was followed by haemoglobin release, induced channel formation in planar membranes and aggregated into a complex of Mr >210000 on erythrocyte membranes. ATpro did not exhibit these properties. ATact formed pores with a diameter of at least 1.3-1.6 nm. We suggest that pore formation on target cell membranes is responsible for the cytolytic activity of alpha toxin. |
| |
| Keywords: | |
|
|
