Alpha Toxin

Alpha Toxin from Clostridium septicum is a member of the family of β-pore forming toxins (β-PFTs) and is identified as the main virulence factor of this bacterium. The toxin is produced as a single, polypeptide, secreted protein. Seven of the toxin monomers oligomerize on mammalian cell membranes creating a ring-structured trans-membrane pore/channel. The pore allows the efflux of K+ and influx of Ca+ which lead to osmotic cell lysis and death. This hydrophilic pore produced by C. septicum Alpha Toxin is estimated to be 1.3-1.6 nm in diameter. A wide variety of nucleated mammalian cells, including IEC-6 (EC50 5.8 ng/ml), Vero (EC50 24.3 ng/ml), CHO (EC50 24.3 ng/ml), MDCK (EC50 14.6 ng/ml), and MDBK (EC50 24.3 ng/ml), have been reported to be sensitive to this toxin.

Because Alpha Toxin binds to GPI-anchored proteins, including surface antigen 1 (SAG1) and SAG3 of several protozoan parasite, the toxin has been used to understand how GPI-anchored proteins are synthesized and transported through the unusual triple-membrane structure of the parasite pellicle to the plasma membrane, for molecular genetic analysis of GPI-anchored biosynthesis, and GPI-anchored protein trafficking. In particular, Toxoplasma gondii is found to be very sensitive to Alpha Toxin (EC50 0.2 nM).

Alpha Toxin can be used in cancer research to screen and identify a number of tumor antigens, such as carcinoembryonic antigen, mesothelin, prostate-specific stem cell antigen, and urokinase plasminogen activator receptor, which are also reported to be elevated in the blood plasma of breast, ovarian, kidney, liver and brain cancer patients. Alpha Toxin has been used to capture these reporter antigens, some of which have been identified by mass spectrometric analysis, which is useful for screening and detecting these tumor antigens as well as finding new biomarkers/targets for various cancers.

Alpha Toxin can be used to develop immunoassays. As Alpha Toxin has been reported to be an immune dominant extracellular antigen, inactive toxin/toxoid, therefore, can be used to develop effective vaccines against C. septicum mediated diseases. Purified Alpha Toxin can also be used to understand the disease progression and in pharmacokinetic studies in animal models.

C. septicum Alpha Toxin produced at List Labs is a recombinant protein expressed in E. coli and is highly purified as a pro-toxin of about 50 kDa protein. The pro-toxin has been activated by trypsin that nicks before the 45th amino acid residue from the C-terminus (KRRGKR398SVD).

• Product #116 Alpha Toxin from C. septicum is provided frozen in 20% glycerol containing MES buffer

Epsilon Toxin

Epsilon Toxin is secreted by toxinotype B and D strains of Clostridium perfringens. Epsilon Toxin belongs to the heptameric β-pore-forming toxin family which includes aerolysin and C. septicum Alpha Toxin. Epsilon Toxin is synthesized as a single, secreted, ~33 kDa protein that is poorly active and is called a prototoxin. Proteases produced by C. perfringens or present in the host lumen convert the prototoxin to a reduced size (~28.6 kDa) active Epsilon Toxin, allowing the toxin to oligomerize to its heptameric β-barrel form. Activation significantly decreases the pI value from 8.02 to 5.36 and most likely creates a conformational change. Epsilon Toxin receptors are yet to be identified, however, lipid rafts associated myelin and lymphocyte protein (MAL) on the membrane have been proposed to be the receptors for epsilon toxins. Epsilon Toxin is much more potent (100X) than aerolysin and C. septicum Alpha Toxin. Epsilon Toxin is classified as a category B bio-threat agent that has potential for malice. In that respect, active/inactive/mutated epsilon toxin has potential for vaccine development and in biodefense research.

High concentrations of Epsilon Toxin induce an increase in the permeability of the intestinal mucosa, mediating the passage of toxin into the blood, disseminating and accumulating particularly in the kidney and brain. Epsilon Toxin efficiently increases the vascular permeability of rat mesentery microvessels or skin vessels after intradermal injection. In the kidney, Epsilon Toxin causes interstitial hemorrhage between tubules and degeneration of proximal and distal epithelium suggesting that kidney is one of the target organs for epsilon toxin. The toxin is able to alter the integrity of the blood brain barrier (BBB) resulting in prominent lesions consisting of perivascular edema described in mice, rats, sheep and calves, which in the acute state, develop foci of necrosis and hemmorhage. A direct and rapid Epsilon Toxin effect in the brain involves the stimulation of glutamate release from glutametargic neurons abundant in the CNS, which is probably the main cause of the neurological symptoms of excitation (convulsions) observed in Epsilon Toxin dependant enterotoxemia in sheep. Epsilon Toxin has also been shown to induce the release of other neurotransmitters such as dopamine. In that respect, Epsilon Toxin can be used as a reagent to stimulate glutametargic neurons where many bacterial neurotoxins inhibit the release of neurotransmitters. Epsilon Toxin has also been reported to be used as delivery vehicle to facilitate the transport of drugs through the BBB for the treatment of experimental malignant brain tumors in mice.

There is a growing body of evidence that indicates Epsilon Toxin may be a potential trigger for human multiple sclerosis (MS), an inflammatory disease of the central nervous system characterized by disruption of blood brain barrier (BBB) and demyelination of the myelin sheath that insulates the neurons. Epsilon Toxin is known to bind and kill the brain’s endothelium cells and oligodendrocytes (myelin producing cells), the same cells that die in MS lesions. Epsilon Toxin has been found to bind to the retinal vasculature and kill meningeal cells; meningeal inflammation and subpial cortical lesions are known pathologies associated with MS. These findings are very important for future MS research, and epsilon toxin will be a valuable reagent and tool to understand the pathophysiology of MS.

Active Epsilon Toxin is highly purified from native C. perfringens.

• Product #126 Epsilon Toxin from C. perfringens is provided lyophilized in PBS buffer.