C. septicum alpha toxin: Importance and applications in infectious disease and cancer research
May 16, 2016
UPDATE: July 13, 2016
Alpha Toxin from C. septicum, product #116L is now available for purchase online. Information on other potential upcoming products can be found on our Product Pipeline.
UPDATE: May 16, 2016
Alpha Toxin from C. septicum is currently in late to final stages of development, and we are accepting orders now. We expect to ship our first orders toward the end of this month or the earlier part of June. Please e-mail your purchase order to ORDERS@listlabs.com.
Product details are as follows:
- Assigned product: #116L
- Price per vial: $275
- Vial size: 50 ug
- Ships on Blue Ice as a Dangerous Good
- Not a Select Agent or a controlled export item
Documents for Product #116L (safety data sheet, certificate of analysis, etc.) will be posted on our website when available. Official availability from stock will be announced in a future update on this blog post. We will also make announcements on social media. Check our Facebook, Twitter, LinkedIn, and Google+, or contact us directly if you would like to be among the first to know when Product #116 is officially available.
Originally published on October 26, 2015
By: Md. Elias, Ph.D, Senior Scientist
List Labs is constantly bringing new products as research reagents, and GMP grades, to the scientific community for the advancement of science. A recombinant C. septicum alpha toxin will soon be added to our product list and can be found in our pipeline information. This toxin can be useful for basic research, immune assay development, vaccine development and more importantly in cancer research. If you have specific interest in this product, please contact us for more information.
Gas gangrene or myonecrosis is a well known fatal disease caused by a number of bacteria such as Clostridium perfringens, Clostridium septicum, group A Streptococcus, Staphylococcus aureus and Vibrio vulnificus (1-4). Infections from these bacteria initiate mainly from traumatic injury, except for C. septicum where no trauma is necessary at the site of infection (5). This disease is characterized by extensive tissue damage, edema, thrombosis and fluid-filled bullae, if left untreated; the complications progress very rapidly and can lead to death (5). C. septicum is a gram-positive, spore forming, obligate anaerobic bacterium that is a member of our normal gut flora as well as of other animals (5). Historically, C. septicum infection played a leading role as the causative agent of traumatic gas gangrene on the battlefield (1). After the advent of antibiotics in the mid 1950, death from C. septicum infection was drastically reduced. Although it was once thought rare, in the recent past, C. septicum infections have increasingly been identified with non-traumatic gas gangrene in patients having pre-existing medical conditions such as colonic carcinoma, defects of the bowel, leukemia, peripheral vascular diseases, diabetes, recent surgery, skin infection/burns and septic abortions (5).
Farm animals and birds (commercial turkeys) are also very vulnerable to C. septicum infection if they are not vaccinated or not treated immediately after the onset of infection. Infection often occurs from deep puncture wounds, castration and calving injuries including navel infections in newborn calves (6). A current study reports evidence for C. septicum as a primary cause of cellulitis in commercial turkeys and is associated with substantial economic loss to turkey producers (7). Turkey cellulitis is an acute diffuse infection of the dermis and subcutaneous tissue with edema.
Pathogenesis starts from the sites with poor vascular supply, although because of pH, electrolyte and osmotic differences, the colon may promote the growth of C. septicum better than most other anatomical regions (8). One of the more aggressive progenitors of gas gangrene is that the infection progresses very rapidly with a mortality rate of approximately 79% in adults, typically occurring within 48 hours of infection. Gas gangrene proceeds via disruption of blood flow to the infected site, resulting in diminished levels of oxygen and nutrients ultimately causing premature cell death and tissue necrosis (9). Tissue necrosis then causes edema and ischemia resulting in metabolic acidosis, fever, and renal failure (9). The carbon dioxide and hydrogen produced during cellular respiration move through tissue planes, causing their separation, producing features characteristic of palpable emphysema (9).
Four toxins have been isolated from C. septicum: the lethal alpha toxin, DNase beta-toxin, hyaluronidase gamma toxin, and the thiol-activated/septicolysin delta toxin (10). Alpha toxin binds to the target cell membrane and forms a channel/pore. It is considered the major virulence factor for intravascular hemolysis and tissue necrosis and is also appeared to be the immune dominant extracellural antigen (11). Purified C. septicum alpha toxin is a valuable reagent to understand the pathophysiology of this disease, development of immune detection assays and vaccines.
The cell surface receptors for alpha toxin have been identified in the recent past (12). Using retroviral mutagenesis, a mutant CHO cell line was generated that is resistant to alpha toxin and it was found that mutations occurred on glycosylphosphatidylinositol (GPI)-anchored membrane proteins. Eventually, it was confirmed that GPI anchored cell surface proteins are the receptors for alpha toxin (12).
GPI anchored proteins have received closer attention from the scientific community recently for another reason. GPI anchoring takes place through a lipid and glycan modification of certain proteins in the endoplasmic reticulum by a multiple subunit enzyme complex known as GPI transamidase (GPIT) (13, 14). Scientists have found that several subunits of GPIT are elevated in various cancers that in turn also increase levels of certain GPI-anchored proteins on the cell surface (13, 14). GPI-anchored proteins are predicted to comprise 1–2% of translated proteins in mammals (15). Several GPI-anchored proteins identified to date are tumor antigens such as carcinoembryonic antigen, mesothelin, prostate-specific stem cell antigen, and urokinase plasminogenactivator receptor, suggesting possible roles for this class of proteins in promoting tumorigenesis (13). Scientists have used C. septicum alpha toxin to capture and identify GPI-anchored proteins from human breast cancer tissues, cells and serum for proteomic analysis (13, 14). Their data indicated that patients with cancers associated with elevated GPI transamidase, showed increased alpha toxin binding of plasma proteins indicating increased levels of GPI anchored proteins. Furthermore, their results revealed very low levels of alpha toxin binding proteins in plasma from patients with no malignant disease indicating few GPI anchored proteins are present. GPI anchored proteins present in plasma from cancers patients are potential bio-markers for cancer detection (13, 14). Investigations also revealed that alpha toxin binds with the GPI glycan region as shown by retained binding of the toxin after removal of the lipid portion of the GPI anchor. Diversity of GPI anchored proteins that bind the toxin indicates that the binding occurs via the GPI glycan without peptide requirements (13, 14). Therefore, C. septicum alpha toxin has a potential to be used as a capture device for specific GPI anchor proteins to screen and identify cancer bio-markers.
- Stevens, D.L., Aldape, M.J., Bryant, A.E., et al., Life-threatening clostridial infections. Anaerobe, 2012. 18(2): p. 254-259. PMID: 22120198
- Mason, K. L. and Aronoff, D. M., Postpartum group A Streptococcus sepsis and maternal immunology. Am J Reprod Immunol. 2012. 67(2): p. 91-100. PMID: 22023345
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- Hickey, M. J., et al., Molecular and cellular basis of microvascular perfusion deficits induced by clostridium perfringens and clostridium septicum. PLoS Pathogens. 2008. 4(4): p. 1-9. PMID: 18404211
- Gordon, V. M., et al., Clostridium septicum alpha toxin uses glycosylphosphatidylinositol anchored protein receptors. J Biol Chem. 1999. 274(38): p. 27274-27280. PMID: 10480947
- Zhao, P., et al., Proteomic identification of glycosylphosphatidylinositol anchor-dependent membrane proteins elevated in breast carcinoma. J Biol Chem. 2012. 287(30): p. 25230-25240. PMID: 22654114
- Dolezal, S., et al., Elevated levels of glycosylphosphatidylinositol anchored proteins in plasma from human cancers detected by C. septicum alpha toxin. Cancer Biomark. 2014. 14(1): p. 55-66. PMID: 24643042
- Eisenhaber, B., et al., Post-translational GPI lipid anchor modification of proteins in kingdoms of life: analysis of protein sequence data from complete genomes. Protein Eng. 2001. 14(1): p. 17-25. PMID: 11287675