Much our understanding of the activity of anthrax toxin is based on in-vitro systems, which delineate the interaction between B. anthracis toxins and the cell surface. These systems however, fail to account for the intimate association of B. anthracis with the circulatory system, including the contribution of serum proteins to the host response and processing of anthrax toxins. Using variety immunologic techniques to inhibit serum processing of B. anthracis Protective Antigen (PA) along with mass spectrometry analysis, we demonstrate that serum digests PA via 2 distinct reactions. In the first reaction, serum cleaves PA83 into 2 fragments to produce PA63 and PA20 fragments, similar to that observed following furin digestion. This is followed by carboxypeptidase-mediated removal of the carboxy-terminal arginine and lysine residues from PA20.
- innate immunity
- lethal toxin
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Agricultural and Biological Sciences(all)
- Immunology and Microbiology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)