Bacterial Protein Toxins

Certain types of bacteria produce hazardous protein toxins that can be harmful to humans and other living organisms which often lead to cell death. Some of these toxins intervene with the signaling pathways of transmembrane or change the permeability of the membrane, while other toxins can enter mammalian cells and alter enzymatic activities and cell signaling. Several protein toxins have AB toxins, whereas part B is the polypeptide that links to the receptor and A is the enzyme. These toxins are characterized by their ability to enter a host cell by receptor-mediated endocytosis. Although these toxins have different routes of entry depending on the type of bacteria that produces them, they all have in common the ability to translocate their catalytic subunit towards a membrane to the cytosol. Some AB toxins require an acidic environment to trigger their translocation. These toxins can penetrate membranes of acidic endosomes. Other toxins rely on recessive transport via the secretory pathway to ER before translocation. Finally, the toxin modifies a specific target in the cytosol, resulting in cell death. This chapter provides a concise overview of these toxins produced by different types of bacteria. The topics covered in this chapter are the types of toxins, their chemical nature, their effect on host cells, the overall process of intoxication, and the mechanism of cell penetration. It also discusses different types of toxins explicitly produced by certain bacteria, e.g. Bacillus anthrax.