Toxins are powerful pathogenicity factors produced by certain bacteria, fungi, animals, and plants which mediate drastic interactions of these pathogens on the organism host. Notably, bacterial toxins were the first compounds which were identified as responsible for severe bacterial diseases in man and animals.
Bacterial toxigenesis is a major mechanism by which pathogenic bacteria produce diseases. They produce two kinds of toxins, lipopolysaccharides and protein toxins. Lipopolysaccharides are cell-associated toxins released after disruption of the cell (endotoxins), whereas protein toxins are synthesized inside the cells and then released to the target cells.
Endotoxins are associated with Gram-negative bacteria and form part of their cell wall structures. More specifically, endotoxins refer to the lipopolysaccharide complex associated with the outer membranes of Gram-negative bacteria.
The toxins are usually liberated from the organism by lysis, but some are shed with outer membrane proteins in outer membrane vesicles.
Bacterial toxins are the most powerful poisons produced in the nature, and are known to retain a very high level of activity at high dilutions. Bacterial toxins proteins capable of achieving multiple remarkable tasks. They function as autonomous molecular devices, targeting specific cells in an organism, punching holes in their membranes, or modifying intracellular components. Intoxication processes involve highly specialized steps of great complexity.
Toxins may damage the eukaryotic cell mem brane by combining with some structural component, or otherwise alter its function. Many toxins combine with specific receptors on the surface membrane, frequently glycoproteins or gangliosides, and penetrate the cell to reach their intracellular target. A common mechanism of entry is absorptive endocytosis.
Structurally, bacterial toxins seem to display some unconventional strategies. For example, toxins may have structurally and functionally identical domains but containing different binding domains (Diphtheria toxin and Pseudomonas ExoA), or could have similar binding domains but different catalytic domains.
General view of bacterial toxin
