Warning: dangerous toxins ahead.

The process of Pseudomonas aeruginosa becoming toxic to its host is an extremely interesting one. The first step to this process is for the Pseudomonas aeruginosa bacteria gain access into the body. For the most part, this is done by unknown contact or through abrasions in tissues. The bacteria then uses its flagella to help “swim” to a particular site to begin the infection process. Once there, Pseudomonas aeruginosa begins to release extracellular enzymes. These enzymes, elastase (shown in figure to the right) and alkaline protease, help to break down the proteins and peptides of the host organism. The importance of this is that it allows the bacterium to bind to the mucus layers that line intestines. This eventually allows for the bacterium to complete the colonization process and produce the biofilm layer insuring its protection from antibodies, antibiotics, and phagocytotic white blood cells. Once a safe biofilm colony has formed, Pseudomonas aeruginosa produces its lethal toxins: Exotoxin A (illustrated in figure to the left) and exoenzyme S. Exotoxin A, once released from the bacterium, attacks the cells of the host and inhibits the ability of the host cells to undergo protein synthesis. Protein synthesis is important to cells because it allows for the production of proteins that are used in enzymes, cellular structures, and hormones. The function of exoenzyme S is not as well understood. However, it is thought that it restricts the immune function of phagocytotic white blood cells, preventing them from getting in the way of Pseudomonas aeruginosa during the invasion process. 

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To learn about how these toxin take a toll on their hosts, visit my interactions page!

To learn more about these toxins, visit:

The Journal of Infectious Diseases