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Bacteria: More than one weapon in their bag




​A collaboration between the researchers at the IBS and the Biology of Cancer and Infection Laboratory of our institute has revealed a new weapon of the arsenal of the bacterium Pseudomonas aeruginosa.

Published on 6 April 2018
Pseudomonas aeruginosa is a bacterium responsible for serious nosocomial infections, particularly in implanted medical device carriers (catheters, prostheses, etc.) and in people with weakened immune systems. It is a very worrying and serious pathogen because many hospital strains have become multi-resistant to antibiotics.

Its main virulence factor, a system called T3SS, injects toxins into the target cells through a molecular syringe. The latter drill a hole through the membrane of the cell that it will infect thanks to a protein duo called translocon. "The two proteins PopB and PopD are synthesized in the bacterium, pass through the needle of the syringe and are inserted into the membrane of the cell that will be infected, explains Andréa Dessen, researcher at the Institute of Structural Biology of Grenoble ( IBS). They form a pore through which the toxins of the bacteria reach their target. "
But that's not all ! In fact, IBS researchers, in collaboration with a team from our institute (Bacterial Pathogenesis and Cellular Responses team at the Biology of Cancer and Infection Laboratory) and the Imperial College of London, have shown that the translocon not only acts as a gateway to the target cell. "Once the translocon inserted in the cell and once the bacterium is removed from its site of contact on the same cell, things are still happening, says the scientist. Deleterious epigenetic changes occur that affect the cell following ion exchange across the pore. This indicates, for the first time, that the translocon is able to act, not only as a pore, but also as a real virulence factor. "



Mechanism of operation of the translocon.

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