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How do pathogenic bacteria control how their injection system is assembled?


Researchers a​​t our institute, in collaboration with the Membrane Proteins Laboratory (IBS), has uncovered the mechanism that controls how the toxin injection machinery of pathogenic bacteria is assembled.​

Published on 4 June 2007
These findings will be used to identify and characterise a whole new target for the development of novel antibiotics raised against the factors of pathogenicity. Gram-negative pathogens have developed a highly complex secretion system for injecting toxins into the cells they infect, a system they synthesize at the bacterial surface. This hollow syringe or needle-shaped structure is a small polymerized protein, which in Pseudomonas aeruginosa is PscF. The research team has demonstrated that before the needle-forming polymerization step, PscF is taken over by two chaperone proteins PscE and PscG in the bacterial cytoplasm, and that both these chaperones are required for needle formation as well as for the cytotoxicity of the bacteria. It is this bacteria that is responsible for fatal infections in people with cystic fibrosis, as well as serious infections in immunosuppressed patients such as severe burn patients or patients with AIDS. The pathogenicity of this bacteria is dependent on how efficiently this secretion system works. The research team showed that the surface of PscG to which the PscF binds can be modified to stop the complex from forming. This prevents the formation of the secretion needle – and consequently prevents toxin injection.

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