Opportunistic Invasion

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Science  20 Oct 2006:
Vol. 314, Issue 5798, pp. 389
DOI: 10.1126/science.314.5798.389a

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen that cannot infect healthy humans unless there is a preexisting injury to the epithelium. Shafikhani and Engel describe how P. aeruginosa capitalizes on epithelial wounds to establish itself within the host by using multiple strategies to prevent wound healing. The pathogen injects a protein termed exotoxin T (ExoT) into the cytosol of target cells using a specialized type III secretion apparatus. Once inside the target host cells, ExoT inhibits cytokinesis: the process by which daughter cells are physically separated during cell division. Two domains of ExoT, an N-terminal GTPase-activating domain and a C-terminal ADP-ribosyl transferase domain, appear to act redundantly, one blocking an early step of cytokinesis, the other blocking a later step. This blocking of cytokinesis prevents further cell proliferation and thus helps to prevent the efficient closure of wounds, allowing access to further bacteria, which can go on to establish an acute infection. — SMH

Proc. Natl. Acad. Sci. U.S.A. 103, 15605 (2006).

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