Abstract
Pseudomonas aeruginosa is an opportunistic, Gram-negative pathogen and an important cause of hospital acquired infections, especially in immunocompromised patients. Highly virulent P. aeruginosa strains use a type III secretion system (T3SS) to inject exoenzyme effectors directly into the cytoplasm of a target host cell. P. aeruginosa strains that express the T3SS effector, ExoU, associate with adverse outcomes in critically ill patients with pneumonia, owing to the ability of ExoU to rapidly damage host cell membranes and subvert the innate immune response to infection. Herein, we review the structure, function, regulation, and virulence characteristics of the T3SS effector ExoU, a highly cytotoxic phospholipase A2 enzyme.
Highlights
Pseudomonas aeruginosa is a Gram-negative, rod-shaped bacterium found in soil and water
As an important cause of nosocomial pneumonia globally, P. aeruginosa is classified as an ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogen listed as critical priority for new research and drug development by the World Health Organization [3,4,5]
Healthcare infections associated with P. aeruginosa exceed 51,000 cases annually in the United States and are responsible for 40% of deaths of patients with ventilator-associated pneumonia (VAP) [6,7,8,9,10]
Summary
Pseudomonas aeruginosa is a Gram-negative, rod-shaped bacterium found in soil and water. P. aeruginosa is a pathogen commonly isolated from patients with acute respiratory infections, which is result from airway epithelial damage due to with mechanical ventilation. ExoU and its chaperone, spcU, are thought to have been acquired through horizontal gene transfer and reside on an 81-kb pathogenicity island [37] In support of this hypothesis, yeast recombinational cloning and sequence analysis revealed exoU has a lower G + C content (59%) compared to exoS encoded by strain PAO1 (67%) and flanking elements homologous to IS407 [37]. Combined with the nucleotide alignment analyses revealing a PLA domain similar to patatin, cPLA2 , and iPLA2 [38], ExoU was postulated to function as a phospholipase hydrolyzing neutral lipids and phospholipids [38,39,40] This model reconciled the rapid cytotoxicity in vitro and significant tissue destruction mediated by.
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