The Pseudomonas aeruginosa ExoY phenotype of high-copy-number recombinants is not detectable in natural isolates

Abstract

The nucleotidyl cyclase ExoY is an effector protein of the type III secretion system of Pseudomonas aeruginosa . We compared the cyclic nucleotide production and lung disease phenotypes caused by the ExoY-overexpressing strain PA103Δ exoUexoT::Tc pUCP exoY , its vector control strain PA103Δ exoUexoT::Tc pUCP18, its loss-of-function control PA103Δ exoUexoT::Tc pUCP exoY K81M and natural ExoY-positive and ExoY-negative isolates in a murine acute airway infection model. Only the P. aeruginosa carrier of the exoY- plasmid produced high levels of cUMP and caused the most severe course of infection. The pathology ascribed to ExoY from studies using the high-copy-number plasmid on mammalian cells in vitro and in vivo was not observed with natural P. aeruginosa isolates. This indicates that the role of ExoY during infection with real-life P. aeruginosa still needs to be resolved.