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. 2000 Jan;68(1):403-6.
doi: 10.1128/IAI.68.1.403-406.2000.

ExoT of cytotoxic Pseudomonas aeruginosa prevents uptake by corneal epithelial cells

B A Cowell  1 , D Y Chen, D W Frank, A J Vallis, S M Fleiszig
Affiliations
Free PMC article

ExoT of cytotoxic Pseudomonas aeruginosa prevents uptake by corneal epithelial cells

B A Cowell et al. Infect Immun. 2000 Jan.
Free PMC article

Abstract

The presence of invasion-inhibitory activity that is regulated by the transcriptional activator ExsA of cytotoxic Pseudomonas aeruginosa has previously been proposed. The results of this study show that both ExoT and ExoS, known type III secreted effector proteins of P. aeruginosa that are regulated by ExsA, possess this activity. Invasion was reduced 94.4% by ExoT and 96.0% by ExoS. Invasion-inhibitory activity is not linked to ADP-ribosylation activity, at least for ExoS, since a noncatalytic mutant also inhibits uptake by an epithelial cell line (invasion was reduced 96. 0% by ExoSE381A).

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Figures

FIG. 1
FIG. 1
PA103exoU inhibits uptake of invasive strains of P. aeruginosa. PA103exoU was coincubated with invasive strains of P. aeruginosa during infection of RCE cells, and uptake was quantified. PA103exoU (□) inhibited the invasion of all strains assayed when coincubated with 6294 (■) (a), 6487 (░⃞) (b), and PA103exoUexsA (formula image) (c). PA103exoUexsA (█) did not inhibit invasion when coincubated with 6294 (■) (d).
FIG. 2
FIG. 2
Uptake of PA103exoU mutants by RCE cells. Bacterial strains were incubated for 3 h with RCE cells before the determination of intracellular bacteria. PA103exoU is noninvasive, and further mutation of exsA or exoT resulted in an invasive phenotype. Complementation with exoT, exoS, or exoSE381A restored invasion-inhibitory activity.
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