Prevalence of ExoY Activity in Pseudomonas aeruginosa Reference Panel Strains and Impact on Cytotoxicity in Epithelial Cells

Silistre, Hazel; Raoux-Barbot, Dorothée; Mancinelli, Federica; Sangouard, Flora; Dupin, Alice; Belyy, Alexander; Deruelle, Vincent; Renault, Louis; Ladant, Daniel; Touqui, Lhousseine; Mechold, Undine

doi:10.3389/fmicb.2021.666097

Cited by 14 publications

(13 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are four characterized effectors in P. aeruginosa: ExoS, ExoT, ExoU and ExoY, with ExoS and ExoU generally being mutually exclusive [7]. While a majority of isolated strains encode the nucleotidyl cyclase ExoY, its effect on various types of host cells has only recently been explored, and it may play a role in limiting cytotoxicity elicited by other effectors [8]. ExoY can contribute to virulence in corneal cells [9], but appears dispensable in some in vivo models despite various in vitro phenotypes [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Exotoxin S secreted by internalized Pseudomonas aeruginosa delays lytic host cell death

et al. 2022

View full text Add to dashboard Cite

The Pseudomonas aeruginosa toxin ExoS, secreted by the type III secretion system (T3SS), supports intracellular persistence via its ADP-ribosyltransferase (ADPr) activity. For epithelial cells, this involves inhibiting vacuole acidification, promoting vacuolar escape, countering autophagy, and niche construction in the cytoplasm and within plasma membrane blebs. Paradoxically, ExoS and other P. aeruginosa T3SS effectors can also have antiphagocytic and cytotoxic activities. Here, we sought to reconcile these apparently contradictory activities of ExoS by studying the relationships between intracellular persistence and host epithelial cell death. Methods involved quantitative imaging and the use of antibiotics that vary in host cell membrane permeability to selectively kill intracellular and extracellular populations after invasion. Results showed that intracellular P. aeruginosa mutants lacking T3SS effector toxins could kill (permeabilize) cells when extracellular bacteria were eliminated. Surprisingly, wild-type strain PAO1 (encoding ExoS, ExoT and ExoY) caused cell death more slowly, the time extended from 5.2 to 9.5 h for corneal epithelial cells and from 10.2 to 13.0 h for HeLa cells. Use of specific mutants/complementation and controls for initial invasion showed that ExoS ADPr activity delayed cell death. Triggering T3SS expression only after bacteria invaded cells using rhamnose-induction in T3SS mutants rescued the ExoS-dependent intracellular phenotype, showing that injected effectors from extracellular bacteria were not required. The ADPr activity of ExoS was further found to support internalization by countering the antiphagocytic activity of both the ExoS and ExoT RhoGAP domains. Together, these results show two additional roles for ExoS ADPr activity in supporting the intracellular lifestyle of P. aeruginosa; suppression of host cell death to preserve a replicative niche and inhibition of T3SS effector antiphagocytic activities to allow invasion. These findings add to the growing body of evidence that ExoS-encoding (invasive) P. aeruginosa strains can be facultative intracellular pathogens, and that intracellularly secreted T3SS effectors contribute to pathogenesis.

show abstract

Section: Introductionmentioning

confidence: 99%

Exotoxin S secreted by internalized Pseudomonas aeruginosa delays lytic host cell death

et al. 2022

View full text Add to dashboard Cite

show abstract

“…The ExoY protein sequence encoded by different P. aeruginosa strains varies. Sequence variations can be without consequences on enzymatic activity, modulate it, or even nearly abolish it, as in the case of the ExoY sequences identified in highly virulent PA14 strains [ 94 , 95 ]. These variations, which may be a consequence of long-term evolution or short-term adaptation of P. aeruginosa strains, complicate the identification of the role of Pa -ExoY exotoxins.…”

Section: Actin-activated Bacterial Toxinsmentioning

confidence: 99%

“…These variations, which may be a consequence of long-term evolution or short-term adaptation of P. aeruginosa strains, complicate the identification of the role of Pa -ExoY exotoxins. In a recent study, we examined the prevalence of ExoY activity in the largely diverse P. aeruginosa isolates of the international P. aeruginosa reference panel [ 95 ]. We found that ExoY GC activity is widespread among P. aeruginosa isolates, including those originating from cystic fibrosis patients, and that activity levels vary between strains (when measured in supernatants of bacterial cultures stimulated to secrete T3SS effectors by Ca++ chelation).…”

Section: Actin-activated Bacterial Toxinsmentioning

confidence: 99%

“…Huber et al showed that Pa -ExoY, when injected alone, elevates cAMP levels in endothelial cells, which is not the case when this toxin is co-delivered with ExoS and ExoT [ 96 ]. Conversely, P. aeruginosa strains lacking ExoY are more cytotoxic to infected human lung epithelial cells than those secreting active ExoY, suggesting that ExoY may partially alleviate the cytotoxic effects of other P. aeruginosa virulence factors under certain conditions [ 95 ].…”

Section: Actin-activated Bacterial Toxinsmentioning

confidence: 99%

See 1 more Smart Citation

Bacterial Nucleotidyl Cyclases Activated by Calmodulin or Actin in Host Cells: Enzyme Specificities and Cytotoxicity Mechanisms Identified to Date

Teixeira-Nunes

Retailleau

Comisso

et al. 2022

IJMS

Self Cite

View full text Add to dashboard Cite

Many pathogens manipulate host cell cAMP signaling pathways to promote their survival and proliferation. Bacterial Exoenzyme Y (ExoY) toxins belong to a family of invasive, structurally-related bacterial nucleotidyl cyclases (NC). Inactive in bacteria, they use proteins that are uniquely and abundantly present in eukaryotic cells to become potent, unregulated NC enzymes in host cells. Other well-known members of the family include Bacillus anthracis Edema Factor (EF) and Bordetella pertussis CyaA. Once bound to their eukaryotic protein cofactor, they can catalyze supra-physiological levels of various cyclic nucleotide monophosphates in infected cells. Originally identified in Pseudomonas aeruginosa, ExoY-related NC toxins appear now to be more widely distributed among various γ- and β-proteobacteria. ExoY-like toxins represent atypical, poorly characterized members within the NC toxin family. While the NC catalytic domains of EF and CyaA toxins use both calmodulin as cofactor, their counterparts in ExoY-like members from pathogens of the genus Pseudomonas or Vibrio use actin as a potent cofactor, in either its monomeric or polymerized form. This is an original subversion of actin for cytoskeleton-targeting toxins. Here, we review recent advances on the different members of the NC toxin family to highlight their common and distinct functional characteristics at the molecular, cytotoxic and enzymatic levels, and important aspects that need further characterizations.

show abstract

“…In in vivo settings, bacteria must naturally come into contact with human cells to induce exoY expression. The in vivo environment may yield lower exoY expression than in vitro , where there are no barriers to prevent exoY expression ( Silistre et al, 2021 ).…”

Section: Pao1 and Pa14 Virulence Determinant Differencesmentioning

confidence: 99%

Pseudomonas aeruginosa reference strains PAO1 and PA14: A genomic, phenotypic, and therapeutic review

Grace

Sahu²,

Owen³

et al. 2022

Front. Microbiol.

View full text Add to dashboard Cite

Pseudomonas aeruginosa is a ubiquitous, motile, gram-negative bacterium that has been recently identified as a multi-drug resistant pathogen in critical need of novel therapeutics. Of the approximately 5,000 strains, PAO1 and PA14 are common laboratory reference strains, modeling moderately and hyper-virulent phenotypes, respectively. PAO1 and PA14 have been instrumental in facilitating the discovery of novel drug targets, testing novel therapeutics, and supplying critical genomic information on the bacterium. While the two strains have contributed to a wide breadth of knowledge on the natural behaviors and therapeutic susceptibilities of P. aeruginosa, they have demonstrated significant deviations from observations in human infections. Many of these deviations are related to experimental inconsistencies in laboratory strain environment that complicate and, at times, terminate translation from laboratory results to clinical applications. This review aims to provide a comparative analysis of the two strains and potential methods to improve their clinical relevance.

show abstract

Prevalence of ExoY Activity in Pseudomonas aeruginosa Reference Panel Strains and Impact on Cytotoxicity in Epithelial Cells

Cited by 14 publications

References 49 publications

Exotoxin S secreted by internalized Pseudomonas aeruginosa delays lytic host cell death

Exotoxin S secreted by internalized Pseudomonas aeruginosa delays lytic host cell death

Bacterial Nucleotidyl Cyclases Activated by Calmodulin or Actin in Host Cells: Enzyme Specificities and Cytotoxicity Mechanisms Identified to Date

Pseudomonas aeruginosa reference strains PAO1 and PA14: A genomic, phenotypic, and therapeutic review

Contact Info

Product

Resources

About