Biological Effects of Pseudomonas aeruginosa Type III-Secreted Proteins on CHO Cells

Vallis, Amy J.; Finck-Barbançon, Viviane; Yahr, Timothy L.; Frank, Dara W.

doi:10.1128/.67.4.2040-2044.1999

Cited by 35 publications

(53 citation statements)

References 18 publications

(32 reference statements)

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“…ExoY-mediated cell rounding associated with adenylate cyclase activity has been shown previously [20]. The present study shows that, as might be expected, this in-volves significant changes in actin distribution and cytoskeleton integrity.…”

Section: Discussionsupporting

confidence: 89%

Actin cytoskeleton disruption by ExoY and its effects onPseudomonas aeruginosainvasion

Cowell

Evans

Fleiszig

2005

FEMS Microbiology Letters

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Three of the Type III-secreted effectors of Pseudomonas aeruginosa (ExoS, ExoT, and ExoY) each alter mammalian cell morphology in culture without causing a loss of cell viability. For ExoS and ExoT this property involves RhoGAP activity, and leads to actin cytoskeleton disruption and a reduced capacity for internalizing bacteria. ExoY does not possess RhoGAP activity. Instead, cell rounding depends upon its adenylate cyclase catalytic region. Since anti-phagocytic activities of ExoS and ExoT are associated with cell rounding and cytoskeleton disruption, we hypothesized that ExoY would also inhibit P. aeruginosa invasion of epithelial cells coinciding with adenylate cyclase-mediated cytoskeleton disruption. The results showed actin disruption of epithelial cells at 2 h post-infection associated with both adenylate cyclase-active ExoY and its catalytic mutant form ExoYK81M, and which coincided with inhibition of bacterial invasion (76% inhibition by ExoY, and 37% by ExoYK81M). Surprisingly, at 4h post-infection, neither form of ExoY inhibited invasion despite extensive actin disruption. These data suggest that ExoY, like ExoS and ExoT, contains more than one active domain affecting mammalian cell function. The data also suggest that cytoskeleton disruption does not necessarily predict invasion inhibitory activity, supporting the recently proposed model that P. aeruginosa internalization can proceed through more than one pathway.

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Section: Discussionsupporting

confidence: 89%

Actin cytoskeleton disruption by ExoY and its effects onPseudomonas aeruginosainvasion

Cowell

Evans

Fleiszig

2005

FEMS Microbiology Letters

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“…Our results indicated that exotoxin A effect did not increase when iron was absent and that exotoxin A was not involved in killing A. castellanii. Previous studies have shown that although the PA103 strain produced large amounts of exotoxin A in vitro (Vallis et al 1999), it was not involved in killing epithelial cells (Apodaca et al 1995). Iron is required to enhance virulence of many bacteria, such as P. aeruginosa, by affecting host cell lysis (Sirtharan 2006), which might explain why the co-cultivated amoeba population died within 5 days in the presence of iron whereas the population died within 8 days when iron was depleted.…”

Section: -200 Bpmentioning

confidence: 99%

“…To date, TTSS effector proteins included four proteins, ExoS, ExoT, ExoU, and ExoY (Sato and Frank 2004). Vallis et al (1999) observed that ExoU and ExoS are cytotoxic causing irreversible damage in morphology and cell membranes of eukaryotes as well as necrotic death, while ExoT and ExoY have no cytotoxic effects. Shaver and Hauser (2004) assessed effects of TTSS proteins on a mouse model of acute pneumonia by measurements of mortality, as well as bacterial persistence in the lung, and they found that secretion of ExoU had the greatest impact on virulence while secretion of ExoS had an intermediate effect and ExoT had a minor effect.…”

Section: -200 Bpmentioning

confidence: 99%

Pseudomonas aeruginosa Utilises Its Type III Secretion System to Kill the Free‐Living Amoeba Acanthamoeba castellanii

Abd

Wretlind

Saeed

et al. 2008

J Eukaryotic Microbiology

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Pseudomonas aeruginosa is a free-living and common environmental bacterium. It is an opportunistic and nosocomial pathogen causing serious human health problems. To overcome its predators, such as macrophages and environmental phagocytes, it utilises different survival strategies, such as the formation of microcolonies and the production of toxins mediated by a type III secretion system (TTSS). The aim of this study was to examine interaction of TTSS effector proteins of P. aeruginosa PA103 with Acanthamoeba castellanii by co-cultivation, viable count, eosin staining, electron microscopy, apoptosis assay, and statistical analysis. The results showed that P. aeruginosa PA103 induced necrosis and apoptosis to kill A. castellanii by the effects of TTSS effector proteins ExoU, ExoS, ExoT, and ExoY. In comparison, Acanthamoeba cultured alone and co-cultured with P. aeruginosa PA103 lacking the known four TTSS effector proteins were not killed. The results are consistent with P. aeruginosa being a strict extracellular bacterium that needs TTSS to survive in the environment, because the TTSS effector proteins are able to kill its eukaryotic predators, such as Acanthamoeba.

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“…ExoS ultimately causes cell death whereas ExoT does not. ExoY alters cell morphology but does not produce cell death (Yahr et al ., 1998;Vallis et al ., 1999).…”

Section: Introductionmentioning

confidence: 99%

Eukaryotic localization, activation and ubiquitinylation of a bacterial type III secreted toxin

et al. 2006

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SummaryType III secretion is a widespread method whereby Gram-negative bacteria introduce toxins into eukaryotic cells. These toxins mimic or subvert a normal cellular process by interacting with a specific target, although how toxins reach their site of action is unclear. We set out to investigate the intracellular localization of a type III toxin of Pseudomonas aeruginosa called ExoU, which has phospholipase activity and requires a eukaryotic factor for activity. We found that ExoU is localized to the plasma membrane and undergoes modification within the cell by addition of two ubiquitin molecules at lysine-178. A region of five amino acids at position 679-683 near the C-terminus of the ExoU protein controls both membrane localization and ubiquitinylation. Site-directed mutagenesis identified a tryptophan at position 681 as crucial for these effects. We found that the same region at position 679-683 was also required for cell toxicity produced by ExoU as well as in vitro phospholipase activity. Localization of the phospholipase ExoU to the plasma membrane is thus required for activation and allows efficient utilization of adjacent substrate phospholipids.

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Biological Effects of Pseudomonas aeruginosa Type III-Secreted Proteins on CHO Cells

Cited by 35 publications

References 18 publications

Actin cytoskeleton disruption by ExoY and its effects onPseudomonas aeruginosainvasion

Actin cytoskeleton disruption by ExoY and its effects onPseudomonas aeruginosainvasion

Pseudomonas aeruginosa Utilises Its Type III Secretion System to Kill the Free‐Living Amoeba Acanthamoeba castellanii

Eukaryotic localization, activation and ubiquitinylation of a bacterial type III secreted toxin

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