High-cell-density regulation of the Pseudomonas aeruginosa type III secretion system: implications for tryptophan catabolites

Shen, Danhong; Filopon, Didier; Chaker, Hichem; Boullanger, Stéphanie; Derouazi, Madiha; Polack, Benoı̂t; Toussaint, Bertrand

doi:10.1099/mic.0.2007/013680-0

Cited by 36 publications

(38 citation statements)

References 83 publications

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“…Although we can only speculate on the mechanism by which IAA-Asp activates gene expression in the two pathogens, it is important to note that a link between Trp metabolites, such as IAA, and bacterial pathogenicity has been made before. In Pseudomonas aeruginosa, a Gram-negative pathogen that causes acute and chronic infections in humans, IAA, NAA, and 3-hydroxykynurenine were shown to inhibit TTSS expression, thus potentially affecting the virulence of this pathogen (Shen et al, 2008). In R. solanacearum, another Trp oxidative metabolite, 3-hydroxy-oxindole, was shown to be synthesized through the concerted action of a six-gene-containing operon under the control of HrpB, itself activated by PhrA and plant cell contact (Delaspre et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

The Conjugated Auxin Indole-3-Acetic Acid–Aspartic Acid Promotes Plant Disease Development

et al. 2012

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Section: Discussionmentioning

confidence: 99%

The Conjugated Auxin Indole-3-Acetic Acid–Aspartic Acid Promotes Plant Disease Development

et al. 2012

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“…Pyocyanin, lectin PA-1L, exotoxin A, and elastase are clearly under the control of the QS network. On the other hand, how QS affects T3SS is still unclear at the moment, as this system seems to be regulated by the rhl system (7,35), by the major Gac/RsmA sensor system (62), by HAQs (60), and by other not yet characterized signals derived from tryptophan catabolism (59). Here, we show that 3O-C 12 -HSL is present in the oprF mutant culture supernatants at lower concentrations than in the wild-type strain culture supernatants.…”

Section: Vol 79 2011mentioning

confidence: 99%

“…Exotoxin A is a lethal toxin which inhibits protein synthesis in mammalian cells (70). The type III secretion system (T3SS) is responsible for the translocation of virulence factors into eukaryotic cells (18,28) and is mildly QS controlled (7,59). T3SS is of major importance in acute infection, by facilitating dissemination of P. aeruginosa through epithelia (27), and in cytotoxicity toward polymorphonuclear cells and macrophages (18).…”

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confidence: 99%

Full Virulence of Pseudomonas aeruginosa Requires OprF

et al. 2011

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OprF is a general outer membrane porin of Pseudomonas aeruginosa, a well-known human opportunistic pathogen associated with severe hospital-acquired sepsis and chronic lung infections of cystic fibrosis patients. A multiphenotypic approach, based on the comparative study of a wild-type strain of P. aeruginosa, its isogenic oprF mutant, and an oprF-complemented strain, showed that OprF is required for P. aeruginosa virulence. The absence of OprF results in impaired adhesion to animal cells, secretion of ExoT and ExoS toxins through the type III secretion system (T3SS), and production of the quorum-sensing-dependent virulence factors pyocyanin, elastase, lectin PA-1L, and exotoxin A. Accordingly, in the oprF mutant, production of the signal molecules N-(3-oxododecanoyl)-L-homoserine lactone and N-butanoyl-L-homoserine lactone was found to be reduced and delayed, respectively. Pseudomonas quinolone signal (PQS) production was decreased, while its precursor, 4-hydroxy-2-heptylquinoline (HHQ), accumulated in the cells. Taken together, these results show the involvement of OprF in P. aeruginosa virulence, at least partly through modulation of the quorum-sensing network. This is the first study showing a link between OprF, PQS synthesis, T3SS, and virulence factor production, providing novel insights into virulence expression.

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“…The former includes a membrane-associated adenylcyclase (CyaB) and a cyclic AMP binding cyclic AMP receptor protein (CRP) homolog called Vfr (53), an Rhl quorum-sensing system (4,22), stationary-phase sigma factor RpoS and its transcriptional activator PsrA (22,41), and a hybrid sensor kinase/response regulator (RtsM/RetS) (19). The latter includes aceA and aceB, encoding the subunits of pyruvate dehydrogenase (11); trpA and kynA, encoding tryptophan synthase and tryptophan dioxygenase (40); truA, encoding pseudouridinase enzyme (1); and mgtE, a magnesium transporter gene (2).…”

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MexT Regulates the Type III Secretion System through MexS and PtrC in Pseudomonas aeruginosa

et al. 2011

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The type III secretion system (T3SS) is the most important virulence factor in Pseudomonas aeruginosa, and its expression level varies in different isolates. We studied the molecular basis for such differences in two laboratory strains, PAK and PAO1. A chromosomal clone library from the high-T3SS-producer strain PAK was introduced into the low-producer strain PAO1, and we found that a mexS gene from PAK confers high T3SS expression in the PAO1 background. Further tests demonstrated that both mexS and its neighboring mexT gene are required for the repression of the T3SS in PAO1, while the PAK genome encodes a defective MexS, accounting for the derepression of the T3SS in PAK and the dominant negative effect when it is introduced into PAO1. MexS is a probable oxidoreductase whose expression is dependent on MexT, a LysR-type transcriptional regulator. Various genetic data support the idea that MexS modulates the transcriptional regulator function of MexT. In searching for the MexT-dependent repressor of the T3SS, a small gene product of PA2486 (ptrC) was found effective in suppressing the T3SS upon overexpression. However, deletion of ptrC in the PAO1 background did not result in derepression of the T3SS, indicating the presence of another repressor for the T3SS. Interestingly, overexpression of functional mexS alone was sufficient to repress T3SS even in the absence of MexT, suggesting that MexS is another mediator of MexT-dependent T3SS repression. Overexpression of mexS alone had no effect on the well-known MexT-dependent genes, including those encoding MexEF efflux pump, elastase, and pyocyanin, indicating alternative regulatory mechanisms. A model has been proposed for the MexS/MexT-mediated regulation of the T3SS, the MexEF efflux pump, and the production of elastase and pyocyanin.

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High-cell-density regulation of the Pseudomonas aeruginosa type III secretion system: implications for tryptophan catabolites

Cited by 36 publications

References 83 publications

The Conjugated Auxin Indole-3-Acetic Acid–Aspartic Acid Promotes Plant Disease Development

The Conjugated Auxin Indole-3-Acetic Acid–Aspartic Acid Promotes Plant Disease Development

Full Virulence of Pseudomonas aeruginosa Requires OprF

MexT Regulates the Type III Secretion System through MexS and PtrC in Pseudomonas aeruginosa

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