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Transcriptomic analysis reveals a global alkyl-quinolone-independent regulatory role for PqsE in facilitating the environmental adaptation of Pseudomonas aeruginosa to plant and animal hosts.

Rampioni G, Pustelny C, Fletcher MP, Wright VJ, Bruce M, Rumbaugh KP, Heeb S, Cámara M, Williams P - Environ. Microbiol. (2010)

Bottom Line: To gain insights into the relationship between the AQ stimulon, the PqsE stimulon and the regulatory function of PqsE, we constructed a pqsE inducible mutant (pqsEind) and compared the transcriptomes of the induced and uninduced states with a pqsA mutant.Furthermore, pqsE was required for swarming motility and virulence in plant and animal infection models in the absence of AQs, while mature biofilm development required both pqsA and pqsE.Taken together these data reveal that PqsE is a key regulator within the QS circuitry facilitating the environmental adaptation of P. aeruginosa.

View Article: PubMed Central - PubMed

Affiliation: School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University Park, University of Nottingham, Nottingham NG7 2RD, UK.

ABSTRACT
The quorum sensing (QS) system of Pseudomonas aeruginosa constitutes a sophisticated genome-wide gene regulatory network employing both N-acylhomoserine lactone and 2-alkyl-4-quinolone (AQ) signal molecules. AQ signalling utilizes 2-heptyl-3-hydroxy-4-quinolone (PQS) and its immediate precursor, 2-heptyl-4-quinolone (HHQ). AQ biosynthesis requires the first four genes of the pqsABCDE operon and while the biochemical function of pqsE is not known, it is required for the production of secondary metabolites such as pyocyanin. To gain insights into the relationship between the AQ stimulon, the PqsE stimulon and the regulatory function of PqsE, we constructed a pqsE inducible mutant (pqsEind) and compared the transcriptomes of the induced and uninduced states with a pqsA mutant. Of 158 genes exhibiting altered expression in the pqsA mutant, 51% were also affected in the pqsE mutant. Following induction of pqsE, 237 genes were differentially expressed compared with the wild-type strain. In the pqsEind strain, pqsA was highly expressed but following induction both pqsA expression and AQ biosynthesis were repressed, revealing a negative autoregulatory role for PqsE. Furthermore, pqsE was required for swarming motility and virulence in plant and animal infection models in the absence of AQs, while mature biofilm development required both pqsA and pqsE. Taken together these data reveal that PqsE is a key regulator within the QS circuitry facilitating the environmental adaptation of P. aeruginosa.

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PqsE restores virulence in nematode, plant and animal infection models in the absence of AQs. A. Caenorhabditis elegans killing assay showing the percentage of nematode survival after 1–6 days of exposure to the P. aeruginosa PAO1 wild type, pqsA pqsEind mutant and pqsA pqsEind mutant transformed with the vector control, pUCP18 or pUCPpqsE respectively. The average of four independent experiments is reported with standard deviation. B. Virulence of the wild type, pqsA mutant and pqsA mutant complemented with pqsE in the lettuce leaf virulence assay. The number of bacterial cells (as colony forming units, cfu) present in 1 mg of lettuce midrib 5 days post injection is shown. Error bars were calculated from five independent experiments. A representative picture of infected midribs is also shown for each strain. C and D. Mouse acute burn wound infection showing the survival rate over time (days after burn/infection) for mice infected with (C) the P. aeruginosa wild type (▵), pqsA (□) and pqsE (○) mutants; 15 mice per mutant and (D) the P. aeruginosa pqsA mutant (□) and the pqsA mutant transformed with either pUCP18 (○) or pUCPpqsE (▵); nine mice per mutant.
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fig03: PqsE restores virulence in nematode, plant and animal infection models in the absence of AQs. A. Caenorhabditis elegans killing assay showing the percentage of nematode survival after 1–6 days of exposure to the P. aeruginosa PAO1 wild type, pqsA pqsEind mutant and pqsA pqsEind mutant transformed with the vector control, pUCP18 or pUCPpqsE respectively. The average of four independent experiments is reported with standard deviation. B. Virulence of the wild type, pqsA mutant and pqsA mutant complemented with pqsE in the lettuce leaf virulence assay. The number of bacterial cells (as colony forming units, cfu) present in 1 mg of lettuce midrib 5 days post injection is shown. Error bars were calculated from five independent experiments. A representative picture of infected midribs is also shown for each strain. C and D. Mouse acute burn wound infection showing the survival rate over time (days after burn/infection) for mice infected with (C) the P. aeruginosa wild type (▵), pqsA (□) and pqsE (○) mutants; 15 mice per mutant and (D) the P. aeruginosa pqsA mutant (□) and the pqsA mutant transformed with either pUCP18 (○) or pUCPpqsE (▵); nine mice per mutant.

Mentions: Given that PqsE restores pyocyanin and lectin production in the absence of AQs, we investigated the impact of pqsE mutation on P. aeruginosa pathogenicity using three well-established plant (lettuce leaf) and animal (Caenorhabditis elegans and mouse) experimental infection models. In these experiments, we compared the virulence of the PAO1 wild type, pqsE mutant and pqsA pqsE double mutant transformed with either the pUCP18 or pUCPpqsE vectors. The data obtained from each infection model are shown in Fig. 3. In the C. elegans model (Fig. 3A), PAO1 killed all of the nematodes after 6 days compared with ∼65% of worms fed with the PAO1 pqsA pqsE mutant. Expression of plasmid-borne pqsE in the pqsA pqsE mutant fully restored virulence. Similar results were also obtained for the pqsE mutant that was less virulent than the wild type unless complemented with pqsE (data not shown). Furthermore, C. elegans fed with the PAO1 pqsA pqsE pUCPpqsE strain exhibited symptoms of sickness, including impaired locomotion much faster (within 1 day) than was observed for C. elegans fed with the wild type (3 days). These worms also showed a significant reduction in fertility.


Transcriptomic analysis reveals a global alkyl-quinolone-independent regulatory role for PqsE in facilitating the environmental adaptation of Pseudomonas aeruginosa to plant and animal hosts.

Rampioni G, Pustelny C, Fletcher MP, Wright VJ, Bruce M, Rumbaugh KP, Heeb S, Cámara M, Williams P - Environ. Microbiol. (2010)

PqsE restores virulence in nematode, plant and animal infection models in the absence of AQs. A. Caenorhabditis elegans killing assay showing the percentage of nematode survival after 1–6 days of exposure to the P. aeruginosa PAO1 wild type, pqsA pqsEind mutant and pqsA pqsEind mutant transformed with the vector control, pUCP18 or pUCPpqsE respectively. The average of four independent experiments is reported with standard deviation. B. Virulence of the wild type, pqsA mutant and pqsA mutant complemented with pqsE in the lettuce leaf virulence assay. The number of bacterial cells (as colony forming units, cfu) present in 1 mg of lettuce midrib 5 days post injection is shown. Error bars were calculated from five independent experiments. A representative picture of infected midribs is also shown for each strain. C and D. Mouse acute burn wound infection showing the survival rate over time (days after burn/infection) for mice infected with (C) the P. aeruginosa wild type (▵), pqsA (□) and pqsE (○) mutants; 15 mice per mutant and (D) the P. aeruginosa pqsA mutant (□) and the pqsA mutant transformed with either pUCP18 (○) or pUCPpqsE (▵); nine mice per mutant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2901523&req=5

fig03: PqsE restores virulence in nematode, plant and animal infection models in the absence of AQs. A. Caenorhabditis elegans killing assay showing the percentage of nematode survival after 1–6 days of exposure to the P. aeruginosa PAO1 wild type, pqsA pqsEind mutant and pqsA pqsEind mutant transformed with the vector control, pUCP18 or pUCPpqsE respectively. The average of four independent experiments is reported with standard deviation. B. Virulence of the wild type, pqsA mutant and pqsA mutant complemented with pqsE in the lettuce leaf virulence assay. The number of bacterial cells (as colony forming units, cfu) present in 1 mg of lettuce midrib 5 days post injection is shown. Error bars were calculated from five independent experiments. A representative picture of infected midribs is also shown for each strain. C and D. Mouse acute burn wound infection showing the survival rate over time (days after burn/infection) for mice infected with (C) the P. aeruginosa wild type (▵), pqsA (□) and pqsE (○) mutants; 15 mice per mutant and (D) the P. aeruginosa pqsA mutant (□) and the pqsA mutant transformed with either pUCP18 (○) or pUCPpqsE (▵); nine mice per mutant.
Mentions: Given that PqsE restores pyocyanin and lectin production in the absence of AQs, we investigated the impact of pqsE mutation on P. aeruginosa pathogenicity using three well-established plant (lettuce leaf) and animal (Caenorhabditis elegans and mouse) experimental infection models. In these experiments, we compared the virulence of the PAO1 wild type, pqsE mutant and pqsA pqsE double mutant transformed with either the pUCP18 or pUCPpqsE vectors. The data obtained from each infection model are shown in Fig. 3. In the C. elegans model (Fig. 3A), PAO1 killed all of the nematodes after 6 days compared with ∼65% of worms fed with the PAO1 pqsA pqsE mutant. Expression of plasmid-borne pqsE in the pqsA pqsE mutant fully restored virulence. Similar results were also obtained for the pqsE mutant that was less virulent than the wild type unless complemented with pqsE (data not shown). Furthermore, C. elegans fed with the PAO1 pqsA pqsE pUCPpqsE strain exhibited symptoms of sickness, including impaired locomotion much faster (within 1 day) than was observed for C. elegans fed with the wild type (3 days). These worms also showed a significant reduction in fertility.

Bottom Line: To gain insights into the relationship between the AQ stimulon, the PqsE stimulon and the regulatory function of PqsE, we constructed a pqsE inducible mutant (pqsEind) and compared the transcriptomes of the induced and uninduced states with a pqsA mutant.Furthermore, pqsE was required for swarming motility and virulence in plant and animal infection models in the absence of AQs, while mature biofilm development required both pqsA and pqsE.Taken together these data reveal that PqsE is a key regulator within the QS circuitry facilitating the environmental adaptation of P. aeruginosa.

View Article: PubMed Central - PubMed

Affiliation: School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University Park, University of Nottingham, Nottingham NG7 2RD, UK.

ABSTRACT
The quorum sensing (QS) system of Pseudomonas aeruginosa constitutes a sophisticated genome-wide gene regulatory network employing both N-acylhomoserine lactone and 2-alkyl-4-quinolone (AQ) signal molecules. AQ signalling utilizes 2-heptyl-3-hydroxy-4-quinolone (PQS) and its immediate precursor, 2-heptyl-4-quinolone (HHQ). AQ biosynthesis requires the first four genes of the pqsABCDE operon and while the biochemical function of pqsE is not known, it is required for the production of secondary metabolites such as pyocyanin. To gain insights into the relationship between the AQ stimulon, the PqsE stimulon and the regulatory function of PqsE, we constructed a pqsE inducible mutant (pqsEind) and compared the transcriptomes of the induced and uninduced states with a pqsA mutant. Of 158 genes exhibiting altered expression in the pqsA mutant, 51% were also affected in the pqsE mutant. Following induction of pqsE, 237 genes were differentially expressed compared with the wild-type strain. In the pqsEind strain, pqsA was highly expressed but following induction both pqsA expression and AQ biosynthesis were repressed, revealing a negative autoregulatory role for PqsE. Furthermore, pqsE was required for swarming motility and virulence in plant and animal infection models in the absence of AQs, while mature biofilm development required both pqsA and pqsE. Taken together these data reveal that PqsE is a key regulator within the QS circuitry facilitating the environmental adaptation of P. aeruginosa.

Show MeSH
Related in: MedlinePlus