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C-type natriuretic peptide modulates quorum sensing molecule and toxin production in Pseudomonas aeruginosa.

Blier AS, Veron W, Bazire A, Gerault E, Taupin L, Vieillard J, Rehel K, Dufour A, Le Derf F, Orange N, Hulen C, Feuilloley MG, Lesouhaitier O - Microbiology (Reading, Engl.) (2011)

Bottom Line: The quantity of 2-nonyl-4-quinolone (HNQ), another quinolone which is synthesized from HHQ, was also reduced after CNP treatment.These results correlate with an induction of lasI transcription 1 h after bacterial exposure to BNP or CNP.Finally, we observed that in PAO1, Vfr protein is essential to the pro-virulent effect of CNP whereas the regulator PtxR supports only a part of the CNP pro-virulent activity.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cold Microbiology - Signals and Micro-environment EA 4312, University of Rouen, 55 Rue Saint Germain, 27000 Evreux, France.

ABSTRACT
Pseudomonas aeruginosa coordinates its virulence expression and establishment in the host in response to modification of its environment. During the infectious process, bacteria are exposed to and can detect eukaryotic products including hormones. It has been shown that P. aeruginosa is sensitive to natriuretic peptides, a family of eukaryotic hormones, through a cyclic nucleotide-dependent sensor system that modulates its cytotoxicity. We observed that pre-treatment of P. aeruginosa PAO1 with C-type natriuretic peptide (CNP) increases the capacity of the bacteria to kill Caenorhabditis elegans through diffusive toxin production. In contrast, brain natriuretic peptide (BNP) did not affect the capacity of the bacteria to kill C. elegans. The bacterial production of hydrogen cyanide (HCN) was enhanced by both BNP and CNP whereas the production of phenazine pyocyanin was strongly inhibited by CNP. The amount of 2-heptyl-4-quinolone (HHQ), a precursor to 2-heptyl-3-hydroxyl-4-quinolone (Pseudomonas quinolone signal; PQS), decreased after CNP treatment. The quantity of 2-nonyl-4-quinolone (HNQ), another quinolone which is synthesized from HHQ, was also reduced after CNP treatment. Conversely, both BNP and CNP significantly enhanced bacterial production of acylhomoserine lactone (AHL) [e.g. 3-oxo-dodecanoyl-homoserine lactone (3OC12-HSL) and butanoylhomoserine lactone (C4-HSL)]. These results correlate with an induction of lasI transcription 1 h after bacterial exposure to BNP or CNP. Concurrently, pre-treatment of P. aeruginosa PAO1 with either BNP or CNP enhanced PAO1 exotoxin A production, via a higher toxA mRNA level. At the same time, CNP led to elevated amounts of algC mRNA, indicating that algC is involved in C. elegans killing. Finally, we observed that in PAO1, Vfr protein is essential to the pro-virulent effect of CNP whereas the regulator PtxR supports only a part of the CNP pro-virulent activity. Taken together, these data reinforce the hypothesis that during infection natriuretic peptides, particularly CNP, could enhance the virulence of PAO1. This activity is relayed by Vfr and PtxR activation, and a general diagram of the virulence activation cascade involving AHL, HCN and exotoxin A is proposed.

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Role of Vfr in the effect of natriuretic peptides on PAO1. (a) Slow killing. Kaplan–Meier survival plots of worms fed with P. aeruginosa MPAO1 control (n = 401) (▪), vfr mutant control (n = 73) (•), BNP-treated vfr mutant (n = 78) (⧫), CNP-treated vfr mutant (n = 40) (▿) or E. coli OP50 (n = 212) (□). Each value is the mean of at least three samples. Pairwise comparisons (log–rank test) of wild-type versus vfr mutant control, P<0.0001. (b) Fast-killing. Worm survival after 48 h or 6 days, (D6) exposure to P. aeruginosa MPAO1 control (n = 291; 1), vfr mutant control (n = 94; 2), BNP-treated vfr mutant (n = 106; 3) or CNP-treated vfr mutant (n = 112; 4). Each value reported is the mean±sem of six samples from two independent experiments. (c) ETA in supernatants from P. aeruginosa MPAO1, vfr mutant control, BNP-treated vfr mutant or CNP-treated vfr mutant. Bars are numbered as in (b). Data are the means±sem of four independent experiments. The mean ETA level in the control was 63.6±9.7 µg µl−1 OD580−1.
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f7: Role of Vfr in the effect of natriuretic peptides on PAO1. (a) Slow killing. Kaplan–Meier survival plots of worms fed with P. aeruginosa MPAO1 control (n = 401) (▪), vfr mutant control (n = 73) (•), BNP-treated vfr mutant (n = 78) (⧫), CNP-treated vfr mutant (n = 40) (▿) or E. coli OP50 (n = 212) (□). Each value is the mean of at least three samples. Pairwise comparisons (log–rank test) of wild-type versus vfr mutant control, P<0.0001. (b) Fast-killing. Worm survival after 48 h or 6 days, (D6) exposure to P. aeruginosa MPAO1 control (n = 291; 1), vfr mutant control (n = 94; 2), BNP-treated vfr mutant (n = 106; 3) or CNP-treated vfr mutant (n = 112; 4). Each value reported is the mean±sem of six samples from two independent experiments. (c) ETA in supernatants from P. aeruginosa MPAO1, vfr mutant control, BNP-treated vfr mutant or CNP-treated vfr mutant. Bars are numbered as in (b). Data are the means±sem of four independent experiments. The mean ETA level in the control was 63.6±9.7 µg µl−1 OD580−1.

Mentions: We observed that the vfr mutant dramatically lost its ability to kill C. elegans in both slow-killing (Fig. 7a) and fast-killing (Fig. 7b) tests. When the vfr mutant was exposed to BNP or CNP, we observed no modification in the virulence activity of this strain (Figs 7a and 8a). In addition, we noted that the vfr mutant produced a small amount of ETA, the levels of which remained unchanged even after exposure to BNP or CNP (Fig. 7c).


C-type natriuretic peptide modulates quorum sensing molecule and toxin production in Pseudomonas aeruginosa.

Blier AS, Veron W, Bazire A, Gerault E, Taupin L, Vieillard J, Rehel K, Dufour A, Le Derf F, Orange N, Hulen C, Feuilloley MG, Lesouhaitier O - Microbiology (Reading, Engl.) (2011)

Role of Vfr in the effect of natriuretic peptides on PAO1. (a) Slow killing. Kaplan–Meier survival plots of worms fed with P. aeruginosa MPAO1 control (n = 401) (▪), vfr mutant control (n = 73) (•), BNP-treated vfr mutant (n = 78) (⧫), CNP-treated vfr mutant (n = 40) (▿) or E. coli OP50 (n = 212) (□). Each value is the mean of at least three samples. Pairwise comparisons (log–rank test) of wild-type versus vfr mutant control, P<0.0001. (b) Fast-killing. Worm survival after 48 h or 6 days, (D6) exposure to P. aeruginosa MPAO1 control (n = 291; 1), vfr mutant control (n = 94; 2), BNP-treated vfr mutant (n = 106; 3) or CNP-treated vfr mutant (n = 112; 4). Each value reported is the mean±sem of six samples from two independent experiments. (c) ETA in supernatants from P. aeruginosa MPAO1, vfr mutant control, BNP-treated vfr mutant or CNP-treated vfr mutant. Bars are numbered as in (b). Data are the means±sem of four independent experiments. The mean ETA level in the control was 63.6±9.7 µg µl−1 OD580−1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3755537&req=5

f7: Role of Vfr in the effect of natriuretic peptides on PAO1. (a) Slow killing. Kaplan–Meier survival plots of worms fed with P. aeruginosa MPAO1 control (n = 401) (▪), vfr mutant control (n = 73) (•), BNP-treated vfr mutant (n = 78) (⧫), CNP-treated vfr mutant (n = 40) (▿) or E. coli OP50 (n = 212) (□). Each value is the mean of at least three samples. Pairwise comparisons (log–rank test) of wild-type versus vfr mutant control, P<0.0001. (b) Fast-killing. Worm survival after 48 h or 6 days, (D6) exposure to P. aeruginosa MPAO1 control (n = 291; 1), vfr mutant control (n = 94; 2), BNP-treated vfr mutant (n = 106; 3) or CNP-treated vfr mutant (n = 112; 4). Each value reported is the mean±sem of six samples from two independent experiments. (c) ETA in supernatants from P. aeruginosa MPAO1, vfr mutant control, BNP-treated vfr mutant or CNP-treated vfr mutant. Bars are numbered as in (b). Data are the means±sem of four independent experiments. The mean ETA level in the control was 63.6±9.7 µg µl−1 OD580−1.
Mentions: We observed that the vfr mutant dramatically lost its ability to kill C. elegans in both slow-killing (Fig. 7a) and fast-killing (Fig. 7b) tests. When the vfr mutant was exposed to BNP or CNP, we observed no modification in the virulence activity of this strain (Figs 7a and 8a). In addition, we noted that the vfr mutant produced a small amount of ETA, the levels of which remained unchanged even after exposure to BNP or CNP (Fig. 7c).

Bottom Line: The quantity of 2-nonyl-4-quinolone (HNQ), another quinolone which is synthesized from HHQ, was also reduced after CNP treatment.These results correlate with an induction of lasI transcription 1 h after bacterial exposure to BNP or CNP.Finally, we observed that in PAO1, Vfr protein is essential to the pro-virulent effect of CNP whereas the regulator PtxR supports only a part of the CNP pro-virulent activity.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cold Microbiology - Signals and Micro-environment EA 4312, University of Rouen, 55 Rue Saint Germain, 27000 Evreux, France.

ABSTRACT
Pseudomonas aeruginosa coordinates its virulence expression and establishment in the host in response to modification of its environment. During the infectious process, bacteria are exposed to and can detect eukaryotic products including hormones. It has been shown that P. aeruginosa is sensitive to natriuretic peptides, a family of eukaryotic hormones, through a cyclic nucleotide-dependent sensor system that modulates its cytotoxicity. We observed that pre-treatment of P. aeruginosa PAO1 with C-type natriuretic peptide (CNP) increases the capacity of the bacteria to kill Caenorhabditis elegans through diffusive toxin production. In contrast, brain natriuretic peptide (BNP) did not affect the capacity of the bacteria to kill C. elegans. The bacterial production of hydrogen cyanide (HCN) was enhanced by both BNP and CNP whereas the production of phenazine pyocyanin was strongly inhibited by CNP. The amount of 2-heptyl-4-quinolone (HHQ), a precursor to 2-heptyl-3-hydroxyl-4-quinolone (Pseudomonas quinolone signal; PQS), decreased after CNP treatment. The quantity of 2-nonyl-4-quinolone (HNQ), another quinolone which is synthesized from HHQ, was also reduced after CNP treatment. Conversely, both BNP and CNP significantly enhanced bacterial production of acylhomoserine lactone (AHL) [e.g. 3-oxo-dodecanoyl-homoserine lactone (3OC12-HSL) and butanoylhomoserine lactone (C4-HSL)]. These results correlate with an induction of lasI transcription 1 h after bacterial exposure to BNP or CNP. Concurrently, pre-treatment of P. aeruginosa PAO1 with either BNP or CNP enhanced PAO1 exotoxin A production, via a higher toxA mRNA level. At the same time, CNP led to elevated amounts of algC mRNA, indicating that algC is involved in C. elegans killing. Finally, we observed that in PAO1, Vfr protein is essential to the pro-virulent effect of CNP whereas the regulator PtxR supports only a part of the CNP pro-virulent activity. Taken together, these data reinforce the hypothesis that during infection natriuretic peptides, particularly CNP, could enhance the virulence of PAO1. This activity is relayed by Vfr and PtxR activation, and a general diagram of the virulence activation cascade involving AHL, HCN and exotoxin A is proposed.

Show MeSH
Related in: MedlinePlus