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The pseudomonas quinolone signal (PQS) balances life and death in Pseudomonas aeruginosa populations.

Häussler S, Becker T - PLoS Pathog. (2008)

Bottom Line: We propose that this dual function fragments populations into less and more stress tolerant members which respond differentially to developing stresses in deteriorating habitats.This suggests that a little poison may be generically beneficial to populations, in promoting survival of the fittest, and in contributing to bacterial multi-cellular behavior.It further identifies PQS as an essential mediator of the shaping of the population structure of Pseudomonas and of its response to and survival in hostile environmental conditions.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Helmholtz Center for Infection Research, Braunschweig, Germany. susanne.haeussler@helmholtz-hzi.de

ABSTRACT
When environmental conditions deteriorate and become inhospitable, generic survival strategies for populations of bacteria may be to enter a dormant state that slows down metabolism, to develop a general tolerance to hostile parameters that characterize the habitat, and to impose a regime to eliminate damaged members. Here, we provide evidence that the pseudomonas quinolone signal (PQS) mediates induction of all of these phenotypes. For individual cells, PQS, an interbacterial signaling molecule of Pseudomonas aeruginosa, has both deleterious and beneficial activities: on the one hand, it acts as a pro-oxidant and sensitizes the bacteria towards oxidative and other stresses and, on the other, it efficiently induces a protective anti-oxidative stress response. We propose that this dual function fragments populations into less and more stress tolerant members which respond differentially to developing stresses in deteriorating habitats. This suggests that a little poison may be generically beneficial to populations, in promoting survival of the fittest, and in contributing to bacterial multi-cellular behavior. It further identifies PQS as an essential mediator of the shaping of the population structure of Pseudomonas and of its response to and survival in hostile environmental conditions.

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Proposed mechanism of the primary anti-oxidant effect and the secondary pro-oxidant effect of PQS.
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ppat-1000166-g007: Proposed mechanism of the primary anti-oxidant effect and the secondary pro-oxidant effect of PQS.

Mentions: To determine whether PQS is a primary anti-oxidant, we measured the absorbance changes of the stable 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical in the presence of PQS. HHQ and ascorbate served as controls. As depicted in Figure 6, PQS is an anti-oxidant that exhibited an anti-oxidant activity comparable to that of ascorbate, whereas the HHQ molecule did not show any antioxidant activity. This observation is explicable by the much stronger electron-donating potential of PQS as compared to HHQ. From a structural perspective, this is due to the bisoxygenated aromatic system of PQS, which may readily be oxidized to the corresponding ortho-quinoid system. On the contrary, this process is much less pronounced for HHQ, which lacks the 3-OH group and may therefore not form directly a quinoid system (Figure 7).


The pseudomonas quinolone signal (PQS) balances life and death in Pseudomonas aeruginosa populations.

Häussler S, Becker T - PLoS Pathog. (2008)

Proposed mechanism of the primary anti-oxidant effect and the secondary pro-oxidant effect of PQS.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2533401&req=5

ppat-1000166-g007: Proposed mechanism of the primary anti-oxidant effect and the secondary pro-oxidant effect of PQS.
Mentions: To determine whether PQS is a primary anti-oxidant, we measured the absorbance changes of the stable 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical in the presence of PQS. HHQ and ascorbate served as controls. As depicted in Figure 6, PQS is an anti-oxidant that exhibited an anti-oxidant activity comparable to that of ascorbate, whereas the HHQ molecule did not show any antioxidant activity. This observation is explicable by the much stronger electron-donating potential of PQS as compared to HHQ. From a structural perspective, this is due to the bisoxygenated aromatic system of PQS, which may readily be oxidized to the corresponding ortho-quinoid system. On the contrary, this process is much less pronounced for HHQ, which lacks the 3-OH group and may therefore not form directly a quinoid system (Figure 7).

Bottom Line: We propose that this dual function fragments populations into less and more stress tolerant members which respond differentially to developing stresses in deteriorating habitats.This suggests that a little poison may be generically beneficial to populations, in promoting survival of the fittest, and in contributing to bacterial multi-cellular behavior.It further identifies PQS as an essential mediator of the shaping of the population structure of Pseudomonas and of its response to and survival in hostile environmental conditions.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Helmholtz Center for Infection Research, Braunschweig, Germany. susanne.haeussler@helmholtz-hzi.de

ABSTRACT
When environmental conditions deteriorate and become inhospitable, generic survival strategies for populations of bacteria may be to enter a dormant state that slows down metabolism, to develop a general tolerance to hostile parameters that characterize the habitat, and to impose a regime to eliminate damaged members. Here, we provide evidence that the pseudomonas quinolone signal (PQS) mediates induction of all of these phenotypes. For individual cells, PQS, an interbacterial signaling molecule of Pseudomonas aeruginosa, has both deleterious and beneficial activities: on the one hand, it acts as a pro-oxidant and sensitizes the bacteria towards oxidative and other stresses and, on the other, it efficiently induces a protective anti-oxidative stress response. We propose that this dual function fragments populations into less and more stress tolerant members which respond differentially to developing stresses in deteriorating habitats. This suggests that a little poison may be generically beneficial to populations, in promoting survival of the fittest, and in contributing to bacterial multi-cellular behavior. It further identifies PQS as an essential mediator of the shaping of the population structure of Pseudomonas and of its response to and survival in hostile environmental conditions.

Show MeSH