RpoS-dependent stress tolerance in Pseudomonas aeruginosa

Jørgensen, Frieda; Bally, Marc; Chapon, Virginie; Michel, Gérard; Lazdunski, Andrée; Williams, Paul; Stewart, Gordon S. A. B.

doi:10.1099/13500872-145-4-835

Cited by 127 publications

(128 citation statements)

References 48 publications

(32 reference statements)

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“…The global stress regulator RpoS (Joergensen et al 1999;Suh et al 1999) was apparently not involved in this response because a rpoS mutant did not differ from the parental strain in our SDS shock experiments (not shown).…”

Section: Discussionmentioning

confidence: 99%

Cell aggregation of Pseudomonas aeruginosa strain PAO1 as an energy-dependent stress response during growth with sodium dodecyl sulfate

et al. 2006

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Pseudomonas aeruginosa strain PAO1 grew with the detergent sodium dodecyl sulfate (SDS). The growth started with the formation of macroscopic cell aggregates which consisted of respiring cells embedded in an extracellular matrix composed of acidic polysaccharides and DNA. Damaged and uncultivable cells accumulated in these aggregates compared to those cells that remained suspended. We investigated the response of suspended cells to SDS under different conditions. At high energy supply, the cells responded with a decrease in optical density and in viable counts, release of protein and DNA, and formation of macroscopic aggregates. This response was not observed if the energy supply was reduced by inhibiting respiration with KCN, or if cells not induced for SDS degradation were exposed to SDS. Exposure to SDS caused cell lysis without aggregation if cells were completely deprived of energy, either by applying anoxic conditions, by addition of CCCP, or by addition of KCN to a mutant defective in cyanideinsensitive respiration. Aggregated cells showed a more than 100-fold higher survival rate after exposure to SDS plus CCCP than suspended cells. Our results demonstrate that cell aggregation is an energy-dependent response of P. aeruginosa to detergent stress which might serve as a survival strategy during growth with SDS.

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Section: Discussionmentioning

confidence: 99%

Cell aggregation of Pseudomonas aeruginosa strain PAO1 as an energy-dependent stress response during growth with sodium dodecyl sulfate

et al. 2006

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“…In certain stress conditions, pip expression would be repressed, thereby inhibiting N-AHL and PCN synthesis in order to focus energy on growth and resistance instead. Indeed, the regulatory cascade for PCN would then be interrupted just downstream of rpoS, leaving the RpoS remaining in the same quantity and able to direct stress resistance, one of its primary roles (Jorgensen et al, 1999;Ramos-Gonzalez & Molin, 1998;Sarniguet et al, 1995;Suh et al, 1999).…”

Section: Relationships Between the Amount Of Rpos/pip And Stressmentioning

confidence: 99%

Role of the phenazine-inducing protein Pip in stress resistance of Pseudomonas chlororaphis

Girard

Rigali

2011

Microbiology

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The triggering of antibiotic production by various environmental stress molecules can be interpreted as bacteria's response to obtain increased fitness to putative danger, whereas the opposite situation – inhibition of antibiotic production – is more complicated to understand. Phenazines enable Pseudomonas species to eliminate competitors for rhizosphere colonization and are typical virulence factors used for model studies. In the present work, we have investigated the negative effect of subinhibitory concentrations of NaCl, fusaric acid and two antibiotics on quorum-sensing-controlled phenazine production by Pseudomonas chlororaphis. The selected stress factors inhibit phenazine synthesis despite sufficient cell density. Subsequently, we have identified connections between known genes of the phenazine-inducing cascade, including PsrA (Pseudomonas sigma regulator), RpoS (alternative sigma factor), Pip (phenazine inducing protein) and PhzI/PhzR (quorum-sensing system). Under all tested conditions, overexpression of Pip or PhzR restored phenazine production while overexpression of PsrA or RpoS did not. This forced restoration of phenazine production in strains overexpressing regulatory genes pip and phzR significantly impairs growth and stress resistance; this is particularly severe with pip overexpression. We suggest a novel physiological explanation for the inhibition of phenazine virulence factors in pseudomonas species responding to toxic compounds. We propose that switching off phenazine-1-carboxamide (PCN) synthesis by attenuating pip expression would favour processes required for survival. In our model, this ‘decision’ point for promoting PCN production or stress resistance is located downstream of rpoS and just above pip. However, a test with the stress factor rifampicin shows no significant inhibition of Pip production, suggesting that stress factors may also target other and so far unknown protagonists of the PCN signalling cascade.

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“…The rpoS gene in P. aeruginosa is involved in the general stress response, the accumulation of certain virulence factors, and twitching motility (Jørgensen et al, 1999 ;Suh et al, 1999). As in E. coli, the stationary-phase sigma factor, RpoS, in P. aeruginosa accumulates as cultures enter the stationary phase (Fujita et al, 1994).…”

Section: Biofilm Formation Of P Aeruginosa Pao1 and Mw20mentioning

confidence: 99%

Experimental reproducibility in flow-chamber biofilms

et al. 2000

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The structural organization of microbial communities is influenced by many factors, e.g. nutrient composition, shear stress and temperature. This paper presents a general method for quantitative comparison of biofilm structures and assessment of experimental reproducibility between independent biofilm experiments. By using a novel computer program, COMSTAT, biofilm structures of Pseudomonas aeruginosa and an isogenic rpoS mutant were quantified. The strains were tagged with the green fluorescent protein (GFP) and grown in flow chambers with a defined minimal medium as substrate. Three independent rounds of biofilm experiments were performed and in each round, each of the two variants was grown in two separate channels. Nine image stacks were acquired in each channel 146 h after inoculation. An analysis of variance model incorporating the factors experiment round, bacterial strain, channel number and image stack number was used to analyse the data calculated by COMSTAT. Experimental reproducibility was verified by estimating the magnitude of the variance of the effects round (σ 2 R ) and the interaction between bacterial strain and round (σ 2 BR ). Mean thickness of the wild-type and rpoS mutant biofilms was estimated at 631 µm (SE 081 µm) and 1685 µm (SE 087 µm), respectively.

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RpoS-dependent stress tolerance in Pseudomonas aeruginosa

Cited by 127 publications

References 48 publications

Cell aggregation of Pseudomonas aeruginosa strain PAO1 as an energy-dependent stress response during growth with sodium dodecyl sulfate

Cell aggregation of Pseudomonas aeruginosa strain PAO1 as an energy-dependent stress response during growth with sodium dodecyl sulfate

Role of the phenazine-inducing protein Pip in stress resistance of Pseudomonas chlororaphis

Experimental reproducibility in flow-chamber biofilms

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