scholarly journals BdlA, a Chemotaxis Regulator Essential for Biofilm Dispersion in Pseudomonas aeruginosa

2006 ◽  
Vol 188 (21) ◽  
pp. 7335-7343 ◽  
Author(s):  
Ryan Morgan ◽  
Steven Kohn ◽  
Sung-Hei Hwang ◽  
Daniel J. Hassett ◽  
Karin Sauer
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Gene Product ◽  
Signaling Cascade ◽  
Environmental Cues ◽  
Environmental Sensing ◽  
Environmental Signals ◽  
Isogenic Mutant ◽  
Biofilm Detachment ◽  
Biofilm Dispersion ◽  
Do So

ABSTRACT Multiple environmental cues have been shown to trigger biofilm detachment, the transition from surface-attached, highly organized communities known as biofilms to the motile lifestyle. The goal of this study was to identify a gene product involved in sensing environmental cues that trigger biofilm dispersion in Pseudomonas aeruginosa. To do so, we focused on novel putative chemotaxis transducer proteins that could potentially be involved in environmental sensing. We identified a locus encoding such a protein that played a role in detachment, as indicated by the observation that an isogenic mutant biofilm could not disperse in response to a variety of environmental cues. The locus was termed bdlA for biofilm dispersion locus. The BdlA protein harbors an MCP (methyl-accepting chemotaxis protein) domain and two PAS (Per-Arnt-Sint) domains that have been shown to be essential for responding to environmental signals in other proteins. The dispersion-deficient phenotype of the bdlA mutant was confirmed by treatment with the biocide H2O2 and by microscopic observations. The dispersion response was independent of motility. bdlA mutant biofilms were found to have increased adherent properties and increased intracellular levels of cyclic di-GMP (c-di-GMP). Our findings suggest that BdlA may be a link between sensing environmental cues, c-di-GMP levels, and detachment. Based on our findings, a possible involvement of BdlA in a signaling cascade resulting in biofilm dispersion is discussed.

scholarly journals The MarR-Type Regulator PA3458 Is Involved in Osmoadaptation Control in Pseudomonas aeruginosa

2021 ◽  
Vol 22 (8) ◽  
pp. 3982
Author(s):  
Karolina Kotecka ◽  
Adam Kawalek ◽  
Kamil Kobylecki ◽  
Aneta Agnieszka Bartosik
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Binding Sites ◽  
Transcriptional Profiling ◽  
Mrna Level ◽  
Transcriptional Regulators ◽  
Resistance Mechanisms ◽  
Chronic Infections ◽  
Environmental Signals ◽  
Regulatory Systems

Pseudomonas aeruginosa is a facultative human pathogen, causing acute and chronic infections that are especially dangerous for immunocompromised patients. The eradication of P. aeruginosa is difficult due to its intrinsic antibiotic resistance mechanisms, high adaptability, and genetic plasticity. The bacterium possesses multilevel regulatory systems engaging a huge repertoire of transcriptional regulators (TRs). Among these, the MarR family encompasses a number of proteins, mainly acting as repressors, which are involved in response to various environmental signals. In this work, we aimed to decipher the role of PA3458, a putative MarR-type TR from P. aeruginosa. Transcriptional profiling of P. aeruginosa PAO1161 overexpressing PA3458 showed changes in the mRNA level of 133 genes; among them, 100 were down-regulated, suggesting the repressor function of PA3458. Concomitantly, ChIP-seq analysis identified more than 300 PA3458 binding sites in P. aeruginosa. The PA3458 regulon encompasses genes involved in stress response, including the PA3459–PA3461 operon, which is divergent to PA3458. This operon encodes an asparagine synthase, a GNAT-family acetyltransferase, and a glutamyl aminopeptidase engaged in the production of N-acetylglutaminylglutamine amide (NAGGN), which is a potent bacterial osmoprotectant. We showed that PA3458-mediated control of PA3459–PA3461 expression is required for the adaptation of P. aeruginosa growth in high osmolarity. Overall, our data indicate that PA3458 plays a role in osmoadaptation control in P. aeruginosa.

scholarly journals The inflammatory response induced by Pseudomonas aeruginosa in macrophages enhances apoptotic cell removal

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adriana Valeria Jäger ◽  
Paula Arias ◽  
Maria Virginia Tribulatti ◽  
Marcela Adriana Brocco ◽  
Maria Victoria Pepe ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Pseudomonas Aeruginosa ◽  
Inflammatory Response ◽  
Apoptotic Cell ◽  
Bacterial Pathogen ◽  
Environmental Cues ◽  
Apoptotic Cells ◽  
Phagocytic Function ◽  
Inflammatory Stimulus ◽  
Inflammatory Conditions

AbstractPathogens phagocytosis and the uptake of apoptotic cells (efferocytosis) are essential macrophages tasks, classically considered as mutually exclusive. Macrophages have been observed to polarize into either pro-inflammatory/microbicidal or anti-inflammatory/efferocytic phenotypes. However, macrophage functions have shown to be more complex. Furthermore, little is known about the regulation of efferocytosis under inflammatory conditions. In this study, we elucidate the modulation of the macrophage efferocytic function during an inflammatory stimulus. We find that bone marrow-derived macrophages (BMDM) are very efficient in engulfing both the bacterial pathogen Pseudomonas aeruginosa and apoptotic cells. BMDM showed a high bactericidal capacity unaffected by the concomitant presence of apoptotic material. Plasticity in macrophage programming, in response to changing environmental cues, may modulate efferocytic capability. In this work, we further show that, after phagocyting and processing Pseudomonas aeruginosa, macrophages highly increase their efferocytic capacity without affecting their phagocytic function. Moreover, we demonstrate that Pseudomonas aeruginosa enhances efferocytosis of these phagocytes through the IL-6 signaling pathway. Our results show that the inflammatory response generated by the bacterial processing enhances these macrophages’ capacity to control inflammation through an increased efferocytosis.

scholarly journals Combinatorial Control of Gene Expression

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Soumya Bhattacharjee ◽  
Kaushik Renganaath ◽  
Rajesh Mehrotra ◽  
Sandhya Mehrotra
Keyword(s):  
Gene Expression ◽  
Short Description ◽  
Controlling Factors ◽  
Environmental Cues ◽  
Control Of Gene Expression ◽  
Environmental Signals ◽  
Combinatorial Control ◽  
Sense And Respond ◽  
Eukaryotic Organisms

The complexity and diversity of eukaryotic organisms are a feat of nature’s engineering. Pulling the strings of such an intricate machinery requires an even more masterful and crafty approach. Only the number and type of responses that they generate exceed the staggering proportions of environmental signals perceived and processed by eukaryotes. Hence, at first glance, the cell’s sparse stockpile of controlling factors does not seem remotely adequate to carry out this response. The question as to how eukaryotes sense and respond to environmental cues has no single answer. It is an amalgamation, an interplay between several processes, pathways, and factors—a combinatorial control. A short description of some of the most important elements that operate this entire conglomerate is given in this paper.

scholarly journals Bicarbonate Evokes Reciprocal Changes in Intracellular Cyclic di-GMP and Cyclic AMP Levels in Pseudomonas aeruginosa

Biology ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 519
Author(s):  
Kasidid Ruksakiet ◽  
Balázs Stercz ◽  
Gergő Tóth ◽  
Pongsiri Jaikumpun ◽  
Ilona Gróf ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cyclic Amp ◽  
Biofilm Formation ◽  
Second Messengers ◽  
Brain Heart Infusion ◽  
Ambient Air ◽  
Dependent Manner ◽  
Environmental Signals ◽  
Common Causes ◽  
Camp Levels

The formation of Pseudomonas aeruginosa biofilms in cystic fibrosis (CF) is one of the most common causes of morbidity and mortality in CF patients. Cyclic di-GMP and cyclic AMP are second messengers regulating the bacterial lifestyle transition in response to environmental signals. We aimed to investigate the effects of extracellular pH and bicarbonate on intracellular c-di-GMP and cAMP levels, and on biofilm formation. P. aeruginosa was inoculated in a brain–heart infusion medium supplemented with 25 and 50 mM NaCl in ambient air (pH adjusted to 7.4 and 7.7 respectively), or with 25 and 50 mM NaHCO3 in 5% CO2 (pH 7.4 and 7.7). After 16 h incubation, c-di-GMP and cAMP were extracted and their concentrations determined. Biofilm formation was investigated using an xCelligence real-time cell analyzer and by crystal violet assay. Our results show that HCO3− exposure decreased c-di-GMP and increased cAMP levels in a dose-dependent manner. Biofilm formation was also reduced after 48 h exposure to HCO3−. The reciprocal changes in second messenger concentrations were not influenced by changes in medium pH or osmolality. These findings indicate that HCO3− per se modulates the levels of c-di-GMP and cAMP, thereby inhibiting biofilm formation and promoting the planktonic lifestyle of the bacteria.

Differential surface competition and biofilm invasion strategies of Pseudomonas aeruginosa PA14 and PAO1

2021 ◽  
Author(s):  
Swetha Kassety ◽  
Stefan Katharios-Lanwermeyer ◽  
George A. O’Toole ◽  
Carey D. Nadell
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Matrix Composition ◽  
Model Organisms ◽  
Culture Methods ◽  
Biofilm Growth ◽  
Biofilm Production ◽  
Direct Competition ◽  
Planktonic Phase ◽  
Do So

Pseudomonas aeruginosa strains PA14 and PAO1 are among the two best characterized model organisms used to study the mechanisms of biofilm formation, while also representing two distinct lineages of P. aeruginosa . Previous work has shown that PA14 and PAO1 use different strategies for surface colonization; they also have different extracellular matrix composition and different propensities to disperse from biofilms back into the planktonic phase surrounding them. We expand on this work here by exploring the consequences of these different biofilm production strategies during direct competition. Using differentially labeled strains and microfluidic culture methods, we show that PAO1 can outcompete PA14 in direct competition during early colonization and subsequent biofilm growth, that they can do so in constant and perturbed environments, and that this advantage is specific to biofilm growth and requires production of the Psl polysaccharide. In contrast, the P. aeruginosa PA14 is better able to invade pre-formed biofilms and is more inclined to remain surface-associated under starvation conditions. These data together suggest that while P. aeruginosa PAO1 and PA14 are both able to effectively colonize surfaces, they do so in different ways that are advantageous under different environmental settings. Importance Recent studies indicate that P. aeruginosa PAO1 and PA14 use distinct strategies to initiate biofilm formation. We investigated whether their respective colonization and matrix secretion strategies impact their ability to compete under different biofilm-forming regimes. Our work shows that these different strategies do indeed impact how these strains fair in direct competition: PAO1 dominates during colonization of a naïve surface, while PA14 is more effective in colonizing a pre-formed biofilm. These data suggest that even for very similar microbes there can be distinct strategies to successfully colonize and persist on surfaces during the biofilm life cycle.

Biofilm dispersion in Pseudomonas aeruginosa

2016 ◽  
Vol 54 (2) ◽  
pp. 71-85 ◽  
Author(s):  
Soo-Kyoung Kim ◽  
Joon-Hee Lee
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Dispersion
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