The Experts below are selected from a list of 4419 Experts worldwide ranked by ideXlab platform
George A Otoole - One of the best experts on this subject based on the ideXlab platform.
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pilz domain protein flgz mediates cyclic di gmp dependent Swarming Motility control in pseudomonas aeruginosa
Journal of Bacteriology, 2016Co-Authors: Amy Baker, Sherry L Kuchma, Andreas Diepold, Jessie E Scott, Giulia Orazi, Judith P Armitage, George A OtooleAbstract:ABSTRACT The second messenger cyclic diguanylate (c-di-GMP) is an important regulator of Motility in many bacterial species. In Pseudomonas aeruginosa, elevated levels of c-di-GMP promote biofilm formation and repress flagellum-driven Swarming Motility. The rotation of P. aeruginosa9s polar flagellum is controlled by two distinct stator complexes, MotAB, which cannot support Swarming Motility, and MotCD, which promotes Swarming Motility. Here we show that when c-di-GMP levels are elevated, Swarming Motility is repressed by the PilZ domain-containing protein FlgZ and by Pel polysaccharide production. We demonstrate that FlgZ interacts specifically with the Motility-promoting stator protein MotC in a c-di-GMP-dependent manner and that a functional green fluorescent protein (GFP)-FlgZ fusion protein shows significantly reduced polar localization in a strain lacking the MotCD stator. Our results establish FlgZ as a c-di-GMP receptor affecting Swarming Motility by P. aeruginosa and support a model wherein c-di-GMP-bound FlgZ impedes Motility via its interaction with the MotCD stator. IMPORTANCE The regulation of surface-associated Motility plays an important role in bacterial surface colonization and biofilm formation. c-di-GMP signaling is a widespread means of controlling bacterial Motility, and yet the mechanism whereby this signal controls surface-associated Motility in P. aeruginosa remains poorly understood. Here we identify a PilZ domain-containing c-di-GMP effector protein that contributes to c-di-GMP-mediated repression of Swarming Motility by P. aeruginosa. We provide evidence that this effector, FlgZ, impacts Swarming Motility via its interactions with flagellar stator protein MotC. Thus, we propose a new mechanism for c-di-GMP-mediated regulation of Motility for a bacterium with two flagellar stator sets, increasing our understanding of surface-associated behaviors, a key prerequisite to identifying ways to control the formation of biofilm communities.
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cyclic di gmp mediated repression of Swarming Motility by pseudomonas aeruginosa pa14 requires the motab stator
Journal of Bacteriology, 2015Co-Authors: Sherry L Kuchma, Judith P Armitage, Nicolas J Delalez, Laura M Filkins, E A Snavely, George A OtooleAbstract:The second messenger cyclic diguanylate (c-di-GMP) plays a critical role in the regulation of Motility. In Pseudomonas aeruginosa PA14, c-di-GMP inversely controls biofilm formation and surface Swarming Motility, with high levels of this dinucleotide signal stimulating biofilm formation and repressing Swarming. P. aeruginosa encodes two stator complexes, MotAB and MotCD, that participate in the function of its single polar flagellum. Here we show that the repression of Swarming Motility requires a functional MotAB stator complex. Mutating the motAB genes restores Swarming Motility to a strain with artificially elevated levels of c-di-GMP as well as stimulates Swarming in the wild-type strain, while overexpression of MotA from a plasmid represses Swarming Motility. Using point mutations in MotA and the FliG rotor protein of the motor supports the conclusion that MotA-FliG interactions are critical for c-di-GMP-mediated Swarming inhibition. Finally, we show that high c-di-GMP levels affect the localization of a green fluorescent protein (GFP)-MotD fusion, indicating a mechanism whereby this second messenger has an impact on MotCD function. We propose that when c-di-GMP level is high, the MotAB stator can displace MotCD from the motor, thereby affecting motor function. Our data suggest a newly identified means of c-di-GMP-mediated control of surface Motility, perhaps conserved among Pseudomonas, Xanthomonas, and other organisms that encode two stator systems.
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deletion mutant library for investigation of functional outputs of cyclic diguanylate metabolism in pseudomonas aeruginosa pa14
Applied and Environmental Microbiology, 2014Co-Authors: Megan E Richman, George A OtooleAbstract:We constructed a library of in-frame deletion mutants targeting each gene in Pseudomonas aeruginosa PA14 predicted to participate in cyclic di-GMP (c-di-GMP) metabolism (biosynthesis or degradation) to provide a toolkit to assist investigators studying c-di-GMP-mediated regulation by this microbe. We present phenotypic assessments of each mutant, including biofilm formation, exopolysaccharide (EPS) production, swimming Motility, Swarming Motility, and twitch Motility, as a means to initially characterize these mutants and to demonstrate the potential utility of this library.
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2 heptyl 4 quinolone a precursor of the pseudomonas quinolone signal molecule modulates Swarming Motility in pseudomonas aeruginosa
Journal of Bacteriology, 2011Co-Authors: Judith H Merritt, Thomas H Hampton, James T Hodgkinson, Matej Janecek, David R Spring, Martin Welch, George A OtooleAbstract:Pseudomonas aeruginosa is an opportunistic pathogen capable of group behaviors, including biofilm forma- tion and Swarming Motility. These group behaviors are regulated by both the intracellular signaling molecule c-di-GMP and acylhomoserine lactone quorum-sensing systems. Here, we show that the Pseudomonas quino- lone signal (PQS) system also contributes to the regulation of Swarming Motility. Specifically, our data indicate that 2-heptyl-4-quinolone (HHQ), a precursor of PQS, likely induces the production of the phenazine-1- carboxylic acid (PCA), which in turn acts via an as-yet-unknown downstream mechanism to repress Swarming Motility. We show that this HHQ- and PCA-dependent Swarming repression is apparently independent of changes in global levels of c-di-GMP, suggesting complex regulation of this group behavior. Pseudomonas aeruginosa is an opportunistic human patho- gen capable of coordinated group behaviors, including swarm- ing Motility and biofilm formation. These group behaviors are regulated by both the intracellular signaling molecule c-di- GMP and the acylhomoserine lactone quorum-sensing (QS) systems (7, 19, 26, 32, 53). P. aeruginosa Swarming Motility occurs on semisolid surfaces (i.e., on 0.5 to 0.7% agar) and is characterized by a fractal-like pattern of tendrils emanating from the point of inoculation (5, arginine in the CF lung is more likely assisting in redox bal- ancing and cellular homeostasis under conditions promoting pyruvate fermentation and anaerobic respiration rather than promoting growth. Given the potential significance of arginine in the context of the CF lung and the arginine-dependent repression of Swarming Motility, we sought to identify molec- ular mechanism(s) of Swarming regulation by arginine. Here, we report the role of the signal molecule 2-heptyl-4- quinolone (HHQ) in the repression of swarm Motility. We also show that HHQ, an intermediate in the synthesis of the Pseu- domonas quinolone signal (PQS), controls Swarming by posi- tively regulating phenazine production. Of the four phenazines produced by P. aeruginosa, phenazine-1-carboxylic acid (PCA) modulates Swarming Motility via an unknown downstream mechanism. We present data to show that this HHQ/PCA- dependent pathway for swarm repression is c-di-GMP inde- pendent. Lastly, we present a model for the control of swarm- ing Motility that may be relevant in the context of the CF lung.
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modulation of pseudomonas aeruginosa surface associated group behaviors by individual amino acids through c di gmp signaling
Research in Microbiology, 2011Co-Authors: Steve P Bernier, Judith H Merritt, Daegon Ha, Wajiha Khan, George A OtooleAbstract:To colonize the cystic fibrosis lung, Pseudomonas aeruginosa establishes sessile communities referred to as biofilms. Although the signaling molecule c-di-GMP governs the transition from motile to sessile growth, the environmental signal(s) required to modulate biofilm formation remain unclear. Using relevant in vivo concentrations of the 19 amino acids previously identified in cystic fibrosis sputum, we demonstrated that arginine, ornithine, isoleucine, leucine, valine, phenylalanine and tyrosine robustly promoted biofilm formation in vitro. Among the seven biofilm-promoting amino acids, only arginine also completely repressed the ability of P. aeruginosa to swarm over semi-solid surfaces, suggesting that arginine may be an environmental cue favoring a sessile lifestyle. Mutating two documented diguanylate cyclases required for biofilm formation (SadC and RoeA) reduced biofilm formation and restored Swarming Motility on arginine-containing medium. Growth on arginine increased the intracellular levels of c-di-GMP, and this increase was dependent on the SadC and RoeA diguanylate cyclases. Strains mutated in sadC, roeA or both also showed a reduction in biofilm formation when grown with the other biofilm-promoting amino acids. Taken together, these results suggest that amino acids can modulate biofilm formation and Swarming Motility, at least in part, by controlling the intracellular levels of c-di-GMP.
Sherry L Kuchma - One of the best experts on this subject based on the ideXlab platform.
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pilz domain protein flgz mediates cyclic di gmp dependent Swarming Motility control in pseudomonas aeruginosa
Journal of Bacteriology, 2016Co-Authors: Amy Baker, Sherry L Kuchma, Andreas Diepold, Jessie E Scott, Giulia Orazi, Judith P Armitage, George A OtooleAbstract:ABSTRACT The second messenger cyclic diguanylate (c-di-GMP) is an important regulator of Motility in many bacterial species. In Pseudomonas aeruginosa, elevated levels of c-di-GMP promote biofilm formation and repress flagellum-driven Swarming Motility. The rotation of P. aeruginosa9s polar flagellum is controlled by two distinct stator complexes, MotAB, which cannot support Swarming Motility, and MotCD, which promotes Swarming Motility. Here we show that when c-di-GMP levels are elevated, Swarming Motility is repressed by the PilZ domain-containing protein FlgZ and by Pel polysaccharide production. We demonstrate that FlgZ interacts specifically with the Motility-promoting stator protein MotC in a c-di-GMP-dependent manner and that a functional green fluorescent protein (GFP)-FlgZ fusion protein shows significantly reduced polar localization in a strain lacking the MotCD stator. Our results establish FlgZ as a c-di-GMP receptor affecting Swarming Motility by P. aeruginosa and support a model wherein c-di-GMP-bound FlgZ impedes Motility via its interaction with the MotCD stator. IMPORTANCE The regulation of surface-associated Motility plays an important role in bacterial surface colonization and biofilm formation. c-di-GMP signaling is a widespread means of controlling bacterial Motility, and yet the mechanism whereby this signal controls surface-associated Motility in P. aeruginosa remains poorly understood. Here we identify a PilZ domain-containing c-di-GMP effector protein that contributes to c-di-GMP-mediated repression of Swarming Motility by P. aeruginosa. We provide evidence that this effector, FlgZ, impacts Swarming Motility via its interactions with flagellar stator protein MotC. Thus, we propose a new mechanism for c-di-GMP-mediated regulation of Motility for a bacterium with two flagellar stator sets, increasing our understanding of surface-associated behaviors, a key prerequisite to identifying ways to control the formation of biofilm communities.
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cyclic di gmp mediated repression of Swarming Motility by pseudomonas aeruginosa pa14 requires the motab stator
Journal of Bacteriology, 2015Co-Authors: Sherry L Kuchma, Judith P Armitage, Nicolas J Delalez, Laura M Filkins, E A Snavely, George A OtooleAbstract:The second messenger cyclic diguanylate (c-di-GMP) plays a critical role in the regulation of Motility. In Pseudomonas aeruginosa PA14, c-di-GMP inversely controls biofilm formation and surface Swarming Motility, with high levels of this dinucleotide signal stimulating biofilm formation and repressing Swarming. P. aeruginosa encodes two stator complexes, MotAB and MotCD, that participate in the function of its single polar flagellum. Here we show that the repression of Swarming Motility requires a functional MotAB stator complex. Mutating the motAB genes restores Swarming Motility to a strain with artificially elevated levels of c-di-GMP as well as stimulates Swarming in the wild-type strain, while overexpression of MotA from a plasmid represses Swarming Motility. Using point mutations in MotA and the FliG rotor protein of the motor supports the conclusion that MotA-FliG interactions are critical for c-di-GMP-mediated Swarming inhibition. Finally, we show that high c-di-GMP levels affect the localization of a green fluorescent protein (GFP)-MotD fusion, indicating a mechanism whereby this second messenger has an impact on MotCD function. We propose that when c-di-GMP level is high, the MotAB stator can displace MotCD from the motor, thereby affecting motor function. Our data suggest a newly identified means of c-di-GMP-mediated control of surface Motility, perhaps conserved among Pseudomonas, Xanthomonas, and other organisms that encode two stator systems.
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cyclic di gmp mediated repression of Swarming Motility by pseudomonas aeruginosa the pily1 gene and its impact on surface associated behaviors
Journal of Bacteriology, 2010Co-Authors: Sherry L Kuchma, Judith H Merritt, John H. Hammond, Alicia E Ballok, Joshua D Rabinowitz, George A OtooleAbstract:The intracellular signaling molecule cyclic-di-GMP (c-di-GMP) has been shown to influence surface-associated behaviors of Pseudomonas aeruginosa, including biofilm formation and Swarming Motility. Previously, we reported a role for the bifA gene in the inverse regulation of biofilm formation and Swarming Motility. The bifA gene encodes a c-di-GMP-degrading phosphodiesterase (PDE), and the ΔbifA mutant exhibits increased cellular pools of c-di-GMP, forms hyperbiofilms, and is unable to swarm. In this study, we isolated suppressors of the ΔbifA Swarming defect. Strains with mutations in the pilY1 gene, but not in the pilin subunit pilA gene, show robust suppression of the Swarming defect of the ΔbifA mutant, as well as its hyperbiofilm phenotype. Despite the ability of the pilY1 mutation to suppress all the c-di-GMP-related phenotypes, the global pools of c-di-GMP are not detectably altered in the ΔbifA ΔpilY1 mutant relative to the ΔbifA single mutant. We also show that enhanced expression of the pilY1 gene inhibits Swarming Motility, and we identify residues in the putative VWA domain of PilY1 that are important for this phenotype. Furthermore, Swarming repression by PilY1 specifically requires the diguanylate cyclase (DGC) SadC, and epistasis analysis indicates that PilY1 functions upstream of SadC. Our data indicate that PilY1 participates in multiple surface behaviors of P. aeruginosa, and we propose that PilY1 may act via regulation of SadC DGC activity but independently of altering global c-di-GMP levels.
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bifa a cyclic di gmp phosphodiesterase inversely regulates biofilm formation and Swarming Motility by pseudomonas aeruginosa pa14
Journal of Bacteriology, 2007Co-Authors: Sherry L Kuchma, Judith H Merritt, Nicole T Liberati, Frederick M. Ausubel, George A OtooleAbstract:The intracellular signaling molecule, cyclic-di-GMP (c-di-GMP), has been shown to influence bacterial behaviors, including Motility and biofilm formation. We report the identification and characterization of PA4367, a gene involved in regulating surface-associated behaviors in Pseudomonas aeruginosa. The PA4367 gene encodes a protein with an EAL domain, associated with c-di-GMP phosphodiesterase activity, as well as a GGDEF domain, which is associated with a c-di-GMP-synthesizing diguanylate cyclase activity. Deletion of the PA4367 gene results in a severe defect in Swarming Motility and a hyperbiofilm phenotype; thus, we designate this gene bifA, for biofilm formation. We show that BifA localizes to the inner membrane and, in biochemical studies, that purified BifA protein exhibits phosphodiesterase activity in vitro but no detectable diguanylate cyclase activity. Furthermore, mutational analyses of the conserved EAL and GGDEF residues of BifA suggest that both domains are important for the observed phosphodiesterase activity. Consistent with these data, the ΔbifA mutant exhibits increased cellular pools of c-di-GMP relative to the wild type and increased synthesis of a polysaccharide produced by the pel locus. This increased polysaccharide production is required for the enhanced biofilm formed by the ΔbifA mutant but does not contribute to the observed Swarming defect. The ΔbifA mutation also results in decreased flagellar reversals. Based on epistasis studies with the previously described sadB gene, we propose that BifA functions upstream of SadB in the control of biofilm formation and Swarming.
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sadc reciprocally influences biofilm formation and Swarming Motility via modulation of exopolysaccharide production and flagellar function
Journal of Bacteriology, 2007Co-Authors: Judith H Merritt, Sherry L Kuchma, George A OtooleAbstract:Pseudomonas aeruginosa has served as an important organism in the study of biofilm formation; however, we still lack an understanding of the mechanisms by which this microbe transitions to a surface lifestyle. A recent study of the early stages of biofilm formation implicated the control of flagellar reversals and production of an exopolysaccharide (EPS) as factors in the establishment of a stable association with the substratum and Swarming Motility. Here we present evidence that SadC (PA4332), an inner membrane-localized diguanylate cyclase, plays a role in controlling these cellular functions. Deletion of the sadC gene results in a strain that is defective in biofilm formation and a hyperswarmer, while multicopy expression of this gene promotes sessility. A ΔsadC mutant was additionally found to be deficient in EPS production and display altered reversal behavior while swimming in high-viscosity medium, two behaviors proposed to influence biofilm formation and Swarming Motility. Epistasis analysis suggests that the sadC gene is part of a genetic pathway that allows for the concomitant regulation of these aspects of P. aeruginosa surface behavior. We propose that SadC and the phosphodiesterase BifA (S. L. Kuchma et al., J. Bacteriol. 189:8165-8178, 2007), via modulating levels of the signaling molecule cyclic-di-GMP, coregulate Swarming Motility and biofilm formation as P. aeruginosa transitions from a planktonic to a surface-associated lifestyle.
Robert E W Hancock - One of the best experts on this subject based on the ideXlab platform.
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Effect of Nitroxides on Swarming Motility and Biofilm Formation, Multicellular Behaviors in Pseudomonas aeruginosa
2020Co-Authors: César De La Fuente-núñez, Fany Reffuveille, Kathryn E Fairfull-smith, Robert E W HancockAbstract:b The ability of nitric oxide (NO) to induce biofilm dispersion has been well established. Here, we investigated the effect of nitroxides (sterically hindered nitric oxide analogues) on biofilm formation and Swarming Motility in Pseudomonas aeruginosa. A transposon mutant unable to produce nitric oxide endogenously (nirS) was deficient in Swarming Motility relative to the wild type and the complemented strain. Moreover, expression of the nirS gene was upregulated by 9.65-fold in wild-type Swarming cells compared to planktonic cells. Wild-type Swarming levels were substantially restored upon the exogenous addition of nitroxide containing compounds, a finding consistent with the hypothesis that NO is necessary for Swarming Motility. Here, we showed that nitroxides not only mimicked the dispersal activity of NO but also prevented biofilms from forming in flow cell chambers. In addition, a nirS transposon mutant was deficient in biofilm formation relative to the wild type and the complemented strain, thus implicating NO in the formation of biofilms. Intriguingly, despite its stand-alone action in inhibiting biofilm formation and promoting dispersal, a nitroxide partially restored the ability of a nirS mutant to form biofilms
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pseudomonas aeruginosa all roads lead to resistance
Trends in Microbiology, 2011Co-Authors: Elena B M Breidenstein, Cesar De La Fuentenunez, Robert E W HancockAbstract:Pseudomonas aeruginosa is often resistant to multiple antibiotics and consequently has joined the ranks of ‘superbugs' due to its enormous capacity to engender resistance. It demonstrates decreased susceptibility to most antibiotics due to low outer membrane permeability coupled to adaptive mechanisms and can readily achieve clinical resistance. Newer research, using mutant library screens, microarray technologies and mutation frequency analysis, has identified very large collections of genes (the resistome) that when mutated lead to resistance as well as new forms of adaptive resistance that can be triggered by antibiotics themselves, in in vivo growth conditions or complex adaptations such as biofilm growth or Swarming Motility.
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induction by cationic antimicrobial peptides and involvement in intrinsic polymyxin and antimicrobial peptide resistance biofilm formation and Swarming Motility of psra in pseudomonas aeruginosa
Journal of Bacteriology, 2008Co-Authors: James W Gooderham, Manjeet Bains, Joseph B Mcphee, Irith Wiegand, Robert E W HancockAbstract:Pseudomonas aeruginosa is an important opportunistic pathogen that causes infections that can be extremely difficult to treat due to its high intrinsic antibiotic resistance and broad repertoire of virulence factors, both of which are highly regulated. It is demonstrated here that the psrA gene, encoding a transcriptional regulator, was upregulated in response to subinhibitory concentrations of cationic antimicrobial peptides. Compared to the wild type and the complemented mutant, a P. aeruginosa PAO1 psrA::Tn5 mutant displayed intrinsic supersusceptibility to polymyxin B, a last-resort antimicrobial used against multidrug-resistant infections, and the bovine neutrophil antimicrobial peptide indolicidin; this supersusceptibility phenotype correlated with increased outer membrane permeabilization by these agents. The psrA mutant was also defective in simple biofilm formation, rapid attachment, and Swarming Motility, all of which could be complemented by the cloned psrA gene. The role of PsrA in global gene regulation was studied by comparing the psrA mutant to the wild type by microarray analysis, demonstrating that 178 genes were up- or downregulated ≥2-fold (P ≤ 0.05). Dysregulated genes included those encoding certain known PsrA targets, those encoding the type III secretion apparatus and effectors, adhesion and Motility genes, and a variety of metabolic, energy metabolism, and outer membrane permeability genes. This suggests that PsrA might be a key regulator of antimicrobial peptide resistance and virulence.
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Swarming of pseudomonas aeruginosa is a complex adaptation leading to increased production of virulence factors and antibiotic resistance
Journal of Bacteriology, 2008Co-Authors: Joerg Overhage, Manjeet Bains, Michelle D Brazas, Robert E W HancockAbstract:In addition to exhibiting swimming and twitching Motility, Pseudomonas aeruginosa is able to swarm on semisolid (viscous) surfaces. Recent studies have indicated that Swarming is a more complex type of Motility influenced by a large number of different genes. To investigate the adaptation process involved in Swarming Motility, gene expression profiles were analyzed by performing microarrays on bacteria from the leading edge of a swarm zone compared to bacteria growing in identical medium under swimming conditions. Major shifts in gene expression patterns were observed under Swarming conditions, including, among others, the overexpression of a large number of virulence-related genes such as those encoding the type III secretion system and its effectors, those encoding extracellular proteases, and those associated with iron transport. In addition, Swarming cells exhibited adaptive antibiotic resistance against polymyxin B, gentamicin, and ciprofloxacin compared to what was seen for their planktonic (swimming) counterparts. By analyzing a large subset of up-regulated genes, we were able to show that two virulence genes, lasB and pvdQ, were required for Swarming Motility. These results clearly favored the conclusion that Swarming of P. aeruginosa is a complex adaptation process in response to a viscous environment resulting in a substantial change in virulence gene expression and antibiotic resistance.
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identification of genes involved in Swarming Motility using a pseudomonas aeruginosa pao1 mini tn5 lux mutant library
Journal of Bacteriology, 2007Co-Authors: Joerg Overhage, Shawn Lewenza, Alexandra K Marr, Robert E W HancockAbstract:During a screening of a mini-Tn5-luxCDABE transposon mutant library of Pseudomonas aeruginosa PAO1 for alterations in Swarming Motility, 36 mutants were identified with Tn5 insertions in genes for the synthesis or function of flagellin and type IV pilus, in genes for the Xcp-related type II secretion system, and in regulatory, metabolic, chemosensory, and hypothetical genes with unknown functions. These mutants were differentially affected in swimming and twitching Motility but in most cases had only a minor additional Motility defect. Our data provide evidence that Swarming is a more complex type of Motility, since it is influenced by a large number of different genes in P. aeruginosa. Conversely, many of the Swarming-negative mutants also showed an impairment in biofilm formation, indicating a strong relationship between these types of growth states.
Judith H Merritt - One of the best experts on this subject based on the ideXlab platform.
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2 heptyl 4 quinolone a precursor of the pseudomonas quinolone signal molecule modulates Swarming Motility in pseudomonas aeruginosa
Journal of Bacteriology, 2011Co-Authors: Judith H Merritt, Thomas H Hampton, James T Hodgkinson, Matej Janecek, David R Spring, Martin Welch, George A OtooleAbstract:Pseudomonas aeruginosa is an opportunistic pathogen capable of group behaviors, including biofilm forma- tion and Swarming Motility. These group behaviors are regulated by both the intracellular signaling molecule c-di-GMP and acylhomoserine lactone quorum-sensing systems. Here, we show that the Pseudomonas quino- lone signal (PQS) system also contributes to the regulation of Swarming Motility. Specifically, our data indicate that 2-heptyl-4-quinolone (HHQ), a precursor of PQS, likely induces the production of the phenazine-1- carboxylic acid (PCA), which in turn acts via an as-yet-unknown downstream mechanism to repress Swarming Motility. We show that this HHQ- and PCA-dependent Swarming repression is apparently independent of changes in global levels of c-di-GMP, suggesting complex regulation of this group behavior. Pseudomonas aeruginosa is an opportunistic human patho- gen capable of coordinated group behaviors, including swarm- ing Motility and biofilm formation. These group behaviors are regulated by both the intracellular signaling molecule c-di- GMP and the acylhomoserine lactone quorum-sensing (QS) systems (7, 19, 26, 32, 53). P. aeruginosa Swarming Motility occurs on semisolid surfaces (i.e., on 0.5 to 0.7% agar) and is characterized by a fractal-like pattern of tendrils emanating from the point of inoculation (5, arginine in the CF lung is more likely assisting in redox bal- ancing and cellular homeostasis under conditions promoting pyruvate fermentation and anaerobic respiration rather than promoting growth. Given the potential significance of arginine in the context of the CF lung and the arginine-dependent repression of Swarming Motility, we sought to identify molec- ular mechanism(s) of Swarming regulation by arginine. Here, we report the role of the signal molecule 2-heptyl-4- quinolone (HHQ) in the repression of swarm Motility. We also show that HHQ, an intermediate in the synthesis of the Pseu- domonas quinolone signal (PQS), controls Swarming by posi- tively regulating phenazine production. Of the four phenazines produced by P. aeruginosa, phenazine-1-carboxylic acid (PCA) modulates Swarming Motility via an unknown downstream mechanism. We present data to show that this HHQ/PCA- dependent pathway for swarm repression is c-di-GMP inde- pendent. Lastly, we present a model for the control of swarm- ing Motility that may be relevant in the context of the CF lung.
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modulation of pseudomonas aeruginosa surface associated group behaviors by individual amino acids through c di gmp signaling
Research in Microbiology, 2011Co-Authors: Steve P Bernier, Judith H Merritt, Daegon Ha, Wajiha Khan, George A OtooleAbstract:To colonize the cystic fibrosis lung, Pseudomonas aeruginosa establishes sessile communities referred to as biofilms. Although the signaling molecule c-di-GMP governs the transition from motile to sessile growth, the environmental signal(s) required to modulate biofilm formation remain unclear. Using relevant in vivo concentrations of the 19 amino acids previously identified in cystic fibrosis sputum, we demonstrated that arginine, ornithine, isoleucine, leucine, valine, phenylalanine and tyrosine robustly promoted biofilm formation in vitro. Among the seven biofilm-promoting amino acids, only arginine also completely repressed the ability of P. aeruginosa to swarm over semi-solid surfaces, suggesting that arginine may be an environmental cue favoring a sessile lifestyle. Mutating two documented diguanylate cyclases required for biofilm formation (SadC and RoeA) reduced biofilm formation and restored Swarming Motility on arginine-containing medium. Growth on arginine increased the intracellular levels of c-di-GMP, and this increase was dependent on the SadC and RoeA diguanylate cyclases. Strains mutated in sadC, roeA or both also showed a reduction in biofilm formation when grown with the other biofilm-promoting amino acids. Taken together, these results suggest that amino acids can modulate biofilm formation and Swarming Motility, at least in part, by controlling the intracellular levels of c-di-GMP.
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cyclic di gmp mediated repression of Swarming Motility by pseudomonas aeruginosa the pily1 gene and its impact on surface associated behaviors
Journal of Bacteriology, 2010Co-Authors: Sherry L Kuchma, Judith H Merritt, John H. Hammond, Alicia E Ballok, Joshua D Rabinowitz, George A OtooleAbstract:The intracellular signaling molecule cyclic-di-GMP (c-di-GMP) has been shown to influence surface-associated behaviors of Pseudomonas aeruginosa, including biofilm formation and Swarming Motility. Previously, we reported a role for the bifA gene in the inverse regulation of biofilm formation and Swarming Motility. The bifA gene encodes a c-di-GMP-degrading phosphodiesterase (PDE), and the ΔbifA mutant exhibits increased cellular pools of c-di-GMP, forms hyperbiofilms, and is unable to swarm. In this study, we isolated suppressors of the ΔbifA Swarming defect. Strains with mutations in the pilY1 gene, but not in the pilin subunit pilA gene, show robust suppression of the Swarming defect of the ΔbifA mutant, as well as its hyperbiofilm phenotype. Despite the ability of the pilY1 mutation to suppress all the c-di-GMP-related phenotypes, the global pools of c-di-GMP are not detectably altered in the ΔbifA ΔpilY1 mutant relative to the ΔbifA single mutant. We also show that enhanced expression of the pilY1 gene inhibits Swarming Motility, and we identify residues in the putative VWA domain of PilY1 that are important for this phenotype. Furthermore, Swarming repression by PilY1 specifically requires the diguanylate cyclase (DGC) SadC, and epistasis analysis indicates that PilY1 functions upstream of SadC. Our data indicate that PilY1 participates in multiple surface behaviors of P. aeruginosa, and we propose that PilY1 may act via regulation of SadC DGC activity but independently of altering global c-di-GMP levels.
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bifa a cyclic di gmp phosphodiesterase inversely regulates biofilm formation and Swarming Motility by pseudomonas aeruginosa pa14
Journal of Bacteriology, 2007Co-Authors: Sherry L Kuchma, Judith H Merritt, Nicole T Liberati, Frederick M. Ausubel, George A OtooleAbstract:The intracellular signaling molecule, cyclic-di-GMP (c-di-GMP), has been shown to influence bacterial behaviors, including Motility and biofilm formation. We report the identification and characterization of PA4367, a gene involved in regulating surface-associated behaviors in Pseudomonas aeruginosa. The PA4367 gene encodes a protein with an EAL domain, associated with c-di-GMP phosphodiesterase activity, as well as a GGDEF domain, which is associated with a c-di-GMP-synthesizing diguanylate cyclase activity. Deletion of the PA4367 gene results in a severe defect in Swarming Motility and a hyperbiofilm phenotype; thus, we designate this gene bifA, for biofilm formation. We show that BifA localizes to the inner membrane and, in biochemical studies, that purified BifA protein exhibits phosphodiesterase activity in vitro but no detectable diguanylate cyclase activity. Furthermore, mutational analyses of the conserved EAL and GGDEF residues of BifA suggest that both domains are important for the observed phosphodiesterase activity. Consistent with these data, the ΔbifA mutant exhibits increased cellular pools of c-di-GMP relative to the wild type and increased synthesis of a polysaccharide produced by the pel locus. This increased polysaccharide production is required for the enhanced biofilm formed by the ΔbifA mutant but does not contribute to the observed Swarming defect. The ΔbifA mutation also results in decreased flagellar reversals. Based on epistasis studies with the previously described sadB gene, we propose that BifA functions upstream of SadB in the control of biofilm formation and Swarming.
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sadc reciprocally influences biofilm formation and Swarming Motility via modulation of exopolysaccharide production and flagellar function
Journal of Bacteriology, 2007Co-Authors: Judith H Merritt, Sherry L Kuchma, George A OtooleAbstract:Pseudomonas aeruginosa has served as an important organism in the study of biofilm formation; however, we still lack an understanding of the mechanisms by which this microbe transitions to a surface lifestyle. A recent study of the early stages of biofilm formation implicated the control of flagellar reversals and production of an exopolysaccharide (EPS) as factors in the establishment of a stable association with the substratum and Swarming Motility. Here we present evidence that SadC (PA4332), an inner membrane-localized diguanylate cyclase, plays a role in controlling these cellular functions. Deletion of the sadC gene results in a strain that is defective in biofilm formation and a hyperswarmer, while multicopy expression of this gene promotes sessility. A ΔsadC mutant was additionally found to be deficient in EPS production and display altered reversal behavior while swimming in high-viscosity medium, two behaviors proposed to influence biofilm formation and Swarming Motility. Epistasis analysis suggests that the sadC gene is part of a genetic pathway that allows for the concomitant regulation of these aspects of P. aeruginosa surface behavior. We propose that SadC and the phosphodiesterase BifA (S. L. Kuchma et al., J. Bacteriol. 189:8165-8178, 2007), via modulating levels of the signaling molecule cyclic-di-GMP, coregulate Swarming Motility and biofilm formation as P. aeruginosa transitions from a planktonic to a surface-associated lifestyle.
Daniel Pletzer - One of the best experts on this subject based on the ideXlab platform.
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peptide 1018 inhibits Swarming and influences anr regulated gene expression downstream of the stringent stress response in pseudomonas aeruginosa
PLOS ONE, 2021Co-Authors: Lauren Wilkinson, Manjeet Bains, Morgan A Alford, Shannon R Coleman, Amy S Lee, Travis M Blimkie, Reza Falsafi, Daniel PletzerAbstract:Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen that causes considerable human morbidity and mortality, particularly in nosocomial infections and individuals with cystic fibrosis. P. aeruginosa can adapt to surface growth by undergoing Swarming Motility, a rapid multicellular movement that occurs on viscous soft surfaces with amino acids as a nitrogen source. Here we tested the small synthetic host defense peptide, innate defense regulator 1018, and found that it inhibited Swarming Motility at concentrations as low as 0.75 μg/ml, well below the MIC for strain PA14 planktonic cells (64 μg/ml). A screen of the PA14 transposon insertion mutant library revealed 29 mutants that were more tolerant to peptide 1018 during Swarming, five of which demonstrated significantly greater Swarming than the WT in the presence of peptide. Transcriptional analysis (RNA-Seq) of cells that were inoculated on Swarming plates containing 1.0 μg/ml peptide revealed differential expression of 1,190 genes compared to cells Swarming on plates without peptide. Furthermore, 1018 treatment distinctly altered the gene expression profile of cells when compared to that untreated cells in the centre of the swarm colonies. Peptide-treated cells exhibited changes in the expression of genes implicated in the stringent stress response including those regulated by anr, which is involved in anaerobic adaptation, indicative of a mechanism by which 1018 might inhibit Swarming Motility. Overall, this study illustrates potential mechanisms by which peptide 1018 inhibits Swarming surface Motility, an important bacterial adaptation associated with antibiotic resistance, virulence, and dissemination of P. aeruginosa.
