Faculty Opinions recommendation of Membrane association of SadC enhances its diguanylate cyclase activity to control exopolysaccharides synthesis and biofilm formation in Pseudomonas aeruginosa.

ABSTRACT 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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Specific Control of Pseudomonas aeruginosa Surface-Associated Behaviors by Two c-di-GMP Diguanylate Cyclases

mBio ◽

10.1128/mbio.00183-10 ◽

2010 ◽

Vol 1 (4) ◽

Cited By ~ 106

Author(s):

Judith H. Merritt ◽

Dae-Gon Ha ◽

Kimberly N. Cowles ◽

Wenyun Lu ◽

Diana K. Morales ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Biofilm Formation ◽

Extracellular Polysaccharide ◽

Diguanylate Cyclase ◽

Flagellar Motility ◽

Critical Question ◽

Cyclic Diguanylate ◽

Critical Signal ◽

Content Type ◽

Wide Range

ABSTRACT The signaling nucleotide cyclic diguanylate (c-di-GMP) regulates the transition between motile and sessile growth in a wide range of bacteria. Understanding how microbes control c-di-GMP metabolism to activate specific pathways is complicated by the apparent multifold redundancy of enzymes that synthesize and degrade this dinucleotide, and several models have been proposed to explain how bacteria coordinate the actions of these many enzymes. Here we report the identification of a diguanylate cyclase (DGC), RoeA, of Pseudomonas aeruginosa that promotes the production of extracellular polysaccharide (EPS) and contributes to biofilm formation, that is, the transition from planktonic to surface-dwelling cells. Our studies reveal that RoeA and the previously described DGC SadC make distinct contributions to biofilm formation, controlling polysaccharide production and flagellar motility, respectively. Measurement of total cellular levels of c-di-GMP in ∆roeA and ∆sadC mutants in two different genetic backgrounds revealed no correlation between levels of c-di-GMP and the observed phenotypic output with regard to swarming motility and EPS production. Our data strongly argue against a model wherein changes in total levels of c-di-GMP can account for the specific surface-related phenotypes of P. aeruginosa. IMPORTANCE A critical question in the study of cyclic diguanylate (c-di-GMP) signaling is how the bacterial cell integrates contributions of multiple c-di-GMP-metabolizing enzymes to mediate its cognate functional outputs. One leading model suggests that the effects of c-di-GMP must, in part, be localized subcellularly. The data presented here show that the phenotypes controlled by two different diguanylate cyclase (DGC) enzymes have discrete outputs despite the same total level of c-di-GMP. These data support and extend the model in which localized c-di-GMP signaling likely contributes to coordination of the action of the multiple proteins involved in the synthesis, degradation, and/or binding of this critical signal.

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The SagS sensory protein modulates biofilm formation and c-di-GMP levels by Pseudomonas aeruginosa in response to glucose-6-phosphate.

10.5194/biofilms9-122 ◽

2020 ◽

Author(s):

Soyoung Park ◽

Jozef Dingemans ◽

Madison Gowett ◽

Karin Sauer

Keyword(s):

Pseudomonas Aeruginosa ◽

Genetic Analysis ◽

Signaling Pathway ◽

Biofilm Formation ◽

Phosphate Concentration ◽

Dependent Manner ◽

Diguanylate Cyclase ◽

Swarming Motility ◽

Two Component ◽

Insight Into

<p>In <em>Pseudomonas aeruginosa</em>, the orphan two-component sensor SagS contributes to both, the transition to biofilm formation and to biofilm cells gaining their heightened tolerance to antimicrobials. However, little is known about the identity of the signals or conditions sensed by SagS to induce the switch to the sessile, drug tolerant mode of growth. Using a modified Biolog phenotype assay to screen for compounds that modulate attachment in a SagS-dependent manner, we identified glucose-6-phosphate to enhance attachment in a manner dependent on the glucose-6-phosphate concentration and SagS. The stimulatory effect was not limited to the attachment as glucose-6-phosphate likewise enhanced biofilm formation. We show that exposure to glucose-6-phosphate results in decreased swarming motility but increased cellular c-di-GMP levels in biofilms. Genetic analysis indicated that the diguanylate cyclase NicD is an activator of biofilm formation and is not only required for enhanced biofilm formation in response to glucose-6-phosphate but also interacts with SagS. Our findings indicate glucose-6-phosphate to likely mimic a signal or conditions sensed by SagS to activate its motile-sessile switch function. Additionally, our findings provide new insight into the interfaces between the ligand-mediated TCS signaling pathway and c-di-GMP levels.</p>

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Subcellular Clustering of the Phosphorylated WspR Response Regulator Protein Stimulates Its Diguanylate Cyclase Activity

mBio ◽

10.1128/mbio.00242-13 ◽

2013 ◽

Vol 4 (3) ◽

Cited By ~ 69

Author(s):

Varisa Huangyutitham ◽

Zehra Tüzün Güvener ◽

Caroline S. Harwood

Keyword(s):

Signal Transduction ◽

Biofilm Formation ◽

Response Regulator ◽

Cluster Formation ◽

Cyclase Activity ◽

Diguanylate Cyclase ◽

Regulator Protein ◽

Response Regulator Protein

ABSTRACT WspR is a hybrid response regulator-diguanylate cyclase that is phosphorylated by the Wsp signal transduction complex in response to growth of Pseudomonas aeruginosa on surfaces. Active WspR produces cyclic di-GMP (c-di-GMP), which in turn stimulates biofilm formation. In previous work, we found that when activated by phosphorylation, yellow fluorescent protein (YFP)-tagged WspR forms clusters that are visible in individual cells by fluorescence microscopy. Unphosphorylated WspR is diffuse in cells and not visible. Thus, cluster formation is an assay for WspR signal transduction. To understand how and why WspR forms subcellular clusters, we analyzed cluster formation and the enzymatic activities of six single amino acid variants of WspR. In general, increased cluster formation correlated with increased in vivo and in vitro diguanylate cyclase activities of the variants. In addition, WspR specific activity was strongly concentration dependent in vitro, and the effect of the protein concentration on diguanylate cyclase activity was magnified when WspR was treated with the phosphor analog beryllium fluoride. Cluster formation appears to be an intrinsic property of phosphorylated WspR (WspR-P). These results support a model in which the formation of WspR-P subcellular clusters in vivo in response to a surface stimulus is important for potentiating the diguanylate cyclase activity of WspR. Subcellular cluster formation appears to be an additional means by which the activity of a response regulator protein can be regulated. IMPORTANCE Bacterial sensor proteins often phosphorylate cognate response regulator proteins when stimulated by an environmental signal. Phosphorylated response regulators then mediate an appropriate adaptive cellular response. About 6% of response regulator proteins have an enzymatic domain that is involved in producing or degrading cyclic di-GMP (c-di-GMP), a molecule that stimulates bacterial biofilm formation. In this work, we examined the in vivo and in vitro behavior of the response regulator-diguanylate cyclase WspR. When phosphorylated in response to a signal associated with surface growth, WspR has a tendency to form oligomers that are visible in cells as subcellular clusters. Our results show that the formation of phosphorylated WspR (WspR-P) subcellular clusters is important for potentiating the diguanylate cyclase activity of WspR-P, making it more active in c-di-GMP production. We conclude that oligomer formation visualized as subcellular clusters is an additional mechanism by which the activities of response regulator-diguanylate cyclases can be regulated.

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Flagellar Stators Activate a Diguanylate Cyclase To Inhibit Flagellar Stators

Journal of Bacteriology ◽

10.1128/jb.00186-19 ◽

2019 ◽

Vol 201 (18) ◽

Author(s):

Daniel B. Kearns

Keyword(s):

Pseudomonas Aeruginosa ◽

Secondary Metabolite ◽

Positive Feedback ◽

Biofilm Formation ◽

Feedback Loop ◽

Diguanylate Cyclase ◽

Positive Feedback Loop ◽

Content Type ◽

Dependent Inhibition

ABSTRACT The bacterial secondary metabolite cyclic di-GMP is a widespread, cytoplasmic signal that promotes a physiological transition in which motility is inhibited and biofilm formation is activated. A paper published in this issue (A. E. Baker, S. S. Webster, A. Diepold, S. L. Kuchma, E. Bordeleau, et al., J Bacteriol 201:e00741-18, 2019, https://doi.org/10.1128/JB.00741-18) makes an important connection between cyclic di-GMP and flagellar components. They show that stator units, which normally interact with the flagellum to power rotation, can alternatively interact with and activate an enzyme that synthesizes cyclic di-GMP in Pseudomonas aeruginosa. Moreover, the same stator units are also the target of cyclic-di-GMP-dependent inhibition such that the more the stators are inhibited, the more cyclic di-GMP is made. The resulting positive-feedback loop not only inhibits motility but also may initiate and stabilize biofilm formation.

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The Diguanylate Cyclase SadC Is a Central Player in Gac/Rsm-Mediated Biofilm Formation in Pseudomonas aeruginosa

Journal of Bacteriology ◽

10.1128/jb.01850-14 ◽

2014 ◽

Vol 196 (23) ◽

pp. 4081-4088 ◽

Cited By ~ 57

Author(s):

J. A. Moscoso ◽

T. Jaeger ◽

M. Valentini ◽

K. Hui ◽

U. Jenal ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Biofilm Formation ◽

Diguanylate Cyclase

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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 ◽

10.1128/jb.01642-09 ◽

2010 ◽

Vol 192 (12) ◽

pp. 2950-2964 ◽

Cited By ~ 97

Author(s):

S. L. Kuchma ◽

A. E. Ballok ◽

J. H. Merritt ◽

J. H. Hammond ◽

W. Lu ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Intracellular Signaling ◽

Biofilm Formation ◽

Diguanylate Cyclase ◽

Swarming Motility ◽

Signaling Molecule ◽

Single Mutant ◽

Epistasis Analysis ◽

Pilin Subunit ◽

Enhanced Expression

ABSTRACT 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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Indirect Modulation of the Intracellular c-Di-GMP Level inShewanella oneidensisMR-1 by MxdA

Applied and Environmental Microbiology ◽

10.1128/aem.01985-10 ◽

2011 ◽

Vol 77 (6) ◽

pp. 2196-2198 ◽

Cited By ~ 13

Author(s):

Shauna Rakshe ◽

Maija Leff ◽

Alfred M. Spormann

Keyword(s):

Biofilm Formation ◽

Shewanella Oneidensis ◽

Cellular Level ◽

Cyclase Activity ◽

Diguanylate Cyclase ◽

Ggdef Domain ◽

Domain Protein

ABSTRACTThe GGDEF domain protein MxdA, which is important for biofilm formation inShewanella oneidensisMR-1, was hypothesized to possess diguanylate cyclase activity. Here, we demonstrate that while MxdA controls the cellular level of c-di-GMP inS. oneidensis, it modulates the c-di-GMP pool indirectly.

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Flagellar stators stimulate c-di-GMP production by Pseudomonas aeruginosa

10.1101/483339 ◽

2018 ◽

Cited By ~ 1

Author(s):

Amy E. Baker ◽

Shanice S. Webster ◽

Andreas Diepold ◽

Sherry L. Kuchma ◽

Eric Bordeleau ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Biofilm Formation ◽

Feedback Loop ◽

Bacterial Cells ◽

Diguanylate Cyclase ◽

Flagellar Motility ◽

Swarming Motility ◽

Surface Attachment ◽

Bidirectional Interactions ◽

Gmp Production

AbstractFlagellar motility is critical for surface attachment and biofilm formation in many bacteria. A key regulator of flagellar motility in Pseudomonas aeruginosa and other microbes is cyclic diguanylate (c-di-GMP). High levels of this second messenger repress motility and stimulate biofilm formation. C-di-GMP levels regulate motility in P. aeruginosa in part by influencing the localization of its two flagellar stator sets, MotAB and MotCD. Here we show that just as c-di-GMP can influence the stators, stators can impact c-di-GMP levels. We demonstrate that the swarming motility-driving stator MotC physically interacts with the transmembrane region of the diguanylate cyclase SadC. Furthermore, we demonstrate that this interaction is capable of stimulating SadC activity. We propose a model by which the MotCD stator set interacts with SadC to stimulate c-di-GMP production in conditions not permissive to motility. This regulation implies a positive feedback loop in which c-di-GMP signaling events cause MotCD stators to disengage from the motor; then disengaged stators stimulate c-di-GMP production to reinforce a biofilm mode of growth. Our studies help define the bidirectional interactions between c-di-GMP and the motility machinery.Importance.The ability of bacterial cells to control motility during early steps in biofilm formation is critical for the transition to a non-motile, biofilm lifestyle. Recent studies have clearly demonstrated the ability of c-di-GMP to control motility via a number of mechanisms, including through controlling transcription of motility-related genes and modulating motor function. Here we provide evidence that motor components can in turn impact c-di-GMP levels. We propose that communication between motor components and c-di-GMP synthesis machinery allows the cell to have a robust and sensitive switching mechanism to control motility during early events in biofilm formation.

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