scholarly journals Cyclic-di-GMP Regulates the Quorum-Sensing System and Biocontrol Activity of Pseudomonas fluorescens 2P24 through the RsmA and RsmE Proteins

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Fei Liang ◽  
Bo Zhang ◽  
Qingqing Yang ◽  
Yang Zhang ◽  
Dehong Zheng ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Pseudomonas Fluorescens ◽  
Genomic Analysis ◽  
Fine Tuning ◽  
Content Type ◽  
Rhizosphere Bacterium ◽  
Wide Range ◽  
Biocontrol Activity ◽  
Biocontrol Potential ◽  
Polyketide Antibiotic

ABSTRACT Pseudomonas fluorescens 2P24 is a rhizosphere bacterium that protects many crop plants against soilborne diseases caused by phytopathogens. The PcoI/PcoR quorum-sensing (QS) system and polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are particularly relevant to the strain’s biocontrol potential. In this study, we investigated the effects of c-di-GMP on the biocontrol activity of strain 2P24. The expression of the Escherichia coli diguanylate cyclase (YedQ) and phosphodiesterase (YhjH) in P. fluorescens 2P24 significantly increased and decreased the cellular concentration of c-di-GMP, respectively. The production of the QS signals N-acyl homoserine lactones (AHLs) and 2,4-DAPG was negatively regulated by c-di-GMP in 2P24. The regulatory proteins RsmA and RsmE were positively regulated by c-di-GMP. Genomic analysis revealed that 2P24 has 23 predicted proteins that contain c-di-GMP-synthesizing or -degrading domains. Among these proteins, C0J56_12915, C0J56_13325, and C0J56_27925 contributed to the production of c-di-GMP and were also involved in the regulation of the QS signal and antibiotic 2,4-DAPG production in P. fluorescens. Overexpression of C0J56_12915, C0J56_13325, and C0J56_27925 in 2P24 impaired its root colonization and biocontrol activities. Taken together, these results demonstrated that c-di-GMP played an important role in fine-tuning the biocontrol traits of P. fluorescens. IMPORTANCE In various bacteria, the bacterial second messenger c-di-GMP influences a wide range of cellular processes. However, the function of c-di-GMP on biocontrol traits in the plant-beneficial rhizobacteria remains largely unclear. The present work shows that the QS system and polyketide antibiotic 2,4-DAPG production are regulated by c-di-GMP through RsmA and RsmE proteins in P. fluorescens 2P24. The diguanylate cyclases (DGCs) C0J56_12915, C0J56_13325, and C0J56_27925 are especially involved in regulating the biocontrol traits of 2P24. Our work also demonstrated a connection between the Gac/Rsm cascade and the c-di-GMP signaling pathway in P. fluorescens.

scholarly journals Metabolic manipulation by Pseudomonas fluorescens: a powerful stratagem against oxidative and metal stress

2020 ◽  
Vol 69 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Alex MacLean ◽  
Anondo Michel Bley ◽  
Varun P. Appanna ◽  
Vasu D. Appanna
Keyword(s):  
Pseudomonas Fluorescens ◽  
Metabolic Networks ◽  
Value Added ◽  
Metal Stress ◽  
Fine Tuning ◽  
Content Type ◽  
Wide Range ◽  
Microbial System ◽  
Central Characteristic ◽  
Living Organisms

Metabolism is the foundation of all living organisms and is at the core of numerous if not all biological processes. The ability of an organism to modulate its metabolism is a central characteristic needed to proliferate, to be dormant and to survive any assault. Pseudomonas fluorescens is bestowed with a uniquely versatile metabolic framework that enables the microbe to adapt to a wide range of conditions including disparate nutrients and toxins. In this mini-review we elaborate on the various metabolic reconfigurations evoked by this microbial system to combat reactive oxygen/nitrogen species and metal stress. The fine-tuning of the NADH/NADPH homeostasis coupled with the production of α-keto-acids and ATP allows for the maintenance of a reductive intracellular milieu. The metabolic networks propelling the synthesis of metabolites like oxalate and aspartate are critical to keep toxic metals at bay. The biochemical processes resulting from these defensive mechanisms provide molecular clues to thwart infectious microbes and reveal elegant pathways to generate value-added products.

scholarly journals Quorum Sensing Signal Selectivity and the Potential for Interspecies Cross Talk

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Samantha Wellington ◽  
E. Peter Greenberg
Keyword(s):  
Quorum Sensing ◽  
Cell Signaling ◽  
Cross Talk ◽  
Homoserine Lactone ◽  
Interspecies Interactions ◽  
Interspecies Competition ◽  
Content Type ◽  
E Coli ◽  
Competition And Cooperation ◽  
Wide Range

ABSTRACTMany species of proteobacteria communicate with kin and coordinate group behaviors through a form of cell-cell signaling called acyl-homoserine lactone (AHL) quorum sensing (QS). Most AHL receptors are thought to be specific for their cognate signal, ensuring that bacteria cooperate and share resources only with closely related kin cells. Although specificity is considered fundamental to QS, there are reports of “promiscuous” receptors that respond broadly to nonself signals. These promiscuous responses expand the function of QS systems to include interspecies interactions and have been implicated in both interspecies competition and cooperation. Because bacteria are frequently members of polymicrobial communities, AHL cross talk between species could have profound impacts. To better understand the prevalence of QS promiscuity, we measured the activity of seven QS receptors in their native host organisms. To facilitate comparison of our results to previous studies, we also measured receptor activity using heterologous expression inEscherichia coli. We found that the standardE. colimethods consistently overestimate receptor promiscuity and sensitivity and that overexpression of the receptors is sufficient to account for the discrepancy between native andE. colireporters. Additionally, receptor overexpression resulted in AHL-independent activity inPseudomonas aeruginosa. Using our activation data, we developed a quantitative score of receptor selectivity. We find that the receptors display a wide range of selectivity and that most receptors respond sensitively and strongly to at least one nonself signal, suggesting a broad potential for cross talk between QS systems.IMPORTANCESpecific recognition of cognate signals is considered fundamental to cell signaling circuits as it creates fidelity in the communication system. In bacterial quorum sensing (QS), receptor specificity ensures that bacteria cooperate only with kin. There are examples, however, of QS receptors that respond promiscuously to multiple signals. “Eavesdropping” by these promiscuous receptors can be beneficial in both interspecies competition and cooperation. Despite their potential significance, we know little about the prevalence of promiscuous QS receptors. Further, many studies rely on methods requiring receptor overexpression, which is known to increase apparent promiscuity. By systematically studying QS receptors in their natural parent strains, we find that the receptors display a wide range of selectivity and that there is potential for significant cross talk between QS systems. Our results provide a basis for hypotheses about the evolution and function of promiscuous signal receptors and for predictions about interspecies interactions in complex microbial communities.

scholarly journals Nonribosomal Peptides, Key Biocontrol Components for Pseudomonas fluorescens In5, Isolated from a Greenlandic Suppressive Soil

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Charlotte F. Michelsen ◽  
Jeramie Watrous ◽  
Mikkel A. Glaring ◽  
Roland Kersten ◽  
Nobuhiro Koyama ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Imaging Mass Spectrometry ◽  
Disease Outbreaks ◽  
Pathogenic Fungi ◽  
Nonribosomal Peptides ◽  
Plant Pathogenic Fungi ◽  
Content Type ◽  
Cyclic Lipopeptide ◽  
Biocontrol Activity

ABSTRACTPotatoes are cultivated in southwest Greenland without the use of pesticides and with limited crop rotation. Despite the fact that plant-pathogenic fungi are present, no severe-disease outbreaks have yet been observed. In this report, we document that a potato soil at Inneruulalik in southern Greenland is suppressive againstRhizoctonia solaniAg3 and uncover the suppressive antifungal mechanism of a highly potent biocontrol bacterium,Pseudomonas fluorescensIn5, isolated from the suppressive potato soil. A combination of molecular genetics, genomics, and matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) imaging mass spectrometry (IMS) revealed an antifungal genomic island in P. fluorescens In5 encoding two nonribosomal peptides, nunamycin and nunapeptin, which are key components for the biocontrol activity by strain In5in vitroand in soil microcosm experiments. Furthermore, complex microbial behaviors were highlighted. Whereas nunamycin was demonstrated to inhibit the mycelial growth of R. solani Ag3, but not that ofPythium aphanidermatum, nunapeptin instead inhibited P. aphanidermatum but not R. solani Ag3. Moreover, the synthesis of nunamycin by P. fluorescens In5 was inhibited in the presence of P. aphanidermatum. Further characterization of the two peptides revealed nunamycin to be a monochlorinated 9-amino-acid cyclic lipopeptide with similarity to members of the syringomycin group, whereas nunapeptin was a 22-amino-acid cyclic lipopeptide with similarity to corpeptin and syringopeptin.IMPORTANCECrop rotation and systematic pest management are used to only a limited extent in Greenlandic potato farming. Nonetheless, although plant-pathogenic fungi are present in the soil, the farmers do not experience major plant disease outbreaks. Here, we show that a Greenlandic potato soil is suppressive againstRhizoctonia solani, and we unravel the key biocontrol components forPseudomonas fluorescensIn5, one of the potent biocontrol bacteria isolated from this Greenlandic suppressive soil. Using a combination of molecular genetics, genomics, and microbial imaging mass spectrometry, we show that two cyclic lipopeptides, nunamycin and nunapeptin, are important for the biocontrol activity of P. fluorescens In5 bothin vitroand in microcosm assays. Furthermore, we demonstrate that the synthesis of nunamycin is repressed by the oomycetePythium aphanidermatum. Overall, our report provides important insight into interkingdom interference between bacteria and fungi/oomycetes.

scholarly journals In VivoProgrammed Gene Expression Based on Artificial Quorum Networks

2015 ◽  
Vol 81 (15) ◽  
pp. 4984-4992 ◽  
Author(s):  
Teng Chu ◽  
Yajun Huang ◽  
Mingyu Hou ◽  
Qiyao Wang ◽  
Jingfan Xiao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Quorum Sensing ◽  
Cell Density ◽  
Protective Antigen ◽  
Expression System ◽  
Edwardsiella Tarda ◽  
Content Type ◽  
Genetic Components ◽  
Wide Range

ABSTRACTThe quorum sensing (QS) system, as a well-functioning population-dependent gene switch, has been widely applied in many gene circuits in synthetic biology. In our work, an efficient cell density-controlled expression system (QS) was established via engineering of theVibrio fischeri luxI-luxRquorum sensing system. In order to achievein vivoprogrammed gene expression, a synthetic binary regulation circuit (araQS) was constructed by assembling multiple genetic components, including the quorum quenching protein AiiA and the arabinose promoter ParaBAD, into the QS system.In vitroexpression assays verified that the araQS system was initiated only in the absence of arabinose in the medium at a high cell density.In vivoexpression assays confirmed that the araQS system presented anin vivo-triggered and cell density-dependent expression pattern. Furthermore, the araQS system was demonstrated to function well in different bacteria, indicating a wide range of bacterial hosts for use. To explore its potential applicationsin vivo, the araQS system was used to control the production of a heterologous protective antigen in an attenuatedEdwardsiella tardastrain, which successfully evoked efficient immune protection in a fish model. This work suggested that the araQS system could program bacterial expressionin vivoand might have potential uses, including, but not limited to, bacterial vector vaccines.

scholarly journals Pleiotropic Effects of RsmA and RsmE Proteins in Pseudomonas Fluorescens 2P24

2020 ◽  
Author(s):  
Yang Zhang ◽  
Bo Zhang ◽  
Haiyan Wu ◽  
Xiaogang Wu ◽  
Qing Yan ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Double Mutant ◽  
Secretion System ◽  
Plant Diseases ◽  
Fine Tuning ◽  
Substantial Portion ◽  
Rna Seq ◽  
Gene Encoding ◽  
Rhizosphere Bacterium ◽  
Production Cell

Abstract Background: Pseudomonas fluorescens 2P24 is a rhizosphere bacterium that produces 2,4-diacetyphloroglucinol (2,4-DAPG) as the decisive secondary metabolite to suppress soilborne plant diseases. The biosynthesis of 2,4-DAPG is strictly regulated by the RsmA family proteins RsmA and RsmE. However, mutation of both of rsmA and rsmE genes results in reduced bacterial growth.Results: In this study, we showed that overproduction of 2,4-DAPG in the rsmA rsmE double mutant influenced the growth of strain 2P24. This delay of growth could be partially reversal when the phlD gene was deleted or overexpression of the phlG gene encoding the 2,4-DAPG hydrolase in the rsmA rsmE double mutant. RNA-seq analysis of the rsmA rsmE double mutant revealed that a substantial portion of the P. fluorescens genome was regulated by RsmA family proteins. These genes are involved in the regulation of 2,4-DAPG production, cell motility, carbon metabolism, and type six secretion system.Conclusions: These results suggest that RsmA and RsmE are the important regulators of genes involved in the plant-associated strain 2P24 ecologic fitness and operate a sophisticated mechanism for fine-tuning the concentration of 2,4-DAPG in the cells.

scholarly journals The Oxidoreductase DsbA1 negatively influences 2,4-diacetylphloroglucinol biosynthesis by interfering the function of Gcd in Pseudomonas fluorescens 2P24

2020 ◽  
Author(s):  
Bo Zhang ◽  
Hui Zhao ◽  
Xiaogang Wu ◽  
Li-Qun Zhang
Keyword(s):  
Pseudomonas Fluorescens ◽  
Glucose Dehydrogenase ◽  
Fine Tuning ◽  
Two Component System ◽  
Independent Manner ◽  
Disulfide Oxidoreductase ◽  
Two Component ◽  
Biocontrol Activity ◽  
Membrane Bound

Abstract The polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG), produced by Pseudomonas fluorescens 2P24, is positively regulated by the GacS-GacA two-component system. Here we reported on the characterization of DsbA1 (disulfide oxidoreductase) as novel regulator of biocontrol activity in P. fluorescens . Our data showed that mutation of dsbA1 caused the accumulation of 2,4-DAPG in a GacA-independent manner. Further analysis indicated that DsbA1 interacts with membrane-bound glucose dehydrogenase Gcd, which positively regulates the production of 2,4-DAPG. Mutation of cysteine (C)-235, C275, and C578 of Gcd, significantly reduced the interaction with DsbA1, enhanced the activity of Gcd and increased 2,4-DAPG production. Taken together, our results suggest that DsbA1 regulates the 2,4-DAPG concentration via fine-tuning the function of Gcd in P. fluorescens 2P24.

scholarly journals The Oxidoreductase DsbA1 negatively influences 2,4-diacetylphloroglucinol biosynthesis by interfering the function of Gcd in Pseudomonas fluorescens 2P24

2019 ◽  
Author(s):  
Bo Zhang ◽  
Hui Zhao ◽  
Xiaogang Wu ◽  
Li-Qun Zhang
Keyword(s):  
Pseudomonas Fluorescens ◽  
Glucose Dehydrogenase ◽  
Fine Tuning ◽  
Two Component System ◽  
Independent Manner ◽  
Disulfide Oxidoreductase ◽  
Two Component ◽  
Biocontrol Activity ◽  
Membrane Bound

Abstract The polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG), produced by Pseudomonas fluorescens 2P24, is positively regulated by the GacS-GacA two-component system. Here we reported on the characterization of DsbA1 (disulfide oxidoreductase) as novel regulator of biocontrol activity in P. fluorescens . Our data showed that mutation of dsbA1 caused the accumulation of 2,4-DAPG in a GacA-independent manner. Further analysis indicated that DsbA1 interacts with membrane-bound glucose dehydrogenase Gcd, which positively regulates the production of 2,4-DAPG. Mutation of cysteine (C)-235, C275, and C578 of Gcd, significantly reduced the interaction with DsbA1, enhanced the activity of Gcd and increased 2,4-DAPG production. Taken together, our results suggest that DsbA1 regulates the 2,4-DAPG concentration via fine-tuning the function of Gcd in P. fluorescens 2P24.

scholarly journals RpoN-Dependent Direct Regulation of Quorum Sensing and the Type VI Secretion System inPseudomonas aeruginosaPAO1

2018 ◽  
Vol 200 (16) ◽  
Author(s):  
Xiaolong Shao ◽  
Xiaoning Zhang ◽  
Yingchao Zhang ◽  
Miao Zhu ◽  
Pan Yang ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
High Throughput Sequencing ◽  
Functional Characterization ◽  
Secretion System ◽  
Global Regulator ◽  
Type Vi Secretion System ◽  
Related Factors ◽  
Content Type ◽  
Type Vi Secretion ◽  
Wide Range

ABSTRACTPseudomonas aeruginosais a Gram-negative opportunistic pathogen of humans, particularly those with cystic fibrosis. As a global regulator, RpoN controls a group of virulence-related factors and quorum-sensing (QS) genes inP. aeruginosa. To gain further insights into the direct targets of RpoNin vivo, the present study focused on identifying the direct targets of RpoN regulation in QS and the type VI secretion system (T6SS). We performed chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) that identified 1,068 binding sites of RpoN, mostly including metabolic genes, a group of genes in QS (lasI,rhlI, andpqsR) and the T6SS (hcpAandhcpB). The direct targets of RpoN have been verified by electrophoretic mobility shifts assays (EMSA),luxreporter assay, reverse transcription-quantitative PCR, and phenotypic detection. TheΔrpoN::Tc mutant resulted in the reduced production of pyocyanin, motility, and proteolytic activity. However, the production of rhamnolipids and biofilm formation were higher in theΔrpoN::Tc mutant than in the wild type. In summary, the results indicated that RpoN had direct and profound effects on QS and the T6SS.IMPORTANCEAs a global regulator, RpoN controls a wide range of biological pathways, including virulence inP. aeruginosaPAO1. This work shows that RpoN plays critical and global roles in the regulation of bacterial pathogenicity and fitness. ChIP-seq provided a useful database to characterize additional functions and targets of RpoN in the future. The functional characterization of RpoN-mediated regulation will improve the current understanding of the regulatory network of quorum sensing and virulence inP. aeruginosaand other bacteria.

scholarly journals The Oxidoreductase DsbA1 negatively influences 2,4-diacetylphloroglucinol biosynthesis by interfering the function of Gcd in Pseudomonas fluorescens 2P24

2019 ◽  
Author(s):  
Xiaogang Wu ◽  
Bo Zhang ◽  
Hui Zhao ◽  
Li-Qun Zhang
Keyword(s):  
Pseudomonas Fluorescens ◽  
Glucose Dehydrogenase ◽  
Fine Tuning ◽  
Two Component System ◽  
Independent Manner ◽  
Disulfide Oxidoreductase ◽  
Two Component ◽  
Biocontrol Activity ◽  
Membrane Bound

Abstract The polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG), produced by Pseudomonas fluorescens 2P24, is positively regulated by the GacS-GacA two-component system. Here we reported on the characterization of DsbA1 (disulfide oxidoreductase) as novel regulator of biocontrol activity in P. fluorescens . Our data showed that mutation of dsbA1 caused the accumulation of 2,4-DAPG in a GacA-independent manner. Further analysis indicated that DsbA1 interacts with membrane-bound glucose dehydrogenase Gcd, which positively regulates the production of 2,4-DAPG. Mutation of cysteine (C)-235, C275, and C578 of Gcd, significantly reduced the interaction with DsbA1, enhanced the activity of Gcd and increased 2,4-DAPG production. Taken together, our results suggest that DsbA1 regulates the 2,4-DAPG concentration via fine-tuning the function of Gcd in P. fluorescens 2P24.

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