scholarly journals Transgenic Plants Producing the Bacterial Pheromone N-Acyl-Homoserine Lactone Exhibit Enhanced Resistance to the Bacterial Phytopathogen Erwinia carotovora

2001 ◽  
Vol 14 (9) ◽  
pp. 1035-1042 ◽  
Author(s):  
Andres Mäe ◽  
Marcos Montesano ◽  
Viia Koiv ◽  
E. Tapio Palva
Keyword(s):  
Quorum Sensing ◽  
Transgenic Tobacco ◽  
Plant Cell Wall ◽  
Ectopic Expression ◽  
Erwinia Carotovora ◽  
Homoserine Lactone ◽  
Defense Responses ◽  
Dependent Manner ◽  
Wild Type ◽  
Enhanced Resistance

Bacterial pheromones, mainly different homoserine lactones, are central to a number of bacterial signaling processes, including those involved in plant pathogenicity. We previously demonstrated that N-oxoacyl-homoserine lactone (OHL) is essential for quorum sensing in the soft-rot phytopathogen Erwinia carotovora. In this pathogen, OHL controls the coordinate activation of genes encoding the main virulence determinants, extracellular plant cell wall degrading enzymes (PCWDEs), in a cell density-dependent manner. We suggest that E. carotovora employ quorum sensing to avoid the premature production of PCWDEs and subsequent activation of plant defense responses. To test whether modulating this sensory system would affect the outcome of a plant-pathogen interaction, we generated transgenic tobacco, producing OHL. This was accomplished by ectopic expression in tobacco of the E. carotovora gene expI, which is responsible for OHL biosynthesis. We show that expI-positive transgenic tobacco lines produced the active pheromone and partially complemented the avirulent phenotype of expI mutants. The OHL-producing tobacco lines exhibited enhanced resistance to infection by wild-type E. carotovora. The results were confirmed by exogenous addition of OHL to wild-type plants, which also resulted in increased resistance to E. carotovora.

scholarly journals Quorum sensing regulation in Erwinia carotovora affects development of Drosophila melanogaster infected larvae

2019 ◽  
Author(s):  
Filipe J. D. Vieira ◽  
Pol Nadal-Jimenez ◽  
Luis Teixeira ◽  
Karina B. Xavier
Keyword(s):  
Drosophila Melanogaster ◽  
Quorum Sensing ◽  
Developmental Delay ◽  
Virulence Factors ◽  
Virulence Factor ◽  
Plant Cell Wall ◽  
Erwinia Carotovora ◽  
Homoserine Lactone ◽  
Pectolytic Enzymes ◽  
Two Component

AbstractMulti-host bacteria must rapidly adapt to drastic environmental changes, relying on integration of multiple stimuli for an optimal genetic response. Erwinia spp. are phytopathogens that cause soft-rot disease in plants. Erwinia carotovora Ecc15 is used as a model for bacterial oral-route infection in Drosophila melanogaster as it harbors a gene, the Erwinia virulence factor (Evf), which has been previously shown to be a major determinant for infection of D. melanogaster gut. However, the factors involved in regulation of evf expression are poorly understood. We investigated whether evf could be controlled by quorum sensing since, in the Erwinia genus, quorum sensing regulates pectolytic enzymes, the major virulence factors needed to infect plants. Here, we show that transcription of evf is positively regulated by quorum sensing in Ecc15 via the acyl-homoserine lactone (AHL) signal synthase ExpI, and the AHL receptors ExpR1 and ExpR2. Moreover, we demonstrate that the GacS/A two-component system is partially required for evf expression. We also show that the load of Ecc15 in the gut depends upon the quorum sensing-mediated regulation of evf. Furthermore, we demonstrate that larvae infected with Ecc15 suffer a developmental delay as a direct consequence of the regulation of evf via quorum sensing. Overall, our results show that Ecc15 relies on quorum sensing to control production of both pectolytic enzymes and Evf. This regulation influences the interaction of Ecc15 with its two known hosts, indicating that quorum sensing and GacS/A signaling systems may impact bacterial dissemination via insect vectors that feed on rotting plants.SignificanceIntegration of genetic networks allows bacteria to rapidly adapt to changing environments. This is particularly important in bacteria that interact with multiple hosts. Erwinia carotovora Ecc15 is a plant pathogen that uses Drosophila melanogaster as a vector. To interact with these two hosts, Ecc15 uses two different sets of virulence factors: plant cell wall-degrading enzymes to infect plants and the Erwinia virulence factor (evf) to infect Drosophila. Our work shows that, despite the virulence factors being different, both are regulated by homoserine lactone quorum sensing and the two component GacS/A system. Moreover, we show that these pathways are essential for Ecc15 loads in the gut of Drosophila and that this interaction carries a cost to the vector in the form of a developmental delay. Our findings provide evidence for the importance of quorum sensing regulation in the establishment of multi-host interactions.

scholarly journals Erwinia carotovora Quorum Sensing System Regulates Host-Specific Virulence Factors and Development Delay in Drosophila melanogaster

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Filipe J. D. Vieira ◽  
Pol Nadal-Jimenez ◽  
Luis Teixeira ◽  
Karina B. Xavier
Keyword(s):  
Cell Wall ◽  
Drosophila Melanogaster ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Plant Cell Wall ◽  
Erwinia Carotovora ◽  
Homoserine Lactone ◽  
Cell Wall Degrading Enzymes ◽  
Content Type ◽  
Pectolytic Enzymes

ABSTRACT Multihost bacteria have to rapidly adapt to drastic environmental changes, relying on a fine integration of multiple stimuli for an optimal genetic response. Erwinia carotovora spp. are phytopathogens that cause soft-rot disease. Strain Ecc15 in particular is a model for bacterial oral-route infection in Drosophila melanogaster as it harbors a unique gene, evf, that encodes the Erwinia virulence factor (Evf), which is a major determinant for infection of the D. melanogaster gut. However, the factors involved in the regulation of evf expression are poorly understood. We investigated whether evf could be controlled by quorum sensing as, in the Erwinia genus, quorum sensing regulates pectolytic enzymes, the major virulence factors needed to infect plants. Here, we show that transcription of evf is positively regulated by quorum sensing in Ecc15 via acyl-homoserine lactone (AHL) signal synthase ExpI and AHL receptors ExpR1 and ExpR2. We also show that the load of Ecc15 in the gut depends upon the quorum sensing-mediated regulation of evf. Furthermore, we demonstrate that larvae infected with Ecc15 suffer a developmental delay as a direct consequence of the regulation of evf via quorum sensing. Finally, we demonstrate that evf is coexpressed with plant cell wall-degrading enzymes (PCWDE) during plant infection in a quorum sensing-dependent manner. Overall, our results show that Ecc15 relies on quorum sensing to control production of both pectolytic enzymes and Evf. This regulation influences the interaction of Ecc15 with its two known hosts, indicating that quorum sensing signaling may impact bacterial dissemination via insect vectors that feed on rotting plants. IMPORTANCE Integration of genetic networks allows bacteria to rapidly adapt to changing environments. This is particularly important in bacteria that interact with multiple hosts. Erwinia carotovora is a plant pathogen that uses Drosophila melanogaster as a vector. To interact with these two hosts, Ecc15 uses different sets of virulence factors: plant cell wall-degrading enzymes to infect plants and the Erwinia virulence factor (evf) to infect Drosophila. Our work shows that, despite the virulence factors being specific for each host, both sets are coactivated by homoserine lactone quorum sensing and by the two-component GacS/A system in infected plants. This regulation is essential for Ecc15 loads in the gut of Drosophila and minimizes the developmental delay caused by the bacteria with respect to the insect vector. Our findings provide evidence that coactivation of the host-specific factors in the plant may function as a predictive mechanism to maximize the probability of transit of the bacteria between hosts.

scholarly journals RelA-Dependent (p)ppGpp Production Controls Exoenzyme Synthesis in Erwinia carotovora subsp. atroseptica

2007 ◽  
Vol 189 (21) ◽  
pp. 7643-7652 ◽  
Author(s):  
Jinhong Wang ◽  
Noemie Gardiol ◽  
Tom Burr ◽  
George P. C. Salmond ◽  
Martin Welch
Keyword(s):  
Quorum Sensing ◽  
Nutrient Limitation ◽  
Pectate Lyase ◽  
Erwinia Carotovora ◽  
Homoserine Lactone ◽  
Competitive Inhibitor ◽  
Pcr Analysis ◽  
Wild Type ◽  
Signal Molecule ◽  
Potent Inducer

ABSTRACT In this report, we investigate the link between nutrient limitation, RelA-mediated (p)ppGpp production, and virulence in the phytopathogen Erwinia carotovora subsp. atroseptica. A relA null mutant (JWC7) was constructed by allelic exchange, and we confirmed that, unlike the wild-type progenitor, this mutant did not produce elevated levels of (p)ppGpp upon nutrient downshift. However, (p)ppGpp production could be restored in strain JWC7 during nutrient limitation by supplying relA in trans. During growth on exoenzyme-inducing minimal medium, the relA mutant showed a diminution in secreted pectate lyase and protease activities and a severe defect in motility. The relA mutant was also impaired in its ability to cause rot in potato tubers. In the presence of serine hydroxamate (a competitive inhibitor of seryl tRNA synthase and a potent inducer of the stringent response in wild-type E. carotovora subsp. atroseptica), exoenzyme production was essentially abolished in JWC7 but could be restored in the presence of plasmid-borne relA. The inhibition of exoenzyme production in JWC7 caused by serine hydroxamate could not be overcome by addition of the quorum-sensing signal molecule, N-3-oxohexanoyl-l-homoserine lactone. Quantitative reverse transcription-PCR analysis of selected RNA species confirmed that the effects of relA on secreted pectate lyase activity and motility could be attributed to a reduction in transcription of the corresponding genes. We conclude that nutrient limitation is a potent environmental cue that triggers (p)ppGpp-dependent exoenzyme production in E. carotovora subsp. atroseptica. Furthermore, our data suggest that nutrient limitation [or rather, (p)ppGpp accumulation] is a prerequisite for effective quorum-sensing-dependent activation of exoenzyme production.

Optimization of Vibrio harveyi Luminometry Assay for Detecting Quorum Sensing Inhibitors

2005 ◽  
Vol 277-279 ◽  
pp. 19-22
Author(s):  
Yeon Hee Kim ◽  
Y. Kim ◽  
Sung Hoon Park ◽  
Jung Sun Kim
Keyword(s):  
Quorum Sensing ◽  
Vibrio Harveyi ◽  
Homoserine Lactone ◽  
Dependent Manner ◽  
Wild Type ◽  
Signal Molecule ◽  
Homoserine Lactones ◽  
Quorum Sensing Inhibitors ◽  
Chain Lengths ◽  
Dose Dependent

The luminometry assay using the wild-type Vibrio harveyi BB120 was evaluated as a possible detection method for quorum sensing inhibitors. The effects of the concentration of the quorum sensing signal molecule (AHL) as well as the cell density of the reporter strain and the different AHL analogues on luminescence expressed as relative light units (RLU) were examined. Inhibition of V. harveyi luminescence was observed in a dose dependent manner for all five AHL analogues. The RLU values exhibited linearity within the range of 2.9 x 102 ~ 3.2 x 105. Detection up to 102nM was possible for dodecanoyl-homoserine lactone and AHLs with alkyl chain lengths of C-8~C-14 were more active than the shorter chain-lengthed hexanoyl-homoserine lactones. Lipophilicity of the AHL seems to affect the sensitivity of the assay.

scholarly journals N-3-Hydroxy Dodecanoyl-DL-homoserine Lactone (OH-dDHL) Triggers Apoptosis of Bone Marrow-Derived Macrophages through the ER- and Mitochondria-Mediated Pathways

2021 ◽  
Vol 22 (14) ◽  
pp. 7565
Author(s):  
Kyungho Woo ◽  
Dong Ho Kim ◽  
Man Hwan Oh ◽  
Ho Sung Park ◽  
Chul Hee Choi
Keyword(s):  
Bone Marrow ◽  
Quorum Sensing ◽  
Deletion Mutant ◽  
Transmembrane Protein ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Host Responses ◽  
Wild Type ◽  
Mutant Strains

Quorum sensing of Acinetobacter nosocomialis for cell-to-cell communication produces N-3-hydroxy dodecanoyl-DL-homoserine lactone (OH-dDHL) by an AnoR/I two-component system. However, OH-dDHL-driven apoptotic mechanisms in hosts have not been clearly defined. Here, we investigated the induction of apoptosis signaling pathways in bone marrow-derived macrophages treated with synthetic OH-dDHL. Moreover, the quorum-sensing system for virulence regulation was evaluated in vivo using wild-type and anoI-deletion mutant strains. OH-dDHL decreased the viability of macrophage and epithelial cells in dose- and time-dependent manners. OH-dDHL induced Ca2+ efflux and caspase-12 activation by ER stress transmembrane protein (IRE1 and ATF6a p50) aggregation and induced mitochondrial dysfunction through reactive oxygen species (ROS) production, which caused cytochrome c to leak. Pretreatment with a pan-caspase inhibitor reduced caspase-3, -8, and -9, which were activated by OH-dDHL. Pro-inflammatory cytokine and paraoxonase-2 (PON2) gene expression were increased by OH-dDHL. We showed that the anoI-deletion mutant strains have less intracellular invasion compared to the wild-type strain, and their virulence, such as colonization and dissemination, was decreased in vivo. Consequently, these findings revealed that OH-dDHL, as a virulence factor, contributes to bacterial infection and survival as well as the modification of host responses in the early stages of infection.

scholarly journals Quorum Sensing: a Transcriptional Regulatory System Involved in the Pathogenicity of Burkholderia mallei

2004 ◽  
Vol 72 (11) ◽  
pp. 6589-6596 ◽  
Author(s):  
Ricky L. Ulrich ◽  
David DeShazer ◽  
Harry B. Hines ◽  
Jeffrey A. Jeddeloh
Keyword(s):  
Quorum Sensing ◽  
Virulence Factor ◽  
Regulatory System ◽  
In Silico Analysis ◽  
Homoserine Lactone ◽  
Burkholderia Mallei ◽  
Wild Type ◽  
Transcriptional Regulatory ◽  
A Cell

ABSTRACT Numerous gram-negative bacterial pathogens regulate virulence factor expression by using a cell density mechanism termed quorum sensing (QS). An in silico analysis of the Burkholderia mallei ATCC 23344 genome revealed that it encodes at least two luxI and four luxR homologues. Using mass spectrometry, we showed that wild-type B. mallei produces the signaling molecules N-octanoyl-homoserine lactone and N-decanoyl-homoserine lactone. To determine if QS is involved in the virulence of B. mallei, we generated mutations in each putative luxIR homologue and tested the pathogenicities of the derivative strains in aerosol BALB/c mouse and intraperitoneal hamster models. Disruption of the B. mallei QS alleles, especially in RJ16 (bmaII) and RJ17 (bmaI3), which are luxI mutants, significantly reduced virulence, as indicated by the survival of mice who were aerosolized with 104 CFU (10 50% lethal doses [LD50s]). For the B. mallei transcriptional regulator mutants (luxR homologues), mutation of the bmaR5 allele resulted in the most pronounced decrease in virulence, with 100% of the challenged animals surviving a dose of 10 LD50s. Using a Syrian hamster intraperitoneal model of infection, we determined the LD50s for wild-type B. mallei and each QS mutant. An increase in the relative LD50 was found for RJ16 (bmaI1) (>967 CFU), RJ17 (bmaI3) (115 CFU), and RJ20 (bmaR5) (151 CFU) compared to wild-type B. mallei (<13 CFU). These findings demonstrate that B. mallei carries multiple luxIR homologues that either directly or indirectly regulate the biosynthesis of an essential virulence factor(s) that contributes to the pathogenicity of B. mallei in vivo.

scholarly journals Ectopic Expression of the Rice Lumazine Synthase Gene Contributes to Defense Responses in Transgenic Tobacco

2010 ◽  
Vol 100 (6) ◽  
pp. 573-581 ◽  
Author(s):  
Tingquan Wu ◽  
An Guo ◽  
Yanying Zhao ◽  
Xiaomeng Wang ◽  
Ying Wang ◽  
...  
Keyword(s):  
Jasmonic Acid ◽  
Transgenic Tobacco ◽  
Plant Defenses ◽  
Higher Plants ◽  
Synergistic Effects ◽  
Ectopic Expression ◽  
Defense Responses ◽  
Flavin Mononucleotide ◽  
Lumazine Synthase ◽  
Ethylene Content

Lumazine synthase (LS) catalyzes the penultimate reaction in the multistep riboflavin biosynthesis pathway, which is involved in plant defenses. Plant defenses are often subject to synergistic effects of jasmonic acid and ethylene whereas LS is a regulator of jasmonic acid signal transduction. However, little is known about whether the enzyme contributes to defense responses. To study the role of LS in plant pathogen defenses, we generated transgenic tobacco expressing the rice (Oryza sativa) LS gene, OsLS. OsLS was cloned and found to have strong identity with its homologues in higher plants and less homology to microbial orthologues. The OsLS protein localized to chloroplasts in three OsLS-expressing transgenic tobacco (LSETT) lines characterized as enhanced in growth and defense. Compared with control plants, LSETT had higher content of both riboflavin and the cofactors flavin mononucleotide and flavin adenine dinucleotide. In LSETT, jasmonic acid and ethylene were elevated, the expression of defense-related genes was induced, levels of resistance to pathogens were enhanced, and resistance was effective to viral, bacterial, and oomycete pathogens. Extents of OsLS expression correlated with increases in flavin, jasmonic acid, and ethylene content, and correlated with increases in resistance levels, suggesting a role for OsLS in defense responses.

scholarly journals The Quorum-Sensing Molecule Autoinducer 2 Regulates Motility and Flagellar Morphogenesis in Helicobacter pylori

2007 ◽  
Vol 189 (17) ◽  
pp. 6109-6117 ◽  
Author(s):  
Bethany A. Rader ◽  
Shawn R. Campagna ◽  
Martin F. Semmelhack ◽  
Bonnie L. Bassler ◽  
Karen Guillemin
Keyword(s):  
Helicobacter Pylori ◽  
Quorum Sensing ◽  
Sigma Factor ◽  
Critical Role ◽  
Soft Agar ◽  
Dependent Manner ◽  
Flagellar Gene ◽  
Wild Type ◽  
Autoinducer 2 ◽  
Mutant Phenotypes

ABSTRACT The genome of the gastric pathogen Helicobacter pylori contains a homologue of the gene luxS, which has been shown to be responsible for production of the quorum-sensing signal autoinducer 2 (AI-2). We report here that deletion of the luxS gene in strain G27 resulted in decreased motility on soft agar plates, a defect that was complemented by a wild-type copy of the luxS gene and by the addition of cell-free supernatant containing AI-2. The flagella of the luxS mutant appeared normal; however, in genetic backgrounds lacking any of three flagellar regulators—the two-component sensor kinase flgS, the sigma factor σ28 (also called fliA), and the anti-sigma factor flgM—loss of luxS altered flagellar morphology. In all cases, the double mutant phenotypes were restored to the luxS + phenotype by the addition of synthetic 4,5-dihydroxy-2,3-pentanedione (DPD), which cyclizes to form AI-2. Furthermore, in all mutant backgrounds loss of luxS caused a decrease in transcript levels of the flagellar regulator flhA. Addition of DPD to luxS cells induced flhA transcription in a dose-dependent manner. Deletion of flhA in a wild-type or luxS mutant background resulted in identical loss of motility, flagella, and flagellar gene expression. These data demonstrate that AI-2 functions as a secreted signaling molecule upstream of FlhA and plays a critical role in global regulation of flagellar gene transcription in H. pylori.

scholarly journals The Xanthomonas type-III effector protein XopS stabilizes CaWRKY40a to regulate defense hormone responses and preinvasion immunity in pepper (Capsicum annuum)

2021 ◽  
Author(s):  
Margot Raffeiner ◽  
Suayib Üstün ◽  
Tiziana Guerra ◽  
Daniela Spinti ◽  
Maria Fitzner ◽  
...  
Keyword(s):  
Gene Expression ◽  
Xanthomonas Campestris ◽  
Stomatal Closure ◽  
Ectopic Expression ◽  
Defense Responses ◽  
Dependent Manner ◽  
Plant Tolerance ◽  
Defense Gene Expression ◽  
Type Iii Effector ◽  
Type Iii

A critical component of plant immunity against invading pathogens is the rapid transcriptional reprogramming of the attacked cell to minimize virulence. Many adapted plant bacterial pathogens use type III effector (T3E) proteins to interfere with plant defense responses, including the induction of immunity genes. The elucidation of effector function is essential to understanding bacterial pathogenesis. Here, we show that XopS, a T3E of Xanthomonas campestris pv. vesicatoria (Xcv), interacts with and inhibits the proteasomal degradation of the transcriptional regulator of defense gene expression WRKY40. Virus-induced gene silencing of WRKY40 in pepper enhanced plant tolerance towards Xcv infection, indicating it represses immunity. Stabilization of WRKY40 by XopS reduces the expression of its targets including salicylic acid (SA)-responsive genes and the jasmonic acid (JA) signaling repressor JAZ8. Xcv bacteria lacking XopS display significantly reduced virulence when surface inoculated onto susceptible pepper leaves. XopS delivery by Xcv, as well as ectopic expression of XopS in Arabidopsis or Nicotiana benthamiana prevented stomatal closure in response to bacteria and biotic elicitors in a WRKY40 dependent manner. This suggests that XopS interferes with preinvasion as well as with apoplastic defense by manipulating WRKY40 stability and gene expression eventually altering phytohormone crosstalk to promote pathogen proliferation.

scholarly journals CbfA, the C-Module DNA-Binding Factor, Plays an Essential Role in the Initiation of Dictyostelium discoideum Development

2004 ◽  
Vol 3 (5) ◽  
pp. 1349-1358 ◽  
Author(s):  
Thomas Winckler ◽  
Negin Iranfar ◽  
Peter Beck ◽  
Ingo Jennes ◽  
Oliver Siol ◽  
...  
Keyword(s):  
Dna Binding ◽  
Cell Density ◽  
Dictyostelium Discoideum ◽  
Ectopic Expression ◽  
Development Program ◽  
Cell Physiology ◽  
Dependent Manner ◽  
Wild Type ◽  
Gene Encoding ◽  
Multicellular Development

ABSTRACT We recently isolated from Dictyostelium discoideum cells a DNA-binding protein, CbfA, that interacts in vitro with a regulatory element in retrotransposon TRE5-A. We have generated a mutant strain that expresses CbfA at <5% of the wild-type level to characterize the consequences for D. discoideum cell physiology. We found that the multicellular development program leading to fruiting body formation is highly compromised in the mutant. The cells cannot aggregate and stay as a monolayer almost indefinitely. The cells respond properly to prestarvation conditions by expressing discoidin in a cell density-dependent manner. A genomewide microarray-assisted expression analysis combined with Northern blot analyses revealed a failure of CbfA-depleted cells to induce the gene encoding aggregation-specific adenylyl cyclase ACA and other genes required for cyclic AMP (cAMP) signal relay, which is necessary for aggregation and subsequent multicellular development. However, the cbfA mutant aggregated efficiently when mixed with as few as 5% wild-type cells. Moreover, pulsing cbfA mutant cells developing in suspension with nanomolar levels of cAMP resulted in induction of acaA and other early developmental genes. Although the response was less efficient and slower than in wild-type cells, it showed that cells depleted of CbfA are able to initiate development if given exogenous cAMP signals. Ectopic expression of the gene encoding the catalytic subunit of protein kinase A restored multicellular development of the mutant. We conclude that sensing of cell density and starvation are independent of CbfA, whereas CbfA is essential for the pattern of gene expression which establishes the genetic network leading to aggregation and multicellular development of D. discoideum.

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