The plant pathogen <i>Pseudomonas fuscovaginae</i> contains two conserved quorum sensing systems involved in virulence and negatively regulated by RsaL and the novel regulator RsaM

Mattiuzzo, Maura; Bertani, Iris; Ferluga, Sara; Cabrio, Laura; Bigirimana, Joseph; Guarnaccia, Corrado; Pongor, Sándor; Maraite, Henri; Venturi, Vittorio

doi:10.1111/j.1462-2920.2010.02316.x

Cited by 58 publications

(79 citation statements)

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“…Despite the importance of P. fuscovaginae as a plant pathogen on several plant hosts around the world, very few studies of the virulence and biology of this pathogen have been performed. In a previous study we investigated the role of the quorum sensing regulatory system in causing sheath brown rot by P. fuscovaginae (9). In the present study, we report the draft genome information of a very virulent P. fuscovaginae strain which, to our knowledge, is the first sequence report of this species.…”

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confidence: 67%

Draft Genome Sequence of Pseudomonas fuscovaginae, a Broad-Host-Range Pathogen of Plants

Patel¹,

Silva²,

Devescovi³

et al. 2012

Journal of Bacteriology

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confidence: 67%

Draft Genome Sequence of Pseudomonas fuscovaginae, a Broad-Host-Range Pathogen of Plants

Patel¹,

Silva²,

Devescovi³

et al. 2012

Journal of Bacteriology

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“…To date, the rsaL gene has been found linked to acyl-HSLdependent QS systems in P. aeruginosa (10,36), in P. putida strains (8,11,35), in Pseudomonas fuscovaginae (24), and in a cluster of 30 Burkholderia spp. (37,38).…”

Section: Discussionmentioning

confidence: 99%

“…In particular, N-acyl-HSL-dependent regulation plays a major role in the pathogenesis of the opportunistic pathogen Pseudomonas aeruginosa and is involved in plant colonization by several Pseudomonas rhizosphere strains (5,12,18,23,24).…”

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confidence: 99%

Functional Characterization of the Quorum Sensing Regulator RsaL in the Plant-Beneficial Strain Pseudomonas putida WCS358

Rampioni¹,

Bertani²,

Pillai³

et al. 2012

Appl Environ Microbiol

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In many bacteria, quorum sensing (QS) systems rely on a signal receptor and a synthase producing N-acyl-homoserine lactone(s) as the signal molecule(s). In some species, the rsaL gene, located between the signal receptor and synthase genes, encodes a repressor limiting signal synthase expression and hence signal molecule production. Here we investigate the molecular mechanism of action of the RsaL protein in the plant growth-promoting rhizobacterium Pseudomonas putida WCS358 (RsaL WCS ). In P. putida WCS358, RsaL WCS displayed a strong repressive effect on the promoter of the QS signal synthase gene, ppuI, while it did not repress the same promoter in Pseudomonas aeruginosa. DNase I protection assays showed that purified RsaL WCS specifically binds to ppuI on a DNA region overlapping the predicted 70 -binding site, but such protection was observed only at high protein concentrations. Accordingly, electrophoretic mobility shift assays showed that the RsaL WCS protein was not able to form stable complexes efficiently with a probe encompassing the ppuI promoter, while it formed stable complexes with the promoter of lasI, the gene orthologous to ppuI in P. aeruginosa. This difference seems to be dictated by the lower dyad symmetry of the RsaL WCS -binding sequence on the ppuI promoter relative to that on the lasI promoter. Comparison of the results obtained in vivo and in vitro suggests that RsaL WCS needs a molecular interactor/cofactor specific for P. putida WCS358 to repress ppuI transcription. We also demonstrate that RsaL WCS regulates siderophore-mediated growth limitation of plant pathogens and biofilm formation, two processes relevant for plant growth-promoting activity.T he cell-cell communication system termed quorum sensing (QS) allows bacterial populations to coordinate gene expression in response to cell density. It is believed that QS constitutes a central element for the social life of bacteria, conferring to the members of a bacterial community the ability to behave as an organized multicellular organism (2, 4).QS systems are based on the production and secretion of signal molecules that accumulate in the extracellular milieu. At a certain concentration, corresponding to the "quorum" cell density, the signal molecules are perceived by dedicated receptors that, once activated, trigger a physiological response concerted in the whole population. The majority of QS systems thus far described in Gram-negative proteobacteria rely on N-acyl homoserine lactones (N-acyl-HSL) as signal molecules; these QS systems have been found in more than 100 bacterial species (14).Several members of the Pseudomonas genus regulate their social behavior through N-acyl-HSL-based QS systems. In particular, N-acyl-HSL-dependent regulation plays a major role in the pathogenesis of the opportunistic pathogen Pseudomonas aeruginosa and is involved in plant colonization by several Pseudomonas rhizosphere strains (5,12,18,23,24).Pseudomonas putida WCS358 is a plant growth-promoting rhizobacterium (PGPR) originally isolated from the ...

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“…The plasmid was transformed in E. coli DH5␣, as previously described (39). The plasmid pMPTswI in combination with pBTswR or pBtswRt was introduced in the heterologous host AHL-negative (AHL Ϫ ) A. tumefaciens NTL4 (43) by triparental conjugation, using HB101 (pRK2013) as a helper strain, as previously described (44). AHL Ϫ A. tumefaciens NTL4 was chosen for reporter studies because it is an alphaproteobacterium, like Rhodobacterales bacterium TS309, and because this strain lacks the pTiC58 plasmid, which carries the QS genes traI and traR, and for this reason cannot interfere with tswR functions.…”

Section: Methodsmentioning

confidence: 99%

A NewN-Acyl Homoserine Lactone Synthase in an Uncultured Symbiont of the Red Sea Sponge Theonella swinhoei

Britstein

Devescovi

Handley

et al. 2016

Appl Environ Microbiol

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i Sponges harbor a remarkable diversity of microbial symbionts in which signal molecules can accumulate and enable cell-cell communication, such as quorum sensing (QS). Bacteria capable of QS were isolated from marine sponges; however, an extremely small fraction of the sponge microbiome is amenable to cultivation. We took advantage of community genome assembly and binning to investigate the uncultured majority of sponge symbionts. We identified a complete N-acyl-homoserine lactone (AHL)-QS system (designated TswIR) and seven partial luxI homologues in the microbiome of Theonella swinhoei. The TswIR system was novel and shown to be associated with an alphaproteobacterium of the order Rhodobacterales, here termed Rhodobacterales bacterium TS309. The tswI gene, when expressed in Escherichia coli, produced three AHLs, two of which were also identified in a T. swinhoei sponge extract. The taxonomic affiliation of the 16S rRNA of Rhodobacterales bacterium TS309 to a sponge-coral specific clade, its enrichment in sponge versus seawater and marine sediment samples, and the presence of spongespecific features, such as ankyrin-like domains and tetratricopeptide repeats, indicate a likely symbiotic nature of this bacterium. Symbiosis between metazoans and microbes exists in virtually every environment, including in marine sponges (phylum Porifera) (1). Marine sponges are important members of shallow and deep reef communities and are a rich source of secondary metabolites with pharmaceutical potential, and these metabolites are often produced by the sponges' microbial symbionts (2, 3). These host-associated bacteria are sponge specific and can comprise up to 35% of the sponge volume (4), spanning at least 47 bacterial phyla (5).In recent years, symbioses between microorganisms and eukaryotic hosts have received growing attention. The host, together with all its symbionts, is now seen as a single entity designated the holobiont, defined as the sum of the genetic information of the host and its microbiota (6). Sponge holobionts provide an enclosed niche in which extensive interactions among dense and diverse microbial populations are accomplished (7). The mechanisms underlying cell-cell interactions among bacteria within the sponge and the genetic regulation systems controlling gene expression in sponge symbionts are largely unknown. One of the best understood microbial quorum-sensing (QS) systems is the one that uses N-acyl-homoserine lactones (AHLs) as signals (e.g., 8-10). QS enables bacteria to regulate their gene expression in a population density-dependent manner. At a low cell density, low levels of AHLs, which diffuse in and out of the bacterial cell, are present. As the bacterial density increases, especially for bacteria enclosed in niches, AHLs accumulate, and once they reach a critical level (quorum), they interact with LuxR cognate receptor proteins, which then affect target gene expression (11). A canonical AHL-QS system produces AHLs via the LuxI family AHL synthase protein and responds to them via the LuxR co...

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The plant pathogen Pseudomonas fuscovaginae contains two conserved quorum sensing systems involved in virulence and negatively regulated by RsaL and the novel regulator RsaM

Cited by 58 publications

References 60 publications

Draft Genome Sequence of Pseudomonas fuscovaginae, a Broad-Host-Range Pathogen of Plants

Draft Genome Sequence of Pseudomonas fuscovaginae, a Broad-Host-Range Pathogen of Plants

Functional Characterization of the Quorum Sensing Regulator RsaL in the Plant-Beneficial Strain Pseudomonas putida WCS358

A NewN-Acyl Homoserine Lactone Synthase in an Uncultured Symbiont of the Red Sea Sponge Theonella swinhoei

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