Quorum Sensing and Expression of Virulence in Pectobacteria

Põllumaa, Lee; Alamäe, Tiina; Mäe, Andres

doi:10.3390/s120303327

Cited by 80 publications

(95 citation statements)

References 109 publications

(183 reference statements)

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“…According to the working model of QS regulation in Pectobacterium species, high levels of ExpI leads to a reduction of rsmA expression, which ultimately results in higher level of PCWDEs gene expression83940. In agreement with this model, in our experiments we observed that under control conditions, rsmA displayed low expression patterns in both strains.…”

Section: Discussionsupporting

confidence: 88%

Plant phenolic volatiles inhibit quorum sensing in pectobacteria and reduce their virulence by potential binding to ExpI and ExpR proteins

Joshi

Khazanov

Senderowitz

et al. 2016

Sci Rep

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Quorum sensing (QS) is a population density-dependent regulatory system in bacteria that couples gene expression to cell density through accumulation of diffusible signaling molecules. Pectobacteria are causal agents of soft rot disease in a range of economically important crops. They rely on QS to coordinate their main virulence factor, production of plant cell wall degrading enzymes (PCWDEs). Plants have evolved an array of antimicrobial compounds to anticipate and cope with pathogens, of which essential oils (EOs) are widely recognized. Here, volatile EOs, carvacrol and eugenol, were shown to specifically interfere with QS, the master regulator of virulence in pectobacteria, resulting in strong inhibition of QS genes, biofilm formation and PCWDEs, thereby leading to impaired infection. Accumulation of the signal molecule N-acylhomoserine lactone declined upon treatment with EOs, suggesting direct interaction of EOs with either homoserine lactone synthase (ExpI) or with the regulatory protein (ExpR). Homology models of both proteins were constructed and docking simulations were performed to test the above hypotheses. The resulting binding modes and docking scores of carvacrol and eugenol support potential binding to ExpI/ExpR, with stronger interactions than previously known inhibitors of both proteins. The results demonstrate the potential involvement of phytochemicals in the control of Pectobacterium.

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Section: Discussionsupporting

confidence: 88%

Plant phenolic volatiles inhibit quorum sensing in pectobacteria and reduce their virulence by potential binding to ExpI and ExpR proteins

Joshi

Khazanov

Senderowitz

et al. 2016

Sci Rep

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“…PGPR are able to stimulate plant growth by direct or indirect mechanisms, like production of phytohormones, mineralization of organic matter, and competing with pathogens (Ortiz-Castro et al, 2009). Some Pseudomonas and Vibrio species were considered to be potential pathogen to wetland plants (Pollumaa et al, 2012). Previously, QS has been shown to control Ti plasmid transfer in tumor-forming Agrobacterium spp.…”

Section: Discussionmentioning

confidence: 99%

“…Previously, QS has been shown to control Ti plasmid transfer in tumor-forming Agrobacterium spp. and virulence factor production in soft-rotting P. carotovorum (Pollumaa et al, 2012; Lang et al, 2016). Communication via diffusible signaling molecules between plants and bacteria has been proposed to be one of the important regulators in symbiotic behaviors (Scott et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Diverse Profiles of AI-1 Type Quorum Sensing Molecules in Cultivable Bacteria from the Mangrove (Kandelia obovata) Rhizosphere Environment

Lao

Jin

et al. 2016

Front. Microbiol.

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Mangrove rhizosphere environment harbors diverse populations of microbes, and some evidence showed that rhizobacteria behavior was regulated by quorum sensing (QS). Investigating the diverse profiles of QS molecules in mangrove ecosystems may shed light on the bacterial roles and lead to a better understanding of the symbiotic interactions between plants and microbes. The aims of the current study focus on identifying AI-1 type QS signals, i.e., acyl homoserine lactones (AHLs), in Kandelia obovata rhizosphere environment. Approximately 1200 rhizobacteria were screened and 184 strains (15.3%) tested were positive. Subsequent 16s rRNA gene sequencing and dereplication analyses identified 24 species from the positive isolates, which were affiliated to three different phyla, including Proteobacteria, Firmicutes, and Actinobacteria. Thin-layer chromatography separation of extracts revealed diverse AHL profiles and detected at least one active compound in the supernatant of these 24 cultivable AHL-producers. The active extracts from these bacterial isolates were further evaluated by ultra performance liquid chromatography-mass spectrometry, and the carbon side chain length ranged from C4 to C14. This is the first report on the diversity of AI-1 type auto-inducers in the mangrove plant K. obovata, and it is imperative to expand our knowledge of plant-bacteria interactions with respect to the maintenance of wetland ecosystem health.

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“…have a large impact on the progress of the disease, as their production leads to the degradation of invaded plant tissue (2,3). The production of these enzymes is dependent on cell density and regulated by quorum sensing through N-acetylhomoserine lactone (5) and intracellular regulators (6,7). Motility and nutrient uptake are also factors influencing phytopathogenicity (4,(8)(9)(10).…”

mentioning

confidence: 99%

SaxA-Mediated Isothiocyanate Metabolism in Phytopathogenic Pectobacteria

Welte

Rosengarten

Graaf

et al. 2016

Appl Environ Microbiol

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Pectobacteria are devastating plant pathogens that infect a large variety of crops, including members of the family Brassicaceae. To infect cabbage crops, these plant pathogens need to overcome the plant's antibacterial defense mechanisms, where isothiocyanates are liberated by hydrolysis of glucosinolates. Here, we found that a Pectobacterium isolate from the gut of cabbage root fly larvae was particularly resistant to isothiocyanate and even seemed to benefit from the abundant Brassica root metabolite 2-phenylethyl isothiocyanate as a nitrogen source in an ecosystem where nitrogen is scarce. The Pectobacterium isolate harbored a naturally occurring mobile plasmid that contained a sax operon. We hypothesized that SaxA was the enzyme responsible for the breakdown of 2-phenylethyl isothiocyanate. Subsequently, we heterologously produced and purified the SaxA protein and characterized the recombinant enzyme. It hydrolyzed 2-phenylethyl isothiocyanate to yield the products carbonyl sulfide and phenylethylamine. It was also active toward another aromatic isothiocyanate but hardly toward aliphatic isothiocyanates. It belongs to the class B metal-dependent beta-lactamase fold protein family but was not, however, able to hydrolyze beta-lactam antibiotics. We discovered that several copies of the saxA gene are widespread in full and draft Pectobacterium genomes and therefore hypothesize that SaxA might be a new pathogenicity factor of the genus Pectobacterium, possibly compromising food preservation strategies using isothiocyanates. P ectobacteria are phytopathogens that cause tuber soft rot and blackleg (stem rot) in many horticulturally and economically important crops during cultivation, transport, or storage. Most Pectobacterium spp., e.g., Pectobacterium carotovorum or P. wasabiae, can be detrimental to many different plants, such as potato, sugar beet, cabbage, wasabi, chicory, and Ornithogalum plants, whereas other Pectobacterium spp., e.g., P. atrosepticum and P. betavasulorum, have a more narrow host range of potato and sugar beet plants, respectively (1).Several pathogenicity factors of soft-rot-causing Pectobacterium spp. have been found during the last decades (2-4). Of these, plant cell wall-degrading enzymes produced by Pectobacterium spp. have a large impact on the progress of the disease, as their production leads to the degradation of invaded plant tissue (2, 3). The production of these enzymes is dependent on cell density and regulated by quorum sensing through N-acetylhomoserine lactone (5) and intracellular regulators (6, 7). Motility and nutrient uptake are also factors influencing phytopathogenicity (4,(8)(9)(10). Besides these general pathogenicity factors, phytopathogens have to overcome the toxicity of plant allelochemicals. Important allelochemicals of members of the family Brassicaceae (cabbages and mustards) are isothiocyanates that are liberated by the glucosinolate-myrosinase defense system (11-13). The antimicrobial effect of isothiocyanates has been mainly attributed to their reactivity w...

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Quorum Sensing and Expression of Virulence in Pectobacteria

Cited by 80 publications

References 109 publications

Plant phenolic volatiles inhibit quorum sensing in pectobacteria and reduce their virulence by potential binding to ExpI and ExpR proteins

Plant phenolic volatiles inhibit quorum sensing in pectobacteria and reduce their virulence by potential binding to ExpI and ExpR proteins

Diverse Profiles of AI-1 Type Quorum Sensing Molecules in Cultivable Bacteria from the Mangrove (Kandelia obovata) Rhizosphere Environment

SaxA-Mediated Isothiocyanate Metabolism in Phytopathogenic Pectobacteria

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