scholarly journals Novel piece of the puzzle: ALI1 is required for oxo-C14-HSL priming in Arabidopsis

2021 ◽  
Author(s):  
Abhishek Shrestha ◽  
Casandra Hernandez-Reyes ◽  
Maja Grimm ◽  
Johannes Krumwiede ◽  
Elke Stein ◽  
...  
Keyword(s):  
Growth Promotion ◽  
Homoserine Lactone ◽  
Side Chain ◽  
Bacterial Cells ◽  
Wild Type ◽  
Resistance Response ◽  
Short Side ◽  
Bacterial Communication ◽  
Homoserine Lactones ◽  
Enhanced Resistance

Quorum sensing (QS) molecules mediate communication between bacterial cells. N-acyl homoserine lactones (AHL) are one of the best-studied groups of QS molecules. In addition to bacterial communication, AHL are involved in interactions with eukaryotes. Short side-chain AHL are readily taken up by plants. They induce root elongation and growth promotion. Hydrophobic long side-chain AHL are usually not transported over long distances although, they may prime plants for enhanced resistance. Unfortunately, studies elucidating the plant factors required for response to AHL are sparse. Here, we provide evidence of a plant protein, namely the AHL-priming protein 1 (ALI1), indispensable for enhanced resistance response induced by the N-3-oxotetradecanoyl-homoserine lactone (oxo-C14-HSL). Comparing Col-0 and the ali1 mutant, we revealed loss of AHL-priming in ali1. This phenomenon is reverted with the reintroduction of ALI1 into ali1. Additional transcriptome analysis revealed that ali1 is less sensitive to oxo-C14-HSL treatment compared to the wild-type. Our results suggest, therefore, that ALI1 is required for oxo-C14-HSL-dependent priming for enhanced resistance in Arabidopsis.

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 Analysis of Quorum-Sensing-Dependent Control of Rhizosphere-Expressed (rhi) Genes in Rhizobium leguminosarum bv. viciae

1999 ◽  
Vol 181 (12) ◽  
pp. 3816-3823 ◽  
Author(s):  
Belen Rodelas ◽  
James K. Lithgow ◽  
Florence Wisniewski-Dye ◽  
Andrea Hardman ◽  
Adam Wilkinson ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Culture Supernatant ◽  
Homoserine Lactone ◽  
Dependent Manner ◽  
Chemical Analyses ◽  
Wild Type ◽  
Homoserine Lactones ◽  
Acyl Homoserine Lactones ◽  
A Cell ◽  
Culture Supernatants

ABSTRACT The rhi genes of Rhizobium leguminosarumbiovar viciae are expressed in the rhizosphere and play a role in the interaction with legumes, such as the pea. Previously (K. M. Gray, J. P. Pearson, J. A. Downie, B. E. A. Boboye, and E. P. Greenberg, J. Bacteriol. 178:372–376, 1996) therhiABC operon had been shown to be regulated by RhiR and to be induced by addedN-(3-hydroxy-7-cis-tetradecenoyl)-l-homoserine lactone (3OH,C14:1-HSL). Mutagenesis of a cosmid carrying the rhiABC and rhiR gene region identified a gene (rhiI) that affects the level of rhiAexpression. Mutation of rhiI slightly increased the number of nodules formed on the pea. The rhiI gene is (likerhiA) regulated by rhiR in a cell density-dependent manner. RhiI is similar to LuxI and other proteins involved in the synthesis of N-acyl-homoserine lactones (AHLs). Chemical analyses of spent culture supernatants demonstrated that RhiI produces N-(hexanoyl)-l-homoserine lactone (C6-HSL) andN-(octanoyl)-l-homoserine lactone (C8-HSL). Both of these AHLs induced rhiA-lacZand rhiI-lacZ expression on plasmids introduced into anAgrobacterium strain that produces no AHLs, showing thatrhiI is positively regulated by autoinduction. However, in this system no induction of rhiA or rhiI with 3OH,C14:1-HSL was observed. Analysis of the spent culture supernatant of the wild-type R. leguminosarum bv. viciae revealed that at least seven different AHLs are made. Mutation ofrhiI decreased the amounts of C6-HSL and C8-HSL but did not block their formation, and in this background the rhiI mutation did not significantly affect the expression levels of the rhiI gene orrhiABC genes or the accumulation of RhiA protein. These observations suggest that there are additional loci involved in AHL production in R. leguminosarum bv. viciae and that they affect rhiI and rhiABC expression. We postulate that the previously observed induction of rhiA by 3OH,C14:1-HSL may be due to an indirect effect caused by induction of other AHL production loci.

scholarly journals Long- and Short-Chain Plant-Produced Bacterial N-Acyl-Homoserine Lactones Become Components of Phyllosphere, Rhizosphere, and Soil

2006 ◽  
Vol 19 (3) ◽  
pp. 227-239 ◽  
Author(s):  
Russell A. Scott ◽  
Jason Weil ◽  
Phuong T. Le ◽  
Paul Williams ◽  
Rupert G. Fray ◽  
...  
Keyword(s):  
Leaf Tissue ◽  
Homoserine Lactone ◽  
Wild Type ◽  
Fresh Weight ◽  
Liquid Chromatograph ◽  
Homoserine Lactones ◽  
Transgenic Lines ◽  
Axenic Conditions ◽  
Root Tissues ◽  
Layer Chromatography

Two N-acyl-homoserine lactone (acyl-HSL) synthase genes, lasI from Pseudomonas aeruginosa and yenI from Yersinia enterocolitica, were introduced into tobacco, individually and in combination. Liquid chromatograph-tandem mass spectrometry and thin-layer chromatography confirmed products of lasI and yenI activity in single and cotransformants. Cotransformants expressing plastid-localized LasI and YenI synthases produced the major acyl-HSLs for each synthase in all tissues tested. Total acyl-HSL signals accumulated in leaf tissue up to 3 pmol/mg of fresh weight, half as much in stem tissue, and approximately 10-fold less in root tissues. Acyl-HSLs were present in aqueous leaf washes from greenhouse-grown transgenic plants. Transgenic lines grown for 14 days under axenic conditions produced detectable levels of acyl-HSLs in root exudates. Ethyl acetate extractions of rhizosphere and nonrhizosphere soil from transgenically grown plants contained active acyl-HSLs, whereas plant-free soil or rhizosphere and nonrhizosphere soil from wild-type plants lacked detectable amounts of acyl-HSLs. This work shows that bioactive acyl-HSLs are exuded from leaves and roots and accumulate in the phytosphere of plants engineered to produce acyl-HSLs. These data further suggest that plants that are bioengineered to synthesize acyl-HSLs can foster beneficial plant-bacteria communications or deter deleterious interactions. Therefore, it is feasible to use bioengineered plants to supplement soils with specific acyl-HSLs to modulate bacterial phenotypes and plant-associated bacterial community structures.

scholarly journals A LysR-Type Transcriptional Regulator in Burkholderia cenocepacia Influences Colony Morphology and Virulence

2007 ◽  
Vol 76 (1) ◽  
pp. 38-47 ◽  
Author(s):  
Steve P. Bernier ◽  
David T. Nguyen ◽  
Pamela A. Sokol
Keyword(s):  
Biofilm Formation ◽  
Homoserine Lactone ◽  
Burkholderia Cenocepacia ◽  
Colony Morphology ◽  
Infection Model ◽  
Bacterial Cells ◽  
Wild Type ◽  
Transmission Electron ◽  
Lung Histopathology ◽  
Seedling Infection

ABSTRACT Burkholderia cenocepacia strain K56-2 typically has rough colony morphology on agar medium; however, shiny colony variants (shv) can appear spontaneously. These shv all had a minimum of 50% reduction in biomass formation and were generally avirulent in an alfalfa seedling infection model. Three shv—K56-2 S15, K56-2 S76, and K56-2 S86—were analyzed for virulence in a chronic agar bead model of respiratory infection and, although all shv were able to establish chronic infection, they produced significantly less lung histopathology than the rough K56-2. Transmission electron microscopy revealed that an extracellular matrix surrounding bacterial cells was absent or reduced in the shv compared to the rough wild type. Transposon mutagenesis was performed on the rough wild-type strain and a mutant with an insertion upstream of ORF BCAS0225, coding for a putative LysR-type regulator, exhibited shiny colony morphology, reduced biofilm production, increased N-acyl homoserine lactone production, and avirulence in alfalfa. The rough parental colony morphotype, biofilm formation, and virulence in alfalfa were restored by providing BCAS0225 in trans in the BCAS0225::pGSVTp-luxCDABF mutant. Introduction of BCAS0225 restored the rough morphotype in several shv which were determined to have spontaneous mutations in this gene. In the present study, we show that the conversion from rough wild type to shv in B. cenocepacia correlates with reduced biofilm formation and virulence, and we determined that BCAS0225 is one gene involved in the regulation of these phenotypes.

scholarly journals Engineering acyl-homoserine lactone-interfering enzymes toward bacterial control

2020 ◽  
Vol 295 (37) ◽  
pp. 12993-13007 ◽  
Author(s):  
Raphaël Billot ◽  
Laure Plener ◽  
Pauline Jacquet ◽  
Mikael Elias ◽  
Eric Chabrière ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Homoserine Lactone ◽  
Communication Process ◽  
Dependent Manner ◽  
Biotechnological Potential ◽  
Bacterial Communication ◽  
Homoserine Lactones ◽  
A Cell ◽  
Eukaryotic Organisms ◽  
Bacterial Control

Enzymes able to degrade or modify acyl-homoserine lactones (AHLs) have drawn considerable interest for their ability to interfere with the bacterial communication process referred to as quorum sensing. Many proteobacteria use AHL to coordinate virulence and biofilm formation in a cell density–dependent manner; thus, AHL-interfering enzymes constitute new promising antimicrobial candidates. Among these, lactonases and acylases have been particularly studied. These enzymes have been isolated from various bacterial, archaeal, or eukaryotic organisms and have been evaluated for their ability to control several pathogens. Engineering studies on these enzymes were carried out and successfully modulated their capacity to interact with specific AHL, increase their catalytic activity and stability, or enhance their biotechnological potential. In this review, special attention is paid to the screening, engineering, and applications of AHL-modifying enzymes. Prospects and future opportunities are also discussed with a view to developing potent candidates for bacterial control.

scholarly journals Presence of Acylated Homoserine Lactones (AHLs) and AHL-Producing Bacteria in Meat and Potential Role of AHL in Spoilage of Meat

2004 ◽  
Vol 70 (7) ◽  
pp. 4293-4302 ◽  
Author(s):  
Jesper Bartholin Bruhn ◽  
Allan Beck Christensen ◽  
Lars Ravn Flodgaard ◽  
Kristian Fog Nielsen ◽  
Thomas Ostenfeld Larsen ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Homoserine Lactone ◽  
Wild Type ◽  
Homoserine Lactones ◽  
Serratia Proteamaculans ◽  
Pure Cultures ◽  
Meat Samples ◽  
Protease Secretion ◽  
Acylated Homoserine Lactones

ABSTRACT Quorum-sensing (QS) signals (N-acyl homoserine lactones [AHLs]) were extracted and detected from five commercially produced vacuum-packed meat samples. Ninety-six AHL-producing bacteria were isolated, and 92 were identified as Enterobacteriaceae. Hafnia alvei was the most commonly identified AHL-producing bacterium. Thin-layer chromatographic profiles of supernatants from six H. alvei isolates and of extracts from spoiling meat revealed that the major AHL species had an Rf value and shape similar to N-3-oxo-hexanoyl homoserine lactone (OHHL). Liquid chromatography-mass spectrometry (MS) (high-resolution MS) analysis confirmed the presence of OHHL in pure cultures of H. alvei. Vacuum-packed meat spoiled at the same rate when inoculated with the H. alvei wild type compared to a corresponding AHL-lacking mutant. Addition of specific QS inhibitors to the AHL-producing H. alvei inoculated in meat or to naturally contaminated meat did not influence the spoilage of vacuum-packed meat. An extracellular protein of approximately 20 kDa produced by the H. alvei wild-type was not produced by the AHL-negative mutant but was restored in the mutant when complemented by OHHL, thus indicating that AHLs do have a regulatory role in H. alvei. Coinoculation of H. alvei wild-type with an AHL-deficient Serratia proteamaculans B5a, in which protease secretion is QS regulated, caused spoilage of liquid milk. By contrast, coinoculation of AHL-negative strains of H. alvei and S. proteamaculans B5a did not cause spoilage. In conclusion, AHL and AHL-producing bacteria are present in vacuum-packed meat during storage and spoilage, but AHL does not appear to influence the spoilage of this particular type of conserved meat. Our data indicate that AHL-producing H. alvei may induce food quality-relevant phenotypes in other bacterial species in the same environment. H. alvei may thus influence spoilage of food products in which Enterobacteriaceae participate in the spoilage process.

scholarly journals Directed Evolution of Vibrio fischeri LuxR for Improved Response to Butanoyl-Homoserine Lactone

2007 ◽  
Vol 73 (18) ◽  
pp. 5775-5781 ◽  
Author(s):  
Andrew C. Hawkins ◽  
Frances H. Arnold ◽  
Rainer Stuermer ◽  
Bernhard Hauer ◽  
Jared R. Leadbetter
Keyword(s):  
Quorum Sensing ◽  
Directed Evolution ◽  
Vibrio Fischeri ◽  
Homoserine Lactone ◽  
Side Chain ◽  
Wild Type ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Chain Lengths ◽  
Quorum Sensing Signals

ABSTRACT LuxR is the 3-oxohexanoyl-homoserine lactone (3OC6HSL)-dependent transcriptional activator of the prototypical acyl-homoserine lactone (AHL) quorum-sensing system of Vibrio fischeri. Wild-type LuxR exhibits no response to butanoyl-HSL (C4HSL) in quantitative bioassays at concentrations of up to 1 μM; a previously described LuxR variant (LuxR-G2E) exhibits a broadened response to diverse AHLs, including pentanoyl-HSL (C5HSL), but not to C4HSL. Here, two rounds of directed evolution of LuxR-G2E generated variants of LuxR that responded to C4HSL at concentrations as low as 10 nM. One variant, LuxR-G4E, had only one change, I45F, relative to the parent LuxR-G2E, which itself differs from the wild type at three residues. Dissection of the four mutations within LuxR-G4E demonstrated that at least three of these changes were simultaneously required to achieve any measurable C4HSL response. The four changes improved both sensitivity and specificity towards C4HSL relative to any of the other 14 possible combinations of those residues. These data confirm that LuxR is evolutionarily pliable and suggest that LuxR is not intrinsically asymmetric in its response to quorum-sensing signals with different acyl-side-chain lengths.

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 Synthesis and Biological Activity of Brassinosteroid Analogues with a Nitrogen-Containing Side Chain

2020 ◽  
Vol 22 (1) ◽  
pp. 155
Author(s):  
Mikhail V. Diachkov ◽  
Karoll Ferrer ◽  
Jana Oklestkova ◽  
Lucie Rarova ◽  
Vaclav Bazgier ◽  
...  
Keyword(s):  
Biological Activity ◽  
Functional Groups ◽  
Side Chain ◽  
Biotic And Abiotic Stresses ◽  
Short Side ◽  
Arabidopsis Root ◽  
Physiological Processes ◽  
Growth Promoting ◽  
The Impact ◽  
Brassinosteroid Analogues

Brassinosteroids are a class of plant hormones that regulate a broad range of physiological processes such as plant growth, development and immunity, including the suppression of biotic and abiotic stresses. In this paper, we report the synthesis of new brassinosteroid analogues with a nitrogen-containing side chain and their biological activity on Arabidopis thaliana. Based on molecular docking experiments, two groups of brassinosteroid analogues were prepared with short and long side chains in order to study the impact of side chain length on plants. The derivatives with a short side chain were prepared with amide, amine and ammonium functional groups. The derivatives with a long side chain were synthesized using amide and ammonium functional groups. A total of 25 new brassinosteroid analogues were prepared. All 25 compounds were tested in an Arabidopsis root sensitivity bioassay and cytotoxicity screening. The synthesized substances showed no significant inhibitory activity compared to natural 24-epibrassinolide. In contrast, in low concentration, several compounds (8a, 8b, 8e, 16e, 22a and 22e) showed interesting growth-promoting activity. The cytotoxicity assay showed no toxicity of the prepared compounds on cancer and normal cell lines.

scholarly journals Evidence of Quorum Sensing in Cyanobacteria by Homoserine Lactones: The Origin of Blooms

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1831
Author(s):  
Natalia Herrera ◽  
Fernando Echeverri
Keyword(s):  
Cell Proliferation ◽  
Quorum Sensing ◽  
Microcystis Aeruginosa ◽  
Industrial Effluents ◽  
Cyanobacterial Blooms ◽  
Cylindrospermopsis Raciborskii ◽  
Bacterial Communication ◽  
Homoserine Lactones ◽  
Exogenous Compounds ◽  
Almost All

Although several theories have been postulated to explain cyanobacterial blooms, their biochemical origin has not yet been found. In this work, we explore the existence of bacterial communication, called quorum sensing, in Microcystis aeruginosa and Cylindrospermopsis raciborskii. Thus, the application of several known acylhomoserine lactones to cultures of both cyanobacteria causes profound metabolic. At 72 h post-application, some of them produced substantial increases in cell proliferation, while others were inhibitors. There was a correlation with colony-forming activity for most of them. According to ELISA analysis, the microcystin levels were increased with some lactones. However, there was a clear difference between M. aeruginosa and C. raciborskii culture since, in the first one, there was an inducing effect on cell proliferation, while in C. raciborskii, the effects were minor. Besides, there were compound inhibitors and inducers of microcystins production in M. aeruginosa, but almost all compounds were only inducers of saxitoxin production in C. raciborskii. Moreover, each lactone appears to be involved in a specific quorum sensing process. From these results, the formation of cyanobacterial blooms in dams and reservoirs could be explained since lactones may come from cyanobacteria and other sources as bacterial microflora-associated or exogenous compounds structurally unrelated to lactones, such as drugs, industrial effluents, and agrochemicals.

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