scholarly journals LuxR Solos in the Plant Endophyte Kosakonia sp. Strain KO348

2020 ◽  
Vol 86 (13) ◽  
Author(s):  
Susan Mosquito ◽  
Xianfa Meng ◽  
Giulia Devescovi ◽  
Iris Bertani ◽  
Alexander M. Geller ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Homoserine Lactone ◽  
The Other ◽  
The Novel ◽  
Homoserine Lactones ◽  
Interkingdom Signaling ◽  
Promoter Studies ◽  
Quorum Sensing Signals ◽  
Target Promoter ◽  
Plant Compounds

ABSTRACT Endophytes are microorganisms that live inside plants and are often beneficial for the host. Kosakonia is a novel bacterial genus that includes several species that are diazotrophic and plant associated. This study revealed two quorum sensing-related LuxR solos, designated LoxR and PsrR, in the plant endophyte Kosakonia sp. strain KO348. LoxR modeling and biochemical studies demonstrated that LoxR binds N-acyl homoserine lactones (AHLs) in a promiscuous way. PsrR, on the other hand, belongs to the subfamily of plant-associated-bacterium (PAB) LuxR solos that respond to plant compounds. Target promoter studies as well as modeling and phylogenetic comparisons suggest that PAB LuxR solos are likely to respond to different plant compounds. Finally, LoxR is involved in the regulation of T6SS and PsrR plays a role in root endosphere colonization. IMPORTANCE Cell-cell signaling in bacteria allows a synchronized and coordinated behavior of a microbial community. LuxR solos represent a subfamily of proteins in proteobacteria which most commonly detect and respond to signals produced exogenously by other microbes or eukaryotic hosts. Here, we report that a plant-beneficial bacterial endophyte belonging to the novel genus of Kosakonia possesses two LuxR solos; one is involved in the detection of exogenous N-acyl homoserine lactone quorum sensing signals and the other in detecting a compound(s) produced by the host plant. These two Kosakonia LuxR solos are therefore most likely involved in interspecies and interkingdom signaling.

scholarly journals Characterization of a Phosphotriesterase-Like Lactonase fromSulfolobus solfataricusand Its Immobilization for Disruption of Quorum Sensing

2010 ◽  
Vol 77 (4) ◽  
pp. 1181-1186 ◽  
Author(s):  
Filomena S. W. Ng ◽  
Daniel M. Wright ◽  
Stephen Y. K. Seah
Keyword(s):  
Quorum Sensing ◽  
Virulence Factors ◽  
Acyl Chain ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Homoserine Lactones ◽  
Specificity Constant ◽  
Chain Lengths ◽  
Quorum Sensing Signals

ABSTRACTSsoPox, a bifunctional enzyme with organophosphate hydrolase andN-acyl homoserine lactonase activities from the hyperthermophilic archaeonSulfolobus solfataricus, was overexpressed and purified from recombinantPseudomonas putidaKT2440 with a yield of 9.4 mg of protein per liter of culture. The enzyme has a preference forN-acyl homoserine lactones (AHLs) with acyl chain lengths of at least 8 carbon atoms, mainly due to lowerKmvalues for these substrates. The highest specificity constant obtained was forN-3-oxo-decanoyl homoserine lactone (kcat/Km= 5.5 × 103M−1·s−1), but SsoPox can also degradeN-butyryl homoserine lactone (C4-HSL) andN-oxo-dodecanoyl homoserine lactone (oxo-C12-HSL), which are important for quorum sensing in ourPseudomonas aeruginosamodel system. WhenP. aeruginosaPAO1 cultures were grown in the presence of SsoPox-immobilized membranes, the production of C4-HSL- and oxo-C12-HSL-regulated virulence factors, elastase, protease, and pyocyanin were significantly reduced. This is the first demonstration that immobilized quorum-quenching enzymes can be used to attenuate the production of virulence factors controlled by quorum-sensing signals.

scholarly journals The GCR1 and GPA1 Participate in Promotion of Arabidopsis Primary Root Elongation Induced by N-Acyl-Homoserine Lactones, the Bacterial Quorum-Sensing Signals

2012 ◽  
Vol 25 (5) ◽  
pp. 677-683 ◽  
Author(s):  
Fang Liu ◽  
Ziriu Bian ◽  
Zhenhua Jia ◽  
Qian Zhao ◽  
Shuishan Song
Keyword(s):  
Quorum Sensing ◽  
Root Elongation ◽  
Primary Root ◽  
Homoserine Lactone ◽  
Collective Behaviors ◽  
Homoserine Lactones ◽  
Acyl Homoserine Lactones ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum ◽  
Quorum Sensing Signals

Many gram-negative bacteria use N-acyl-homoserine lactones (AHL) as quorum-sensing signals to coordinate their collective behaviors. Accumulating evidence indicates that plants can respond to AHL. However, little is known about the molecular mechanism of plants reacting to these bacterial signals. In this study, we show that the treatment of Arabidopsis roots with N-3-oxo-hexanoyl-homoserine lactone (3OC6-HSL) and N-3-oxo-octanoyl-homoserine lactone (3OC8-HSL) resulted in significant root elongation. The genetic analysis revealed that the T-DNA insertional mutants of gcr1, encoding a G-protein-coupled receptor GCR1, were insensitive to 3OC6-HSL or 3OC8-HSL in assays of root growth. The loss-of-function mutants of the sole canonical Gα subunit GPA1 showed no response to AHL promotion of root elongation whereas Gα gain-of-function plants overexpressing either the wild type or a constitutively active version of Arabidopsis Gα exhibited the exaggerated effect on root elongation caused by AHL. Furthermore, the expression of GCR1 and GPA1 were significantly upregulated after plants were contacted with both AHL. Taken together, our results suggest that GCR1 and GPA1 are involved in AHL-mediated elongation of Arabidopsis roots. This provides insight into the mechanism of plant responses to bacterial quorum-sensing signals.

scholarly journals Octanoyl-Homoserine Lactone Is the Cognate Signal for Burkholderia mallei BmaR1-BmaI1 Quorum Sensing

2007 ◽  
Vol 189 (14) ◽  
pp. 5034-5040 ◽  
Author(s):  
Breck A. Duerkop ◽  
Ricky L. Ulrich ◽  
E. Peter Greenberg
Keyword(s):  
Quorum Sensing ◽  
Promoter Region ◽  
Homoserine Lactone ◽  
Burkholderia Mallei ◽  
Homoserine Lactones ◽  
E Coli ◽  
Cognate Receptor ◽  
System A ◽  
Acyl Homoserine Lactones ◽  
Quorum Sensing Signals

ABSTRACT Acyl-homoserine lactones (HSLs) serve as quorum-sensing signals for many Proteobacteria. Members of the LuxI family of signal generators catalyze the production of acyl-HSLs, which bind to a cognate receptor in the LuxR family of transcription factors. The obligate animal pathogen Burkholderia mallei produces several acyl-HSLs, and the B. mallei genome has four luxR and two luxI homologs, each of which has been established as a virulence factor. To begin to delineate the relevant acyl-HSL signals for B. mallei LuxR homologs, we analyzed the BmaR1-BmaI1 system. A comparison of acyl-HSL profiles from B. mallei ATCC 23344 and a B. mallei bmaI1 mutant indicates that octanoyl-HSL synthesis is BmaI1 dependent. Furthermore, octanoyl-HSL is the predominant acyl-HSL produced by BmaI1 in recombinant Escherichia coli. The synthesis of soluble BmaR1 in recombinant E. coli requires octanoyl-HSL or decanoyl-HSL. Insoluble aggregates of BmaR1 are produced in the presence of other acyl-HSLs and in the absence of acyl-HSLs. The bmaI1 promoter is activated by BmaR1 and octanoyl-HSL, and a 20-bp inverted repeat in the bmaI1 promoter is required for bmaI1 activation. Purified BmaR1 binds to this promoter region. These findings implicate octanoyl-HSL as the signal for BmaR1-BmaI1 quorum sensing and show that octanoyl-HSL and BmaR1 activate bmaI1 transcription.

scholarly journals Revisiting the quorum-sensing hierarchy in Pseudomonas aeruginosa: the transcriptional regulator RhlR regulates LasR-specific factors

Microbiology ◽  
2009 ◽  
Vol 155 (3) ◽  
pp. 712-723 ◽  
Author(s):  
Valérie Dekimpe ◽  
Eric Déziel
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Transcriptional Regulator ◽  
Homoserine Lactone ◽  
The Other ◽  
Virulence Determinants ◽  
Late Stationary Phase ◽  
Regulatory Systems ◽  
Specific Factors

Pseudomonas aeruginosa uses the two major quorum-sensing (QS) regulatory systems las and rhl to modulate the expression of many of its virulence factors. The las system is considered to stand at the top of the QS hierarchy. However, some virulence factors such as pyocyanin have been reported to still be produced in lasR mutants under certain conditions. Interestingly, such mutants arise spontaneously under various conditions, including in the airways of cystic fibrosis patients. Using transcriptional lacZ reporters, LC/MS quantification and phenotypic assays, we have investigated the regulation of QS-controlled factors by the las system. Our results show that activity of the rhl system is only delayed in a lasR mutant, thus allowing the expression of multiple virulence determinants such as pyocyanin, rhamnolipids and C4-homoserine lactone (HSL) during the late stationary phase. Moreover, at this stage, RhlR is able to overcome the absence of the las system by activating specific LasR-controlled functions, including production of 3-oxo-C12-HSL and Pseudomonas quinolone signal (PQS). P. aeruginosa is thus able to circumvent the deficiency of one of its QS systems by allowing the other to take over. This work demonstrates that the QS hierarchy is more complex than the model simply presenting the las system above the rhl system.

scholarly journals Host modification of a bacterial quorum-sensing signal induces a phenotypic switch in bacterial symbionts

2017 ◽  
Vol 114 (40) ◽  
pp. E8488-E8497 ◽  
Author(s):  
Cleo Pietschke ◽  
Christian Treitz ◽  
Sylvain Forêt ◽  
Annika Schultze ◽  
Sven Künzel ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Bacterial Communities ◽  
Homoserine Lactone ◽  
Innate Immune ◽  
Expression Data ◽  
Phenotypic Switch ◽  
Host Colonization ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum ◽  
Quorum Sensing Signals

Bacterial communities colonize epithelial surfaces of most animals. Several factors, including the innate immune system, mucus composition, and diet, have been identified as determinants of host-associated bacterial communities. Here we show that the early branching metazoan Hydra is able to modify bacterial quorum-sensing signals. We identified a eukaryotic mechanism that enables Hydra to specifically modify long-chain 3-oxo-homoserine lactones into their 3-hydroxy-HSL counterparts. Expression data revealed that Hydra’s main bacterial colonizer, Curvibacter sp., responds differentially to N-(3-hydroxydodecanoyl)-l-homoserine lactone (3OHC12-HSL) and N-(3-oxododecanoyl)-l-homoserine lactone (3OC12-HSL). Investigating the impacts of the different N-acyl-HSLs on host colonization elucidated that 3OHC12-HSL allows and 3OC12-HSL represses host colonization of Curvibacter sp. These results show that an animal manipulates bacterial quorum-sensing signals and that this modification leads to a phenotypic switch in the bacterial colonizers. This mechanism may enable the host to manipulate the gene expression and thereby the behavior of its bacterial colonizers.

scholarly journals Bacterial populations in the rhizosphere of tobacco plants producing the quorum-sensing signals hexanoyl-homoserine lactone and 3-oxo-hexanoyl-homoserine lactone

2004 ◽  
Vol 51 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Cathy D'Angelo-Picard ◽  
Denis Faure ◽  
Aurélien Carlier ◽  
Stéphane Uroz ◽  
Aurélie Raffoux ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Homoserine Lactone ◽  
Tobacco Plants ◽  
Bacterial Populations ◽  
Quorum Sensing Signals

Chemical identification of N -acyl homoserine lactone quorum-sensing signals produced by Sinorhizobium meliloti strains in defined medium

2003 ◽  
Vol 180 (6) ◽  
pp. 494-497 ◽  
Author(s):  
Max Teplitski ◽  
Anatol Eberhard ◽  
Matthew R. Gronquist ◽  
Mengsheng Gao ◽  
Jayne B. Robinson ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Sinorhizobium Meliloti ◽  
Homoserine Lactone ◽  
Defined Medium ◽  
Acyl Homoserine Lactone ◽  
Chemical Identification ◽  
Quorum Sensing Signals
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