Quorum sensing and RsaM regulons of the rice pathogen Pseudomonas fuscovaginae

Uzelac, Gordana; Patel, Hitendra Kumar; Devescovi, Giulia; Licastro, Danilo; Venturi, Vittorio

doi:10.1099/mic.0.000454

Cited by 16 publications

(17 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Genes involved in translation, ribosomal structure and biogenesis were also found to be under QS control (category J; 3.0% AHL − ; 9.4% phzR − ), including a large number of 50S and 30S ribosomal proteins as well as the 16S rRNA processing protein, RimM. Similar results were demonstrated for the PfsI/R QS regulon of the rice pathogen Pseudomonas fuscovaginae , where the majority of genes positively regulated by PfsI/R are involved in translation, ribosomal structure and biogenesis, including 20 ribosomal proteins and RimM (49).…”

Section: Resultssupporting

confidence: 58%

Investigation of the quorum-sensing regulon of the biocontrol bacterium Pseudomonas chlororaphis strain PA23

Shah

Gislason

Becker

et al. 2019

Preprint

View full text Add to dashboard Cite

Pseudomonas chlororaphis strain PA23 is a biocontrol agent capable of protecting canola from stem rot disease caused by the fungal pathogen Sclerotinia sclerotiorum. PA23 produces several of inhibitory compounds that are under control of a complex regulatory network. Included in this cascade is the PhzRI quorum sensing (QS) system, which plays an essential role in PA23 biocontrol. The focus of the current study was to employ RNA sequencing to explore the spectrum of PA23 genes under QS control. Transcriptomic profiling revealed 545 differentially expressed genes (365 downregulated; 180 upregulated) in the phzR mutant and 534 genes (382 downregulated; 152 upregulated) in the AHL-deficient PA23-6863. In both strains, decreased expression of phenazine, pyrrolnitrin, and exoprotease biosynthetic genes was observed. We have previously reported that QS activates expression of these genes and their encoded products. In addition, elevated siderophore and decreased chitinase gene expression was observed in the QS-deficient stains, which was confirmed by phenotypic analysis. Inspection of the promoter regions revealed the presence of “phz-box” sequences in only 58 of the 807 differentially expressed genes, suggesting that much of the QS regulon is indirectly regulated. Consistent with this notion, 41 transcriptional regulators displayed altered expression in one or both of the QS-deficient strains. Collectively, our findings indicate that QS governs expression of approximately 13% of the PA23 genome affecting diverse functions ranging from secondary metabolite production to general metabolism. To the best of our knowledge, this represents the first global transcriptomic analysis of the QS regulon of a biocontrol pseudomonad.

show abstract

Section: Resultssupporting

confidence: 58%

Investigation of the quorum-sensing regulon of the biocontrol bacterium Pseudomonas chlororaphis strain PA23

Shah

Gislason

Becker

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

“…S1B ). This gene encodes an hypothetical protein, homologous to the negative AHL biosynthesis modulatory protein RsaM originally identified in the plant pathogen P. fuscovaginae UBP0736 (8, 9), hence designated RsaM1. In B. cenocepacia H111, the homologue Bc RsaM was described as an important repressor of the CepI/CepR QS system, and proposed to inhibit the production of C 8 -HSL by regulating the activity and/or stability of the LuxI-type synthase CepI and the LuxR-type transcriptional regulator CepR, as well as the orphan LuxR-type transcriptional regulator CepR2 (10, 11).…”

Section: Discussionmentioning

confidence: 99%

“…These genes are generally separated by a gene encoding an RsaM-like protein that was originally identified in the plant pathogen Pseudomonas fuscovaginae and shown to be a major negative regulator of both AHLs biosynthesis and expression of the AHL synthase-coding genes (8). It was also recently reported to act as a global regulator mediating the expression of numerous genes through and out of the QS regulon in P. fuscovaginae (9). The function of RsaM-like proteins has been investigated in the Burkholderia genus, and could be important for balancing and fine-tuning of QS-dependant regulation (10).…”

Section: Introductionmentioning

confidence: 98%

TworsaMhomologues encode central regulatory elements modulating quorum sensing expression inBurkholderia thailandensis

Déziel

Guillouzer

Groleau

2017

Preprint

View full text Add to dashboard Cite

The bacterium Burkholderia thailandensis possesses three conserved N-acyl-L-homoserine lactone (AHL) quorum sensing (QS) systems designated BtaI1/BtaR1 (QS-1), BtaI2/BtaR2 (QS-2), and BtaI3/BtaR3 (QS-3). These QS-systems are associated with the biosynthesis of N-octanoyl-homoserine lactone (C8-HSL), N-3-hydroxy-decanoyl-homoserine lactone (3OHC10-HSL), as well as N-3-hydroxy-octanoyl-homoserine lactone (3OHC8-HSL), which are produced by the LuxI-type synthase BtaI1, BtaI2, and BtaI3, and modulated by the LuxR-type transcriptional regulators BtaR1, BtaR2, and BtaR3. Both btaR1/btaI1 and btaR2/btaI2 gene clusters contain an additional gene that is conserved in the Burkholderia genus, homologous to a gene coding for the negative AHL biosynthesis modulatory protein RsaM originally identified in the phytopathogen Pseudomonas fuscovaginae, and hence designated rsaM1 and rsaM2. We have characterized the function of these two rsaM homologues and demonstrated their involvement in the regulation of AHLs biosynthesis in B. thailandensis strain E264. We measured the production of C8-HSL, 3OHC10-HSL, and 3OHC8-HSL by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in the wild-type strain and in the rsaM1- and rsaM2- mutants, and monitored the transcription of btaI1, btaI2, and btaI3 using chromosomal mini-CTX-lux transcriptional reporters. The expression of btaR1, btaR2, and btaR3 was also measured by quantitative everse-transcription PCR (qRT-PCR). We demonstrate that the QS-1 system is repressed by RsaM1, whereas RsaM2 principally represses the QS-2 system. We also found that both rsaM1 and rsaM2 are QS-controlled, as well as negatively auto-regulated. We conclude that RsaM1 and RsaM2 are an integral part of the QS modulatory circuitry of B. thailandensis, and play a major role in the hierarchical and homeostatic organization of the QS-1, QS-2, and QS-3 systems.ImportanceQuorum sensing (QS) is a global regulatory mechanism of genes expression depending on bacterial density. QS is commonly involved in the coordination of genes expression associated with the establishment of host-pathogen interactions and acclimatization to the environment. We present the functional characterization of the two rsaM homologues designated rsaM1 and rsaM2 in the regulation of the multiple QS systems coexisting in the non-pathogenic bacterium Burkholderia thailandensis, widely used as a model system for the study of the pathogen Burkholderia pseudomallei. We found that inactivation of these rsaM homologues, which are clustered with the other QS genes, profoundly affects the QS regulatory circuity of B. thailandensis. It is proposed that these genes code for QS repressors and we conclude that they constitute essential regulatory components of the QS modulatory network of B. thailandensis, and provide additional layers of regulation to modulate the expression of QS-controlled genes, including those encoding virulence/survival factors and linked to environmental adaptation in B. pseudomallei.

show abstract

“…Transcriptional gene promoter activity studies of six promoters were performed in PSA. All constructs were made in the promoter probe vector pBBRGFPGm (Uzelac et al, 2017) carrying gene for gentamycin resistance. The promoters of the six genes were: gene1818 encoding for a putative peptidase C1, gene4120 encoding for a Sugar ABC transporter, gene 4321 coding for twitching motility protein, gene4820 encoding for two component sensor histidine kinase protein, gene3774 encodoing a histidine kinase, and gene3474 encoding for L-aspartate oxidase (Supplementary Table 4).…”

Section: Methodsmentioning

confidence: 99%

“…PCR amplified promoters regions using primers listed in Table 2, were transcriptionally fused to a promoterless gfp gene in vector pBBRGFP (Table 3). The gene promoter constructs pBBR-promoters-GFP were then electroporated into PSA WT as previously described (Uzelac, et al, 2017). By replicating the same growth conditions of the RNAseq experiment as described above, gene promoter activity was determined as a measurement of the intensity of GFP fluorescence at 510nm measuring cultures using microplate reader (Perkin Elmer EnVision 2104).…”

Section: Methodsmentioning

confidence: 99%

The spent culture supernatant ofPseudomonas syringaecontains azelaic acid

Javvadi

Cescutti

Rizzo

et al. 2017

Preprint

Self Cite

View full text Add to dashboard Cite

Pseudomonas syringae pv. actinidiae (PSA) is an emerging kiwifruit bacterial pathogen which since 2008 has caused considerable losses. No quorum sensing (QS) signaling molecule has yet been reported from PSA and the aim of this study was to identify possible intercellular signals produced by PSA. A metabolome analysis resulted in the identification of 83 putative compounds, one of them was the nine carbon saturated dicarboxylic acid azelaic acid which for several reasons was decided to further study. Firstly azelaic acid, which is a straight chained nine-carbon (C9) saturated dicarboxylic acid, has been reported in plants as mobile signal that primes systemic defenses. Secondly its structure, which is associated with fatty acid biosynthesis, is similar to other known bacterial QS signals like the Diffusible Signal Facor (DSF). Analytical and structural studies by NMR spectroscopy confirmed that in the PSA spent supernatant azelaic acid was present. Quantification studies further revealed that 20 µg/L of azelaic acid was present and was also found in spent supernatants of several other P. syringae pathovars. An RNAseq transcriptome study however did not reveal whether azelaic acid behaved as a QS molecule. This is the first report of the possible natural biosynthesis of azelaic acid by bacteria.

show abstract

Quorum sensing and RsaM regulons of the rice pathogen Pseudomonas fuscovaginae

Cited by 16 publications

References 64 publications

Investigation of the quorum-sensing regulon of the biocontrol bacterium Pseudomonas chlororaphis strain PA23

Investigation of the quorum-sensing regulon of the biocontrol bacterium Pseudomonas chlororaphis strain PA23

TworsaMhomologues encode central regulatory elements modulating quorum sensing expression inBurkholderia thailandensis

The spent culture supernatant ofPseudomonas syringaecontains azelaic acid

Contact Info

Product

Resources

About