The Complex Quorum Sensing Circuitry of
            <i>Burkholderia thailandensis</i>
            Is Both Hierarchically and Homeostatically Organized

Guillouzer, Servane Le; Groleau, Marie‐Christine; Déziel, Éric

doi:10.1128/mbio.01861-17

Cited by 24 publications

(52 citation statements)

References 33 publications

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“…The ScmR transcriptional regulator was shown to influence the biosynthesis of C 8 -HSL, 3OHC 10 -HSL, and 3OHC 8 -HSL (26), the main AHLs produced by B. thailandensis E264 (10, 11, 13, 14). Therefore, we assumed that ScmR could intervene in the regulation of gene expression, inter alia , by impacting the QS-1, QS-2, and/or QS-3 systems of B. thailandensis E264.…”

Section: Resultsmentioning

confidence: 99%

“…While Mao et al (26) defined the ScmR regulon during the stationary phase, we established the impact of ScmR on the expression of genes during the logarithmic phase of growth. It must be emphasized that the growth stage is an important variable when investigating QS, and this is especially relevant for B. thailandensis , a bacterium for which we reported significant differences in QS regulation depending on the growth stage (11). We confirmed that ScmR is a global regulator of gene expression in B. thailandensis E264 (Fig.…”

Section: Discussionmentioning

confidence: 97%

“…Expression from the promoter region of scmR was quantified by measuring the luminescence of B. thailandensis E264 cultures carrying the corresponding chromosomal mini-CTX- lux transcriptional reporter, as described previously (11). Overnight bacterial cultures were diluted in TSB to an initial OD 600 of 0.1 and incubated as indicated above.…”

Section: Methodsmentioning

confidence: 99%

“…The members of the Bptm group carry multiple LuxI/LuxR QS systems that are associated with the biosynthesis of numerous AHL signaling molecules (4, 7–9). These QS systems are referred to as the BtaI1/BtaR1 (QS-1), BtaI2/BtaR2 (QS-2), and BtaI3/BtaR3 (QS-3) QS systems in B. thailandensis (10, 11). The QS-1 system is composed of the BtaR1 transcriptional regulator and the BtaI1 synthase, which synthesizes N- octanoyl-L-homoserine lactone (C 8 -HSL) (12, 13).…”

Section: Introductionmentioning

confidence: 99%

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ScmR, a global regulator of gene expression, quorum sensing, pH homeostasis, and virulence inBurkholderia thailandensis

Guillouzer

Groleau

Mauffrey

et al. 2019

Preprint

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AbstractThe nonpathogenic soil saprophyte Burkholderia thailandensis is a member of the Burkholderia pseudomallei-thailandensis-mallei (Bptm) group, which also comprises the closely related human pathogens Burkholderia pseudomallei and Burkholderia mallei responsible for the diseases melioidosis and glanders, respectively. ScmR, a recently identified LysR-type transcriptional regulator (LTTR) in B. thailandensis acts as a global transcriptional regulator throughout the stationary phase, and modulates the production of a wide range of secondary metabolites, including N-acyl-L-homoserine lactones (AHLs) and 4-hydroxy-3-methyl-2-alkylquinoline (HMAQ), virulence in the model host Caenorhabditis elegans, as well as several quorum sensing (QS)-dependent phenotypes. We have investigated the role of ScmR in B. thailandensis strain E264 during the exponential phase. We used RNA-Sequencing (RNA-Seq) transcriptomic analyses to identify the ScmR regulon, which was compared to the QS-controlled regulon, showing a considerable overlap between the ScmR-regulated genes and those controlled by QS. We characterized several genes modulated by ScmR, using quantitative reverse transcription-PCR (qRT-PCR) or mini-CTX-lux transcriptional reporters, including the oxalate biosynthetic gene obc1 required for pH homeostasis, the orphan LuxR-type transcriptional regulator BtaR5-encoding gene, the bsa (Burkholderia secretion apparatus) type III secretion system (T3SS) genes essential for both B. pseudomallei and B. mallei pathogenicity, as well as the scmR gene itself. We confirmed that the transcription of scmR is under QS control, presumably ensuring fine-tuned modulation of gene expression. Finally, we demonstrate that ScmR influences virulence using the fruit fly model host Drosophila melanogaster. We conclude that ScmR represents a central component of the B. thailandensis QS regulatory network.ImportanceCoordination of the expression of genes associated with bacterial virulence and environmental adaptation is often dependent on quorum sensing (QS). The QS circuitry of the nonpathogenic bacterium Burkholderia thailandensis, which is widely used as a model system for the study of the human pathogen Burkholderia pseudomallei, is complex. We found that the recently identified LysR-type transcriptional regulator (LTTR), ScmR, which is highly conserved and involved in the control of virulence/survival factors in the Burkholderia genus, is a global regulator mediating gene expression through the multiple QS systems coexisting in B. thailandensis, as well as independently of QS. We conclude that ScmR represents a key QS modulatory network element, ensuring tight regulation of the transcription of QS-controlled genes, particularly those required for acclimatization to the environment.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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ScmR, a global regulator of gene expression, quorum sensing, pH homeostasis, and virulence inBurkholderia thailandensis

Guillouzer

Groleau

Mauffrey

et al. 2019

Preprint

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“…The OD600 and relative luminescence were measured using a CLARIOstar plate reader at 10-minute intervals for 24 hours. Experiments assessing the effect of C8-HSL additions on CepR and CepI transcription were performed according to Le Guillouzer et al (88). Briefly, cultures were supplemented with C8-HSL (Sigma-Aldrich) resuspended in acetonitrile (10 µM final concentration) and added to cultures with acetonitrile added alone used as a negative control.…”

Section: Digestionmentioning

confidence: 99%

Loss ofO-linked protein glycosylation inBurkholderia cenocepaciaimpairs biofilm formation and siderophore production via alteration of quorum sensing regulation

Oppy

Jebeli

Kuba

et al. 2019

Preprint

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O-linked protein glycosylation is a conserved feature of the Burkholderia genus. For Burkholderia cenocepacia, the addition of the trisaccharide β-Gal-(1,3)-α-GalNAc-(1,3)-β-GalNAc to membrane exported proteins is required for virulence and resistance to environmental stress. However, the underlying causes of the defects observed in the absence of glycosylation are unclear. This study demonstrates that the global B. cenocepacia proteome undergoes dramatic changes consistent with alterations in global transcriptional regulation in the absence of glycosylation. Using luciferase reporter assays and DNA cross-linking analysis, we confirm the repression of the master quorum sensing regulon CepR/I in response to the loss of glycosylation, which leads to the abolition of biofilm formation, defects in siderophore production, and reduced virulence. The abundance of most of the known glycosylated proteins did not significantly change in the glycosylation-defective mutants except for BCAL1086 and BCAL2974, which were found in reduced amount, suggesting they could be degraded.However, the loss of these two proteins was not responsible for driving the proteomic alterations, as well as for reduced virulence and siderophore production. Together, our resultsshow that loss of glycosylation in B. cenocepacia results in a global cell reprogramming via alteration of the CepR/I regulon, which cannot be explained by the abundance changes in known B. cenocepacia glycoproteins. IMPORTANCEProtein glycosylation is increasingly recognised as a common protein modification in bacterial species. Despite this commonality our understanding of the role of most glycosylation systems in bacterial physiology and pathogenesis is incomplete. In this work, we investigated the effect of the disruption of O-linked glycosylation in the opportunistic pathogen Burkholderia cenocepacia using a combination of proteomic, molecular and phenotypic assays. We find that in contrast to recent findings on the N-linked glycosylation systems of Campylobacter jejuni, O-linked glycosylation does not appear to play a role in proteome stabilization of most glycoproteins. Our results reveal that virulence attenuation observed within glycosylation-null B. cenocepacia strains are consistent with alteration of the master virulence regulator CepR.The repression of CepR transcription and its associated phenotypes support a model in which the virulence defects observed in glycosylation-null strains are at least in part due to transcriptional alteration and not the direct result of the loss of glycosylation per-se. This research unravels the pleotropic effects of O-linked glycosylation in B. cenocepacia, demonstrating that its loss does not simply affect the stability of the glycoproteome, but also interferes with transcription and the broader proteome.

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Quorum sensing as a potential target for increased production of rhamnolipid biosurfactant in Burkholderia thailandensis E264

Irorere

Kwiencien

Tripathi

et al. 2019

Appl Microbiol Biotechnol

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Burkholderia thailandensis E264 is a potential non-pathogenic substitute for producing rhamnolipid biosurfactant, replacing the pathogenic Pseudomonas aeruginosa . However, it has low rhamnolipid production and longer fermentation time. We have earlier suggested that media supplementation with exogenous quorum sensing (QS) molecules could lead to early onset of biosynthesis and increased rhamnolipid yield. Here, we assessed the effect of single, double or triple mutations in the various QS systems of B. thailandensis on rhamnolipid production, with the view to see which system(s) have the most impact on rhamnolipid yield and subsequently use the QS molecule to potentially increase yield in the wild-type B. thailandensis . The triple mutant strain had a rhamnolipid yield of 4.46 ± 0.345 g/l at 240 h of fermentation which was significantly higher than that of the wild type (0.94 ± 0.06 g/l), an unexpected outcome. To gain more insight as to how this might occur, we studied substrate metabolism and energy storage in the form of polyhydroxyalkanoate (PHA) by both the triple mutant and the wild type. We observed increased glycerol metabolism and reduced PHA production in the triple mutant compared with the wild type. Glycerol concentration at 240 h and maximum PHA productivity (g/gDCB) were 8.76 g/l or 16.19 g/l and 21.80% or 31.4% in either the triple mutant or the wild type respectively. Complementation of the triple-mutant cultures with exogenous QS molecules restored rhamnolipid production to similar levels as the wild type. QS therefore is a potential target for increased rhamnolipid production in B. thailandensis . Electronic supplementary material The online version of this article (10.1007/s00253-019-09942-5) contains supplementary material, which is available to authorized users.

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The Complex Quorum Sensing Circuitry of Burkholderia thailandensis Is Both Hierarchically and Homeostatically Organized

Cited by 24 publications

References 33 publications

ScmR, a global regulator of gene expression, quorum sensing, pH homeostasis, and virulence inBurkholderia thailandensis

ScmR, a global regulator of gene expression, quorum sensing, pH homeostasis, and virulence inBurkholderia thailandensis

Loss ofO-linked protein glycosylation inBurkholderia cenocepaciaimpairs biofilm formation and siderophore production via alteration of quorum sensing regulation

Quorum sensing as a potential target for increased production of rhamnolipid biosurfactant in Burkholderia thailandensis E264

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