scholarly journals TworsaMhomologues encode central regulatory elements modulating quorum sensing expression inBurkholderia thailandensis

2017 ◽  
Author(s):  
Servane Le Guillouzer ◽  
Marie-Christine Groleau ◽  
Eric Déziel
Keyword(s):  
Quorum Sensing ◽  
Functional Characterization ◽  
Gene Clusters ◽  
Homoserine Lactone ◽  
Regulatory Elements ◽  
Burkholderia Thailandensis ◽  
Gene Coding ◽  
Genes Expression ◽  
In The Wild

AbstractThe bacteriumBurkholderia thailandensispossesses three conservedN-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 ofN-octanoyl-homoserine lactone (C8-HSL),N-3-hydroxy-decanoyl-homoserine lactone (3OHC10-HSL), as well asN-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. BothbtaR1/btaI1andbtaR2/btaI2gene clusters contain an additional gene that is conserved in theBurkholderiagenus, homologous to a gene coding for the negative AHL biosynthesis modulatory protein RsaM originally identified in the phytopathogenPseudomonas fuscovaginae, and hence designatedrsaM1andrsaM2. We have characterized the function of these tworsaMhomologues and demonstrated their involvement in the regulation of AHLs biosynthesis inB. thailandensisstrain 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 thersaM1-andrsaM2-mutants, and monitored the transcription ofbtaI1,btaI2, andbtaI3 using chromosomal mini-CTX-luxtranscriptional reporters. The expression ofbtaR1,btaR2, andbtaR3 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 bothrsaM1andrsaM2are QS-controlled, as well as negatively auto-regulated. We conclude that RsaM1 and RsaM2 are an integral part of the QS modulatory circuitry ofB. 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 tworsaMhomologues designatedrsaM1andrsaM2in the regulation of the multiple QS systems coexisting in the non-pathogenic bacteriumBurkholderia thailandensis, widely used as a model system for the study of the pathogenBurkholderia pseudomallei. We found that inactivation of thesersaMhomologues, which are clustered with the other QS genes, profoundly affects the QS regulatory circuity ofB. 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 ofB. 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 inB. pseudomallei.

scholarly journals TworsaMHomologues Encode Central Regulatory Elements Modulating Quorum Sensing inBurkholderia thailandensis

2018 ◽  
Vol 200 (14) ◽  
Author(s):  
Servane Le Guillouzer ◽  
Marie-Christine Groleau ◽  
Eric Déziel
Keyword(s):  
Quorum Sensing ◽  
Functional Characterization ◽  
Gene Clusters ◽  
Homoserine Lactone ◽  
Regulatory Elements ◽  
Gene Encoding ◽  
Burkholderia Thailandensis ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
In The Wild

ABSTRACTThe bacteriumBurkholderia thailandensispossesses threeN-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 ofN-octanoyl-homoserine lactone (C8-HSL),N-3-hydroxy-decanoyl-homoserine lactone (3OHC10-HSL), andN-3-hydroxy-octanoyl-homoserine lactone (3OHC8-HSL), which are produced by the LuxI-type synthases BtaI1, BtaI2, and BtaI3 and modulated by the LuxR-type transcriptional regulators BtaR1, BtaR2, and BtaR3. ThebtaR1-btaI1andbtaR2-btaI2gene clusters each carry an additional gene encoding a homologue of the QS repressor RsaM originally identified in the phytopathogenPseudomonas fuscovaginaeand thus here namedrsaM1andrsaM2, respectively. We have characterized the functions of these two conservedrsaMhomologues and demonstrated their involvement in the regulation of AHL biosynthesis inB. thailandensisstrain E264. We quantified 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 thersaM1andrsaM2mutants, and we monitoredbtaI1,btaI2, andbtaI3expression using chromosomal mini-CTX-luxtranscriptional reporters. The transcription ofbtaR1,btaR2, andbtaR3was also measured by quantitative reverse transcription-PCR (qRT-PCR). We observed that RsaM1 mainly represses the QS-1 system, whereas RsaM2 principally represses the QS-2 system. We also found that bothrsaM1andrsaM2are QS controlled and negatively autoregulated. We conclude that RsaM1 and RsaM2 are an integral part of the QS circuitry ofB. thailandensisand play a major role in the hierarchical and homeostatic organization of the QS-1, QS-2, and QS-3 systems.IMPORTANCEQuorum sensing (QS) is commonly involved in the coordination of gene transcription associated with the establishment of host-pathogen interactions and acclimatization to the environment. We present the functional characterization of tworsaMhomologues in the regulation of the multiple QS systems coexisting in the nonpathogenic bacteriumBurkholderia thailandensis, which is widely used as a model system for the study of the human pathogenBurkholderia pseudomallei. We found that inactivation of thesersaMhomologues, which are clustered with the other QS genes, profoundly affects the QS circuitry ofB. thailandensis. We conclude that they constitute essential regulatory components of the QS modulatory network and provide additional layers of regulation to modulate the transcription of QS-controlled genes, particularly those linked to environmental adaptation.

scholarly journals Functional characterization of quorum sensing LuxR-type transcriptional regulator, EasR in Enterobacter asburiae strain L1

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10068
Author(s):  
Yin Yin Lau ◽  
Kah Yan How ◽  
Wai-Fong Yin ◽  
Kok-Gan Chan
Keyword(s):  
Quorum Sensing ◽  
Functional Characterization ◽  
In Silico Analysis ◽  
Transcriptional Regulator ◽  
Homoserine Lactone ◽  
Signaling Molecules ◽  
Species Interaction ◽  
Health Crisis ◽  
Enterobacter Asburiae

Over the past decades, Enterobacter spp. have been identified as challenging and important pathogens. The emergence of multidrug-resistant Enterobacteria especially those that produce Klebsiella pneumoniae carbapenemase has been a very worrying health crisis. Although efforts have been made to unravel the complex mechanisms that contribute to the pathogenicity of different Enterobacter spp., there is very little information associated with AHL-type QS mechanism in Enterobacter spp. Signaling via N-acyl homoserine lactone (AHL) is the most common quorum sensing (QS) mechanism utilized by Proteobacteria. A typical AHL-based QS system involves two key players: a luxI gene homolog to synthesize AHLs and a luxR gene homolog, an AHL-dependent transcriptional regulator. These signaling molecules enable inter-species and intra-species interaction in response to external stimuli according to population density. In our recent study, we reported the genome of AHL-producing bacterium, Enterobacter asburiae strain L1. Whole genome sequencing and in silico analysis revealed the presence of a pair of luxI/R genes responsible for AHL-type QS, designated as easI/R, in strain L1. In a QS system, a LuxR transcriptional protein detects and responds to the concentration of a specific AHL controlling gene expression. In E. asburiae strain L1, EasR protein binds to its cognate AHLs, N-butanoyl homoserine lactone (C4-HSL) and N–hexanoyl homoserine lactone (C6-HSL), modulating the expression of targeted genes. In this current work, we have cloned the 693 bp luxR homolog of strain L1 for further characterization. The functionality and specificity of EasR protein in response to different AHL signaling molecules to activate gene transcription were tested and validated with β-galactosidase assays. Higher β-galactosidase activities were detected for cells harboring EasR, indicating EasR is a functional transcriptional regulator. This is the first report documenting the cloning and characterization of transcriptional regulator, luxR homolog of E. asburiae.

scholarly journals Quorum-Sensing Control of Antibiotic Synthesis in Burkholderia thailandensis

2009 ◽  
Vol 191 (12) ◽  
pp. 3909-3918 ◽  
Author(s):  
Breck A. Duerkop ◽  
John Varga ◽  
Josephine R. Chandler ◽  
Snow Brook Peterson ◽  
Jake P. Herman ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Gene Clusters ◽  
Homoserine Lactone ◽  
Evolutionary Divergence ◽  
Peptide Antibiotics ◽  
Burkholderia Thailandensis ◽  
Antibiotic Synthesis ◽  
Gram Positive Bacteria ◽  
Sensing Systems ◽  
Close Relatives

ABSTRACT The genome of Burkholderia thailandensis codes for several LuxR-LuxI quorum-sensing systems. We used B. thailandensis quorum-sensing deletion mutants and recombinant Escherichia coli to determine the nature of the signals produced by one of the systems, BtaR2-BtaI2, and to show that this system controls genes required for the synthesis of an antibiotic. BtaI2 is an acyl-homoserine lactone (acyl-HSL) synthase that produces two hydroxylated acyl-HSLs, N-3-hydroxy-decanoyl-HSL (3OHC10-HSL) and N-3-hydroxy-octanoyl-HSL (3OHC8-HSL). The btaI2 gene is positively regulated by BtaR2 in response to either 3OHC10-HSL or 3OHC8-HSL. The btaR2-btaI2 genes are located within clusters of genes with annotations that suggest they are involved in the synthesis of polyketide or peptide antibiotics. Stationary-phase cultures of wild-type B. thailandensis, but not a btaR2 mutant or a strain deficient in acyl-HSL synthesis, produced an antibiotic effective against gram-positive bacteria. Two of the putative antibiotic synthesis gene clusters require BtaR2 and either 3OHC10-HSL or 3OHC8-HSL for activation. This represents another example where antibiotic synthesis is controlled by quorum sensing, and it has implications for the evolutionary divergence of B. thailandensis and its close relatives Burkholderia pseudomallei and Burkholderia mallei.

scholarly journals The complex quorum sensing circuitry ofBurkholderia thailandensisis both hierarchically and homeostatically organized

2017 ◽  
Author(s):  
Servane Le Guillouzer ◽  
Marie-Christine Groleau ◽  
Eric Déziel
Keyword(s):  
Quorum Sensing ◽  
Regulatory Network ◽  
Target Genes ◽  
Wide Spectrum ◽  
Expression Profiles ◽  
Homoserine Lactone ◽  
Growth Stages ◽  
Dependent Manner ◽  
Burkholderia Thailandensis ◽  
In The Wild

AbstractThe genome of the bacteriumBurkholderia thailandensisencodes for three complete LuxI/LuxR-type quorum sensing (QS) systems: BtaI1/BtaR1 (QS-1), BtaI2/BtaR2 (QS-2), and BtaI3/BtaR3 (QS-3). The LuxR-type transcriptional regulators BtaR1, BtaR2, and BtaR3 modulate the expression of target genes in association with variousN-acyl-L-homoserine lactones (AHLs) as signaling molecules produced by the LuxI-type synthases BtaI1, BtaI2, and BtaI3. We have systematically dissected the complex QS circuitry ofB. thailandensisstrain E264. Direct quantification of octanoyl-homoserine lactone (C8-HSL),N-3-hydroxy-decanoyl-homoserine lactone (3OHC10-HSL), andN-3-hydroxy-octanoyl-homoserine lactone (3OHC8-HSL), the primary AHLs produced by this bacterium, was performed in the wild-type strain and in QS deletion mutants. This was compared to the expression ofbtaI1,btaI2, andbtaI3 using chromosomal mini-CTX-luxtranscriptional reporters. Furthermore, transcription ofbtaR1,btaR2, andbtaR3 was monitored by quantitative reverse-transcription PCR (qRT-PCR). We observed that C8-HSL, 3OHC10-HSL, and 3OHC8-HSL are differentially produced over time during bacterial growth and correlate with thebtaI1,btaI2, andbtaI3 genes expression profiles, revealing a sequential activation of the corresponding QS systems. Moreover, transcription of thebtaR1,btaR2, andbtaR3 genes is modulated by AHLs, showing that their regulation depend on themselves, and on other systems. We conclude that the three QS systems inB. thailandensisare interdependent, suggesting that they cooperate dynamically and function in a concerted manner in modulating the expression of QS target genes through a sequential regulatory network.ImportanceQuorum sensing (QS) is a widespread bacterial communication system coordinating the expression of specific genes in a cell density-dependent manner and allowing bacteria to synchronize their activities and to function as multicellular communities. QS plays a crucial role in bacterial pathogenicity by regulating the expression of a wide spectrum of virulence/survival factors and is essential to environmental adaptation. The results presented here demonstrate that the multiple QS systems coexisting in the bacteriumBurkholderia thailandensis, considered as the avirulent version of the human pathogenBurkholderia pseudomalleiand thus commonly used as an alternative study model, are hierarchically and homeostatically organized. We found these QS systems finely integrated into a complex regulatory network, including transcriptional and post-transcriptional interactions, and further incorporating growth stages and temporal expression. These results provide a unique, comprehensive illustration of a sophisticated QS network and will contribute to a better comprehension of the regulatory mechanisms that can be involved in the expression of QS-controlled genes, in particular those associated with the establishment of host-pathogen interactions and acclimatization to the environment.

Abstract 050: Fine-mapping and Bioinformatics Characterization of QT Interval Loci in African Americans: The Population Architecture Using Genomics and Epidemiology (PAGE) Study

Circulation ◽  
2012 ◽  
Vol 125 (suppl_10) ◽  
Author(s):  
Christy L Avery ◽  
Praveen Sethupathy ◽  
Steven Buyske ◽  
Q. C He ◽  
Dan Y Lin ◽  
...  
Keyword(s):  
African American ◽  
African Americans ◽  
Fine Mapping ◽  
Qt Interval ◽  
Functional Characterization ◽  
Regulatory Elements ◽  
European Ancestry ◽  
Functional Evaluation ◽  
Human Cardiomyocytes

The QT interval (QT) is a heritable trait and its prolongation is an established risk factor for ventricular tachyarrhythmia and sudden cardiac death. Most genetic studies of QT have examined populations of European ancestry, although the increased genetic diversity in populations of African descent provides opportunity for fine-mapping, which can help narrow association signals and identify candidates for functional characterization. We examined whether eleven previously identified QT loci comprising 6,681 variants on the Illumina Metabochip array were associated with QT in 7,516 African American participants from the Atherosclerosis Risk in Communities study and Women’s Health Initiative clinical trial. Among associated loci, we used conditional analyses and queried bioinformatics databases to identify and functionally categorize signals. We identified nine of the eleven QT loci in African American populations ( P <0.0045 under an additive genetic model adjusting for ancestry and demographic characteristics: NOS1AP, ATP1B1, SCN5A, SLC35F1, KCNH2, KCNQ1, LITAF, NDRG4, and RFFL ). We also identified two independent secondary signals in NOS1AP and ATP1B1 ( P < 7.4x10 −6 ). Conditional analyses adjusting for published loci in European populations demonstrated that eight of these eleven SNPs (nine primary; two secondary) were independent of previously reported SNPs. We then performed the first bioinformatics-based functional characterization of QT loci using the eleven primary and secondary variants and SNPs in strong LD (r 2 > 0.5) among these African American participants. Only the SCN5A locus included a non-synonymous coding variant (rs1805124, H558R, r 2 = 0.7 with primary SNP rs9871385, P = 4.7x10 −4 ). The remaining ten loci harbored variants located exclusively within non-coding regions. Specifically, three contained SNPs within candidate long-range regulatory elements in human cardiomyocytes, five were in or near annotated promoter regions, and the remaining two were in un-annotated, but highly conserved non-coding elements. Several of the QT risk alleles at these SNPs significantly alter the predicted binding affinity for transcription factors, such as TBX5 and AhR, which have been previously implicated in cardiac formation and function. In summary, the findings provide compelling evidence that the same genes influence variation in QT across global populations and that additional, independent signals exist in African Americans. Moreover, of those SNPs identified as strong candidates for functional evaluation, the majority implicate gene regulatory dysfunction in QT prolongation.

scholarly journals Functional characterization of Lilium lancifolium cold-responsive Zinc Finger Homeodomain (ZFHD) gene in abscisic acid and osmotic stress tolerance

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11508
Author(s):  
Yubing Yong ◽  
Yue Zhang ◽  
Yingmin Lyu
Keyword(s):  
Abscisic Acid ◽  
Transgenic Plants ◽  
Zinc Finger ◽  
Promoter Region ◽  
Salt Water ◽  
Functional Characterization ◽  
Regulatory Elements ◽  
Response Analysis ◽  
Lilium Lancifolium

Background. We have previously performed an analysis of the cold-responsive transcriptome in the mature leaves of tiger lily (Lilium lancifolium) by gene co-expression network identification. The results has revealed that a ZFHD gene, notated as encoding zinc finger homeodomain protein, may play an essential regulating role in tiger lily response to cold stress. Methods. A further investigation of the ZFHD gene (termed as LlZFHD4) responding to osmotic stresses, including cold, salt, water stresses, and abscisic acid (ABA) was performed in this study. Based on the transcriptome sequences, the coding region and 5′ promoter region of LlZFHD4 were cloned from mature tiger lily leaves. Stress response analysis was performed under continuous 4 °C, NaCl, PEG, and ABA treatments. Functional characterization of LlZFHD4 was conducted in transgenic Arabidopsis, tobacco, and yeast. Results. LlZFHD4 encodes a nuclear-localized protein consisting of 180 amino acids. The N-terminal region of LlZFHD4 has transcriptional activation activity in yeast. The 4 °C, NaCl, PEG, and ABA treatments induced the expression of LlZFHD4. Several stress- or hormone-responsive cis-acting regulatory elements (T-Box, BoxI. and ARF) and binding sites of transcription factors (MYC, DRE and W-box) were found in the core promoter region (789 bp) of LlZFHD4. Also, the GUS gene driven by LlZFHD4 promoter was up-regulated by cold, NaCl, water stresses, and ABA in Arabidopsis. Overexpression of LlZFHD4 improved cold and drought tolerance in transgenic Arabidopsis; higher survival rate and better osmotic adjustment capacity were observed in LlZFHD4 transgenic plants compared to wild type (WT) plants under 4 °C and PEG conditions. However, LlZFHD4 transgenic plants were less tolerant to salinity and more hypersensitive to ABA compared to WT plants. The transcript levels of stress- and ABA-responsive genes were much more up-regulated in LlZFHD4 transgenic Arabidopsis than WT. These results indicate LlZFHD4 is involved in ABA signaling pathway and plays a crucial role in regulating the response of tiger lily to cold, salt and water stresses.

scholarly journals Quorum sensing in Vibrio anguillarum: characterization of the vanI/vanR locus and identification of the autoinducer N-(3-oxodecanoyl)-L-homoserine lactone.

1997 ◽  
Vol 179 (9) ◽  
pp. 3004-3012 ◽  
Author(s):  
D L Milton ◽  
A Hardman ◽  
M Camara ◽  
S R Chhabra ◽  
B W Bycroft ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Vibrio Anguillarum ◽  
Homoserine Lactone

The regulatory elements of PLZF gene are not conserved as reveled by molecular cloning and functional characterization of PLZF gene promoter of Clarias batrachus

Gene Reports ◽  
2019 ◽  
Vol 16 ◽  
pp. 100402
Author(s):  
Swapnarani Nayak ◽  
Lipika Patnaik ◽  
Meenati Manjari Soren ◽  
V. Chakrapani ◽  
Shibani Dutta Mohapatra ◽  
...  
Keyword(s):  
Molecular Cloning ◽  
Functional Characterization ◽  
Gene Promoter ◽  
Regulatory Elements ◽  
Clarias Batrachus

scholarly journals Malleilactone Is a Burkholderia pseudomallei Virulence Factor Regulated by Antibiotics and Quorum Sensing

2018 ◽  
Vol 200 (14) ◽  
Author(s):  
Jennifer R. Klaus ◽  
Jacqueline Deay ◽  
Benjamin Neuenswander ◽  
Wyatt Hursh ◽  
Zhe Gao ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Caenorhabditis Elegans ◽  
Quorum Sensing ◽  
Virulence Factor ◽  
Mammalian Cells ◽  
Burkholderia Pseudomallei ◽  
Gene Clusters ◽  
Close Relative ◽  
Burkholderia Thailandensis ◽  
Content Type

ABSTRACT Burkholderia pseudomallei , the causative agent of melioidosis, encodes almost a dozen predicted polyketide (PK) biosynthetic gene clusters. Many of these are regulated by LuxR-I-type acyl-homoserine (AHL) quorum-sensing systems. One of the PK gene clusters, the mal gene cluster, is conserved in the close relative Burkholderia thailandensis . The B. thailandensis mal genes code for the cytotoxin malleilactone and are regulated by a genetically linked LuxR-type transcription factor, MalR. Although AHLs typically interact with LuxR-type proteins to modulate gene transcription, the B. thailandensis MalR does not appear to be an AHL receptor. Here, we characterize the mal genes and MalR in B. pseudomallei . We use chemical analyses to demonstrate that the B. pseudomallei mal genes code for malleilactone. Our results show that MalR and the mal genes contribute to the ability of B. pseudomallei to kill Caenorhabditis elegans . In B. thailandensis , antibiotics like trimethoprim can activate MalR by driving transcription of the mal genes, and we demonstrate that some of the same antibiotics induce expression of B. pseudomallei malR . We also demonstrate that B. pseudomallei MalR does not respond directly to AHLs. Our results suggest that MalR is indirectly repressed by AHLs, possibly through a repressor, ScmR. We further show that malleilactone is a B. pseudomallei virulence factor and provide the foundation for understanding how malleilactone contributes to the pathology of melioidosis infections. IMPORTANCE Many bacterially produced polyketides are cytotoxic to mammalian cells and are potentially important contributors to pathogenesis during infection. We are interested in the polyketide gene clusters present in Burkholderia pseudomallei , which causes the often-fatal human disease melioidosis. Using knowledge gained by studies in the close relative Burkholderia thailandensis , we show that one of the B. pseudomallei polyketide biosynthetic clusters produces a cytotoxic polyketide, malleilactone. Malleilactone contributes to B. pseudomallei virulence in a Caenorhabditis elegans infection model and is regulated by an orphan LuxR family quorum-sensing transcription factor, MalR. Our studies demonstrate that malleilactone biosynthesis or MalR could be new targets for developing therapeutics to treat melioidosis.

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