Cross-Species Comparison of the Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei Quorum-Sensing Regulons

Majerczyk, Charlotte D.; Brittnacher, M.; Jacobs, Michael A.; Armour, Christopher D.; Radey, Matthew C.; Bunt, Richard C.; Hayden, Hillary S.; Bydalek, Ryland; Greenberg, E. Peter

doi:10.1128/jb.01974-14

Cited by 46 publications

(54 citation statements)

References 50 publications

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“…Recent RNA-seq studies by Greenberg and coworkers have allowed identification of a core set of genes that is QS-activated in the Pseudomallei group pathogens, which include B. thailandensis, B. pseudomallei, and B. mallei (19,22). Because of the importance of LTTRs in regulating secondary metabolite production in other Proteobacteria, we searched the RNA-seq datasets for transcriptional regulators that were common to all three strains.…”

Section: Resultsmentioning

confidence: 99%

“…Consequently, MvfR has advanced to a target for the development of strategies to combat P. aeruginosa infections. Orthologs of scmR are also abundantly expressed in B. pseudomallei and B. mallei as a function of QS (22). It will be interesting to examine the roles of scmR in virulence factor production in these strains and to explore whether interfering with its function can lead to effective therapies against Pseudomallei group pathogens.…”

Section: Discussionmentioning

confidence: 99%

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Discovery of scmR as a global regulator of secondary metabolism and virulence in Burkholderia thailandensis E264

Mao

Bushin

Moon

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

140

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Bacteria produce a diverse array of secondary metabolites that have been invaluable in the clinic and in research. These metabolites are synthesized by dedicated biosynthetic gene clusters (BGCs), which assemble architecturally complex molecules from simple building blocks. The majority of BGCs in a given bacterium are not expressed under normal laboratory growth conditions, and our understanding of how they are silenced is in its infancy. Here, we have addressed this question in the Gram-negative model bacterium Burkholderia thailandensis E264 using genetic, transcriptomic, metabolomic, and chemical approaches. We report that a previously unknown, quorum-sensing-controlled LysR-type transcriptional regulator, which we name ScmR (for secondary metabolite regulator), serves as a global gatekeeper of secondary metabolism and a repressor of numerous BGCs. Transcriptionally, we find that 13 of the 20 BGCs in B. thailandensis are significantly (threefold or more) upor down-regulated in a scmR deletion mutant (ΔscmR). Metabolically, the ΔscmR strain displays a hyperactive phenotype relative to wild type and overproduces a number of compound families by 18-to 210-fold, including the silent virulence factor malleilactone. Accordingly, the ΔscmR mutant is hypervirulent both in vitro and in a Caenorhabditis elegans model in vivo. Aside from secondary metabolism, ScmR also represses biofilm formation and transcriptionally activates ATP synthesis and stress response. Collectively, our data suggest that ScmR is a pleiotropic regulator of secondary metabolism, virulence, biofilm formation, and other stationary phase processes. A model for how the interplay of ScmR with pathwayspecific transcriptional regulators coordinately silences virulence factor production is proposed.biosynthetic gene clusters | natural products | Burkholderia thailandensis | regulation | virulence

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Discovery of scmR as a global regulator of secondary metabolism and virulence in Burkholderia thailandensis E264

Mao

Bushin

Moon

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

140

View full text Add to dashboard Cite

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“…Each study focused on a different organism, and the growth conditions also differed; hence, the number of genes that were differentially regulated in response to QS processes varied. In recent studies, the QS regulons represented up to 6.2% of the coding sequences in the P. aeruginosa genome (for lasI and lasR and for rhlI and rhlR) (58), up to 8.1% of the coding sequences in the Yersinia pestis genome (59), up to 8.0% coding sequences in the B. thailandensis genome (28), 0.8% of the coding sequences in the B. mallei genome, 3.6% coding sequences in the B. pseudomallei genome (30), and between 4.9 and 7.3% of the coding sequences in the in S. fredii NGR234 genome (40). We observed that 11.5% of all genes were differentially regulated by the three BGPG1 QS systems, and it was recently reported that up to 19.6% of the BGR1 genes were regulated in a QS-dependent manner in a tofI mutant (34).…”

Section: Global Pattern Of Qs-dependent Gene Expression In Bgpg1mentioning

confidence: 99%

“…Additionally, the phenotypes of the wild-type and mutant strains were comparatively studied, and a common set of orthologous QS-regulated genes was identified in B. glumae PG1 and the recently studied model organisms from the Bptm group (28,30).…”

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confidence: 99%

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Genome-Wide RNA Sequencing Analysis of Quorum Sensing-Controlled Regulons in the Plant-Associated Burkholderia glumae PG1 Strain

Gao

Krysciak

Petersen

et al. 2015

Appl Environ Microbiol

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dBurkholderia glumae PG1 is a soil-associated motile plant-pathogenic bacterium possessing a cell density-dependent regulation system called quorum sensing (QS). Its genome contains three genes, here designated bgaI1 to bgaI3, encoding distinct autoinducer-1 (AI-1) synthases, which are capable of synthesizing QS signaling molecules. Here, we report on the construction of B. glumae PG1 ⌬bgaI1, ⌬bgaI2, and ⌬bgaI3 mutants, their phenotypic characterization, and genome-wide transcriptome analysis using RNA sequencing (RNA-seq) technology. Knockout of each of these bgaI genes resulted in strongly decreased motility, reduced extracellular lipase activity, a reduced ability to cause plant tissue maceration, and decreased pathogenicity. RNA-seq analysis of all three B. glumae PG1 AI-1 synthase mutants performed in the transition from exponential to stationary growth phase revealed differential expression of a significant number of predicted genes. In comparison with the levels of gene expression by wild-type strain B. glumae PG1, 481 genes were differentially expressed in the ⌬bgaI1 mutant, 213 were differentially expressed in the ⌬bgaI2 mutant, and 367 were differentially expressed in the ⌬bgaI3 mutant. Interestingly, only a minor set of 78 genes was coregulated in all three mutants. The majority of the QS-regulated genes were linked to metabolic activities, and the most pronounced regulation was observed for genes involved in rhamnolipid and Flp pilus biosynthesis and the type VI secretion system and genes linked to a clustered regularly interspaced short palindromic repeat (CRISPR)-cas gene cluster. Q uorum sensing (QS) is a cell density-dependent gene regulation system in bacteria (1) in which the population density is sensed through the accumulation of bacterially produced signaling molecules called autoinducers (AIs). This cell-to-cell signaling process allows the microbial population to synchronize group behavior and alter its gene expression accordingly. QS is involved in a wide array of regulatory circuits, among which are pathogenicity, secretion of extracellular proteins, secondary metabolite production, and others (2). Key QS signaling molecules in many Gram-negative bacteria are N-acyl-homoserine lactones (AHLs) (3-5), synthesized mainly through LuxI homologs (EC 2.3.1.184) using S-adenosylmethionine (SAM), and an acyl-acyl carrier protein (acyl-ACP) from the fatty acid biosynthesis pathway (6). LuxR-type receptor/regulator proteins are involved in AHL signal perception. Together with LuxR, other proteins may be part of this regulatory circuit.The motile, rod-shaped Gram-negative soil bacterium Burkholderia glumae is considered to be a seed-borne pathogen that causes panicle blight of rice (7). B. glumae has also been reported to infect other plant species, like tomato, sunflower, and pepper (8, 9). Although it is not classified as a human pathogen, a single case of the isolation of B. glumae from a clinical sample was reported (10), indicating that at least some strains of this pathogen may be associated w...

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Reporter‐Guided Transposon Mutant Selection for Activation of Silent Gene Clusters in Burkholderia thailandensis

et al. 2020

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Most natural product biosynthetic gene clusters that can be observed bioinformatically are silent. This insight has prompted the development of several methodologies for inducing their expression. One of the more recent methods, termed reporter‐guided mutant selection (RGMS), entails creation of a library of mutants that is then screened for the desired phenotype via reporter gene expression. Herein, we apply a similar approach to Burkholderia thailandensis and, using transposon mutagenesis, mutagenize three strains, each carrying a fluorescent reporter in the malleilactone (mal), capistruin (cap), or an unidentified ribosomal peptide (tomm) gene cluster. We show that even a small library of <500 mutants can be used to induce expression of each cluster. We also explore the mechanism of activation and find that inhibition of pyrimidine biosynthesis is linked to the induction of the mal cluster. Both a transposon insertion into pyrF as well as small‐molecule‐mediated inhibition of PyrF trigger malleilactone biosynthesis. Our results pave the way toward the broad application of RGMS and related approaches to Burkholderia spp.

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Cross-Species Comparison of the Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei Quorum-Sensing Regulons

Cited by 46 publications

References 50 publications

Discovery of scmR as a global regulator of secondary metabolism and virulence in Burkholderia thailandensis E264

Discovery of scmR as a global regulator of secondary metabolism and virulence in Burkholderia thailandensis E264

Genome-Wide RNA Sequencing Analysis of Quorum Sensing-Controlled Regulons in the Plant-Associated Burkholderia glumae PG1 Strain

Reporter‐Guided Transposon Mutant Selection for Activation of Silent Gene Clusters in Burkholderia thailandensis

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