Saturation mutagenesis of a CepR binding site as a means to identify new quorum-regulated promoters in Burkholderia cenocepacia

Ye, Wei; Ryan, Gina; Flores-Mireles, Ana L.; Costa, Esther Da; Schneider, David J.; Winans, Stephen C.

doi:10.1111/j.1365-2958.2010.07469.x

Cited by 13 publications

(18 citation statements)

References 62 publications

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“…A recent study has reported a different consensus sequence in B. cenocepacia K56‐2, as well as the experimental demonstration of the direct regulation for two genes, BCAL0510 and BCAM1869 (Wei et al. ). BCAM1869 is an ortholog of Bamb_4117, which is located between cepR and cepI , and for which we have predicted a putative cep box (Fig.…”

Section: Discussionmentioning

confidence: 95%

“…This approach does not allow to discriminate genes directly or indirectly controlled by QS (Wei et al. ). To partially circumvent this shortcoming, we have performed a bioinformatics search for the presence of putative cep boxes upstream of transcriptional units identified in the screening.…”

Section: Discussionmentioning

confidence: 99%

“…Comparative genomics was used to predict cep boxes. Three different cep box consensus from previous reports (Chambers et al 2006;Wei et al 2011) were used in order to write three RNAMotif descriptors (Macke et al 2001). A search in all the Burkholderia genomes (Winsor et al 2008) with relaxed parameters provided thousands of hits.…”

Section: Bioinformatics Search For Putative Cep Boxesmentioning

confidence: 99%

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Identification of quorum sensing‐controlled genes in Burkholderia ambifaria

et al. 2013

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The Burkholderia cepacia complex (Bcc) comprises strains with a virulence potential toward immunocompromised patients as well as plant growth–promoting rhizobacteria (PGPR). Owing to the link between quorum sensing (QS) and virulence, most studies among Bcc species have been directed toward QS of pathogenic bacteria. We have investigated the QS of B. ambifaria, a PGPR only infrequently recovered from patients. The cepI gene, responsible for the synthesis of the main signaling molecule N-octanoylhomoserine lactone (C8-HSL), was inactivated. Phenotypes of the B. ambifaria cepI mutant we observed, such as increased production of siderophores and decreased proteolytic and antifungal activities, are in agreement with those of other Bcc cepI mutants. The cepI mutant was then used as background strain for a whole-genome transposon-insertion mutagenesis strategy, allowing the identification of 20 QS-controlled genes, corresponding to 17 loci. The main functions identified are linked to antifungal and antimicrobial properties, as we have identified QS-controlled genes implicated in the production of pyrrolnitrin, burkholdines (occidiofungin-like molecules), and enacyloxins. This study provides insights in the QS-regulated functions of a PGPR, which could lead to beneficial potential biotechnological applications.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Bioinformatics Search For Putative Cep Boxesmentioning

confidence: 99%

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Identification of quorum sensing‐controlled genes in Burkholderia ambifaria

et al. 2013

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“…Genetic organization of the B. cenocepacia bcam1869 locus. The bcam1869, cepI, and bcam1871 genes are transcriptionally induced by CepR-OHL complexes [25]. B).…”

Section: Figmentioning

confidence: 99%

RsaM: a transcriptional regulator of Burkholderia spp. with novel fold

et al. 2014

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Burkholderia cepacia complex (Bcc) is a set of closely related bacterial species that are notorious pathogens of cystic fibrosis patients, responsible for life-threatening lung infections. Expression of several virulence factors of Bcc is controlled by a mechanism known as quorum sensing (QS). QS is a means of bacterial communication used to coordinate gene expression in a cell-density–dependent manner. The system involves the production of diffusible signaling molecules (N-acyl-L-homoserine lactones, AHLs), that bind to cognate transcriptional regulators and influence their ability to regulate gene expression. One such system that is highly conserved in Bcc consists of CepI and CepR. CepI is AHL synthase, while CepR is an AHL-dependent transcription factor. In most members of the Bcc group, the cepI and cepR genes are divergently transcribed and separated by additional genes. One of them, bcam1869, encodes the BcRsaM protein, which was recently postulated to modulate the abundance or activity of CepI or CepR. Here we show the crystal structure of BcRsaM from B. cenocepacia J2315. It is a single-domain protein with unique topology and presents a novel fold. The protein is a dimer in the crystal and in solution. This regulator has no known DNA binding motifs and direct binding of BcRsaM to the cepI promoter could not be detected in in vitro assays. Therefore, we propose that the modulatory action of RsaM might result from interactions with other components of the QS machinery rather than from direct association with the DNA promoter.

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“…Typically, quorum-sensing systems operate as transcription networks regulated by a LuxR-type transcription regulator and its cognate AHL (reviewed in reference 3). While many studies on quorum sensing have focused on extending the known regulon (4)(5)(6)(7)(8)(9)(10)(11)(12)(13), few have considered the temporary aspects of transcription regulation (12). Interestingly, studies on regulatory networks are revealing the dynamic behavior and precision timing of transcription control (14,15).…”

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confidence: 99%

Temporal Expression Program of Quorum Sensing-Based Transcription Regulation in Sinorhizobium meliloti

Charoenpanich

Meyer

Becker

et al. 2013

Journal of Bacteriology

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The Sin quorum sensing (QS) system of S. meliloti activates exopolysaccharide and represses flagellum production. The system consists of an N-acyl-homoserine lactone (AHL) synthase, SinI, and at least two LuxR-type regulators, SinR and ExpR. SinR appears to be independent of AHLs for its control of sinI expression, while ExpR is almost completely dependent upon AHLs. In this study, we confirmed 7 previously detected ExpR-DNA binding sites and used the consensus sequence to identify another 26 sites, some of which regulate genes previously not known to be members of the ExpR/AHL regulon. The activities of promoters dependent upon ExpR/AHL were titrated against AHL levels, with varied outcomes in AHL sensitivity. The data suggest a type of temporal expression program whereby the activity of each promoter is subject to a specific range of AHL concentrations. For example, genes responsible for exopolysaccharide production are activated at lower concentrations of AHLs than those required for the repression of genes controlling flagellum production. Several features of ExpR-regulated promoters appear to determine their response to AHLs. The location of the ExpR-binding site with respect to the relevant transcription start within each promoter region determines whether ExpR/AHL activates or represses promoter activity. Furthermore, the strength of the response is dependent upon the concentration of AHLs. We propose that this differential sensitivity to AHLs provides a bacterial colony with a transcription control program that is dynamic and precise.

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Saturation mutagenesis of a CepR binding site as a means to identify new quorum-regulated promoters in Burkholderia cenocepacia

Cited by 13 publications

References 62 publications

Identification of quorum sensing‐controlled genes in Burkholderia ambifaria

Identification of quorum sensing‐controlled genes in Burkholderia ambifaria

RsaM: a transcriptional regulator of Burkholderia spp. with novel fold

Temporal Expression Program of Quorum Sensing-Based Transcription Regulation in Sinorhizobium meliloti

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