Analysis of the quorum‐sensing regulon of the opportunistic pathogen <b><i>Burkholderia cepacia</i></b> H111 by proteomics

Riedel, Katharina; Arevalo-Ferro, Catalina; Reil, Gerold; Görg, Angelika; Lottspeich, Friedrich; Eberl, Leo

doi:10.1002/elps.200390089

Cited by 76 publications

(80 citation statements)

References 35 publications

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“…However, no function has been assigned to this gene so far. These results are in full agreement with those of a recent proteomics study, which identified AidA among those proteins that were missing in the cepI mutant H111-I compared to the wild-type strain H111 (46).…”

Section: Resultssupporting

confidence: 92%

“…Cellular localization of AidA. A recent proteome analysis of the QS regulon of B. cenocepacia H111 identified AidA as an AHL-regulated protein in the intracellular, extracellular, and surface-bound protein fractions (46). To determine the cellular localization of AidA, we performed Western blotting on samples that were fractionated as described in Materials and Methods.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, CepR tightly controls expression of cepI, creating a positive feedback loop that ensures a very rapid increase in virulence factor production once the regulatory system has been triggered. A comparison of the two-dimensional protein patterns of the B. cenocepacia strain H111 and its isogenic cepI mutant H111-I showed that 6% of the proteins detected were differentially expressed (46). Amino-terminal sequence analysis identified several proteins that were downregulated in the cepI mutant, including a putative superoxide dismutase, a peroxidase, a FimA homologue, and a predicted ABC transporter system.…”

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confidence: 99%

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Identification of a Novel Virulence Factor in Burkholderia cenocepacia H111 Required for Efficient Slow Killing of Caenorhabditis elegans

Huber¹,

Feldmann²,

Köthe³

et al. 2004

Infect Immun

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Burkholderia cenocepacia H111, which was isolated from a cystic fibrosis patient, employs a quorum-sensing (QS) system, encoded by cep, to control the expression of virulence factors as well as the formation of biofilms. The QS system is thought to ensure that pathogenic traits are expressed only when the bacterial population density is high enough to overwhelm the host before it is able to mount an efficient response. While the wild-type strain effectively kills the nematode Caenorhabditis elegans, the pathogenicity of mutants with defective quorum sensing is attenuated. To date, very little is known about the cep-regulated virulence factors required for nematode killing. Here we report the identification of a cep-regulated gene, whose predicted amino acid sequence is highly similar to the QS-regulated protein AidA of the plant pathogen Ralstonia solanacearum. By use of polyclonal antibodies directed against AidA, it is demonstrated that the protein is expressed in the late-exponential phase and accumulates during growth arrest. We show that B. cenocepacia H111 AidA is essential for slow killing of C. elegans but has little effect on fast killing, suggesting that the protein plays a role in the accumulation of the strain in the nematode gut. Thus, AidA appears to be required for establishing an infection-like process rather than acting as a toxin. Furthermore, evidence is provided that AidA is produced not only by B. cenocepacia but also by many other strains of the Burkholderia cepacia complex.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Identification of a Novel Virulence Factor in Burkholderia cenocepacia H111 Required for Efficient Slow Killing of Caenorhabditis elegans

Huber¹,

Feldmann²,

Köthe³

et al. 2004

Infect Immun

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“…However, our results are preliminary results which only suggest the existence of a quorum-sensing regulon in A. ferrooxidans. Proteomic and transcriptomic studies like those performed with other bacteria (P. aeruginosa, B. cepacia H111, and S. meliloti) should help demonstrate the existence of a QS regulon in A. ferrooxidans (5,10,30,35,38,46).…”

Section: Resultsmentioning

confidence: 99%

Evidence for a Functional Quorum-Sensing Type AI-1 System in the Extremophilic Bacterium Acidithiobacillus ferrooxidans

Farah

Vera

Morin

et al. 2005

Appl Environ Microbiol

124

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Acidithiobacillus ferrooxidans is one of the main acidophilic chemolithotrophic bacteria involved in the bioleaching of metal sulfide ores. The bacterium-mineral interaction requires the development of biofilms, whose formation is regulated in many microorganisms by type AI-1 quorum sensing. Here, we report the existence and characterization of a functional type AI-1 quorum-sensing system in A. ferrooxidans. This microorganism produced mainly acyl-homoserine lactones (AHL) with medium and large acyl chains and different C-3 substitutions, including 3-hydroxy-C 8 -AHL, 3-hydroxy-C 10 -AHL, C 12 -AHL, 3-oxo-C 12 -AHL, 3-hydroxy-C 12 -AHL, C 14 -AHL, 3-oxo-C 14 -AHL, 3-hydroxy-C 14 -AHL, and 3-hydroxy-C 16 -AHL. A quorum-sensing genetic locus that includes two open reading frames, afeI and afeR, which have opposite orientations and code for proteins with high levels of similarity to members of the acyl synthase (I) and transcriptional regulator (R) protein families, respectively, was identified. Overexpression of AfeI in Escherichia coli and the associated synthesis of AHLs confirmed that AfeI is an AHL synthase. As determined by reverse transcription-PCR, the afeI and afeR genes were transcribed in A. ferrooxidans. The transcription levels of the afeI gene were higher in cells grown in sulfur and thiosulfate media than in iron-grown cells. Phosphate starvation induced an increase in the transcription levels of afeI which correlated with an increase in AHL levels. Two afe boxes which could correspond to the AfeR binding sites were identified upstream of the afeI gene. This is the first report of a functional type AI-1 quorum-sensing system in an acidophilic chemolithotrophic microorganism, and our results provide a very interesting opportunity to explore the control and regulation of biofilm formation during the bioleaching process.Quorum sensing (QS) is a widespread phenomenon that enables bacterial cells to establish cell-cell communication and to regulate the expression of specific genes in response to local changes in cell density (6,48,49). QS provides the means to coordinate the activities of cells so that they function as a multicellular unit and communicate with eukaryotic hosts (6,20,48,49). In gram-negative bacteria, depending on the autoinductor (AI) molecule, two QS processes have been described: type AI-1, which is involved mainly in intraspecies communication, and type AI-2, which is related to interspecies communication (20,49).The type AI-1 QS regulatory system is composed of four elements: (i) a transcriptional regulator (protein family R); (ii) a cis-acting DNA palindromic sequence; (iii) an acyl-homoserine lactone (AHL), which is the signaling molecule or autoinducer (AI-1); and (iv) the AHL synthase protein (protein family I), which synthesizes the AI (6,20,48,49). It is currently accepted that AI-1 diffuses freely between the cellular and external environments and complexes with the R protein only at a high cell density. The AHL-R complex binds through the R carboxyl domain to the specific site...

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“…Surprisingly, however, we observed that the cepR mutant, H111-R, was as pathogenic as the wild type in G. mellonella (Table 2). This discrepancy may be explained by fact that CepR acts as both a positive and a negative regulator in B. cenocepacia (53). It is therefore likely that in the cepR mutant, expression of G. mellonella-specific virulence factors is derepressed.…”

Section: Vol 77 2009 Virulence Of B Cenocepacia In Multiple Hosts mentioning

confidence: 99%

Identification of Specific and Universal Virulence Factors in Burkholderia cenocepacia Strains by Using Multiple Infection Hosts

et al. 2009

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Over the past few decades, strains of the Burkholderia cepacia complex have emerged as important pathogens for patients suffering from cystic fibrosis. Identification of virulence factors and assessment of the pathogenic potential of Burkholderia strains have increased the need for appropriate infection models. In previous studies, different infection hosts, including mammals, nematodes, insects, and plants, have been used. At present, however, the extent to which the virulence factors required to infect different hosts overlap is not known. The aim of this study was to analyze the roles of various virulence factors of two closely related Burkholderia cenocepacia strains, H111 and the epidemic strain K56-2, in a multihost pathogenesis system using four different model organisms, namely, Caenorhabditis elegans, Galleria mellonella, the alfalfa plant, and mice or rats. We demonstrate that most of the identified virulence factors are specific for one of the infection models, and only three factors were found to be essential for full pathogenicity in several hosts: mutants defective in (i) quorum sensing, (ii) siderophore production, and (iii) lipopolysaccharide biosynthesis were attenuated in at least three of the infection models and thus may represent promising targets for the development of novel anti-infectives.The Burkholderia cepacia complex (BCC) comprises a group of the following 17 formally named bacterial species: Burkholderia cepacia,

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Analysis of the quorum‐sensing regulon of the opportunistic pathogen Burkholderia cepacia H111 by proteomics

Cited by 76 publications

References 35 publications

Identification of a Novel Virulence Factor in Burkholderia cenocepacia H111 Required for Efficient Slow Killing of Caenorhabditis elegans

Identification of a Novel Virulence Factor in Burkholderia cenocepacia H111 Required for Efficient Slow Killing of Caenorhabditis elegans

Evidence for a Functional Quorum-Sensing Type AI-1 System in the Extremophilic Bacterium Acidithiobacillus ferrooxidans

Identification of Specific and Universal Virulence Factors in Burkholderia cenocepacia Strains by Using Multiple Infection Hosts

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