AHL-driven quorum-sensing circuits: their frequency and function among the Proteobacteria

Case, Rebecca J.; Labbate, Maurizio; Kjelleberg, Staffan

doi:10.1038/ismej.2008.13

Cited by 258 publications

(209 citation statements)

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“…At the station at 28.6 o N 65.1 o W, Trichodesmium colonies were also assayed using a cell-specific APase method (Dyhrman et al, 2002), and microscopic inspection clearly showed APase activity by epibionts in the colonies (Figure 2), particularly in the colonies exposed to the AHL cocktail (although this method is qualitative and not amenable to rigorous statistical comparisons (Hynes et al, 2009)). Given this observation, and the fact that available genomes from cyanobacteria, including Trichodesmium, lack clear homologs of genes encoding known AHL receptors (Case et al, 2008), we posit that the increase in APase activity (Figure 1) primarily reflected the response of bacterial epibionts and not the response of Trichodesmium. Although Trichodesmium does contain genes that align weakly at the amino acid level to authentic LuxR homologs, the key residues in the AHL-binding regions (Vannini et al, 2002;Pantankar and González, 2009) are absent, indicating that these Trichodesmium genes are unlikely to have AHLbinding functionality (Supplementary Figure 3).…”

Section: Resultsmentioning

confidence: 99%

“…However, the distribution of APase activity among epibionts and Trichodesmium within colonies is highly variable even within the same environment (Dyhrman et al, 2002;Hynes et al, 2009), and the mechanisms driving the variability in this behavior are unknown. Proteobacteria related to those within Trichodesmium consortia (Hewson et al, 2009;Hmelo, 2010) are known to employ quorum sensing (QS; a cell-density dependent signaling system), based on acylated homoserine lactones (AHLs; Supplementary Figure 1) to coordinate their behavior (Wagner-Döbler et al, 2005;Case et al, 2008). Furthermore, it was recently shown that AHL-based QS is sustainable at the cell densities typical of Trichodesmium colonies (Hmelo and Van Mooy, 2009;Hmelo et al, in press).…”

Section: Introductionmentioning

confidence: 99%

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Quorum sensing control of phosphorus acquisition in Trichodesmium consortia

et al. 2011

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Colonies of the cyanobacterium Trichodesmium are abundant in the oligotrophic ocean, and through their ability to fix both CO 2 and N 2 , have pivotal roles in the cycling of carbon and nitrogen in these highly nutrient-depleted environments. Trichodesmium colonies host complex consortia of epibiotic heterotrophic bacteria, and yet, the regulation of nutrient acquisition by these epibionts is poorly understood. We present evidence that epibiotic bacteria in Trichodesmium consortia use quorum sensing (QS) to regulate the activity of alkaline phosphatases (APases), enzymes used by epibionts in the acquisition of phosphate from dissolved-organic phosphorus molecules. A class of QS molecules, acylated homoserine lactones (AHLs), were produced by cultivated epibionts, and adding these AHLs to wild Trichodesmium colonies collected at sea led to a consistent doubling of APase activity. By contrast, amendments of (S)-4,5-dihydroxy-2,3-pentanedione (DPD)-the precursor to the autoinducer-2 (AI-2) family of universal interspecies signaling molecules-led to the attenuation of APase activity. In addition, colonies collected at sea were found by high performance liquid chromatography/mass spectrometry to contain both AHLs and AI-2. Both types of molecules turned over rapidly, an observation we ascribe to quorum quenching. Our results reveal a complex chemical interplay among epibionts using AHLs and AI-2 to control access to phosphate in dissolved-organic phosphorus.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quorum sensing control of phosphorus acquisition in Trichodesmium consortia

et al. 2011

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“…For example, it has been shown that Escherichia coli, which does not produce AHLs, can respond to AHLs via the orphan AHL receptor SdiA, leading to specific changes in gene expression (Hughes et al, 2010). Moreover, a phylogenetic survey by Case et al (2008) demonstrated that 45 out of 512 complete genomes contained incomplete QS circuits, with homologues of the AHL receptor gene luxR but not the AHL synthase gene luxI. In our system, it was observed that several members of two dominant genera in the community, that is, Candidatus Competibacter and Candidatus Accumulator, previously demonstrated to be essential for granulation through the production of granulan associated with the EPS (Seviour et al, 2011), were positively correlated with QS and granulation (cluster 2), suggesting that they may participate in, or benefit from, QS even though they have not yet been demonstrated to produce AHL signals or carry AHL receptor homologues.…”

Section: Discussionmentioning

confidence: 99%

The role of quorum sensing signalling in EPS production and the assembly of a sludge community into aerobic granules

et al. 2014

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Quorum sensing (QS) signalling has been extensively studied in single species populations. However, the ecological role of QS in complex, multi-species communities, particularly in the context of community assembly, has neither been experimentally explored nor theoretically addressed. Here, we performed a long-term bioreactor ecology study to address the links between QS, organization and composition of complex microbial communities. The conversion of floccular biomass to highly structured granules was found to be non-random, but strongly and positively correlated with N-acyl-homoserine-lactone (AHL)-mediated QS. Specific AHLs were elevated up to 100-fold and were strongly associated with the initiation of granulation. Similarly, the levels of particular AHLs decreased markedly during the granular disintegration phase. Metadata analysis indicated that granulation was accompanied by changes in extracellular polymeric substance (EPS) production and AHL add-back studies also resulted in increased EPS synthesis. In contrast to the commonly reported nanomolar to micromolar signal concentrations in pure culture laboratory systems, QS signalling in the granulation ecosystem occurred at picomolar to nanomolar concentrations of AHLs. Given that low concentrations of AHLs quantified in this study were sufficient to activate AHL bioreporters in situ in complex granular communities, AHL mediated QS may be a common feature in many natural and engineered ecosystems, where it coordinates community behaviour.

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“…In this particular case, a combination of different LuxR homologs code for 6 different AHLs: C8HSL, C10HSL, OHC6HSL, OHC8HSL, OHC10HSL and OHC12HSL [164]. In Burkholderia mallei, 2-5 homologs of LuxR exist and it may overcome the effect of QSI by over expressing the signal molecule for one such homolog [165]. This repertoire of different signal synthases and signals provides a safeguard.…”

Section: Duplications In Qssmentioning

confidence: 99%

Potential Emergence of Multi-quorum Sensing Inhibitor Resistant (MQSIR) Bacteria

et al. 2015

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Expression of certain bacterial genes only at a high bacterial cell density is termed as quorum-sensing (QS). Here bacteria use signaling molecules to communicate among themselves. QS mediated genes are generally involved in the expression of phenotypes such as bioluminescence, biofilm formation, competence, nodulation, and virulence. QS systems (QSS) vary from a single in Vibrio spp. to multiple in Pseudomonas and Sinorhizobium species. The complexity of QSS is further enhanced by the multiplicity of signals: (1) peptides, (2) acyl-homoserine lactones, (3) diketopiperazines. To counteract this pathogenic behaviour, a wide range of bioactive molecules acting as QS inhibitors (QSIs) have been elucidated. Unlike antibiotics, QSIs don't kill bacteria and act at much lower concentration than those of antibiotics. Bacterial ability to evolve resistance against multiple drugs has cautioned researchers to develop QSIs which may not generate undue pressure on bacteria to develop resistance against them. In this paper, we have discussed the implications of the diversity and multiplicity of QSS, in acting as an arsenal to withstand attack from QSIs and may use these as reservoirs to develop multi-QSI resistance.

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AHL-driven quorum-sensing circuits: their frequency and function among the Proteobacteria

Cited by 258 publications

References 10 publications

Quorum sensing control of phosphorus acquisition in Trichodesmium consortia

Quorum sensing control of phosphorus acquisition in Trichodesmium consortia

The role of quorum sensing signalling in EPS production and the assembly of a sludge community into aerobic granules

Potential Emergence of Multi-quorum Sensing Inhibitor Resistant (MQSIR) Bacteria

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