Structural Basis and Specificity of Acyl-Homoserine Lactone Signal Production in Bacterial Quorum Sensing

Watson, William T.; Minogue, Timothy D.; Val, Dale L.; Bodman, Susanne B. von; Churchill, Mair E. A.

doi:10.1016/s1097-2765(02)00480-x

Cited by 232 publications

(291 citation statements)

References 52 publications

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“…2F; also see Fig. S1) (18), whereas 3-oxo-C6-HSL and C6-HSL were produced (18,19) in E. coli by the T140A mutant of EsaI enzyme (referred to herein as EsaI). Over 90% (34/36) of the denatonium-responsive cells also showed robust responses to 60-to 120-μM concentrations of the LasI-or EsaI-produced AHLs as well as to the synthetic AHLs ( Fig.…”

Section: Resultsmentioning

confidence: 99%

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Nasal chemosensory cells use bitter taste signaling to detect irritants and bacterial signals

Tizzano

Gulbransen

Vandenbeuch

et al. 2010

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

358

443

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The upper respiratory tract is continually assaulted with harmful dusts and xenobiotics carried on the incoming airstream. Detection of such irritants by the trigeminal nerve evokes protective reflexes, including sneezing, apnea, and local neurogenic inflammation of the mucosa. Although free intra-epithelial nerve endings can detect certain lipophilic irritants (e.g., mints, ammonia), the epithelium also houses a population of trigeminally innervated solitary chemosensory cells (SCCs) that express T2R bitter taste receptors along with their downstream signaling components. These SCCs have been postulated to enhance the chemoresponsive capabilities of the trigeminal irritant-detection system. Here we show that transduction by the intranasal solitary chemosensory cells is necessary to evoke trigeminally mediated reflex reactions to some irritants including acyl–homoserine lactone bacterial quorum-sensing molecules, which activate the downstream signaling effectors associated with bitter taste transduction. Isolated nasal chemosensory cells respond to the classic bitter ligand denatonium as well as to the bacterial signals by increasing intracellular Ca 2 + . Furthermore, these same substances evoke changes in respiration indicative of trigeminal activation. Genetic ablation of either Gα-gustducin or TrpM5, essential elements of the T2R transduction cascade, eliminates the trigeminal response. Because acyl–homoserine lactones serve as quorum-sensing molecules for Gram-negative pathogenic bacteria, detection of these substances by airway chemoreceptors offers a means by which the airway epithelium may trigger an epithelial inflammatory response before the bacteria reach population densities capable of forming destructive biofilms.

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Section: Resultsmentioning

confidence: 99%

“…AHL bacterial signaling molecules were produced in E. coli expressing AHL synthase genes (EsaI and LasI) and were purified using solid-phase extraction procedures as described previously (18,19). The purified extracts were analyzed (Fig.…”

Section: Methodsmentioning

confidence: 99%

Nasal chemosensory cells use bitter taste signaling to detect irritants and bacterial signals

Tizzano

Gulbransen

Vandenbeuch

et al. 2010

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

358

443

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“…70) As shown in Fig. 5, this catalytic reaction is thought to be proceeded by a twostep mechanism involving the intermediate acyl-ACP to the amino group of SAM and lactonization of the methionine part, concomitant with the release of methylthioadenosine (MTA).…”

Section: Inhibitors Of Acylhomoserine Lactone-synthesizing Enzymementioning

confidence: 99%

Frontier studies on highly selective bio-regulators useful for environmentally benign agricultural production

Hayashi

2015

Bioscience, Biotechnology, and Biochemistry

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Fungal metabolites active for insects were obtained from fermentation products using okara media. The mechanisms of action of these compounds against insects were clarified using voltage clamp electrophysiology. The branching factor inducing hyphal branching in arbuscular mycorrhizal (AM) fungi was isolated from the root exudates of Lotus japonicus and identified as 5-deoxystrigol. Strigolactones were originally identified as seed germination stimulants of parasitic weeds; therefore, synthetic strigolactones were developed to exhibit the inducing activity of hyphal branching in AM fungi and diminish the stimulating activity of seed germination of parasitic weeds. Signaling molecules, acylhomoserine lactones (AHLs), in quorum sensing were identified in the fungal strain Mortierella alpina A-178, and the true producer of AHLs was clarified as symbiotic bacteria in the fungus. Since acyl-(S)-adenosylmethionine analogs may be good candidates for competitive inhibitors of AHL synthases, intermediate mimics in the biosynthesis of AHLs have been synthesized.

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“…We have shown in previous studies that P. stewartii utilizes the EsaI͞EsaR QS regulatory system to govern the cell density-dependent expression of the well characterized cps gene system that encodes the structural functions for EPS synthesis (30,35). EsaI is a typical AHL signal synthase that catalyzes the preferential synthesis of N-3-oxo-hexanoyl homoserine lactone (35,36). EsaR is a homologue of LuxR but differs from the paradigm by functioning as a repressor of transcription at low cell density or in the absence of the QS signal (30,35,37,38).…”

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confidence: 99%

Quorum-sensing regulation governs bacterial adhesion, biofilm development, and host colonization in Pantoea stewartii subspecies stewartii

Koutsoudis¹,

Tsaltas

Minogue

et al. 2006

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

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220

166

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The phytopathogenic bacterium Pantoea stewartii subsp. stewartii synthesizes stewartan exo͞capsular polysaccharide (EPS) in a cell density-dependent manner governed by the EsaI͞EsaR quorumsensing (QS) system. This study analyzes biofilm development and host colonization of the WT and QS regulatory mutant strains of P. stewartii. First, we show that the cell density-dependent synthesis of stewartan EPS, governed by the EsaI͞EsaR QS system, is required for proper bacterial adhesion and development of spatially defined, 3D biofilms. Second, a nonvirulent mutant lacking the esaI gene adheres strongly to surfaces and develops densely packed, less structurally defined biofilms in vitro. This strain appears to be arrested in a low cell density developmental mode. Exposure of this strain to exogenous N-acyl-homoserine lactone counteracts this adhesion phenotype. Third, QS mutants lacking the EsaR repressor attach poorly to surfaces and form amorphous biofilms heavily enmeshed in excess EPS. Fourth, the WT strain disseminates efficiently within the xylem, primarily in a basipetal direction. In contrast, the two QS mutant strains remain largely localized at the site of infection. Fifth, and most significantly, epifluorescence microscopic imaging of infected leaf tissue and excised xylem vessels reveals that the bacteria colonize the xylem with unexpected specificity, particularly toward the annular rings and spiral secondary wall thickenings of protoxylem, as opposed to indiscriminate growth to fill the xylem lumen. These observations are significant to bacterial plant pathogenesis in general and may reveal targets for disease control.maize ͉ xylem ͉ pathogenesis ͉ dissemination

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Structural Basis and Specificity of Acyl-Homoserine Lactone Signal Production in Bacterial Quorum Sensing

Cited by 232 publications

References 52 publications

Nasal chemosensory cells use bitter taste signaling to detect irritants and bacterial signals

Nasal chemosensory cells use bitter taste signaling to detect irritants and bacterial signals

Frontier studies on highly selective bio-regulators useful for environmentally benign agricultural production

Quorum-sensing regulation governs bacterial adhesion, biofilm development, and host colonization in Pantoea stewartii subspecies stewartii

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