Helicobacter pylori perceives the quorum-sensing molecule AI-2 as a chemorepellent via the chemoreceptor TlpB

Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
Microbiology (Impact Factor: 2.56). 05/2011; 157(Pt 9):2445-55. DOI: 10.1099/mic.0.049353-0
Source: PubMed


Helicobacter pylori moves in response to environmental chemical cues using a chemotaxis two-component signal-transduction system. Autoinducer-2 (AI-2) is a quorum-sensing signal produced by the LuxS protein that accumulates in the bacterial environment in a density-dependent manner. We showed previously that a H. pylori luxS mutant was defective in motility on soft agar plates. Here we report that deletion of the luxS gene resulted in swimming behaviour with a reduced frequency of stops as compared to the wild-type strain. Stopping frequency was restored to wild-type levels by genetic complementation of the luxS mutation or by addition of synthetic 4,5-dihydroxy-2,3-pentanedione (DPD), which cyclizes to form AI-2. Synthetic DPD also increased the frequency of stops in wild-type H. pylori, similar to the behaviour induced by the known chemorepellent HCl. We found that whereas mutants lacking the chemoreceptor genes tlpA, tlpC or tlpD responded to an exogenous source of synthetic DPD, the chemoreceptor mutant tlpB was non-responsive to a gradient or uniform distribution of the chemical. Furthermore, a double mutant lacking both tlpB and luxS exhibited chemotactic behaviour similar to the tlpB single mutant, whereas a double mutant lacking both tlpB and the chemotransduction gene cheA behaved like a nonchemotactic cheA single mutant, supporting the model that tlpB functions in a signalling pathway downstream of luxS and upstream of cheA. We conclude that H. pylori perceives LuxS-produced AI-2 as a chemorepellent via the chemoreceptor TlpB.

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Available from: Karen Ottemann, Jul 21, 2014
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    • "Taxis has been observed towards compounds that serve as carbon or energy sources like sugars, amino acids or organic acids (Mesibov and Adler, 1972; Adler et al., 1973; Seymour and Doetsch, 1973; Moulton and Montie, 1979). In addition, chemotaxis has been reported for other classes of compounds like neurotransmitters, plant hormones or quorum sensing signals (Bansal et al., 2007; Antunez-Lamas et al., 2009; Hegde et al., 2011; Rader et al., 2011). Typically, the specificity of a chemotactic response is determined by the chemoreceptor that is at the beginning of the chemosensory signaling cascade. "
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    • "TlpA has been shown to recognize arginine and bicarbonate as attractants since a tlpA-knockout mutant of H. pylori mutant lost chemotactic response to these chemical stimuli [17]. In contrast, TlpB recognizes acid [15] and the quorum-sensing molecule autoinducer-2 (AI-2) as repellents [18]. Analysis of the atomic-resolution structure of TlpB revealed a homodimer that contains Per-ARNT-Sim (PAS) domains and is thought to respond to pH through urea-mediated stabilization of the secondary structure [19]. "
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    • "Recently, Rader et al. [12] described that the chemoreceptor TlpB functiones as AI-2 receptor in Helicobacter pylori. Despite of the existence of chemoreceptors in C. jejuni, which would suggest the existence of a corresponding receptor, no TlpB receptor homolog has been found yet. "
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