Article

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: 3.06). 05/2011; 157(Pt 9):2445-55. DOI:10.1099/mic.0.049353-0 pp.2445-55
Source: PubMed

ABSTRACT 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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Keywords

chemoreceptor genes tlpA
 
chemoreceptor mutant tlpB
 
chemoreceptor TlpB
 
chemotaxis two-component signal-transduction system
 
chemotransduction gene cheA
 
double mutant
 
environmental chemical cues
 
form AI-2
 
H. pylori
 
H. pylori luxS mutant
 
Helicobacter pylori moves
 
known chemorepellent HCl
 
luxS mutation
 
LuxS protein
 
LuxS-produced AI-2
 
nonchemotactic cheA single mutant
 
synthetic 4,5-dihydroxy-2,3-pentanedione
 
tlpB single mutant
 
wild-type H. pylori
 
wild-type strain