title: Quorum sensing and self-quorum quenching in the intracellular pathogen Brucellamelitensis.
abstract: Brucella quorum sensing has been described as an important regulatory system controlling crucial virulence determinants such as the VirB type IV secretion system and the flagellar genes. However, the basis of quorum sensing, namely the production of autoinducers in Brucella has been questioned. Here, we report data obtained from the use of a genetic tool allowing the in situ detection of long-chain N-acyl-homoserine lactones (AHL) activity at single bacterium level in Brucella melitensis. These data are consistent with an intrinsic production of AHL by B. melitensis in low concentration both during in vitro growth and macrophage infection. Moreover, we identified a protein, named AibP, which is homologous to the AHL-acylases of various bacterial species. In vitro and during infection, expression of aibP coincided with a decrease in endogenous AHL activity within B. melitensis, suggesting that AibP could efficiently impair AHL accumulation. Furthermore, we showed that deletion of aibP in B. melitensis resulted in enhanced virB genes expression and VirB8 production as well as in a reduced flagellar genes expression and production of FlgE (hook protein) and FliC (flagellin) in vitro. Altogether, these results suggest that AHL-dependent quorum sensing and AHL-quorum quenching coexist in Brucella, at least to regulate its virulence.
authors.affiliation: URBM, Department of Biology, University of Namur, Namur, Belgium.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Terwagne
authors.affiliation: URBM, Department of Biology, University of Namur, Namur, Belgium.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Mirabella
authors.affiliation: URBM, Department of Biology, University of Namur, Namur, Belgium.
authors.forename: Julien
authors.initials: J
authors.lastname: Lemaire
authors.affiliation: URBM, Department of Biology, University of Namur, Namur, Belgium.
authors.forename: Chantal
authors.initials: C
authors.lastname: Deschamps
authors.affiliation: URBM, Department of Biology, University of Namur, Namur, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: De Bolle
authors.affiliation: URBM, Department of Biology, University of Namur, Namur, Belgium.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Letesson
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism; D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D017347:Brucella melitensis / Q000472:pathogenicity / Q000502:physiology*; D002460:Cell Line; D005407:Flagella / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D053038:Quorum Sensing / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; D000581:Amidohydrolases; C019665:amidase