title: Halogenated furanones inhibit quorum sensing through accelerated LuxR turnover.
abstract: N-acyl-L-homoserine lactones (AHLs) are co-regulatory ligands required for control of the expression of genes encoding virulence traits in many Gram-negative bacterial species. Recent studies have indicated that AHLs modulate the cellular concentrations of LuxR-type regulatory proteins by binding and fortifying these proteins against proteolytic degradation (Zhu & Winans, 2001 ). Halogenated furanones produced by the macroalga Delisea pulchra inhibit AHL-dependent gene expression. This study assayed for an in vivo interaction between a tritiated halogenated furanone and the LuxR protein of Vibrio fischeri overproduced in Escherichia coli. Whilst a stable interaction between the algal metabolite and the bacterial protein was not found, it was noted by Western analysis that the half-life of the protein is reduced up to 100-fold in the presence of halogenated furanones. This suggests that halogenated furanones modulate LuxR activity but act to destabilize, rather than protect, the AHL-dependent transcriptional activator. The furanone-dependent reduction in the cellular concentration of the LuxR protein was associated with a reduction in expression of a plasmid encoded P(luxI)-gfp(ASV) fusion suggesting that the reduction in LuxR concentration is the mechanism by which furanones control expression of AHL-dependent phenotypes. The mode of action by which halogenated furanones reduce cellular concentrations of the LuxR protein remains to be characterized.
authors.affiliation: Department of Microbiology, Technical University of Denmark, 2800 Lyngby, Denmark2.|School of Microbiology and Immunology, University of New South Wales, Sydney, Australia1.
authors.forename: Michael
authors.initials: M
authors.lastname: Manefield
authors.affiliation: Department of Microbiology, Technical University of Denmark, 2800 Lyngby, Denmark2.
authors.forename: Thomas Bovbjerg
authors.initials: TB
authors.lastname: Rasmussen
authors.affiliation: Department of Microbiology, Technical University of Denmark, 2800 Lyngby, Denmark2.
authors.forename: Morten
authors.initials: M
authors.lastname: Henzter
authors.affiliation: Department of Microbiology, Technical University of Denmark, 2800 Lyngby, Denmark2.
authors.forename: Jens Bo
authors.initials: JB
authors.lastname: Andersen
authors.affiliation: Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, Australia3.
authors.forename: Peter
authors.initials: P
authors.lastname: Steinberg
authors.affiliation: Centre for Marine Biofouling and Bio-Innovation, University of New South Wales, Sydney, Australia3.|School of Microbiology and Immunology, University of New South Wales, Sydney, Australia1.
authors.forename: Staffan
authors.initials: S
authors.lastname: Kjelleberg
authors.affiliation: Department of Microbiology, Technical University of Denmark, 2800 Lyngby, Denmark2.
authors.forename: Michael
authors.initials: M
authors.lastname: Givskov
mesh_terms: D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D005663:Furans / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial; D007700:Kinetics; D012097:Repressor Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D014733:Vibrio / Q000235:genetics / Q000502:physiology
chemical_list: D005663:Furans; D012097:Repressor Proteins; D015534:Trans-Activators; C064778:LuxR autoinducer binding proteins