title: Octanoyl-homoserine lactone is the cognate signal for Burkholderia mallei BmaR1-BmaI1 quorum sensing.
abstract: Acyl-homoserine lactones (HSLs) serve as quorum-sensing signals for many Proteobacteria. Members of the LuxI family of signal generators catalyze the production of acyl-HSLs, which bind to a cognate receptor in the LuxR family of transcription factors. The obligate animal pathogen Burkholderia mallei produces several acyl-HSLs, and the B. mallei genome has four luxR and two luxI homologs, each of which has been established as a virulence factor. To begin to delineate the relevant acyl-HSL signals for B. mallei LuxR homologs, we analyzed the BmaR1-BmaI1 system. A comparison of acyl-HSL profiles from B. mallei ATCC 23344 and a B. mallei bmaI1 mutant indicates that octanoyl-HSL synthesis is BmaI1 dependent. Furthermore, octanoyl-HSL is the predominant acyl-HSL produced by BmaI1 in recombinant Escherichia coli. The synthesis of soluble BmaR1 in recombinant E. coli requires octanoyl-HSL or decanoyl-HSL. Insoluble aggregates of BmaR1 are produced in the presence of other acyl-HSLs and in the absence of acyl-HSLs. The bmaI1 promoter is activated by BmaR1 and octanoyl-HSL, and a 20-bp inverted repeat in the bmaI1 promoter is required for bmaI1 activation. Purified BmaR1 binds to this promoter region. These findings implicate octanoyl-HSL as the signal for BmaR1-BmaI1 quorum sensing and show that octanoyl-HSL and BmaR1 activate bmaI1 transcription.
authors.affiliation: Department of Microbiology, University of Washington School of Medicine, 1959 N. E. Pacific Street, Box 357242, Seattle, WA 98195-7242, USA.
authors.forename: Breck A
authors.initials: BA
authors.lastname: Duerkop
authors.forename: Ricky L
authors.initials: RL
authors.lastname: Ulrich
authors.forename: E Peter
authors.initials: EP
authors.lastname: Greenberg
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001483:Base Sequence; D001665:Binding Sites; D042726:Burkholderia mallei / Q000235:genetics / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009795:Octanes / Q000737:chemistry / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D053038:Quorum Sensing / Q000235:genetics / Q000502:physiology*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D001426:Bacterial Proteins; D009795:Octanes; C088386:homoserine lactone; D015107:4-Butyrolactone; C026728:octane