Reversible acyl-homoserine lactone binding to purified Vibrio fischeri LuxR protein.
نویسندگان
چکیده
The Vibrio fischeri LuxR protein is the founding member of a family of acyl-homoserine lactone-responsive quorum-sensing transcription factors. Previous genetic evidence indicates that in the presence of its quorum-sensing signal, N-(3-oxohexanoyl) homoserine lactone (3OC6-HSL), LuxR binds to lux box DNA within the promoter region of the luxI gene and activates transcription of the luxICDABEG luminescence operon. We have purified LuxR from recombinant Escherichia coli. Purified LuxR binds specifically and with high affinity to DNA containing a lux box. This binding requires addition of 3OC6-HSL to the assay reactions, presumably forming a LuxR-3OC6-HSL complex. When bound to the lux box at the luxI promoter in vitro, LuxR-3OC6-HSL enables E. coli RNA polymerase to initiate transcription from the luxI promoter. Unlike the well-characterized LuxR homolog TraR in complex with its signal (3-oxo-octanoyl-HSL), the LuxR-30C6-HSL complex can be reversibly inactivated by dilution, suggesting that 3OC6-HSL in the complex is not tightly bound and is in equilibrium with the bulk solvent. Thus, although LuxR and TraR both bind 3-oxoacyl-HSLs, the binding is qualitatively different. The differences have implications for the ways in which these proteins respond to decreases in signal concentrations or rapid drops in population density.
منابع مشابه
Directed evolution of Vibrio fischeri LuxR for improved response to butanoyl-homoserine lactone.
LuxR is the 3-oxohexanoyl-homoserine lactone (3OC6HSL)-dependent transcriptional activator of the prototypical acyl-homoserine lactone (AHL) quorum-sensing system of Vibrio fischeri. Wild-type LuxR exhibits no response to butanoyl-HSL (C4HSL) in quantitative bioassays at concentrations of up to 1 microM; a previously described LuxR variant (LuxR-G2E) exhibits a broadened response to diverse AHL...
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متن کاملConversion of the Vibrio fischeri transcriptional activator, LuxR, to a repressor.
The Vibrio fischeri luminescence (lux) operon is regulated by a quorum-sensing system that involves the transcriptional activator (LuxR) and an acyl-homoserine lactone signal. Transcriptional activation requires the presence of a 20-base inverted repeat termed the lux box at a position centered 42.5 bases upstream of the transcriptional start of the lux operon. LuxR has proven difficult to stud...
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LuxR-type transcriptional regulators play key roles in quorum-sensing systems that employ acyl-homoserine lactones (acyl-HSLs) as signal molecules. These proteins mediate quorum control by changing their interactions with RNA polymerase and DNA in response to binding their cognate acyl-HSL. The evolutionarily related LuxR-type proteins exhibit considerable diversity in primary sequence and in t...
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عنوان ژورنال:
- Journal of bacteriology
دوره 186 3 شماره
صفحات -
تاریخ انتشار 2004