Production of Acyl-Homoserine Lactone Quorum-Sensing Signals by Gram-Negative Plant-Associated Bacteria (original) (raw)

Many gram-negative bacteria regulate expression of specialized gene sets in response to population density. This regulatory mechanism, called autoinduction or quorumsensing, is based on the production by the bacteria of a small, diffusible signal molecule called the autoinducer. In the most well-studied systems the autoinducers are N-acylated derivatives of l-homoserine lactone (acyl-HSL). Signal specificity is conferred by the length, and the nature of the substitution at C-3, of the acyl side-chain. We evaluated four acyl-HSL bioreporters, based on tra of Agrobacterium tumefaciens, lux of Vibrio fischeri, las of Pseudomonas aeruginosa, and pigment production by Chromobacterium violaceum, for their ability to detect sets of 3-oxo acyl-HSLs, 3-hydroxy acyl-HSLs, and alkanoyl-HSLs with chain lengths ranging from C4to C12. The traG::lacZ fusion reporter from the A. tumefaciens Ti plasmid was the single most sensitive and versatile detector of the four. Using this reporter, we screened...