In Pantoea stewartii subsp. stewartii, two regulatory proteins are key to the process of cell-cell communication known as quorum sensing: the LuxI and LuxR homologues EsaI and EsaR. Most LuxR homologues function as activators of transcription in the presence of their cognate acylated homoserine lactone (AHL) signal. However, EsaR was initially found to function as a repressor in the absence of ...

Acyl homoserine lactones (acyl-HSLs) are important intercellular signaling molecules used by many bacteria to monitor their population density in quorum-sensing control of gene expression. These signals are synthesized by members of the LuxI family of proteins. To understand the mechanism of acyl-HSL synthesis we have purified the Pseudomonas aeruginosa RhlI protein and analyzed the kinetics of...

Virulence and adaptability of many Gram-negative bacterial species are associated with an N-acylhomoserine lactone (AHL) gene regulation mechanism called quorum sensing (QS). The arrangement of quorum sensing genes is variable throughout bacterial genomes, although there are unifying themes that are common among the various topological arrangements. A bioinformatics survey of 1,403 complete bac...

N-acylhomoserine lactone-dependent quorum sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeri is the paradigm of Gram-negative quorum-sensing systems; however, it is not found in all vibrios. A more complex quorum-sensing regulation is found in V. harveyi. Three parallel systems transmit signals via phosphorelays ...