Haynes Lab:Notebook/Characterizing AHL quorum sensing homologs
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We are investigating how acyl-homoserine lactone (AHL) quorum sensing pathways from different bacterial strains interact. Bacteria use quorum sensing to monitor population density and regulate virulence, biofilm formation, sporulation, competence, and disruption of neighboring bacterial biofilms. One type of quorum sensing uses AHLs as signaling molecules. Homologous pathways in different species use different functional AHL molecules that vary in the length of the carbon chain and types of side groups. The pathways generally consist of the AHL-synthase LuxI-like protein, the AHL-binding LuxR-like transcription factor, and LuxR/AHL-complex-activated promoters. Quorum sensing is triggered when high external AHL concentration drives net influx, and AHL binds and activates the LuxR-like transcription factor. Currently, there is limited information about many AHL quorum sensing pathways’ behaviors and degrees of overlap between these pathways. We are performing cell-signaling experiments to characterize and discover the extent of overlap of these pathways. We are making Sender cells containing a LuxI-homolog and Receiver cells containing a LuxR-homolog and LuxR/AHL-complex-activated promoters controlling a fluorescent output. By quantifying Sender cell culture supernatant using HPLC, we can determine activation thresholds for Receiver cells for different LuxI-homologs as well as AHLs. This work will result in a clearer overarching understanding of quorum sensing kinetics and evolution and will produce a map of pathway interaction that can be used for bioengineering of multicellular systems.