Team:TPHS SanDiego

In an effort to expand the toolkit available to synthetic biologists, we've taken a system natively responsible for transcriptional activation and modified it to control transcriptional repression. The LasR system from Pseudomonas Aeruginosa requires the presence of a small molecule, C12-3-oxo-AHL, to induce activation of the Plas promoter. By modifying the -10 and -35 sites of the promoter, as well as shifting the location of the LasR binding sites, the new Plas promoter (Plas*) was changed from an inducible to a repressible promoter. Through adding this second functionality, the Plas* promoter could be used in conjunction with a wildtype Plas promoter to control two separate genes whose expression levels are always out of sync. Furthermore, if the bacteria are transfected with a plasmid encoding LasI, the bacteria will be able to turn off gene expression at a critical population density, instead of only being able to turn on gene expression.