This part is an improvement of the 2017 East Chapel Hill iGem "CHOP" operon. At fluoride concentrations of 2uM and above, the delta-CRCB E. coli strain (strain JW0619-1 from the Yale Coli Genetics Stock Center) will grow on chloramphenicol. This vector is designed with Xhol cutting sites so one may easily remove and replace different segments of the operon to screen for combinations of riboswitch and promoter with highest effectivity.
To summarize, here is how this part functions in the presence of fluoride:
1. delta-CRCB E. coli accumulates fluoride intracellularly due to the lack of the fluoride efflux channel.
2. Fluoride binds to the fluoride riboswitch and activates the chloramphenicol acetyltransferase enzyme, which allows for bacterial growth on plates that contain the antibiotic chloramphenicol.
This is BBa_K2843002 operon with the "Fluoride Binding Mutant", which is a mutant of the fluoride RBS. This served as a control for our experiments because if there is growth of delta-CRCB E. coli on the chloramphenicol plates than this indicates that growth of delta-CRCB is not entirely dependent only on the presence of fluoride.