Team:MIT k415301
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The original pTSMa plasmid from the Collins paper. This plasmid has been modified so that it now contains cI that is hypersensitive to cleavage by RecA = Low Power Toggle.
E.Coli population density as a function of UV exposure. Measured by drip assay.
K415300 From the 2010 MIT iGEM Team.See the Parts Registry Page!! → This part is a variation of a Collins/Kobayashi UV Toggle (2004) from an article in PNAS. It is a bistable toggle (on or off state) and switching to state 1 is induced by UV exposure and to state 2 is IPTG. If the toggle is set with IPTG, the cells will express cI which will inhibit Plambda. If this is exposed to certain levels of UV (see power modulations) cI is cleaved by Rec-A (a UV induced enzyme) and lacI expression begins and inhibits Ptrc. The site directed mutagenesis that the 2010 MIT iGEM team performed on the Collins toggle pTSMa in order to change it into a Low Power Toggle. This part improves upon its predecessor K415300 in that it requires less UV power to switch states, thus killing fewer cells (see E.Coli death curve). This plasmid differs genetically from K415300 in that its inhibitory lambda cI protein is more sensitive to Rec-A cleavage. We got the idea for hypersensitive cI from this paper which calls for a single point mutation in the protein. By changing the Glu233->Lys, we were able to create a toggle that is more sensitive to UV induction. We accomplished this mutation through site directed mutagenesis. The following data was taken from cells co-transformed with pTSMa and K415069.
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