Our goal in this experiment was to compare the activity of the repressors BM3R1, TAL14, and TAL21.
We created a plasmid containing each repressor under the control of the doxycycline-inducible promoter TRE, which allowed us to modulate the repressor expression by varying the concentration of doxycycline added. We also cloned a repressible promoter controlling the expression of a fluorescent protein. This plasmid allowed us to measure the amount of repression occurring.
In order for us to analyze the level of repression, we need to see sustained presence of the repressor. Upon increasing the concentration of doxycycline, we were unable to see that sustained presence of the repressors. From the results of testing BM3R1 below, it can be seen that although there is activation early on, the production of repressor falls at 500 nM. This could possibly be due to errors in doxycycline dilutions at 500 nM and above.