Memory Unit

As memory units we are using bistable autoinducing loops that can be suppressed via a reversed antisense promoter (jammer). The autoinducing loop act as amplifier of the input signal with the promoter inducing expression of its own transcription factor. To switch off the loop, we adopted the endogenous device from the 2009 iGEM team of British Columbia, which implemented a reverse antisense promoter downstream of the coding sequence (https://2009.igem.org/Team:British_Columbia/Jammer).

Our implementation

In our implementation the first memory unit is based on a modified (WHY THE HELL ARE WE STILL STUCK WITH THIS MODIFIED VERSION OF THE PROMOTER??)lambda Prm promoter (Bba_I12006) producing its own inducer cI. By means of the reversed antisense lasB promoter it will be repressed in the presence of LasR. The second memory unit consists of the lasB promoter (BBa_R0079) producing its own induction factor LasR. Both autoinducing loops can be repressed by an arabinose inducible reverse antisense pBad promoter. The transcription factor genes (cI and LasR) were fused in various combinations with different RBS and degradation tags, resulting in 12 different construct variants. These enable us to study the dynamics of expression and half-life of different autoinducing loop components in order to subsequently determine the constructs that best meets the criteria for bistability.

Results

TODO Firstly, we would like to test the leakage of promoter by cotransform autoinducing loop plasmid and reporter plasmid under control of appropriate promoter. Secondly, cotransformation assembled input and output systems with plasmid bearing various-variants of autoinducing loops would provide information about memory unit behaviour in time. Finally, integration of experimental data and our model would lead us to fine-tuned the expected system behaviour.