Team:Berkeley

Biosensors have widespread applications ranging from diagnostics to environmental monitoring. Vibrio cholerae's ToxR system can be used as a component in biological devices capable of detecting a wide variety of molecules. A periplasmic domain causes ToxR homodimerization, activating transcription of the ctx promoter. By replacing the periplasmic domain of ToxR with existing or engineered ligand-dependent homodimers, we hope to link ToxR dimerization (and gene expression) to the presence of specific ligands. Initially, ToxR constructs proved to be toxic to E. coli. To address ToxR toxicity, we screened microarray data for promoters that exhibited stress-based down regulation. We constructed a negative feedback system with the rffGH promoter, which permits the use of potentially toxic proteins like our various ToxR chimeras. By fusing existing or engineered ligand dependent homodimers to ToxR, this modular system can be applied to develop new biosensors.

A protein with great potential as a general biosensor system.

Our method for expressing interesting (but toxic) proteins.

Chimeric proteins that drive translation off of the Pctx promoter.

Bacteria designed to detect environmental estrogen contamination.

We are a cohesive team of 7 undergraduates and 3 advisers. iGEM has taught an incredible amount of information about synthetic biology and ourselves. We have learned many different techniques in the lab, but the most important part about iGEM is that we learned to be critical thinkers. We created a project together, carried it out together, and we are going to present at the Jamboree together. Of course this was no easy task and took us twice as long as it would have taken a graduate student, but when we get it right, it is because we figured out how to do it on our own. This accomplishment increases confidence. In a few months, our team has worked together effectively to get a complicated project done. This means we have to work tightly together and it forces us to trust one another.