Berkeley iGEM 2011


Biosensors have widespread applications ranging from diagnostics to environmental monitoring. Vibrio cholerae's ToxR system can be used as a component in biological sensing devices. ToxS 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 toxic to E. coli. We built a stress-regulated transcription system that drives relatively high expression of toxic proteins. This allowed us to further engineer ToxR chimeras. We fused an estrogen-dependent dimer with ToxR hoping to create an estrogen biosensor. We observed a range of constitutive phenotypes and plan more experiments to engineer a dose-dependent transcriptional response to estrogen. By fusing existing or engineered ligand dependent homodimers to ToxR, this modular system can be used to build new biosensors.

A protein with great potential as a general biosensor system.

Chimeric proteins that drive translation off of the Pctx promoter.

Our method for expressing interesting (but toxic) proteins.

Bacteria engineered to detect the presence of estrogen.

We are Team Berkeley, a cohesive unit of 7 undergraduates and 3 advisers. Earlier this year we planned a complex and risky project, given the short amount of time iGEM made available. We quickly learned each others strengths and weaknesses and developed standard systems of organizational management in order to synchronize our efforts for the many parallel tasks at hand. We created protocols, shared them with one another, and worked together on troubleshooting. Using google docs to keep up with the status of cloning projects, the results of assays, material logistics, or the final steps required to complete a project ensured that through the months of hard work, we fine-tuned our ability to work together. As a team, we have learned firsthand how the synthetic biology community relies on the goal-oriented cooperation of skilled individuals from very different backgrounds and with very different skill sets. Some of us have strong engineering backgrounds while others of us have strong biology backgrounds, but we all share a desire to build synthetic biological systems that solve human problems. We are proud of the project that we have created which we will present at the Jamboree together in October.

The UC Berkeley iGEM team would like to thank Autodesk and Agilent for their financial support and Synberc, for their administrative support.