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.

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