Team:NTNU-Trondheim/Press

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.