Development of whole cell biosensors mediated by bacteria chemoreceptors (614.5)

Abstract

Whole cell biosensors are part of an emerging strategy to build new tools for diagnostic and therapeutic applications. The goal is to re‐engineer bacterial cells to respond to environmental cues or chemicals. Whole cell biosensors typically express a sensor protein targeting the ligand of interest that is coupled with a genetic regulatory system to produce a measureable signal by the host cell. We have adapted an AraC‐based transcriptional reporter assay to create a new whole cell biosensor that may be used for the creation of new sensor proteins. In our bio‐reporter system, Trg is translationally‐fused to AraC such that dimerization of the Trg‐AraC results in expression of the reporter gene. The presence of analyte will be detected in the periplasm of the cell by inclusion of an engineered periplasmic binding protein (PBP) specific for this molecule. The bound protein then interacts with Trg causing a conformational change. This dimerization of the Trg‐AraC fusion in the cytoplasm will then switch on gene expression of the reporter gene, green fluorescent protein (GFP). This mechanism reports dose‐response fluorescence detection in the presence of the analyte. Ultimately this bio‐reporter system will allow us to design new PBPs with selectivity for specific chemical entities and for construction of a genetic switch inside bacterial cells that precisely reports the presence of the analyte using a fluorescence reporter system.