Mutation of the peptide-regulated transcription factor ComR for amidated peptide specificity and heterologous function inLactiplantibacillus plantarumWCFS1

There is a growing interest in the use of probiotic bacteria as biosensors for the detection of disease. However, there is a lack of bacterial receptors developed for specific disease biomarkers. Here, we have investigated the use of the peptide-regulated transcription factor ComR from S treptococcus spp . for specific peptide biomarker detection. ComR exhibits a number of attractive features that are potentially exploitable to create an exquisitely sensitive biomolecular switch for engineered biosensor circuitry within the probiotic organism Lactiplantibacillus plantarum WCFS1. By screening a library of ComR mutant protein variants, we identified mutations that increased the specificity of ComR toward an amidated version of its cognate extracellular signaling peptide, demonstrating the potential for ComR to detect this important class of biomarker.