Development of Biosensor for 3-Hydroxypropionic Acid

In this study, whole-cell biosensors that detect and indicate the concentration of 3-hydroxypropionic acid (3-HP) by producing a green fluorescent signal were developed using a transcription factor (TF)-responsive 3- HP inducible promoter identified in the Pseudomonas denitrificans 3-HP degradation pathway. Upon forming a complex with 3-HP, the MmsR TF protein, a LysR-type transcriptional regulator (LTTR), binds to the PmmsA promoter and controls the expression of the PmmsA-regulated gfp reporter gene in response to the concentration of 3-HP. Furthermore, by enhancing the expression of MmsR and through mutagenesis of the PmmsA promoter region, three well-performing biosensors were developed that covered a wide dynamic range of 3-HP (0.01-100 mM when added externally) with ~100-fold signal change upon induction in P. denitrificans. The 3-HP biosensor machinery, composed of MmsR, the PmmsA promoter and gfp could also function well in E. coli and P. putida. The developed 3-HP biosensors should be useful for engineering 3-HP-producing strains and the enzymes associated with its production