Identifying, Characterizing, and Engineering a Phenolic Acid-Responsive Transcriptional Factor from Bacillus amyloliquefaciens

Transcriptional factors-based biosensorsare commonly used in metabolicengineering for inducible control of gene expression and related applicationssuch as high-throughput screening and dynamic pathway regulations.Mining for novel transcriptional factors is essential for expandingthe usability of these toolsets. Here, we report the identification,characterization, and engineering of a phenolic acid responsive regulatorPadR from Bacillus amyloliquefaciens (BaPadR). ThisBaPadR-based biosensor system showed a unique ligand preference andexhibited a high output strength comparable to that of commonly usedinducible expression systems. Through engineering the DNA bindingregion of BaPadR, we further enhanced the dynamic range of the biosensorsystem. The DNA sequences that are responsible for BaPadR recognitionwere located by promoter truncation and hybrid promoter building.To further explore the tunability of the sensor system, base substitutionswere performed on the BaPadR binding region of the phenolic acid decarboxylasepromoter (P-padC) and the hybrid promoter. This novel biosensorsystem can serve as a valuable tool in future synthetic biology applications.