Structure-Guided Design of Artificial Transcription Factor for a Progesterone Biosensor.

Transcription factors (TFs) can be used in genetic circuits and biosensors in the field of synthetic biology. Traditionally, TFs derived from prokaryotic organisms are transferred to more complex eukaryotic cells to achieve gene control; however, TFs in eukaryotes are rarely transferred to prokaryotes. Herein, an artificial TF responsive to progesterone was designed through MD simulations, and the linker fine-tuned the convergence of the DNA-binding domain and activation domain as the desired conformation guide to design an artificial TF ProB assembled from the QF_DBD, the ligand-binding domain, linker, and QF_AD. The ProB acted on the synthetic promoter QT, which is composed of QUAS, 10-bp space, T7, and the RBS, which controlled the transcription of the biosensor GFP in E. coli. The performance of the whole-cell progesterone biosensor was optimized via a bacterial enrichment strategy, which made the biosensor highly sensitive (LOD 0.15 μg/L and EC₅₀ 26.58 μg/L), preferably in the working temperature range (20-30 °C), with only a 56.4 min detection time and a working concentration range of 0.15-40 μg/L, and the performance reached the requirements of clinical application. This report presents effective strategies and valuable insights into the design of non-natural TFs and their artificial systems in prokaryotes.