Development of Metabolite-Responsive Transcription Factor Systems as Modular Platforms for Gene Expression Control.

Area of Science:

• Synthetic biology
• Metabolic engineering

Background:

• Traditional inducible systems often co-express genes, limiting control.
• Metabolite-inducible systems offer potential for finer gene regulation.

Purpose of the Study:

• To evaluate MarR and TtgR systems for gene regulation beyond reporter assays.
• To demonstrate independent control of multiple genes using transcription factor (TF)-specific promoters.

Main Methods:

• Validated ligand-dependent transcription using eGFP reporter.
• Replaced reporter with flavonoid O-methyltransferases (OMTs) under TF-specific promoters.
• Analyzed product levels using High-Performance Liquid Chromatography (HPLC).

Main Results:

• Both MarR and TtgR systems demonstrated TF-based expression without impacting enzyme activity.
• Salicylic acid (MarR) induction yielded greater product gains than 4'-hydroxyflavanone (TtgR) induction.
• Basal expression levels influenced overall fold-changes, indicating room for optimization.

Conclusions:

• MarR and TtgR systems provide a robust framework for orthogonal and modular gene control.
• Genetic engineering of components is necessary to reduce leakiness and enhance dynamic range.
• These systems have potential applications in biosensing, metabolic engineering, and programmable pathway design.