A cross-species inducible system for enhanced protein expression and multiplexed metabolic pathway fine-tuning in bacteria

Inducible systems are crucial to metabolic engineering and synthetic biology, enabling organisms that function as biosensors and produce valuable compounds. However, almost all inducible systems are strain-specific, limiting comparative analyses and applications across strains rapidly. This study designed and presented a robust workflow for developing the cross-species inducible system. By applying this approach, two reconstructed inducible systems (a 2,4-diacetylphloroglucinol-inducible system PphlF3R1 and an anhydrotetracycline-inducible system Ptet2R2*) were successfully developed and demonstrated to function in three model microorganisms, including Escherichia coli, Bacillus subtilis and Corynebacterium glutamicum. To enhance their practicality, both inducible systems were subsequently placed on the plasmid and genome for detailed characterization to determine the optimal expression conditions. Furthermore, the more efficient inducible system Ptet2R2* was employed to express various reporter proteins and gene clusters in these three strains. Moreover, the aTc-inducible system Ptet2R2*, combined with T7 RNA polymerase and dCas12a, was utilized to develop a single-input genetic circuit that enables the simultaneous activation and repression of gene expression. Overall, the cross-species inducible system serves as a stringent, controllable and effective tool for protein expression and metabolic pathway control in different bacteria.