Fig. 5: Schematic diagram of the smart regulatory hub constructed based on the metabolic properties of the aromatic compound biofunnel and the feedback regulatory elements of the core metabolites.
From: Lignin valorization to bioplastics with an aromatic hub metabolite-based autoregulation system
The establishment of the regulatory hub relies on a combination of microbial biofunnel metabolic properties and PcaQ/PPCA of response to the core intermediate protocatechuic acid. In the regulatory hub, the expression of key enzymes of the rate-limiting step, such as aromatic aldehyde dehydrogenase and demethylase, were regulated by PcaQ/PPCA. The autoregulation process relies on the leaky expression of the promoter PPCA to convert different types of monomeric substrates such as vanillin will be partially converted to protocatechuic acid. The modified PcaQ R145K/PPCA was better regulated in response to low concentrations of protocatechuic acid, and the expression levels of key enzymes in the pathway of conversion of upstream substrates to protocatechuic acid, such as aldehyde dehydrogenase and demethylase, were enhanced by feedback. Multiple types of lignin-derived aromatic compounds can achieve metabolic regulation without the need for additional inducers.
