Whole-cell P450 biocatalysts using engineered Escherichia coli with fine-tuned heme supply

Abstract

By exploiting versatile P450 enzymes, whole-cell biocatalysis can be performed to synthesize valuable compounds in Escherichia coli. However, the insufficient supply of heme limits the whole-cell P450 biocatalytic activity. Here we report a strategy of improving intracellular heme supply for enhancing the catalytic efficiencies of P450s. After comparing the effects of enhancing heme transport and biosynthesis on P450 activities, intracellular heme supply was optimized through the integrated expression of necessary synthetic genes at proper ratio and the assembly of rate-limiting enzymes using DNA-guided scaffolds. By the combined use of mutated heme-sensitive biosensor and small regulatory RNA systems, the intracellular heme level was fine-tuned. The catalytic efficiencies of three different P450s, BM3, sca-2 and CYP105D7, were enhanced through fine-tuning heme supply for the synthesis of hydroquinone, pravastatin, and 7,3',4'-trihydroxyisoflavone as examples of chemical intermediate, drug, and natural product, respectively. This strategy will be useful to produce other hemoproteins with high activities.