Whole-cell-catalyzed hydrogenation/deuteration of aryl halides with a genetically repurposed photodehalogenase

Artificial enzymes with new-to-nature reactivity are highly desirable to expand the repertoire of biocatalysis for sustainable synthesis. To this end, artificial photoenzymes embedded with a prominent photoredox catalyst established in synthetic chemistry can harness light energy to trigger electron transfer transformations of abiological substrates. Herein, we demonstrate that a benzophenone photocatalyst encoded in a yellow fluorescent protein named reductive photodehalogenase (RPDase) can proficiently mediate the biocatalytic hydrodehalogenation and deuterodehalogenation of aryl halides. Unlike natural metal-cofactor-dependent dehalogenases evolved for the bioremediation of specific substrates, this metal-free photo enzyme operates in combination with formate via an entirely unnatural catalytic mechanism and exhibits marked substrate generality. Taking advantage of the biorthogonality of RPDase and the genetic code expansion method, we further demonstrated the first whole cell photobiocatalysis using recombinant Escherichia coli cells that express RPDase. Our results show that artificial enzymes bearing a synthetic organophotocatalyst is promising to generate a non -natural metabolism for valuable abiological reactions.

Automated summary

Artificial enzymes using light energy to trigger electron transfer reactions have been developed for sustainable biocatalysis. By encoding a benzophenone photocatalyst in a yellow fluorescent protein, we demonstrated efficient biocatalytic hydrodehalogenation and deuterodehalogenation of aryl halides. The metal-free enzyme operates via an unnatural catalytic mechanism and shows substrate generality. We also successfully demonstrated whole cell photobiocatalysis using recombinant Escherichia coli cells that express the artificial enzyme.