Multidrug resistance regulators (MDRs) as scaffolds for the design of artificial metalloenzymes

The choice of protein scaffolds is an important element in the design of artificial metalloenzymes. Herein, we introduce Multidrug Resistance Regulators (MDRs) from the TetR family as a viable class of protein scaffolds for artificial metalloenzyme design. In vivo incorporation of the metal binding amino acid (2,2-bipyridin-5yl)alanine (BpyA) by stop codon suppression methods was used to create artificial metalloenzymes from three members of the TetR family of MDRs: QacR, CgmR and RamR. Excellent results were achieved with QacR Y123BpyA in the Cu²⁺ catalyzed enantioselective vinylogous Friedel–Crafts alkylation reaction with ee's up to 94% of the opposite enantiomer that was achieved with other mutants and the previously reported LmrR-based artificial metalloenzymes.