Remolding laccase for whole-cell and in vivo modulation of dopamine signal

Biocatalytic regulation of dopamine signals paves an effective and biocompatible way to modulate dopaminergic functions and disorders. Here, we report the remolding of bacterial laccase, catalyzing conversions of dopamine and O₂ to <i>o</i>-quinone and H₂O, into a biocatalytic neuromodulator by reactive oxygen species-free dopamine catabolism. Given the poor activity of native laccase in the physiological context because of OH^- inhibition of its geometrically constrained O₂-reducing center, we designed a highly dynamic Ru-Cu binuclear center to counteract the inhibition effect. Structural and computational investigations unravel a self-adaptive catalytic mechanism by reversive Ru-Cu active site reconfiguration that lowers the kinetic barriers for O₂-to-H₂O conversion in neutral solution. The remolded laccase exhibits substantial enhancement of physiological activity (up to one order of magnitude) and improved catecholamine substrate specificity, enabling whole-cell down-regulation of vesicular dopamine and extracellular erasure of evoked dopamine signals in intact brains. Our work elucidates a picture of artificial metalloenzymes for neuromodulation through a rationalized neurotransmitter metabolism pathway.