Quantitative control of subcellular protein localization with a photochromic dimerizer.

Artificial control of intracellular protein dynamics with high precision provides deep insight into complicated biomolecular networks. Optogenetics and caged compound-based chemically induced dimerization (CID) systems are emerging as tools for spatiotemporally regulating intracellular protein dynamics. However, both technologies face several challenges for accurate control such as the duration of activation, deactivation rate and repetition cycles. Herein, we report a photochromic CID system that uses the photoisomerization of a ligand so that both association and dissociation are controlled by light, enabling quick, repetitive and quantitative regulation of the target protein localization upon illumination with violet and green light. We also demonstrate the usability of the photochromic CID system as a potential tool to finely manipulate intracellular protein dynamics during multicolor fluorescence imaging to study diverse cellular processes. We use this system to manipulate PTEN-induced kinase 1 (PINK1)-Parkin-mediated mitophagy, showing that PINK1 recruitment to the mitochondria can promote Parkin recruitment to proceed with mitophagy.