Development of a Photoactivatable Proximity Labeling Method for the Identification of Nuclear Proteins

The precise characterization of organellar proteomes is essential for deciphering a variety of cellular functions at the molecular level. We here report a photoactivatable proximity labeling method for identifying organellar proteomes with high spatiotemporal resolution. In our strategy, a photosensitizer targeted to the nucleus of live cells is irradiated with light to locally generate singlet oxygen. An o-phenylenediamine-based substrate then promiscuously tags nearby proteins. This method coupled with LC-MS/MS allowed the specific identification of nuclear proteins, including typical nuclear proteins such as histones and lamins.