Zero-length photo-crosslinking by organoiridium catalyst for intracellular interactome mapping

Abstract

Abstract Direct zero-length photo-crosslinking by a single photocatalyst has great value in exploring protein–protein interactions for understanding important biological events. However, its application in living cells has been challenging. Herein, we rationally designed an organoiridium catalyst with enhanced photo-crosslinking efficiency based on its triplet excited state lifetime and devised a proteomic method with HaloTag and the green fluorescent protein (GFP)-GFP binding protein (GBP) system involving photo-crosslinking by organoiridium catalyst for intracellular interactome mapping (POINT). POINT achieved spatiotemporal resolution of three subnuclear proteins (PTBP1, POU2F1, and PSMA2), including an undruggable target in the nucleus, detected interactors of PTBP1 that were not detected by TurboID-based enzymatic labelling, and revealed unknown potential interactors of POU2F1 and PSMA2. POINT can have expanded applicability in detecting various disease-relevant target proteins, thus accelerating novel protein interaction network identification.