A Toolkit for Manipulating Cellular Behavior: Peptide with Tryptophan-Selective Ru-TAP Complex Regioselectively Photolabeling Specific Protein in Live Cell

Using a chemical approach to crosslink functionally versatile bioeffectors (such as peptides) to native proteins of interest (POI) directly inside a living cell is a useful toolbox for chemical biologists. However, this goal has not been reached due to unsatisfactory chemoselectivity, regioselectivity, and protein-selectivity in in-cellulo protein labeling. Herein we report a highly selective photoaffinity labeling (PAL) method using a tryptophan-specific Ru-TAP complex as photocrosslinker (Trp-tag). Aside from the high selectivity, the PAL is blue light driven by a photoinduced electron transfer (PeT) and allows the bioeffector to bear an additional UV-responsive unit. The two different photosensitivities are demonstrated by blue light photocrosslinking a UV-sensitive peptide to POI. The remote-control functionality of the peptide allows POI inhibition after blue light irradiation, and reactivation upon UV photolysis. Cytoskeletal dynamics regulation is demonstrated via the unprecedented in-cellulo POI photomanipulation, which opens a new avenue to endogenous protein modification for novel functions.