Engineering an acetyllysine reader with a photocrosslinking amino acid for interactome profiling.

The site-specific installation of light-activable crosslinker unnatural amino acids offers a powerful approach to trap transient protein-protein interactions both in vitro and in vivo. Herein, we engineer a bromodomain to introduce 4-benzoyl-L-phenylalanine (BzF) using amber suppressor mutagenesis without compromising its ability to recognize the acetylated histone proteins. We demonstrate the high crosslinking efficiency of the engineered reader towards the interacting partners and its suitability for profiling the transient bromodomain interactome.