Genetically encoding an aliphatic diazirine for protein photocrosslinking

Photo cross linking is an important approach that allows discovery and detailed investigation of protein-protein, protein-oligonucleotide, and protein-small molecule interactions with high temporal and spatial resolution. A major limitation to the universal application of this methodology is the site specific introduction of efficient aliphatic photo cross linking probes into proteins of interest. Here, we report a novel aliphatic diazirine amino acid and its genetically encoded, site-specific incorporation into proteins in bacterial and mammalian cells. Furthermore, we demonstrate efficient photo cross linking of a test protein in vitro and in vivo.