Chemical Protein Modification: Tools for Synthetic Biology

Post-translational modification (PTM) is an important step in protein biosynthesis that increases the range of functions of a protein. Given the ubiquity and variety of natural covalent modifications of proteins, it is important to understand their precise role. Since modified proteins are often difficult to obtain from pure sources or from recombinant translation systems, chemical access can resolve supply issues.[1] Precise chemical modification of proteins is a daunting challenge in chemoselectivity: the reaction must proceed efficiently in buffered aqueous media at or near room temperature and select a single reactive residue among hundreds of competing functional groups. In the work presented, the unique reactivity of cysteine is explored.[2] Two complimentary methods have been developed for the selective formation of thioethers.[3, 4] Additionally, chemical introduction of S-ally cysteine allowed us to take advantage of the enhanced reactivity of allyl sulfides in CM, and we were able to post-translationally modify proteins via carbon-carbon bond formation.[5] These methods are efficient strategies to access phosphorylated, glycosylated, polyprenylated, and methyl-lysine modified, well-defined proteins.