Site-selective synthetic acylation of a target protein in living cells promoted by a chemical catalyst/donor system.

Cell biology is tightly regulated by posttranslational modifications of proteins. Methods to modulate posttranslational modifications in living cells without relying on enzymes or genetic manipulation are, however, largely underexplored. We previously reported that a chemical catalyst (DSH) conjugated with a nucleosome-binding ligand can activate an acyl-CoA and promote site-selective lysine acylation of histones in test tubes. In-cell acylation by this catalyst system is challenging, however, mainly due to the low cell-permeability of acyl-CoA and the propensity of DSH to form inactive disulfide. Here we report a new catalyst system effective for in-cell acylation, comprising a cell-permeable acyl donor and pro-drugged DSH. Using E. coli dihydrofolate reductase and trimethoprim as a model protein and ligand pair, the catalyst system enabled site-selective acylation of the target protein in living cells. The findings will lead to the development of useful chemical biology tools and new therapeutic strategies capable of synthetically modulating posttranslational modifications.