Genetic Incorporation of N(ε)-Formyllysine, a New Histone Post-translational Modification

Lysine formylation is a newly discovered post-translational modification (PTM) in histones and other nuclear proteins; it has a well-recognized but poorly defined role in chromatin conformation modulation and gene expression. To date, there is no general method to site-specifically incorporate N(ε)-formyllysine at a defined site of a protein. Here we report the highly efficient genetic incorporation of the unnatural amino acid N(ε)-formyllysine into proteins produced in Escherichia coli and mammalian cells, by using an orthogonal N(ε)-formyllysine tRNAsynthetase/tRNACUA pair. This technique can be applied to study the role of lysine formylation in epigenetic regulation.