Fig. 1: Demethylation and recognition of N^ε-methylated lysines by erasing enzymes and reader proteins.

a JmjC KDMs catalyse demethylation of N^ε-trimethyllysine residues. Our work explored recognition of the simplest positively charged N^ε-trimethyllysine analogue, i.e., the trimethylphosphonium derivative, by N^ε-methyllysine binding proteins and N^ε-methyllysine demethylases. n: number of methyl groups (3–1). b View from a structure of a JmjC KDM (KDM4A_JmjC, light blue) complexed with H3K9me₃ (yellow) and NOG (N-oxalylglycine, a 2OG analogue, white) (PDB: 2OQ6). c View from a structure of a reader (TAF3_PHD, purple) complexed with H3K4me₃ (yellow) (PDB: 2K17). Nitrogen: dark blue; oxygen: red; sulphur: yellow; zinc: grey; nickel: orange.