Involved in the biosynthesis of terminal alkyne-containing amino acids such as L-propargylglycine (Pra) and L-beta-ethynylserine, that are produced as antibiotics by S.cattleya. Catalyzes the chlorination of L-lysine at the C4 position, leading to the production of 4-chloro-L-lysine. 2-oxoglutarate + chloride + H(+) + L-lysine + O2 = 4-chloro-L-lysine + CO2 + H2O + succinate Amino-acid metabolism. Antibiotic biosynthesis. Cells lacking this gene no longer produce detectable amounts of L-propargylglycine and L-beta-ethynylserine, that are terminal alkyne-containing amino acids produced by wild-type S.cattleya. Belongs to the alpha-ketoglutarate/Fe-dependent halogenase family.