Figure 1.

(A) Dehydroalanine (Dha) and dehydrobutyrine (Dhb) formation during lantibiotic biosynthesis arises from the dehydration of serine and threonine residues, respectively. Cysteine addition to the unsaturated amino acids generates the thioether crosslinks. (B) Lacticin 481 biosynthesis catalyzed by lacticin 481 synthetase (LctM). The enzyme dehydrates specific serine and threonine residues of the substrate LctA and subsequently catalyzes cysteine addition to the dehydrated amino acids, generating two lanthionines and one methyllanthionine. The dual cysteine protease and ABC transport protein LctT is responsible for leader peptide removal and transport of the mature lantibiotic out of the cell.