Figure 1

The biosynthesis and defining chemical features of TOMM and lanthionine-containing natural products. (A) Through the action of a trimeric 'BCD' complex, consisting of a cyclodehydratase (green), dehydrogenase (yellow) and docking/scaffolding protein (blue), thiazoles and (methyl/oxazoles are incorporated onto a peptidic scaffold (black). These heterocycles are synthesized from serine/threonine (X = O) and cysteine (X = S) residues of an inactive precursor peptide and yield a bioactive natural product. The chemical transformations carried out by the cyclodehydratase the dehydrogenase are shown, along with the corresponding mass change in Daltons. (B) A bifunctional synthase, LanM, catalyzes both the dehydration and Michael-type addition steps required to synthesize lanthionine crosslinks.