NosA catalyzing carboxyl-terminal amide formation in nosiheptide maturation via an enamine dealkylation on the serine-extended precursor peptide

The functional characterization of a novel protein NosA in nosiheptide biosynthesis has provided an unusual C-terminal amide forming strategy in general for maturing certain amide-terminated thiopeptides by processing their precursor peptides featuring a serine extension. NosA has acted as an intermediate bearing a bis-dehydroalanine tail and has catalyzed an enamide dealkylation to remove the acrylate unit originating from the extended serine residue.