In Vitro Biosynthesis of the Nonproteinogenic Amino Acid Methoxyvinylglycine

Abstract

AbstractOxyvinylglycines are a family of nonproteinogenic amino acids featuring an essential vinyl ether conferring mechanism‐based inhibition of pyridoxal phosphate enzymes. The gene clusters for a few oxyvinylglycines are known, yet the biosynthetic origin of the vinyl ether is elusive. The in vitro biosynthesis of methoxyvinylglycine or l‐2‐amino‐4‐methoxy‐trans‐3‐butenoic acid (AMB) is reported. It is shown that AMB is made from glutamate as an alanyl‐AMB dipeptide and the rationale is provided for the N‐term Ala. Using a chemical capture method, the order and timing of the modifications on non‐ribosomal peptide synthetase (NRPS)‐bound substrates was determined, including a cryptic hydroxylation of the Glu β‐carbon. Eliminating this hydroxy group likely generates a key α,β‐dehydroamino acid intermediate that facilitates decarboxylation. This work sheds light on vinyl ether biosynthesis and uncovers new NRPS chemistry.