CHAPTER 3: Thioesterase Domain-mediated Macrocyclization of Non-ribosomal Peptides

Macrocyclic non-ribosomal peptides (NRPs) are an important class of natural products that exhibit significant and unique bioactivities. These small to medium-sized molecules are biosynthesized by highly versatile, multifunctional enzymes known as non-ribosomal peptide synthetases (NRPSs) that assemble linear peptides in a peptidyl carrier protein (PCP)-dependent assembly line fashion. The macrocyclization of precursor linear peptides is typically carried out by thioesterase (TE) domains that are found adjacent to the final carrier protein in the terminal NRPS module and are responsible for termination of the biosynthesis. Here we review the classes of macrocyclic NRPs and the function, mechanism, structure, and PCP–TE domain interaction. In addition, we review the recent discovery and preparative advances of a chemoenzymatic approach using isolated TE domains.