Figure 12.
NRPS-catalyzed formation of β-lactones and β-lactams. (A) Structure of representative β-lactone and β-lactam-containing NRPs (B) Role of ObiF and ObiD in lactone synthesis including A domain-catalyzed activation and loading of DHB and Phe*, C domain-catalyzed amide bond formation to generate the pseudo dipeptide, and TE domain-catalyzed lactonization to release the product from the NRPS. A similar strategy is utilized to generate the β-lactam in sulfacezin. DHB, 2,3-dihydroxybenzoic acid; Phe*, β-hydroxy-p-nitro-homophenylalanine.