NRPS megasynthases - the A to X of assembling peptide antibiotics

Focuses on the period 2020-2025Antibiotics remain a cornerstone of modern medicine, with natural products representing many of the molecules used in the clinic or in agriculture. Nonribosomal peptides represent a significant class within our antibiotic arsenal, with the tantalising prospects for engineering the megaenzyme machineries that produce these molecules continuing to captivate the fields of enzymology, biocatalysis and discovery. Recent studies have demonstrated that there is significant diversity yet to be elucidated within both the types of molecules produced by these assembly lines and the enzymatic machineries that produce them, and thus the field of antibiotics produced by NRPS biosynthesis will continue to grow. This review seeks to highlight the impressive nature of recent discoveries made by the field over the period from 2020-2025, including the identification of novel antimicrobial peptides produced by NRPS assembly lines, exemplars of novel substrates and transformations within the assembly of these peptides, the role of chemistry in supporting both the discovery and engineering of these pathways, and key discoveries that challenge established paradigms within the field in terms of how nature can assemble bioactive antimicrobial peptides.