Antibiotics synthesized by posttranslational modification

Peptides that have antimicrobial activity are synthesized by many prokaryotic and eukaryotic organisms. Antimicrobial peptides commonly contain unusual amino acids that contribute to their properties and functions. Although bacteria synthesize most of these peptides by nonribosomal mechanisms, this review focuses on those that are synthesized by pathways that involve posttranslational modification of ribosomally synthesized precursor peptides. A particularly interesting class of these antimicrobial peptides is the lantibiotics, of which nisin and subtilin are the longest-known examples, although nearly a dozen new lantibiotics have been discovered in recent years. The fact that the lantibiotic structures are derived from gene-encoded peptides means that structural analogs of natural lantibiotics can be constructed by mutagenesis of their structural genes. Recent advances in our understanding of the molecular genetics of lantibiotics has made the construction of novel lantibiotics with enhanced chemical and antimicrobial properties possible. This review describes these advances and proposes future trends of research, as well as potential application of engineered lantibiotics, in the context of the general field of antimicrobial peptides.