LANTIBIOTICS AND MICROCINS - NOVEL POSTTRANSLATIONAL MODIFICATIONS OFPOLYPEPTIDES

Unique peptide modification mechanisms have attracted considerable int erest from scientists working in both applied and basic research. The design, genetic engineering and production of unusually modified pepti des for use in areas such as biomedical applications and food technolo gy has rapidly become a small, but exciting, new branch of biotechnolo gy. Both lantibiotics and microcins are antimicrobial peptides which c ontain combinations of thioether bridges, alpha,beta-unsaturated amino acids, D-amino acids, N-, C-terminal and heteroaromatic backbone modi fications, all of which arise from posttranslational modifications of Ser, Thr, Cys and Gly residues in a ribosomally-synthesised precursor polypeptide. The structures of many of the lantibiotics have been eluc idated and the structure of C-13-,N-15-labelled microcin B17 has been solved. In addition, the total synthesis of microcin B17, and a number of analogues, was recently accomplished. The previously undescribed e nzymes apparently responsible for dehydration, ring formation, oxidati ve decarboxylation, hydrogenation, and leader peptide cleavage are cur rently being characterised.