Combinatorial approaches for introducing additional modifications into lantibiotics

Lantibiotics, a kind of antimicrobial proteins, are attracting more and more interest of researchers all over the world due to their unique bacteria-killing mechanisms resulting from their unique structures. Diverse enzymes are required to construct these structures. In our study, the functionality of different enzymes has been studied in detail on designed peptides. For example, one enzyme (GdmD) can remove the side group (carboxyl group) of the C-terminal cysteine of a designed peptide; another enzyme, LtnJ is able to introduce D-alanine on lantibiotics if the flanking residues of the substrate amino acid are carefully designed. Furthermore, one hydroxylase from actinobacteria, CinX, has been proven to hydroxylate the aspartic acid on lantibiotics. The successful applications of these enzymes to introduce unique structures on designed proteins inspire a new way to expand the diversity of lantibiotics. Using the tools studied in this thesis we are looking forward to finding some novel molecules with improved properties such as stability and specificity.