title: Synthesis, antimicrobial activity, and membrane permeabilizing properties of C-terminally modified nisin conjugates accessed by CuAAC.
abstract: Functionalization of the lantibiotic nisin with fluorescent reporter molecules is highly important for the understanding of its mode of action as a potent antimicrobial peptide. In addition to this, multimerization of nisin to obtain multivalent peptide constructs and conjugation of nisin to bioactive molecules or grafting it on surfaces can be attractive methods for interference with bacterial growth. Here, we report a convenient method for the synthesis of such nisin conjugates and show that these nisin derivatives retain both their antimicrobial activity and their membrane permeabilizing properties. The synthesis is based on the Cu(I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC) as a bioorthogonal ligation method for large and unprotected peptides in which nisin was C-terminally modified with propargylamine and subsequently efficiently conjugated to a series of functionalized azides. Two fluorescently labeled nisin conjugates together with a dimeric nisin construct were prepared while membrane insertion as well as antimicrobial activity were unaffected by these modifications. This study shows that C-terminal modification of nisin does not deteriorate biological activity in sharp contrast to N-terminal modification and therefore C-terminally modified nisin analogues are valuable tools to study the antibacterial mode of action of nisin. Furthermore, the ability to use stoichiometric amounts of the azide containing molecule opens up possibilities for surface tethering and more complex multivalent structures.
authors.affiliation: Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University , P.O. Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Jack C
authors.initials: JC
authors.lastname: Slootweg
authors.forename: Steffen
authors.initials: S
authors.lastname: van der Wal
authors.forename: H C
authors.initials: HC
authors.lastname: Quarles van Ufford
authors.forename: Eefjan
authors.initials: E
authors.lastname: Breukink
authors.forename: Rob M J
authors.initials: RM
authors.lastname: Liskamp
authors.forename: Dirk T S
authors.initials: DT
authors.lastname: Rijkers
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001386:Azides / Q000737:chemistry*; D001412:Bacillus subtilis / Q000187:drug effects; D002384:Catalysis; D002463:Cell Membrane Permeability; D060326:Chemistry Techniques, Synthetic; D003300:Copper / Q000737:chemistry*; D019281:Dimerization; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D008968:Molecular Conformation; D009561:Nisin / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000480:Alkynes; D000890:Anti-Infective Agents; D001386:Azides; D009561:Nisin; D003300:Copper