Structural Features of the Final Intermediate in the Biosynthesis of the Lantibiotic Nisin. Influence of the Leader Peptide

Abstract

The antimicrobial membrane-interacting polypeptide nisin is a prominent member of the lantibiotic family, the members of which contain thioether-bridged residues called lanthionines. To gain insight into the complex biosynthesis and the structure/function relationship of lantibiotics, the final intermediate in the biosynthesis of nisin A was studied by nuclear magnetic resonance spectroscopy. In aqueous solution the leader peptide part of this precursor adopts predominantly a random coil structure, as does the synthetic leader peptide itself. The spatial structure of the fully modified nisin part of the precursor is similar to that of nisin in water. The leader peptide part does not interact with the nisin part of the precursor molecule. Thus, these two parts of the precursor do not influence each other's conformation significantly. The conformation of the precursor was also studied while complexed to micelles of dodecylphosphocholine, mimicking the primary target of the antimicrobial activity of nisin, i.e. the cytoplasmic membrane. The location of the molecule relative to the micelles was investigated by using micelle-inserted spin-labeled 5-doxylstearic acid. It was observed that the N-terminal half of the nisin part of the precursor interacts in a different way with micelles than does the corresponding part of mature nisin, whereas no significant differences were found for the C-terminal half of the nisin part. In this model system the leader peptide is in contact with the micelles. It is concluded that the strongly reduced in vivo activity of the precursor molecule relative to that of nisin is not caused by a difference in the spatial structure of nisin and of the corresponding part of precursor nisin in water or by a shielding of the membrane interaction surface of the nisin part of the precursor by the leader peptide. Probably a different interaction of the N-terminal part of the nisin region with membranes contributes to the low activity by preventing productive insertion. The residues of the leader peptide part just next to the nisin part are likely to contribute most to the low activity of the precursor.

Characterization of the Antimicrobial Peptide Penisin, a Class Ia Novel Lantibiotic from Paenibacillus sp. Strain A3

“…The results of CD and NMR analyses revealed it to be a random coil, which is in agreement with the other lantibiotics with multiple thioether bonds reported earlier (42)(43)(44). Thus, they do not exhibit any conformation-related obligations while present inside the host.…”

Follow the leader: the use of leader peptides to guide natural product biosynthesis

“…2 online). NMR studies on fully processed nisin attached to its leader peptide did not reveal any interactions between the leader and the nisin molecule, both in solution and in micelles 18 . Moreover, none of the investigated lantibiotic leader peptides displayed secondary structure in aqueous solution, although they attain α-helical conformations in trifluoroethanol 19 and structure prediction tools anticipate helical character.…”

Mechanistic Understanding of Lanthipeptide Biosynthetic Enzymes

“…39 Conceptually, the leader sequence may facilitate biosynthesis by interacting with processing enzymes, by assisting in the transport of the processed peptide product, and/or by contributing to immunity within the producing organism. 248 Experiments suggest that the leader sequence of the fully modified NisA precursor does not directly interact with the modified core peptide, either in solution or in lipid micelles, 249 thus providing no evidence for a direct role of the leader in the chemical transformations in the core peptide.…”