Insights into In Vivo Activities of Lantibiotics from Gallidermin and Epidermin Mode-of-Action Studies

Abstract

The activity of lanthionine-containing peptide antibiotics (lantibiotics) is based on different killing mechanisms which may be combined in one molecule. The prototype lantibiotic nisin inhibits peptidoglycan synthesis and forms pores through specific interaction with the cell wall precursor lipid II. Gallidermin and epidermin possess the same putative lipid II binding motif as nisin; however, both peptides are considerably shorter (22 amino acids, compared to 34 in nisin). We demonstrate that in model membranes, lipid II-mediated pore formation by gallidermin depends on membrane thickness. With intact cells, pore formation was less pronounced than for nisin and occurred only in some strains. In Lactococcus lactis subsp. cremoris HP, gallidermin was not able to release K ؉ , and a mutant peptide, [A12L]gallidermin, in which the ability to form pores was disrupted, was as potent as wild-type gallidermin, indicating that pore formation does not contribute to killing. In contrast, nisin rapidly formed pores in the L. lactis strain; however, it was approximately 10-fold less effective in killing. The superior activity of gallidermin in a cell wall biosynthesis assay may help to explain this high potency. Generally, it appears that the multiple activities of lantibiotics combine differently for individual target strains.

The Lantibiotic NAI-107 Binds to Bactoprenol-bound Cell Wall Precursors and Impairs Membrane Functions

“…The response strongly overlaps with that of gallidermin-treated cells, suggesting high mechanistic similarity between these two lantibiotics. Gallidermin integrates into membranes, with pore formation occurring only in some bacteria and correlating with membrane thickness and fatty acid branching (29,36,47). In contrast to nisin, which needs to dock to lipid II for membrane integration and pore formation, gallidermin shows very high association and low dissociation constants for binding to phospholipid bilayers, indicating that it readily integrates into the membrane independently of lipid II binding.…”

“…3A). Whole cell assays were repeated with different strains (M. luteus DSM 1790, S. simulans, B. subtilis 168, and S. aureus ATCC 29213) to exclude membrane effects dependent on membrane thickness and lipid composition of the target strain as described for gallidermin or epidermin (21,29). To better estimate the contribution of the slow membrane depolarization (Fig.…”

“…Overall NAI-107 seems to combine two known lipid II targeting motifs ( Fig. 1) with its 1-11 N-terminal sequence being similar to nisin and its C-terminal ring system, which shares structural elements with epidermin and mersacidin (3,29). NAI-107 is currently in late preclinical development and displays efficacy in animal models of multidrug-resistant infections superior to the drugs of last resort, linezolid and vancomycin (30).…”

Activity and Export of Engineered Nisin-(1-22) Analogs

“…However, even without the capacity to form pores, epidermin and gallidermin were shown to be 10 to 20 times more potent against L. lactis subsp. cremoris HP than nisin [28]. This led us to the idea that the activity of truncated nisin might be optimized via genetic engineering.…”

Analysis of membrane interactions of antibiotic peptides using ITC and biosensor measurements

“…In contrast to nisin, due to the short molecular length, gallidermin is hardly able to form pores in membranes via peptide-lipid II complexes. Therefore, the primary mode of action of gallidermin is obviously based on the interaction with lipid II resulting in inhibition of cell wall synthesis [12].…”