Influence of Ca2+ Ions on the Activity of Lantibiotics Containing a Mersacidin-Like Lipid II Binding Motif

Mersacidin binds to lipid II and thus blocks the transglycosylation step of the cell wall biosynthesis. Binding of lipid II involves a special motif, the so-called mersacidin-lipid II binding motif, which is conserved in a major subgroup of lantibiotics. We analyzed the role of Ca2+ ions in the mode of action of mersacidin and some related peptides containing a mersacidin-like lipid II binding motif. We found that the stimulating effect of Ca2+ ions on the antimicrobial activity known for mersacidin also applies to plantaricin C and lacticin 3147. Ca2+ ions appear to facilitate the interaction of the lantibiotics with the bacterial membrane and with lipid II rather than being an essential part of a peptide-lipid II complex. In the case of lacticin 481, both the interaction with lipid II and the antimicrobial activity were Ca2+ independent.