Lantibiotic structural elements. (A) Covalent structures for mutacin 1140, epidermin, and nisin with the lanthionine rings labeled from N- to C-terminus. (B) Leader sequence alignments of structurally related class I type AI lantibiotics; that is, mutacin 1140 produced by Streptococcus mutans, nisin produced by Lactococcus lactis, subtilin produced by Bacillus subtilis, epidermin produced by Staphylococcus epidermidis, gallidermin produced by Staphylococcus gallinarium, Pep5 produced by Staphylococcus epidermidis, epilancin K7 produced by Staphylococcus epidermidis (Gross and Morell 1971; Allgaier et al. 1986; Kellner et al. 1988; Kaletta et al. 1989; Piard et al. 1992; Klein and Entian 1994; Vandekamp et al. 1995; Hillman et al. 1998). (C) Secondary structure prediction using SOPMA for mutacin 1140 leader peptide; h (alpha helix), e (extended strand), c (random coil), t (beta turn). Alpha helical regions are in bold, while random coils are underlined in the leader peptide sequence.