gallidermin and mersacidin

Mersacidin, gallidermin, and nisin are lantibiotics, antimicrobial peptides containing lanthionine. They show potent antibacterial activity. All three interfere with cell wall biosynthesis by binding lipid II, but they display different levels of interaction with the cytoplasmic membrane. On one end of the spectrum, mersacidin interferes with cell wall biosynthesis by binding lipid II without integrating into bacterial membranes. On the other end of the spectrum, nisin readily integrates into membranes, where it forms large pores. It destroys the membrane potential and causes leakage of nutrients and ions. Gallidermin, in an intermediate position, also readily integrates into membranes. However, pore formation occurs only in some bacteria and depends on membrane composition. In this study, we investigated the impact of nisin, gallidermin, and mersacidin on cell wall integrity, membrane pore formation, and membrane depolarization in Bacillus subtilis. The impact of the lantibiotics on the cell envelope was correlated to the proteomic response they elicit in B. subtilis. By drawing on a proteomic response library, including other envelope-targeting antibiotics such as bacitracin, vancomycin, gramicidin S, or valinomycin, YtrE could be identified as the most reliable marker protein for interfering with membrane-bound steps of cell wall biosynthesis. NadE and PspA were identified as markers for antibiotics interacting with the cytoplasmic membrane.

Topics: Bacillus subtilis; Bacterial Proteins; Bacteriocins; Biological Transport; Biomarkers; Cell Membrane; Cell Wall; Electrophoresis, Gel, Two-Dimensional; Membrane Potentials; Nisin; Peptides; Potassium; Proteome; Structure-Activity Relationship; Uridine Diphosphate N-Acetylmuramic Acid

Four lantibiotics namely epidermin, gallidermin, lanthiopeptin and mersacidin, have been studied by fast atom bombardment mass spectrometry. The molecular ion clusters of these compounds can be detected with reasonable abundance. The low-mass regions of the spectra show the presence of ions characteristic of the amino acids in the peptides. The mass distribution of the sequence ions provides information about the location of sulphur bridges the occurrence of which is a common feature of these kinds of molecules. The two isomeric compounds epidermin and gallidermin differ only in a leucine/isoleucine exchange at position 6. These two compounds can be distinguished on the basis of the tandem mass spectrum of m/z 86, the immonium ion of leucine and isoleucine.

Topics: Amino Acid Sequence; Anti-Bacterial Agents; Bacteriocins; Molecular Sequence Data; Molecular Weight; Peptide Fragments; Peptides; Peptides, Cyclic; Spectrometry, Mass, Fast Atom Bombardment