Solution structure of plantaricin C, a novel lantibiotic

Plantaricin C, a bacteriocin produced by a Lactobacillus plantarum strain o f dairy origin, is a lantibiotic. One dehydroalanine, one lanthionine and t hree beta-methyl-lanthionine residues were found in its 27 amino acid seque nce. The plantaricin C structure has two parts: the first comprises the six NH2-terminal residues, four of which are lysines, which confer a strong po sitive charge to this stretch. The amino acids in positions 7 and 27 form t he lanthionine bridge, giving a globular conformation to the rest of the mo lecule. The beta-methyl-lanthionine bridges are established between residue s 12-15, 13-18 and 23-26. This central region has a charge distribution com patible with an amphipathic alpha-helix, through which plantaricin C would become inserted into the membrane matrix of sensitive organisms, provoking the opening of pores and leakage of the cytoplasmic content.