Two-component anti-Staphylococcus aureus lantibiotic activity produced by Staphylococcus aureus C55

Staphylococcus aureus C55 was Shown to produce bacteriocin activity compris ing three distinct peptide components, termed staphylococcins C55 alpha, C5 5 beta, and C55 gamma. The three peptides were purified to homogeneity by a simple four-step purification procedure that consisted of ammonium sulfate precipitation followed by XAD-2 and reversed-phase (C-8 and C-18) chromato graphy. The yield following C-8 chromatography was about 86%, with a more-t han-300-fold increase in specific activity. When combined in approximately equimolar amounts, staphylococcins C55 alpha and C55 beta acted synergistic ally to kill S. aureus or Micrococcus luteus but not S. epidermidis strains . The N-terminal amino acid sequences of all three peptides were obtained a nd staphylococcins C55 alpha and C55 beta were shown to be lanthionine-cont aining (lantibiotic) molecules with molecular weights of 3,339 and 2,993, r espectively. The C55 gamma peptide did not appear to be a lantibiotic, nor did it augment the inhibitory activities of staphylococcin C55 alpha and/or C55 beta. Plasmids of 2.5 and 32.0 kb are present in strain C55, and follo wing growth of this strain at elevated temperature (42 degrees C), a large proportion of the progeny failed to produce strong bacteriocin activity and also lost the 32.0-kb plasmid. Protoplast transformation of these bacteria with purified 32-kb plasmid DNA regenerates the ability to produce the str ong bacteriocin activity.