Initial binding sites of antimicrobial peptides in Staphylococcus aureus and Escherichia coli

We examined the initial binding sites of magainin 1, cecropin P1 and lactof erricin B in Staphylococcus aureus and Escherichia coli. All 3 peptides mer e active against E. coli, whereas only lactoferricin B exerted any activity against S. aureus. Soluble lipoteichoic acid and lipopolysaccharide both i nteracted with all 3 peptides, whereas soluble teichoic acid interacted wit h lactoferricin B only. Antibodies against teichoic acid diminished the act ivity of lactoferricin B, while antibodies against lipoteichoic acid had no influence on the activity of lactoferricin B. Antibodies against lipopolys accharide diminished the activity of lactoferricin B and magainin 1, but ha d no effect on the activity of cecropin P1 against E. coli. We conclude tha t the initial binding sites of lactoferricin B in S. aureus, and of lactofe rricin B and magainin 1 in E. coli, are teichoic acid and lipopolysaccharid e, respectively. Cecropin P1 seems to interact with a different binding sit e than those of magainin I and lactoferricin B in E. coli.