Modulation of the Activity of Secretory Phospholipase A 2 by Antimicrobial Peptides

Abstract

ABSTRACT The antimicrobial peptides magainin 2, indolicidin, and temporins B and L were found to modulate the hydrolytic activity of secretory phospholipase A 2 (sPLA 2 ) from bee venom and in human lacrimal fluid. More specifically, hydrolysis of phosphatidylcholine (PC) liposomes by bee venom sPLA 2 at 10 μM Ca 2+ was attenuated by these peptides while augmented product formation was observed in the presence of 5 mM Ca 2+ . The activity of sPLA 2 towards anionic liposomes was significantly enhanced by the antimicrobial peptides at low [Ca 2+ ] and was further enhanced in the presence of 5 mM Ca 2+ . Similarly, with 5 mM Ca 2+ the hydrolysis of anionic liposomes was enhanced significantly by human lacrimal fluid sPLA 2 , while that of PC liposomes was attenuated. These results indicate that concerted action of antimicrobial peptides and sPLA 2 could improve the efficiency of the innate response to infections. Interestingly, inclusion of a cationic gemini surfactant in the vesicles showed an essentially similar pattern on sPLA 2 activity, suggesting that the modulation of the enzyme activity by the antimicrobial peptides may involve also charge properties of the substrate surface.