Bactericidal properties of group IIA and group V phospholipases A2

Group V phospholipase A(2) (PLA(2)) is a recently characterized 14-kDa secretory PLA(2) of mammalian heart and macrophage-derived cells. Group IIA PLA(2), which is structurally close to group V PLA(2), has been shown to kill Gram-positive bacteria in vitro and to prevent symptoms of Gram-positive infection in vivo. We studied the antibacterial properties of fully active recombinant rat group IIA and V PLA(2)s. Both group IIA and V PLA(2)s were highly bactericidal against Gram-positive bacteria, including methicillin-resistant staphylococci and vancomycin-resistant enterococci. Only high concentrations of group IIA PLA(2) showed some bactericidal effect against the Gram-negative bacterium Escherichia coli. Our results confirm that group IIA PLA(2) is a potent antibacterial enzyme against Gram-positive bacteria. Moreover, we show here that group V PLA(2) is a novel antibacterial mammalian protein, but is less potent than group IIA PLA(2). Both enzymes may be considered as future therapeutic agents against bacterial infections.