Human group IIA secreted phospholipase A2 (PLA2G2A, sPLA2-IIA) is an acute phase protein that is induced in the serum under inflammatory conditions (Crowl RM et al. 1991; Lindbom J et al. 2002). PLA2G2A is a highly cationic protein with a positive charge globally distributed over the protein surface (Wery LP et al. 1991; Scott DL et al. 1994; Birts CN et al. 2010). The structure supports two functions of the protein
- An antibacterial role where the enzyme catalyzes the calcium-dependent hydrolysis of phospholipids in the bacterial membranes causing leakage of cell content (Buckland AG et al. 2000a,b; Foreman-Wykert AK et al. 1999; Beers SA et al. 2002; Nevalainen TJ et al. 2008)
- A proposed non-catalytic role in which PLA2G2A forms supramolecular aggregates with anionic phospholipid vesicles or debris (Bezzine S et al. 2002; Birts CN et al. 2008). These aggregates are then internalized via interactions with cell surface heparin sulphate proteoglycans and macropinocytosis for disposal by macrophages.
PLA2G2A shows bactericidal activity against various bacterial pathogens, in particular, against gram-positive bacteria such as Micrococcus luteus, Listeria innocua and Staphylococcus aureus though the sensitivity varies greatly between species (Buckland AG et al. 2000b; Beers SA et al. 2002; Koprivnjak T et al. 2002).