ABSTRACT
Figure 1 Sites ofaction ofvarious phospholipases. (a) AI and A2-PLA. and PLA2 ; B-PLB; C-PLC; D-PLD. (b) Lyso-PL (lysophospholipid) and Lyso-PL transacylase.
lipases A, B, C, and D (Fig. la). Phospholipase B (PLB) can release the sn-l and sn-2 fatty acids, and has both hydrolase (fatty acid release) and lysophospholipase-transacylase (LPTA) activities. The hydrolase activity cleaves fatty acids from phospholipids (PLB activity) and Iysophospholipids (Iysophospholipase [Lyso-PL] activity), while the transacylase activity produces phospholipid by transferring a free fatty acid to a Iysophospholipid (Fig. Ib). Accordingly, PLB was also referred to as lysophospholipase or Iysophospholipase-transacylase enzymes. By cleaving phospholipids, phospholipases destabilize the membrane, leading to cell lysis. Evidence implicating phospholipases in host cell penetration, injury, and lysis by micro-organisms has been reported for Rickettsia rickettsii [24], Toxoplasma gondii [25,26], Entamoeba histolytica [27], and C. albicans [5]. Among fungi, phospholipases have been identified as virulence factors
for Candida albicans, Cryptococcus neoformans. Aspergillus fumigatus-the three most common fungal pathogens to infect the human system [5,28,29].
