Hydrolytic Action of Phospholipases on Bacterial Membranes

Substrate specificities of phospholipases C [EC 3.1.4.3] from Clostridium novyi, Clostridium per-fringens. Bacillus cereus, and Pseudomonas aureofaciens were studied under the same conditions. Phospholipases C from Clostridium novyi and Bacillus cereus show wide substrate specificities while those of Clostridium perfringens and Pseudomonas aureofaciens show relatively narrow specificities. On the basis of these results, the hydrolytic actions of these phospholipases on membrane lipids of Escherichia coli, Bacillus cereus, and Clostridium novyi were examined under the same conditions. The enzymes of Clostridium novyi and Bacillus cereus attacked all the membranes and their lipid extracts, hydrolyzing phosphatidylethanolamine, phosphatidylglycerol, lyso-phosphatidylethanolamine, and o-aminoacylphosphatidylglycerol. Phospholipase C from Pseudomonas aureofaciens attacked these three membranes and their lipid extracts, hydrolyzing phosphatidylethanolamine. Phospholipase C from Clostridium perfringens hardly attacked the phospholipids of these bacterial membranes. However, phospholipase C from Clostridium perfringens hydrolyzed phosphatidylethanolamine in a mixture containing lipid extract from Escherichia coli membrane and purified phosphatidylcholine from egg yolk. Phospholipases C [EC 3.1.4.3] obtained from Bacillus cereus and Clostridium perfringens have been used to investigate the structure and function of biological membranes (1-4). We have investi-gated the actions of phospholipases C from Clo-stridium novyi, Clostridium perfringens, and Pseu-domonas aureofaciens on the membranes of mam-malian erythrocytes (5). In the present paper, we describe the substrate specificities and hydrolytic actions on bacterial membranes of phospholipases under the same conditions for the purpose of dis-crimination of their properties and actions on the membranes. Abbreviation: SDC, sodium deoxycholate. MATERIALS AND METHOD