Hydrolytic action of phospholipases on bacterial membranes

Substrate specificities of phospholipases C[EC 3.1.4.3] from Clostridium novyi, Clostridium perfringens, 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.