Outer membrane phospholipase A from Acinetobacter sp. HO1-N

The presence of phospholipase A and lysophospholipase activities in culture supernatant fluid from Alteromonas espejiana

Culture supernatants from late Log phase cultures of Alteromonas espejiana hydrolyzed phosphatidylinositol to glycerylphosphorylinositol and free fatty acid. No lysophosphatidylimositol was detected. The phospholipase activity degraded up to 50% of the substrate and displayed a broad pH optimum from 6.5-8.5. The activity was slightly stimulated in the presence of either Mg2+ or Ca2+, but was not inhibited by EDTA. The apparent Km for phosphatidylinositol was 1.5 mM. Culture supernatants also contained deacylating activity which released fatty acid from phosphatidylcholine and erythrocyte ghosts.

Phospholipase A activity in supernatants from cultures of Bacteroides melaninogenicus

The phospholipase A activity in culture supernatants of two strains of Bacteroides melaninogenicus is described. The enzyme utilize phosphatidylcholine as substrate and produce mainly lysophosphatidylcholine and free fatty acids. The activities are Ca2+-independent, are not affected by the presence of a chelating agent, have a broad pH range (5-9) and an optimum temperature for activity of approx. 50 degrees C. The activity in a growing bacterial culture increases from the end of the lag phase to the late exponential phase of growth. Analysis of the products resulting from the actions of the enzymes on L-alpha-palmitoyl-beta-oleoyl[1-14C]phosphatidylcholine indicates that the enzymes are phospholipase A1 (EC 3.1.1.32).

Identification and synthesis of acyl-phosphatidylglycerol in Acinetobacter sp. HO1-N

A minor phospholipid from Acinetobacter sp. HO1-N was identified as acyl-phosphatidylglycerol. Acyl-phosphatidylglycerol synthesis by outer-membrane preparations appeared to be a result of phospholipase A activity.

Characterization of lysocardiolipin from Acinetobacter sp. HO1-N

Triacyl-lysocardiolipin (triacyl-LCL) and diacyl-LCL were isolated from Acinetobacter sp. HO1-N, and their structures were determined by chemical, physical, and enzymatic procedures. Deacylation of triacyl-LCL and diacyl-LCL yielded bis-glycerylphosphorylglycerol. Periodate oxidation of both lysolipids was negative. Diglyceride and 2-monoglyceride resulted from the acetic acid hydrolysis of triacyl-LCL, whereas 2-monoglyceride was the sole product obtained from diacyl-LCL. Cardiolipin (CL)-specific phospholipase D treatment of triacyl-LCL yielded lysophosphatidylglycerol and phosphatidic acid. Pancreatic lipase treatment of CL yielded triacyl-LCL and diacyl-LCL. 31P nuclear magnetic resonance spectrometry showed two resonance peaks separated by 40 HZ for CL, two overlapping peaks separated by 14 HZ for triacyl-LCL, and one peak for diacyl-LCL. The proportion of lysocardiolipin increased as a function of cell age, representing 2 to 3% of the total phospholipids in early- and mid-exponential growth, 5 to 7% in late-exponential growth, and 12% in the stationary growth phase.