MODE OF ACTION OF A BACTERIOCIN FROM ERWINIA CAROTOVORA III. PROPERTIES OF PHOSPHOLIPASE A OF ERWINIA CAROTOVORA AND ITS INVOLVEMENT IN PHOSPHOLIPID DEGRADATION CAUSED BY CAROTOVORICIN

[摘要] Phospholipase A in the outer membrane of Erwinia carotovora 645ArT was found to be activated by various detergents such as cholate, deoxycholate and Triton X-100, and methanol. The enzyme was inhibited by ethylenediaminetetraacetic acid, and Ca2+ was required for the enzyme activity. The enzyme hydrolyzed phosphatidylethanolamine and phosphatidylglycerol to form nearly equimolar amounts of free fatty acids and lysophospholipids. Cardiolipin, however, was not susceptible to the enzyme. In a mutant strain deficient in the phospholipase A activity, the rate of degradation of membrane phospholipid caused by carotovoricin Er, a bacteriocin from Erwinina carotovora strain Er, declined to about 1/10 of that of the parent strain under similar conditions. Lysis caused by carotovoricin Er also diminished in the phospholipase A-deficient mutant. These results imply that carotovoricin Er provokes an activation of phospholipase A in sensitive cells, and subsequently, degradation of membane phospholipid and cell lysis result. Phospholipase A-deficient mutant, however, still retained sensitivity to killing activity of carotovoricin Er. Hence, it could be concluded that activation of phospholipase A is not related to the primary bactericidal action of the bacteriocin.

[学科分类] 微生物学和免疫学