Goldfine H, Johnston N C, Knob C
Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia 19104-6076.
J Bacteriol. 1993 Jul;175(14):4298-306. doi: 10.1128/jb.175.14.4298-4306.1993.
Listeria monocytogenes secretes a phospholipase C (PLC) which has 39% amino acid sequence identity with the broad-specificity PLC from Bacillus cereus. Recent work indicates that the L. monocytogenes enzyme plays a role during infections of mammalian cells (J.-A. Vazquez-Boland, C. Kocks, S. Dramsi, H. Ohayon, C. Geoffroy, J. Mengaud, and P. Cossart, Infect. Immun. 60:219-230, 1992). The homogeneous enzyme has a specific activity of 230 mumol/min/mg when phosphatidylcholine (PC) is dispersed in sodium deoxycholate. With phospholipid-Triton X-100 mixed micelles, the enzyme had a broad pH optimum between 5.5 and 8.0, and the rates of lipid hydrolysis were in the following order: PC > phosphatidylethanolamine (PE) > phosphatidylserine > sphingomyelin >> phosphatidylinositol (PI). Activity on PC was stimulated 35% by 0.5 M NaCl and 60% by 0.05 mM ZnSO4. When Escherichia coli phospholipids were dispersed in Triton X-100, PE and phosphatidylglycerol, but not cardiolipin, were hydrolyzed. The enzyme was active on all phospholipids of vesiculated human erythrocytes including PI, which was rapidly hydrolyzed at pH 7.0. PI was also hydrolyzed in PI-PC-cholesterol liposomes by the nonspecific PLC from L. monocytogenes and by the homologous enzyme from B. cereus. The water-soluble hydrolysis product was identified as inositol-1-phosphate. For the hydrolysis of human erythrocyte ghost phospholipids, a broad pH optimum was also observed. 32P-labelled Clostridium butyricum protoplasts, which are rich in ether lipids, were treated with PLC. The enzyme hydrolyzed the plasmalogen form of PE, its glycerol acetal, and cardiolipin, in addition to PE. I-, Cl- and F- stimulated activity on either PC- Triton X-100 mixed micelles or human erythrocyte ghosts, unlike the enzyme from B. cereus which is strongly inhibited by halides. Tris-HCl, phosphate, and calcium nitrate had similar inhibitory effects on the enzyme on the enzymes from L. monocytogenes and B. cereus.
单核细胞增生李斯特菌分泌一种磷脂酶C（PLC），它与蜡样芽孢杆菌的广谱特异性PLC具有39%的氨基酸序列同一性。最近的研究表明，单核细胞增生李斯特菌的这种酶在感染哺乳动物细胞的过程中发挥作用（J.-A. 巴斯克斯 - 博兰德、C. 科克斯、S. 德拉姆西、H. 奥哈扬、C. 杰弗里、J. 蒙戈、P. 科萨尔，《感染与免疫》60:219 - 230，1992年）。当磷脂酰胆碱（PC）分散在脱氧胆酸钠中时，该纯酶的比活性为230 μmol/分钟/毫克。对于磷脂 - 吐温X - 100混合胶束，该酶在5.5至8.0之间有较宽的最适pH值，脂质水解速率顺序如下：PC＞磷脂酰乙醇胺（PE）＞磷脂酰丝氨酸＞鞘磷脂＞＞磷脂酰肌醇（PI）。0.5 M NaCl可使PC的活性提高35%，0.05 mM ZnSO₄可使其提高60%。当大肠杆菌磷脂分散在吐温X - 100中时，PE和磷脂酰甘油可被水解，但心磷脂不能。该酶对泡状人红细胞的所有磷脂都有活性，包括PI，在pH 7.0时PI可被快速水解。PI在PI - PC - 胆固醇脂质体中也可被单核细胞增生李斯特菌的非特异性PLC和蜡样芽孢杆菌的同源酶水解。水溶性水解产物被鉴定为肌醇 - 1 - 磷酸。对于人红细胞膜磷脂的水解，也观察到较宽的最适pH值。用PLC处理富含醚脂的³²P标记丁酸梭菌原生质体。该酶除了水解PE外，还能水解PE的缩醛磷脂形式、其甘油缩醛以及心磷脂。I⁻、Cl⁻和F⁻可刺激该酶对PC - 吐温X - 100混合胶束或人红细胞膜的活性，这与蜡样芽孢杆菌的酶不同，后者会被卤化物强烈抑制。Tris - HCl、磷酸盐和硝酸钙对单核细胞增生李斯特菌和蜡样芽孢杆菌的酶有类似的抑制作用。
