Isolation, Chemical Composition, and Ultrastructural Features of the Cell Membrane of the Mycoplasma-Like Organism Spiroplasma citri
Isolation, Chemical Composition, and Ultrastructural Features of the Cell Membrane of the Mycoplasma-Like Organism Spiroplasma citri
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类支原体柑橘螺原体细胞膜的分离、化学成分和超微结构特征
DOI：
10.1128/jb.116.3.1421-1435.1973
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发表时间：
1973
影响因子：
3.2
通讯作者：
S. Rottem
中科院分区：
文献类型：
--
作者：
S. Razin;M. Hasin;Z. Ne'eman;S. Rottem
柑橘螺旋体是一种从感染顽固性疾病的柑橘中分离出来的类似支原体的有机体，其薄片显示这些有机体受到单一的三层质膜的限制。然而，在未清洗细胞的冷冻蚀刻制剂中经常可以看到额外的外层。这些生物被发现对渗透休克的裂解极其敏感。用这种方法分离的柑橘链霉菌的细胞膜在超微结构和大体化学成分上与支原体相似。分离的膜在断面上呈现典型的三层状，在冷冻蚀刻制备物中呈现典型的颗粒密布的断裂面。蛋白质和脂肪占膜总干重的80%以上，膜密度约为1.180 g/cm~3。胆固醇占总膜脂的20%以上。生物合成的磷脂酰甘油是主要的磷脂。膜制剂中含有大量的氨基己糖(15~35μg/mg膜蛋白)。我们的结果支持这一观点，即柑橘黄色葡萄球菌不具有革兰氏阳性或革兰氏阴性的细胞壁，尽管它可能被其他类型的包膜或粘液层包裹，至少是暂时的。
Thin sections of Spiroplasma citri, a mycoplasma-like organism isolated from citrus infected with “Stubborn” disease, showed the organisms to be limited by a single trilaminar plasma membrane. An additional outer layer could, however, be frequently seen in freeze-etched preparations of unwashed cells. The organisms were found to be extremely sensitive to lysis by osmotic shock. The cell membrane of S. citri isolated in this way resembled that of mycoplasmas in ultrastructure and gross chemical composition. The isolated membranes showed the characteristic trilaminar shape in section and the typical particle-studded fracture faces in freeze-etched preparations. Protein and lipid formed over 80% of the total dry weight of the membrane, which had a density of ~1.180 g/cm3. Cholesterol constituted over 20% of the total membrane lipid. Phosphatidyl-glycerol, synthesized by the organisms, was the major phospholipid. Significant amounts of hexosamine (15 to 35 μg/mg of membrane protein) could be found in the membrane preparations. Our results support the thesis that S. citri does not possess a cell wall, either of the gram-positive or the gram-negative type, though it may be coated by some other type of an envelope or by a slime layer, at least temporarily.