Phosphatidylcholine formation is the predominant lipid biosynthetic event in the hemoparasite Babesia bovis
Phosphatidylcholine formation is the predominant lipid biosynthetic event in the hemoparasite Babesia bovis
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DOI：
10.1016/s0166-6851(99)00209-1
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发表时间：
2000-02-25
影响因子：
1.5
通讯作者：
Palmer, GH
中科院分区：
文献类型：
--
作者：
Florin-Christensen, J;Suarez, CE;Palmer, GH
这项工作检查了被顶复门巴贝虫寄生虫（与疟原虫密切相关的生物体）感染的牛红细胞的脂质组成和代谢。我们发现感染牛巴贝虫 (i-RBC) 的红细胞会积聚脂质，并且磷脂酰胆碱显着增加。与在相同条件下培养的未感染红细胞 (n-RBC) 相比，磷脂酸、二酰基甘油和胆固醇酯。在感染二联巴贝斯虫的红细胞培养物中观察到类似的模式。纯化的牛芽孢杆菌裂殖子的脂质谱显示，磷脂酰胆碱是该寄生虫中最丰富的磷脂（占总磷脂的 31.8% +/- 2.8），与牛 n-RBC 明显不同，后者仅占次要成分（4.8% +/- 0.6）。牛双歧杆菌培养物将放射性标记的胆碱掺入复合脂质中，尤其是磷脂酰胆碱。鞘磷脂和溶血磷脂酰胆碱中回收少量。当使用[C-14]硬脂酸酯作为前体时，标记模式再次给出了磷脂酰胆碱的最高掺入，而鞘磷脂、磷脂酰肌醇、磷脂酰乙醇胺和磷脂酸的掺入较少。二酰基甘油和少量胆固醇酯是发现的唯一标记的中性脂质。牛芽孢杆菌还将[H-3]肌醇掺入磷脂酰肌醇中。使用 n-RBC 作为对照进行平行孵育，未与盟友前体掺入极性或中性脂质中。这些结果表明，在 i-RBC 中观察到的脂质变化可以根据巴贝斯寄生虫的脂质生物合成活性来解释。 i-RBC 和 n-RBC 磷脂脂肪酸甲酯的气相色谱-质谱 (GC-MS) 分析显示两者具有相同的定性组成。然而。 i-RBC 具有较高的饱和脂肪酸与不饱和脂肪酸比率，并且牛 B. 牛培养物不会使 [C-14] 硬脂酸去饱和。胆固醇是 GC-MS 检测到的唯一甾醇。 i-RBC 和 n-RBC 的磷脂酶 A(2) 处理显示 i-RBC 中的溶血作用没有增强，表明红细胞膜磷脂组成基本上没有被寄生虫改变。用 [I-125] Bolton-Hunter 标记 i-RBC 或 n-RBC 导致 i-RBC 中磷脂酰丝氨酸标记增强。这项研究提供了有关 B、牛脂质构成和生物合成的第一个数据。他们表明磷脂酰胆碱的形成是这些细胞中主要的生物合成过程。宿主红细胞和寄生虫之间磷脂酰胆碱含量的显着差异表明，它可能是针对牛巴贝斯虫病的化疗和免疫预防的有用靶标。 (C) 2000 Elsevier Science B.V. 保留所有权利。
This work examines the lipid composition and metabolism of bovine red blood cells infected by apicomplexan Babesia parasites, organisms closely related to Plasmodium sp. We found that erythrocytes infected with Babesia bovis (i-RBC) accumulate lipids and show striking increases in phosphatidylcholine. phosphatidic acid, diacylglycerol and cholesteryl esters as compared to uninfected erythrocytes cultured under the same conditions (n-RBC). A similar pattern was observed in cultures of erythrocytes infected with Babesia bigemina. The lipid profile of purified B. bovis merozoites showed that phosphatidylcholine is the most abundant phospholipid in this parasite (31.8% +/- 2.8 of total phospholipid), markedly differing from bovine n-RBC, in which it is only a minor component (4.8% +/- 0.6). B. bovis cultures incorporate radiolabeled choline into complex lipids, especially phosphatidylcholine. with minor amounts recovered in sphingomyelin and lysophosphatidylcholine. When [C-14] stearate was used as precursor, the labeling pattern again gave the highest incorporation into phosphatidylcholine, with lesser incorporation in sphingomyelin, phosphatidylinositol, phosphatidylethanolamine and phosphatidic acid. Diacylglycerol and small amounts of cholesteryl esters were the only labeled neutral lipids found. B. bovis also incorporates [H-3] myo-inositol into phosphatidylinositol. Parallel incubations with n-RBC as a control yielded no incorporation into either polar or neutral lipids with ally precursor. These results indicate that the lipid changes observed in i-RBC can be explained on the basis of the lipid biosynthetic activities of the babesial parasite. Gas chromatography-mass spectrometry (GC-MS) analysis of fatty acid methyl esters from phospholipids of i-RBC and n-RBC showed the same qualitative composition in both. However. i-RBC had higher ratios of saturated to unsaturated fatty acids and B. bovis cultures did not desaturate [C-14] stearate. Cholesterol was the only sterol detected by GC-MS. Phospholipase A(2) treatment of i-RBC and n-RBC revealed no enhanced hemolytic effects in i-RBC, suggesting that the erythrocyte membrane phospholipid composition is essentially unaltered by the parasite. Labeling of i-RBC or n-RBC with [I-125] Bolton-Hunter resulted in an enhanced phosphatidylserine labeling in i-RBC. This study provides the first data on B, bovis lipid constitution and biosynthesis. They show that phosphatidylcholine formation is the main biosynthetic process in these cells. The striking differences in the contents of phosphatidylcholine between host erythrocytes and the parasite suggests that it may be a useful target for both chemotherapy and immunoprophylaxis against bovine babesiosis. (C) 2000 Elsevier Science B.V. All rights reserved.