Glycophorin as a Receptor for Escherichia coli α-hemolysin in erythrocytes
Glycophorin as a Receptor for Escherichia coli α-hemolysin in erythrocytes
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DOI：
10.1074/jbc.m006792200
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发表时间：
2001-04-20
影响因子：
4.8
通讯作者：
Ostolaza, H
中科院分区：
文献类型：
--
作者：
Cortajarena, AL;Goñi, FM;Ostolaza, H
大肠杆菌铜溶血素 (HlyA) 可以裂解红细胞 (RBC) 和脂质体，但细胞裂解时的 HlyA 浓度比脂质体（大单层囊泡）低 1-2 个数量级。用胰蛋白酶而不是胰凝乳蛋白酶处理红细胞，会降低红细胞对脂质体水平的 HlyA 的敏感性。由于血型糖蛋白（红细胞表面的主要蛋白质之一）比胰凝乳蛋白酶更容易被胰蛋白酶水解，因此测试了 HlyA 与血型糖蛋白特异性结合的可能性。为此目的，进行了许多实验。 (a) HlyA 与纯化的血型糖蛋白预孵育，之后发现它对红细胞和脂质体均无活性，(b) 用抗血型糖蛋白抗体处理红细胞可保护细胞免受 HlyA 裂解，(c) 固定化的 HlyA 能够结合存在于红细胞血影去污剂裂解液中的血型糖蛋白。 (d) 将血型糖蛋白掺入纯磷脂酰胆碱脂质体中，显着增加了囊泡对 HlyA 的敏感性。 (e) 用胰蛋白酶处理含有血型糖蛋白的脂质体，使囊泡恢复到原来的低敏感性。在 RBC 中，HlyA 亚溶解浓度下，HlyA 与血型糖蛋白的结合常数估计为 1.5 x 10(-9) M。
Escherichia coli cu-hemolysin (HlyA) can lyse both red blood cells (RBC) and liposomes, However, the cells are lysed at HlyA concentrations 1-2 orders of magnitude lower than liposomes (large unilamellar vesicles). Treatment of RBC with trypsin, but not with chymotrypsin, reduces the sensitivity of RBC toward HlyA to the level of the liposomes, Since glycophorin, one of the main proteins in the RBC surface, can be hydrolyzed by trypsin much more readily than by chymotrypsin, the possibility was tested of a specific binding of HlyA to glycophorin, With this purpose, a number of experiments were performed. (a) HlyA was preincubated with purified glycophorin, after which it was found to be inactive against both RBC and liposomes, (b) Treatment of RBC with an anti-glycophorin antibody protected the cells against HlyA lysis, (c) Immobilized HlyA was able to bind glycophorin present in a detergent lysate of RBC ghosts. (d) Incorporation of glycophorin into pure phosphatidylcholine liposomes increased notoriously the sensitivity of the vesicles toward HlyA (e) Treatment of the glycophorin-containing liposomes with trypsin reverted the vesicles to their original low sensitivity, The above results are interpreted in terms of glycophorin acting as a receptor for HlyA in RBC. The binding constant of HlyA for glycophorin was estimated, in RBC at sublytic HlyA concentrations, to be 1.5 x 10(-9) M.