Wnek A P, McClane B A
Department of Microbiology, University of Pittsburgh, School of Medicine, Pennsylvania 15261.
Microb Pathog. 1986 Feb;1(1):89-100. doi: 10.1016/0882-4010(86)90035-5.
The rabbit intestinal brush border membrane (BBM) receptors for Clostridium perfringens type A (CPE) and cholera (CT) enterotoxins were compared. Initial studies characterized binding of 125I-CPE to isolated BBMs as specific, saturable, and irreversible. BBMs appear to contain a single type of CPE binding site. Protease pretreatment of BBMs strongly reduced subsequent specific binding of 125I-CPE but not 125I-CT, while neuraminidase pretreatment had little effect on binding of either enterotoxin. Proteases did not significantly release pre-bound 125I-CPE. Preincubation of CPE with an affinity-purified preparation containing a previously identified (Biochem. Biophys. Res. Commun. 112, 1099-105) CPE-binding protein resulted in reduced specific binding of 125I-CPE and an inhibition of CPE biologic activity. Similar experiments showed that CPE-binding protein had no effect on CT binding or biologic activity. Gangliosides had no significant effect on specific binding or biologic activity of CPE but reduced CT binding and biologic activity. Lipids, including gangliosides, separated by thin layer chromatography specifically bound CT but not CPE. Preincubation of BBMs with CT did not reduce subsequent binding of 125I-CPE; conversely, prebound CPE did not affect subsequent 125I-CT binding. These results strongly suggest that CPE does not share the CT BBM receptor ganglioside GM1, and support a role for the CPE-binding protein in CPE binding.
对A型产气荚膜梭菌（CPE）和霍乱（CT）肠毒素的兔肠刷状缘膜（BBM）受体进行了比较。初步研究表明，125I-CPE与分离的BBM的结合具有特异性、可饱和性和不可逆性。BBM似乎含有单一类型的CPE结合位点。用蛋白酶预处理BBM可显著降低随后125I-CPE的特异性结合，但不影响125I-CT的结合，而用神经氨酸酶预处理对两种肠毒素的结合影响不大。蛋白酶不会显著释放预先结合的125I-CPE。将CPE与含有先前鉴定的（《生物化学与生物物理研究通讯》112, 1099 - 105）CPE结合蛋白的亲和纯化制剂预孵育，会导致125I-CPE的特异性结合减少，并抑制CPE的生物活性。类似的实验表明，CPE结合蛋白对CT的结合或生物活性没有影响。神经节苷脂对CPE的特异性结合或生物活性没有显著影响，但会降低CT的结合和生物活性。通过薄层色谱分离的脂质，包括神经节苷脂，特异性结合CT但不结合CPE。用CT预孵育BBM不会降低随后125I-CPE的结合；相反，预先结合的CPE不会影响随后125I-CT的结合。这些结果强烈表明，CPE不共享CT的BBM受体神经节苷脂GM1，并支持CPE结合蛋白在CPE结合中的作用。
