Interaction of tetanus toxin with lipid vesicles at low pH. Protection of specific polypeptides against proteolysis.
Interaction of tetanus toxin with lipid vesicles at low pH. Protection of specific polypeptides against proteolysis.
复制标题
低 pH 条件下破伤风毒素与脂质囊泡的相互作用。
DOI：
10.1016/s0021-9258(18)88855-x
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
P. Boquet
中科院分区：
文献类型：
--
作者：
M. Roa;P. Boquet
两个主要的多肽，Mr约27，000和21，000，保护胃蛋白酶蛋白水解时，asolectin囊泡和125 I标记的破伤风毒素组成的混合物进行pH值从7.2下降到3.0。用毒素的氨基末端部分（称为片段B）获得了相同的结果。发现这些多肽在以下条件下不受保护：（i）当从混合物中省略囊泡时;（ii）当囊泡的外部pH保持在7.2并且胰蛋白酶用作蛋白水解剂时;以及（iii）当囊泡在加入毒素之前或之后破裂时。通过特异性免疫沉淀，我们鉴定了保护的多肽作为破伤风毒素的中心片段的一部分。此外，一个15.5 kDa的多肽，属于毒素片段C，被证明是特别耐消化的各种蛋白酶，即使在没有脂质囊泡。基于这些发现，我们提出了一个模型的破伤风毒素进入其靶细胞。
Two main polypeptides, Mr about 27,000 and 21,000, were protected against pepsin proteolysis when a mixture consisting of asolectin vesicles and 125I-labeled tetanus toxin was subjected to a pH drop from 7.2 to 3.0. The same result was obtained with the amino-terminal portion of the toxin (called fragment B). These polypeptides were not found to be protected in the following conditions: (i) when vesicles were omitted from the mixture; (ii) when the external pH of the vesicles was maintained at 7.2 and trypsin was used as a proteolytic agent; and (iii) when the vesicles were ruptured either before or after addition of the toxin. By specific immunoprecipitation, we identified the protected polypeptides as part of the central fragment of tetanus toxin. In addition, a 15.5-kDa polypeptide, belonging to toxin fragment C, was shown to be particularly resistant to digestion by various proteases, even in the absence of lipid vesicles. Based on these findings, we propose a model for entry of tetanus toxin into its target cells.