Molecular mechanisms of receptor recognition by Clostridium botulinum neurotoxins.

肉毒杆菌神经毒素受体识别的分子机制。

基本信息

批准号：
09660343
负责人：
KOZAKI Shunji
金额：
$ 2.43万
依托单位：
Osaka Prefecture University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09660343/
关键词：
Clostridium botulinum neurotoxin recptor synaptotagmin synaptobrevin ganglioside ボツリヌス毒素神経毒

项目摘要

Clostridium botulinum type B neurotoxin recognizes a complex of synaptotagmin II and ganglioside GTlb/GD1a as the high-affinity binding site. Recombinant deletion mutant of synaptotagmin II allowed us to demonstrate that the N-terminal domain including the transmembrane region retain the toxin binding activity while the C-terminal domain is not involved in constituting the toxin receptor. The direct binding of GTlb to the deletion mutants revealed that the transmembrane region is required to bind GTlb, suggesting that synaptotagmin II bind to the ceramide portion of ganglioside within the plasma membrane. Monoclonal antibody against GTlb effectively inhibited not only type B neurotoxin but also type A neurotoxin binding to brain synaptosomes. In addition, the monoclonal antibody antagonized the action of both neurotoxins on synaptic transmisstion of rat superior cervival ganglion neurons. They suggest that GTlb functions as a component of the receptor complex.The neurotoxin of the strain associated with type B infant botulism showed antigenic and biological properties different from that of food-borne botulism-related strain. The neurotoxin derived from infant botulism was found to possess a toxicity 10 times lower than that of the authentic neurotoxin. However, synaptobrevin, an intracellular target protein, was digested to the same extent by both neurotoxins. Therefore, we concluded that such low toxicity of infant botulism-related neurotoxin is attributed to the receptor-recognition site in the molecule.

B 型肉毒梭菌神经毒素将突触结合蛋白 II 和神经节苷脂 GT1b/GD1a 的复合物识别为高亲和力结合位点。突触结合蛋白 II 的重组缺失突变体使我们能够证明，包括跨膜区的 N 端结构域保留了毒素结合活性，而 C 端结构域不参与毒素受体的构成。 GT1b与缺失突变体的直接结合揭示了结合GT1b需要跨膜区域，这表明突触结合蛋白II与质膜内神经节苷脂的神经酰胺部分结合。针对GT1b的单克隆抗体不仅有效抑制B型神经毒素，而且还有效抑制A型神经毒素与脑突触体的结合。此外，单克隆抗体拮抗两种神经毒素对大鼠颈上神经节神经元突触传递的作用。他们认为GTlb作为受体复合物的一个组成部分起作用。与B型婴儿肉毒杆菌中毒相关的菌株的神经毒素表现出与食源性肉毒杆菌中毒相关菌株不同的抗原和生物学特性。研究发现，源自婴儿肉毒杆菌中毒的神经毒素的毒性比真正的神经毒素低 10 倍。然而，突触短蛋白（一种细胞内靶蛋白）被两种神经毒素消化的程度相同。因此，我们得出结论，婴儿肉毒杆菌相关神经毒素的低毒性归因于分子中的受体识别位点。