The C terminus of component C2II of Clostridium botulinum C2 toxin is essential for receptor binding
The C terminus of component C2II of Clostridium botulinum C2 toxin is essential for receptor binding
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DOI：
10.1128/iai.68.8.4566-4573.2000
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发表时间：
2000-08-01
影响因子：
3.1
通讯作者：
Aktories, K
中科院分区：
文献类型：
--
作者：
Blöcker, D;Barth, H;Aktories, K
二元肉毒梭菌C2毒素由两种单独的蛋白质组成，即结合组分C2 II（80.5 kDa）和肌动蛋白-ADP-核糖基化酶组分C2 I（49.4 kDa）。对于其细胞毒性作用，C2 II结合细胞膜受体并通过受体介导的内吞作用诱导C2 I进入细胞。本研究通过构建C2 Ⅱ截短蛋白并制备抗C2 Ⅱ选择性区域的多克隆抗体，研究了C2 Ⅱ的结构与功能的关系。针对C2 II的C末端（氨基酸592至721）产生的抗体抑制C2 II与细胞的结合。该抗体阻止了人工膜中C2 II低聚物的孔形成，但不影响现有通道的特性。为了进一步确定负责受体结合的区域，我们构建了C2 II缺失的蛋白质;具体而言，它们缺乏氨基酸残基592至721和7个C末端氨基酸残基。截短的蛋白质仍然形成十二烷基硫酸钠稳定的寡聚体，但不能结合细胞。我们的数据表明，C末端的C2 II介导的蛋白质结合细胞和7个C-末端的氨基酸是结构上重要的受体结合。
The binary Clostridium botulinum C2 toxin consists of two separate proteins, the binding component C2II (80.5 kDa) and the actin-ADP-ribosylating enzyme component C2I (49.4 kDa). For its cytotoxic action, C2II binds to a cell membrane receptor and induces cell entry of C2I via receptor-mediated endocytosis. Here we studied the structure-function relationship of C2II by constructing truncated C2II proteins and producing polyclonal antisera against selective regions of C2II. An antibody raised against the C terminus (amino acids 592 to 721) of C2II inhibited binding of C2II to cells. The antibody prevented pore formation by C2II oligomers in artificial membranes but did not influence the properties of existing channels. To further define the region responsible for receptor binding, we constructed proteins with deletions in C2II; specifically, they lacked amino acid residues 592 to 721 and the 7 C-terminal amino acid residues. The truncated proteins still formed sodium dodecyl sulfate-stable oligomers but were unable to bind to cells. Our data indicate that the C terminus of C2II mediates binding of the protein to cells and that the 7 C-terminal amino acids are structurally important for receptor binding.