Role of Ca2+-binding motif in cytotoxicity induced by Clostridium perfringens iota-toxin
Role of Ca2+-binding motif in cytotoxicity induced by Clostridium perfringens iota-toxin
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DOI：
10.1016/j.micpath.2007.10.010
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发表时间：
2008-04-01
影响因子：
3.8
通讯作者：
Sakurai, Jun
中科院分区：
文献类型：
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作者：
Kobayashi, Keiko;Nagahama, Masahiro;Sakurai, Jun
产气荚膜梭菌I毒素是由酶组分（Ia）和结合组分（Ib）组成的二元毒素。我们研究了Ib的保守的Ca 2+结合基序在I毒素的细胞毒性中的作用。随着细胞外Ca ~（2+）浓度的增加，毒素的细胞毒性增强。表面等离子体共振分析表明，la与lb的寡聚体的结合依赖于Ca 2+的浓度。然而，Ca ~（2+）的加入对I-125标记的Ib与细胞的结合没有影响。我们用丙氨酸替换Ib的Ca 2+结合基序中的Asp-8、-10和-12。D8 A、D10 A和D12 A与细胞结合并在野生型Ib的约一半处形成寡聚体。在Ia存在下，Ib变体的细胞毒性比野生型Ib的细胞毒性小约500倍。免疫荧光研究表明，这些变异体像野生型Ib一样内化于早期内体。然而，野生型Ib诱导Ia在细胞中的内化，但这些变体没有。结果表明，在Ca ~（2+）存在下，lb的N端区域的保守的Ca ~（2+）结合基序在lb与la的相互作用中起作用。(C)2007爱思唯尔有限公司保留所有权利。
Clostridium perfringens iota-toxin is a binary toxin composed of an enzymatic component (Ia) and a binding component (Ib). We investigated the role of the conserved Ca2+-binding motif of lb in the cytotoxicity of iota-toxin. The cytotoxicity of iota-toxin increased with all increase in the concentration of extracellular Ca2+. A surface plasnion resonance analysis showed that the binding of la to the oligomer of lb is dependent oil the concentration of Ca2+. However, the addition of Ca2+ had no effect on the binding of I-125-labeled lb to the cells. We replaced Asp-8, -10, and -12 in the Ca2+-binding motif of lb with alanine. D8A, D10A, and D12A bound to the cell and formed an oligomer at about half of the wild-type lb. The cytotoxicity of lb variants in the presence of la was about 500-fold less than that of wild-type lb. Immunofluorescence Study showed that these variants were internalized in the early endosomes like wild-type Ib. However, wild-type Ib-induced internalization of Ia in the cells, but these variants did not. The result indicates that the conserved Ca2+-binding motif in the N-terminal region of lb plays a role in the interaction of lb with la in the presence of Ca2+. (C) 2007 Elsevier Ltd. All rights reserved.