The p21 Rho-activating toxin cytotoxic necrotizing factor 1 is endocytosed by a clathrin-independent mechanism and enters the cytosol by an acidic-dependent membrane translocation step
The p21 Rho-activating toxin cytotoxic necrotizing factor 1 is endocytosed by a clathrin-independent mechanism and enters the cytosol by an acidic-dependent membrane translocation step
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DOI：
10.1091/mbc.11.5.1775
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发表时间：
2000-05-01
影响因子：
3.3
通讯作者：
Boquet, P
中科院分区：
文献类型：
--
作者：
Contamin, S;Galmiche, A;Boquet, P
细胞毒性坏死因子1（CNF 1）是由大肠杆菌致病菌株产生的蛋白质，其激活p21 Rho-GTP结合蛋白，诱导肌动蛋白细胞骨架的深刻重组。CNF 1以高亲和力（Kd = 20 pM）结合HEp-2细胞上的其细胞表面受体。在HEp-2细胞中，CNF 1的作用在菲律宾肽存在下不被阻断，菲律宾肽是一种被描述为通过小窝样机制减少霍乱毒素内化的药物。此外，HEp-2细胞，其表达的蛋白质的显性负性形式，损害网格蛋白包被的囊泡的形成和转铁蛋白的内化（Eps 15，发动蛋白或interstin-Src同源性3），仍然是敏感的CNF 1。在这方面，CNF 1的内吞作用类似于植物毒素蓖麻毒素。然而，与蓖麻毒素不同，CNF 1不穿过高尔基体，并且需要酸性细胞区室以类似于白喉毒素所需的方式将其酶活性转移到胞质溶胶中。如白喉毒素所示，CNF 1的pH依赖性膜易位步骤可以通过短暂暴露于小于或等于5.2的FH在质膜水平上模拟。CNF 1是第一个描述的细菌毒素，其在将催化结构域递送至细胞胞质溶胶中使用网格蛋白非依赖性内吞机制和酸依赖性膜转位步骤。
Cytotoxic necrotizing factor 1 (CNF1), a protein produced by pathogenic strains of Escherichia coli, activates the p21 Rho-GTP-binding protein, inducing a profound reorganization of the actin cytoskeleton. CNF1 binds to its cell surface receptor on HEp-2 cells with high affinity (K-d = 20 pM). In HEp-2 cells the action of CNF1 is not blocked in the presence of filipin, a drug described to reduce cholera toxin internalization by the caveolae-like mechanism. Moreover, HEp-2 cells, which express a dominant negative form of proteins that impair the formation of clathrin coated-vesicles and internalization of transferrin (Eps15, dynamin or intersectin-Src homology 3), are still sensitive to CNF1. In this respect, the endocytosis of CNF1 is similar to the plant toxin ricin. However, unlike ricin toxin, CNF1 does not cross the Golgi apparatus and requires an acidic cell compartment to transfer its enzymatic activity into the cytosol in a manner similar to that required by diyhtheria toxin. As shown for diphtheria toxin, the pH-dependent membrane translocation step of CNF1 could be mimicked at the level of the plasma membrane by a brief exposure to a FH of less than or equal to 5.2. CNF1 is the first bacterial toxin described that uses both a clathrin-independent endocytic mechanism and an acidic-dependent membrane translocation step in its delivery of the catalytic domain to the cell cytosol.