SrfABC Toxin from Xenorhabdus stockiae Induces Cytotoxicity and Apoptosis in HeLa Cells
SrfABC Toxin from Xenorhabdus stockiae Induces Cytotoxicity and Apoptosis in HeLa Cells
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DOI：
10.3390/toxins11120685
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发表时间：
2019-11
期刊：
影响因子：
4.2
通讯作者：
Yawei Sun;Guoyong Zhang;Xiaoqing Hou;Shuai Xiao;Xi Yang;Yali Xie;Xiyin Huang;Fan Wang;Xiangtao Mo;Xuezhi Ding;L. Xia;Shengbiao Hu
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文献类型：
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作者：
Yawei Sun;Guoyong Zhang;Xiaoqing Hou;Shuai Xiao;Xi Yang;Yali Xie;Xiyin Huang;Fan Wang;Xiangtao Mo;Xuezhi Ding;L. Xia;Shengbiao Hu
我们之前的研究表明，srfABC操纵子最初在肠沙门氏菌中被鉴定为ssrb调控的与鞭毛2类操纵子聚集在一起的操纵子，对昆虫中肠CF-203细胞具有显著的细胞毒性，对棉铃虫幼虫具有可注射的杀虫活性。srfABC操纵子在细菌中广泛分布，这就提出了其在不同物种中的生物学作用问题。在本研究中，我们研究了SrfABC毒素对哺乳动物细胞系的细胞毒性作用。当在大肠杆菌细胞质中同时表达时，SrfABC对所有测试的哺乳动物癌细胞系（B16, 4T-1， Hep-3B和HeLa）表现出剂量依赖性的细胞毒性。细胞内表达SrfA-FLAG、SrfB-FLAG或SrfC-FLAG也能抑制HeLa细胞的增殖和凋亡。与HeLa细胞单独孵育时，SrfA、SrfB和SrfC蛋白可单独进入HeLa细胞，诱导细胞凋亡和细胞毒性。SrfC蛋白在SrfA和/或SrfB蛋白的帮助下从细胞质转移到细胞核。虽然SrfA、SrfB和SrfC蛋白单独表现出对HeLa细胞的细胞毒性作用，但这三种成分都是完全细胞毒性所必需的。天然PAGE和共免疫沉淀实验表明，SrfA、SrfB和SrfC蛋白可以相互作用，形成异质复合物。
Our previous study showed that the srfABC operon, which was originally identified in Salmonella enterica as an SsrB-regulated operon clustered with the flagellar class 2 operon, exhibited significant cytotoxicity against insect midgut CF-203 cells and injectable insecticidal activity against Helicoverpa armigera larvae. The srfABC operon was widely distributed among bacteria, which raises the question of their biological roles in different species. In this study, we investigated the cytotoxic effect of SrfABC toxin on mammalian cell lines. When simultaneously expressed in the Escherichia coli cytoplasm, SrfABC exhibited cytotoxicity against all tested mammalian cancer cell lines (B16, 4T-1, Hep-3B, and HeLa) in a dose-dependent manner. Intracellular expression of SrfA–FLAG, SrfB–FLAG, or SrfC–FLAG also resulted in inhibition of proliferation and apoptosis on HeLa cells. When incubated with HeLa cells separately, SrfA, SrfB, and SrfC proteins alone could enter HeLa cells, then induce apoptosis and cytotoxicity. SrfC protein shifts its localization from cytoplasm to nucleus with the aid of SrfA and/or SrfB protein. Although SrfA, SrfB, and SrfC proteins alone exhibited a cytotoxic effect against HeLa cells, all three components were essential for the full cytotoxicity. Native PAGE and co-immunoprecipitation assay demonstrated that SrfA, SrfB, and SrfC proteins could interact with each other and form a heteromeric complex.