EseE of Edwardsiella tarda Augments Secretion of Translocon Protein EseC and Expression of the escC-eseE Operon
EseE of Edwardsiella tarda Augments Secretion of Translocon Protein EseC and Expression of the escC-eseE Operon
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DOI：
10.1128/iai.00106-16
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发表时间：
2016-06
影响因子：
3.1
通讯作者：
Jia Yi;Shui Bing Xiao;Zhifeng Zeng;Jin-Fang Lu;Lu Yi Liu;Z. A. Laghari;P. Nie;H. Yu;H. Xie
中科院分区：
文献类型：
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作者：
Jia Yi;Shui Bing Xiao;Zhifeng Zeng;Jin-Fang Lu;Lu Yi Liu;Z. A. Laghari;P. Nie;H. Yu;H. Xie
摘要迟缓爱德华氏菌是一种重要的革兰氏阴性病原菌，它利用III型分泌系统（T3 SS）将效应子递送到宿主细胞中以促进细菌的存活和复制。这些效应子通过由三种分泌蛋白质（即EseB、EseC和EseD）组成的易位子复合物易位到宿主细胞中。EseB和EseD的分泌需要称为EscC的伴侣蛋白，而EseC的分泌需要伴侣EscA。在这项研究中，我们确定了一种新的蛋白质（EseE），也调节EseC的分泌。eseE缺失突变体分泌更少的EseC到上清液中，伴随着细菌细胞内EseC水平的增加。我们还证明了EseE直接与EseC在下拉测定中相互作用。有趣的是，EseC，EseE和EscA能够形成三元复合物，如下拉和凝胶过滤试验所示。特别重要的是，eseE的缺失导致细菌沉淀物和上清液级分中EseB和EseD蛋白的水平降低。此外，实时荧光定量PCR分析表明，EseE正调控的translocon操纵子escC-eseE，包括escC，eseB，escA，eseC，eseD，和eseE的转录。EseE对转座子组分/操纵子的这些作用似乎具有功能性后果，因为ΔeseE菌株被野生型E胜过。蓝鲈混合感染中的迟发性。总之，我们的研究结果表明，EseE不仅作为EseC的伴侣，但也作为一个积极的调节器控制的易位子操纵子escC-eseE的表达，从而有助于E的发病机制。鱼中的迟缓
ABSTRACT Edwardsiella tarda is an important Gram-negative pathogen that employs a type III secretion system (T3SS) to deliver effectors into host cells to facilitate bacterial survival and replication. These effectors are translocated into host cells through a translocon complex composed of three secreted proteins, namely, EseB, EseC, and EseD. The secretion of EseB and EseD requires a chaperone protein called EscC, whereas the secretion of EseC requires the chaperone EscA. In this study, we identified a novel protein (EseE) that also regulates the secretion of EseC. An eseE deletion mutant secreted much less EseC into supernatants, accompanied by increased EseC levels within bacterial cells. We also demonstrated that EseE interacted directly with EseC in a pulldown assay. Interestingly, EseC, EseE, and EscA were able to form a ternary complex, as revealed by pulldown and gel filtration assays. Of particular importance, the deletion of eseE resulted in decreased levels of EseB and EseD proteins in both the bacterial pellet and supernatant fraction. Furthermore, real-time PCR assays showed that EseE positively regulated the transcription of the translocon operon escC-eseE, comprising escC, eseB, escA, eseC, eseD, and eseE. These effects of EseE on the translocon components/operon appeared to have a functional consequence, since the ΔeseE strain was outcompeted by wild-type E. tarda in a mixed infection in blue gourami fish. Collectively, our results demonstrate that EseE not only functions as a chaperone for EseC but also acts as a positive regulator controlling the expression of the translocon operon escC-eseE, thus contributing to the pathogenesis of E. tarda in fish.