Targeting of enteropathogenic Escherichia coli EspF to host mitochondria is essential for bacterial pathogenesis -: Critical role of the 16th leucine residue in EspF
Targeting of enteropathogenic Escherichia coli EspF to host mitochondria is essential for bacterial pathogenesis -: Critical role of the 16th leucine residue in EspF
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DOI：
10.1074/jbc.m411550200
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发表时间：
2005-01-28
影响因子：
4.8
通讯作者：
Sasakawa, C
中科院分区：
文献类型：
--
作者：
Nagai, T;Abe, A;Sasakawa, C
肠致病性大肠杆菌（EPEC）附着于宿主细胞并诱导附着和消退WE)病变是其显著的致病特征。EPEC感染还会导致宿主细胞死亡和肠黏膜损伤，这部分依赖于效应物之一的EspF。在这项研究中，我们证明了EspF是一种线粒体进口蛋白，具有功能性线粒体靶向信号（MTS），因为EspF进入线粒体的活性被MTS缺失突变体取消了。用谷氨酸取代第16亮氨酸（EspF(L16E)）完全消除了EspF活性。感染野生型而非突变型（DeltaespF）的HeLa细胞会降低线粒体膜电位（DeltaPsi(m)），导致细胞死亡。DeltaespF/pEsF感染细胞后，DeltaespF/pEspF（L16E）未恢复，而DeltaespF/pEspF(m)感染细胞后，DeltaPsi(m)下降，细胞死亡，提示MTS中的16亮氨酸是EspF功能的关键氨基酸。为了证明EspF在体内的影响，我们利用啮齿柠檬酸杆菌，用DeltaespF（CR）、DeltaespF(CR)/pEspF（CR）或DeltaespF(CR)/pEspF(L16E)（CR）感染C3H/HeJ小鼠。这些结果表明，从小鼠的致死率和肠道组织病理学角度来看，EspF活性有助于细菌的发病机制，并促进细菌在肠道黏膜的定植。
The attachment of enteropathogenic Escherichia coli (EPEC) to host cells and the induction of attaching and effacing WE) lesions are prominent pathogenic features. EPEC infection also leads to host cell death and damage to the intestinal mucosa, which is partly dependent upon EspF, one of the effectors. In this study, we demonstrate that EspF is a mitochondrial import protein with a functional mitochondrial targeting signal (MTS), because EspF activity for importing into the mitochondria was abrogated by MTS deletion mutants. Substitution of the 16th leucine with glutamic acid (EspF(L16E)) completely abolished EspF activity. Infection of HeLa cells with wild type but not the espF mutant (DeltaespF) decreased mitochondrial membrane potential (DeltaPsi(m)), leading to cell death. The DeltaPsi(m) decrease and cell death were restored in cells infected with DeltaespF/pEsF but not DeltaespF/pEspF(L16E), suggesting that the 16th leucine in the MTS is a critical amino acid for EspF function. To demonstrate the impact of EspF in vivo, we exploited Citrobacter rodentium by infecting C3H/HeJ mice with DeltaespF(CR), DeltaespF(CR)/pEspF(CR), or DeltaespF(CR)/pEspF(L16E)(CR). These results indicate that EspF activity contributes to bacterial pathogenesis, as judged by murine lethality and intestinal histopathology, and promotion of bacterial colonization of the intestinal mucosa.