NleH effectors interact with Bax inhibitor-1 to block apoptosis during enteropathogenic Escherichia coli infection
NleH effectors interact with Bax inhibitor-1 to block apoptosis during enteropathogenic Escherichia coli infection
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DOI：
10.1073/pnas.0911609106
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发表时间：
2010-02-16
影响因子：
11.1
通讯作者：
Frankel, Gad
中科院分区：
文献类型：
--
作者：
Hemrajani, Cordula;Berger, Cedric N.;Frankel, Gad
人类病原体肠致病性（EPEC）和肠出血性大肠杆菌以及相关的小鼠病原体啮齿柠檬酸杆菌（Citrobacter rodentium）通过其过多的III型分泌的效应子（包括触发早期凋亡反应）破坏多种宿主细胞信号传导途径。然而，EPEC感染的细胞不发展晚期凋亡症状。在这项研究中，我们表明，NleH家族效应，志贺氏菌效应激酶OspG的同系物，阻断细胞凋亡。在EPEC感染期间，NleH效应子抑制胞质Ca 2+浓度升高、核浓缩、半胱天冬酶-3活化和膜起泡，并促进细胞存活。单独的NleH 1足以防止由促凋亡化合物星形孢菌素、布雷菲德菌素A和衣霉素诱导的半胱天冬酶原-3切割。利用C.在啮齿动物中，我们发现NleH抑制体内细菌附着位点处的半胱氨酸天冬氨酸蛋白酶-3酶原切割。酵母双杂交筛选确定了内质网六跨膜蛋白Bax抑制剂-1（BI-1）作为NleH相互作用的伴侣。我们将NleH结合位点定位到BI-1的N-末端40个氨基酸。BI-1的敲低导致NleH的抗凋亡活性的丧失。这些结果表明，NleH效应物是细胞凋亡的抑制剂，其可以通过BI-1起作用以实现其细胞保护功能。
The human pathogens enteropathogenic (EPEC) and enterohemorrhagic Escherichia coli and the related mouse pathogen Citrobacter rodentium subvert a variety of host cell signaling pathways via their plethora of type III secreted effectors, including triggering of an early apoptotic response. EPEC-infected cells do not develop late apoptotic symptoms, however. In this study we demonstrate that the NleH family effectors, homologs of the Shigella effector kinase OspG, blocks apoptosis. During EPEC infection, NleH effectors inhibit elevation of cytosolic Ca2+ concentrations, nuclear condensation, caspase-3 activation, and membrane blebbing and promote cell survival. NleH1 alone is sufficient to prevent procaspase-3 cleavage induced by the proapoptotic compounds staurosporine, brefeldin A, and tunicamycin. Using C. rodentium, we found that NleH inhibits procaspase-3 cleavage at the bacterial attachment sites in vivo. A yeast two-hybrid screen identified the endoplasmic reticulum six-transmembrane protein Bax inhibitor-1 (BI-1) as an NleH-interacting partner. We mapped the NleH-binding site to the N-terminal 40 amino acids of BI-1. Knockdown of BI-1 resulted in the loss of NleH's antiapoptotic activity. These results indicate that NleH effectors are inhibitors of apoptosis that may act through BI-1 to carry out their cytoprotective function.