EPEC Recruits a Cdc42-Specific GEF, Frabin, To Facilitate PAK Activation and Host Cell Colonization.
EPEC Recruits a Cdc42-Specific GEF, Frabin, To Facilitate PAK Activation and Host Cell Colonization.
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DOI：
10.1128/mbio.01423-20
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发表时间：
2020-11-03
期刊：
影响因子：
6.4
通讯作者：
Koronakis V
中科院分区：
文献类型：
--
作者：
Singh V;Hume PJ;Davidson A;Koronakis V
肠致病性大肠杆菌（EPEC）是儿童腹泻的主要原因，特别是在发展中国家。EPEC通过附着于宿主肠道中的细胞来启动感染，触发在粘附病原体正下方形成富含肌动蛋白的“基座”结构。这些细菌将它们自己的受体注入宿主细胞，受体与病原体表面的蛋白质结合后触发基座形成。多种其他蛋白质也被递送到宿主肠道的细胞中，它们共同作用以劫持宿主信号传导途径来驱动基座产生。在这里，我们展示了EPEC如何劫持宿主蛋白Frabin，它在细胞中创造了病原体操纵促进基座形成的特定途径所必需的条件。这为EPEC引起的疾病的这一重要早期阶段提供了新的见解。肠致病性大肠杆菌（EPEC）是一种胞外病原体，通过在细菌下方形成“肌动蛋白纤维”而紧密粘附于宿主细胞，这是致病的关键步骤。EPEC注射操纵宿主细胞信号级联的效应蛋白以触发基座组装。我们最近已经表明，这样的效应，EspG，劫持p21激活激酶（PAK），并维持其激活状态，以驱动必要的病原体附着到靶细胞的细胞骨架变化。这种PAK的EspG颠覆需要宿主细胞中的活性Rho家族小GTP酶。在这里，我们表明，EPEC本身促进激活Rho GTPases通过招募Frabin，宿主鸟嘌呤核苷酸交换因子（GEF）的Rho GTPases Cdc 42。没有Frabin的细胞表现出显著较低的EPEC诱导的PAK激活，基座形成和细菌附着。Frabin募集到EPEC附着位点是由EspG驱动的，并且需要磷脂酰肌醇4，5-二磷酸（PIP 2）和宿主Arf 6的局部富集。我们的研究结果确定Frabin作为EPEC的关键目标，以确保肌动蛋白基座形成所需的细胞GTP酶的激活状态。
Enteropathogenic Escherichia coli (EPEC) is a leading cause of diarrhea in children, especially in the developing world. EPEC initiates infection by attaching to cells in the host intestine, triggering the formation of actin-rich “pedestal” structures directly beneath the adherent pathogen. These bacteria inject their own receptor into host cells, which upon binding to a protein on the pathogen surface triggers pedestal formation. Multiple other proteins are also delivered into the cells of the host intestine, which work together to hijack host signaling pathways to drive pedestal production. Here we show how EPEC hijacks a host protein, Frabin, which creates the conditions in the cell necessary for the pathogen to manipulate a specific pathway that promotes pedestal formation. This provides new insights into this essential early stage in disease caused by EPEC. Enteropathogenic Escherichia coli (EPEC) is an extracellular pathogen that tightly adheres to host cells by forming “actin pedestals” beneath the bacteria, a critical step in pathogenesis. EPEC injects effector proteins that manipulate host cell signaling cascades to trigger pedestal assembly. We have recently shown that one such effector, EspG, hijacks p21-activated kinase (PAK) and sustains its activated state to drive the cytoskeletal changes necessary for attachment of the pathogen to target cells. This EspG subversion of PAK required active Rho family small GTPases in the host cell. Here we show that EPEC itself promotes the activation of Rho GTPases by recruiting Frabin, a host guanine nucleotide exchange factor (GEF) for the Rho GTPase Cdc42. Cells devoid of Frabin showed significantly lower EPEC-induced PAK activation, pedestal formation, and bacterial attachment. Frabin recruitment to sites of EPEC attachment was driven by EspG and required localized enrichment of phosphatidylinositol 4,5-bisphosphate (PIP2) and host Arf6. Our findings identify Frabin as a key target for EPEC to ensure the activation status of cellular GTPases required for actin pedestal formation.