Modulation of host cytoskeleton function by the enteropathogenic Escherichia coli and Citrobacter rodentium effector protein EspG
Modulation of host cytoskeleton function by the enteropathogenic Escherichia coli and Citrobacter rodentium effector protein EspG
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DOI：
10.1128/iai.73.5.2586-2594.2005
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发表时间：
2005-05-01
影响因子：
3.1
通讯作者：
Finlay, BB
中科院分区：
文献类型：
--
作者：
Hardwidge, PR;Deng, WY;Finlay, BB
EspG 是一种保守蛋白，由附着和消除 (A/E) 病原体（包括致病性和肠出血性大肠杆菌和啮齿类柠檬酸杆菌）的肠细胞消除 (LEE) 基因座编码。 EspG 通过 III 型分泌系统递送到受感染的宿主细胞中。 EspG 在毒力中的作用尚未明确。在这里，我们描述了探测 EspG 体外和体内毒力特征和生物活性的实验。啮齿类 C. rodentium espG 突变体表现出定植 C57BL/6 小鼠和引起结肠增生的能力显着降低。在受感染小鼠受感染结肠上皮细胞的顶端区域检测到带有表位标记的 EspG，部分定位于另一种 LEE 编码的效应蛋白 Tir。在遗传筛选和凝胶覆盖测定中发现 EspG 与哺乳动物微管蛋白相互作用。 EspG 与微管蛋白的结合引起局部微管解聚，通过未明确的机制导致肌动蛋白应力纤维形成。 EspG在酵母中的异源表达导致细胞质微管结构和功能的丧失，阻碍芽发育和核分裂之间的协调。表达 EspG 的酵母也无法控制皮质肌动蛋白极性。我们认为，EspG 有助于 A/E 病原体通过调节宿主细胞骨架建立感染的能力，涉及瞬时微管破坏和肌动蛋白聚合，其方式类似于福氏志贺菌 VirA 蛋白。
EspG is a conserved protein encoded by the locus of enterocyte effacement (LEE) of attaching and effacing (A/E) pathogens, including enteropathogenic and enterohemorrhagic Escherichia coli and Citrobacter rodentium. EspG is delivered into infected host cells by a type III secretion system. The role of EspG in virulence has not yet been defined. Here we describe experiments that probe the virulence characteristics and biological activities of EspG in vitro and in vivo. A C. rodentium espG mutant displayed a significantly reduced ability to colonize C57BL/6 mice and to cause colonic hyperplasia. Epitope-tagged EspG was detected in the apical regions of infected colonic epithelial cells in infected mice, partially localizing with another LEE-encoded effector protein, Tir. EspG was found to interact with mammalian tubullin in both genetic screens and gel overlay assays. Binding to tubulin by EspG caused localized microtubule depolymerization, resulting in actin stress fiber formation through an undefined mechanism. Heterologous expression of EspG in yeast resulted in loss of cytoplasmic microtubule structure and function, preventing coordination between bud development and nuclear division. Yeast expressing EspG were also unable to control cortical actin polarity. We suggest that EspG contributes to the ability of A/E pathogens to establish infection through a modulation of the host cytoskeleton involving transient microtubule destruction and actin polymerization in a manner akin to the Shigella flexneri VirA protein.