Molecular mimicry by an F-box effector of Legionella pneumophila hijacks a conserved polyubiquitination machinery within macrophages and protozoa.
Molecular mimicry by an F-box effector of Legionella pneumophila hijacks a conserved polyubiquitination machinery within macrophages and protozoa.
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DOI：
10.1371/journal.ppat.1000704
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发表时间：
2009-12
期刊：
影响因子：
6.7
通讯作者：
Kwaik YA
中科院分区：
文献类型：
--
作者：
Price CT;Al-Khodor S;Al-Quadan T;Santic M;Habyarimana F;Kalia A;Kwaik YA
嗜肺军团菌在水环境中的各种原生动物和巨噬细胞中的增殖能力表明，进化保守的真核过程是一种显着的进化和微生物利用。嗜肺乳杆菌Ankyrin B(AnkB)是一种非典型的F-box蛋白，是嗜肺乳杆菌唯一已知的Dot/ICM易位效应因子，对巨噬细胞和原生动物宿主的空泡内增殖是必不可少的。我们发现AnkB的F-box结构域和9L10P保守残基对于细菌在细胞内的增殖和巨噬细胞、盘基网柄菌和棘阿米巴中含有军团菌的空泡(LCV)快速获得多泛素化蛋白是必不可少的。有趣的是，AnkB的易位和多泛素化蛋白在巨噬细胞和棘阿米巴中的募集在细菌附着的5分钟内迅速被胞外细菌触发。在哺乳动物细胞内异位表达的AnkB定位于细胞外围，在那里它与宿主Skp1共定位并招募多泛素化蛋白，这导致与亲本菌株相似的ankB突变体恢复细胞内生长。虽然异位表达的AnkB-9L10P/AA突变体定位于细胞外周，但它不招募多泛素蛋白，也无法反式挽救ankB突变的细胞内生长缺陷。AnkB而不是AnkB-9L10P/AA变异体与宿主Skp1在体内直接相互作用。重要的是，RNAi介导的Skp1表达沉默使得细胞不允许嗜肺乳杆菌在细胞内增殖。AnkB在开发多泛素化机制中的作用对于军团病小鼠模型中肺内细菌的增殖至关重要。因此，AnkB展示了一种新的真核生物F-box蛋白的分子和功能模拟，它利用保守的多泛素化机制在进化上遥远的宿主内进行细胞内增殖。嗜肺军团菌大量存在于水环境中的各种原生动物中，当它入侵肺部的人类巨噬细胞时，会引起一种名为军团病的严重肺炎。嗜肺乳杆菌在巨噬细胞和原生动物体内入侵和增殖的能力依赖于特定的蛋白质通过特殊的分泌装置转移到入侵的细胞中，这些蛋白质调节各种宿主细胞的过程。在这些转位蛋白中，AnkB对于嗜肺乳杆菌在巨噬细胞和原生动物中的细胞内生长是不可或缺的。在这里，我们证明了AnkB对于建立一个良好的细胞内复制生态位是必不可少的，它通过促进多泛素化蛋白对含有军团菌的空泡(LCV)的装饰来建立良好的细胞内复制生态位。AnkB效应器通过模拟宿主细胞F-box蛋白的作用实现这一点，F-box蛋白是SCF泛素连接酶复合体的一个高度保守的成分，在单细胞生物体和哺乳动物细胞中都存在。我们的研究为细胞内病原体通过分子模仿劫持进化保守的宿主细胞过程，在各种宿主中建立有利的复制生态位并导致哺乳动物疾病的能力提供了新的见解。
The ability of Legionella pneumophila to proliferate within various protozoa in the aquatic environment and in macrophages indicates a remarkable evolution and microbial exploitation of evolutionarily conserved eukaryotic processes. Ankyrin B (AnkB) of L. pneumophila is a non-canonical F-box-containing protein, and is the only known Dot/Icm-translocated effector of L. pneumophila essential for intra-vacuolar proliferation within both macrophages and protozoan hosts. We show that the F-box domain of AnkB and the 9L10P conserved residues are essential for intracellular bacterial proliferation and for rapid acquisition of polyubiquitinated proteins by the Legionella-containing vacuole (LCV) within macrophages, Dictyostelium discoideum, and Acanthamoeba. Interestingly, translocation of AnkB and recruitment of polyubiquitinated proteins in macrophages and Acanthamoeba is rapidly triggered by extracellular bacteria within 5 min of bacterial attachment. Ectopically expressed AnkB within mammalian cells is localized to the periphery of the cell where it co-localizes with host SKP1 and recruits polyubiquitinated proteins, which results in restoration of intracellular growth to the ankB mutant similar to the parental strain. While an ectopically expressed AnkB-9L10P/AA variant is localized to the cell periphery, it does not recruit polyubiquitinated proteins and fails to trans-rescue the ankB mutant intracellular growth defect. Direct in vivo interaction of AnkB but not the AnkB-9L10P/AA variant with the host SKP1 is demonstrated. Importantly, RNAi-mediated silencing of expression of SKP1 renders the cells non-permissive for intracellular proliferation of L. pneumophila. The role of AnkB in exploitation of the polyubiquitination machinery is essential for intrapulmonary bacterial proliferation in the mouse model of Legionnaires' disease. Therefore, AnkB exhibits a novel molecular and functional mimicry of eukaryotic F-box proteins that exploits conserved polyubiquitination machinery for intracellular proliferation within evolutionarily distant hosts. Legionella pneumophila is abundantly found in the aquatic environment within various protozoa and can cause a severe pneumonia called Legionnaires' disease when it invades human macrophages in the lung. The ability of L. pneumophila to invade and proliferate within macrophages and protozoa is dependent on the translocation of specific proteins into the invaded cell via a specialized secretory device, and these proteins modulate various host cell processes. Of these translocated proteins, AnkB is indispensable for intracellular growth of L. pneumophila within macrophages and protozoa. Here we show that AnkB is essential for establishing a favorable intracellular replicative niche by promoting the decoration of the Legionella containing vacuole (LCV) with polyubiquitinated proteins. The AnkB effector achieves this by mimicking the action of host cell F-box proteins, a highly conserved component of the SCF ubiquitin ligase complex that is found in both unicellular organisms and mammalian cells. Our study provides new insights into the ability of intracellular pathogens to hijack evolutionarily conserved host cell processes through molecular mimicry to establish a favorable replicative niche within various hosts and to cause disease in mammals.
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影响因子：
7.8
作者：
Russell, ID;Grancell, AS;Sorger, PK
通讯作者：
Sorger, PK
影响因子：
3.6
作者：
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影响因子：
10.5
作者：
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通讯作者：
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影响因子：
3.6
作者：
Al-Khodor S;Price CT;Habyarimana F;Kalia A;Abu Kwaik Y
通讯作者：
Abu Kwaik Y
影响因子：
6.7
作者：
Dorer MS;Kirton D;Bader JS;Isberg RR
通讯作者：
Isberg RR