Ehrlichia chaffeensis uses its surface protein EtpE to bind GPI-anchored protein DNase X and trigger entry into mammalian cells.
Ehrlichia chaffeensis uses its surface protein EtpE to bind GPI-anchored protein DNase X and trigger entry into mammalian cells.
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DOI：
10.1371/journal.ppat.1003666
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发表时间：
2013
期刊：
影响因子：
6.7
通讯作者：
Rikihisa Y
中科院分区：
文献类型：
--
作者：
Mohan Kumar D;Yamaguchi M;Miura K;Lin M;Los M;Coy JF;Rikihisa Y
chaffelichia chaffeensis是一种专性细胞内立克次体病原体，在单核/巨噬细胞和几种非吞噬细胞中进入并复制。沙非伊虫进入哺乳动物细胞不仅是引起人畜共患病、单核细胞埃利希体病的必要条件，也是其存活的必要条件。目前尚不清楚沙非叶蝉是否进化出了一种特殊的表面蛋白，作为“入侵”来调节其进入。我们报告了一种新的切入触发蛋白，EtpE的埃利希氏体作为入侵的功能。EtpE是一种外膜蛋白，是一种针对EtpE （c -末端片段，EtpE- c）的抗体，它能极大地抑制沙菲伊布结合、进入和感染吞噬细胞和非吞噬细胞。etpe - c免疫小鼠可显著抑制沙非伊虫感染。EtpE-C包被的乳胶珠用于研究EtpE-C是否介导细胞侵袭，它既能进入吞噬细胞，也能进入非吞噬细胞，并被阻断沙菲E.进入的化合物所阻断。这些化合物都不能阻断吞噬细胞对非包被珠的摄取。酵母双杂交筛选显示，dna酶X，一个糖基磷脂酰肌醇锚定的哺乳动物细胞表面蛋白结合EtpE-C。通过远western印迹、亲和下拉、免疫共沉淀、免疫荧光标记和活细胞图像分析证实了这一点。etpe -c包被珠粒进入野生型小鼠骨髓源性巨噬细胞（bmmdms），而它们既不结合也不进入DNase X-/-小鼠骨髓源性巨噬细胞。抗dna酶X抗体或dna酶X被小干扰RNA敲除的抗体会破坏沙菲E.的结合、进入和感染。DNase X-/-小鼠感染沙菲E. E. BMDMs的进入率和感染率以及实验感染的DNase X-/-小鼠外周血细菌载量均显著低于野生型小鼠。因此，这种必需的细胞内病原体进化出一种独特的蛋白质EtpE，它结合DNase X进入并感染真核细胞。这项研究首次证明了入侵蛋白及其哺乳动物受体，以及它们在任何卵泡物种中的体内相关性。人类单核细胞埃利希体病（HME）发现于1986年，1998年被美国疾病控制与预防中心指定为国家法定传染病。HME是美国最普遍、威胁生命的新发传染病之一。HME是由一种叫做沙菲埃利希体的细菌引起的，通过被感染的蜱虫叮咬传播。这种细菌具有进入人体白细胞并进行复制的特殊能力，这一特性对细菌的生存至关重要。沙非棘球绦虫如何进入宿主细胞一直是个谜。目前的研究表明，沙菲沙蚕的外表面蛋白EtpE与宿主细胞表面特异性蛋白DNase X结合，这种配体-受体相互作用是诱导细菌进入宿主细胞所必需的。为了检验EtpE免疫是否能预防沙非叶蝉感染，我们用重组EtpE蛋白免疫小鼠，并用活沙非叶蝉攻毒。与对照组相比，接种了EtpE蛋白的小鼠感染明显减少。缺乏DNase X的小鼠也对感染有抵抗力。该研究表明，EtpE介导的沙非埃希菌进入途径在感染哺乳动物中是重要的，EtpE可以纳入未来的HME疫苗设计中。
Ehrlichia chaffeensis, an obligatory intracellular rickettsial pathogen, enters and replicates in monocytes/macrophages and several non-phagocytic cells. E. chaffeensis entry into mammalian cells is essential not only for causing the emerging zoonosis, human monocytic ehrlichiosis, but also for its survival. It remains unclear if E. chaffeensis has evolved a specific surface protein that functions as an ‘invasin’ to mediate its entry. We report a novel entry triggering protein of Ehrlichia, EtpE that functions as an invasin. EtpE is an outer membrane protein and an antibody against EtpE (the C-terminal fragment, EtpE-C) greatly inhibited E. chaffeensis binding, entry and infection of both phagocytes and non-phagocytes. EtpE-C-immunization of mice significantly inhibited E. chaffeensis infection. EtpE-C-coated latex beads, used to investigate whether EtpE-C can mediate cell invasion, entered both phagocytes and non-phagocytes and the entry was blocked by compounds that block E. chaffeensis entry. None of these compounds blocked uptake of non-coated beads by phagocytes. Yeast two-hybrid screening revealed that DNase X, a glycosylphosphatidyl inositol-anchored mammalian cell-surface protein binds EtpE-C. This was confirmed by far-Western blotting, affinity pull-down, co-immunoprecipitation, immunofluorescence labeling, and live-cell image analysis. EtpE-C-coated beads entered bone marrow-derived macrophages (BMDMs) from wild-type mice, whereas they neither bound nor entered BMDMs from DNase X-/- mice. Antibody against DNase X or DNase X knock-down by small interfering RNA impaired E. chaffeensis binding, entry, and infection. E. chaffeensis entry and infection rates of BMDMs from DNase X-/- mice and bacterial load in the peripheral blood in experimentally infected DNase X-/- mice, were significantly lower than those from wild-type mice. Thus this obligatory intracellular pathogen evolved a unique protein EtpE that binds DNase X to enter and infect eukaryotic cells. This study is the first to demonstrate the invasin and its mammalian receptor, and their in vivo relevance in any ehrlichial species. Human monocytic ehrlichiosis (HME), discovered in 1986, was designated as a nationally notifiable disease by Centers for Disease Control and Prevention in 1998. HME is one of the most prevalent, life-threatening emerging infectious diseases in the United States. HME is caused by a bacterium, Ehrlichia chaffeensis and is transmitted by the bite of infected ticks. This bacterium has special ability to enter and replicate inside human white blood cells and this feature is very essential for the bacterial survival. How E. chaffeensis enters host cells has been a mystery. The present study revealed that E. chaffeensis outer-surface protein named EtpE binds a specific host cell-surface protein, DNase X, and this ligand-receptor interaction is required to induce bacterial entry into its host cells. In order to test whether E. chaffeensis infection can be prevented by EtpE immunization, mice were immunized with the recombinant EtpE protein, and challenged with live E. chaffeensis. Infection was significantly reduced in the EtpE protein-immunized mice compared to controls. Mice lacking DNase X were also resistant to infection. This study shows EtpE-mediated entry pathway of E. chaffeensis is important in infecting mammals and EtpE can be incorporated into a future HME vaccine design.
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影响因子：
4.5
作者：
Dunning Hotopp JC;Lin M;Madupu R;Crabtree J;Angiuoli SV;Eisen JA;Seshadri R;Ren Q;Wu M;Utterback TR;Smith S;Lewis M;Khouri H;Zhang C;Niu H;Lin Q;Ohashi N;Zhi N;Nelson W;Brinkac LM;Dodson RJ;Rosovitz MJ;Sundaram J;Daugherty SC;Davidsen T;Durkin AS;Gwinn M;Haft DH;Selengut JD;Sullivan SA;Zafar N;Zhou L;Benahmed F;Forberger H;Halpin R;Mulligan S;Robinson J;White O;Rikihisa Y;Tettelin H
通讯作者：
Tettelin H
影响因子：
7.8
作者：
MCABEE, DD;GRINNELL, F
通讯作者：
GRINNELL, F
影响因子：
3.2
作者：
Bao, Weichao;Kumagai, Yumi;Rikihisa, Yasuko
通讯作者：
Rikihisa, Yasuko
影响因子：
14.9
作者：
Bagos, PG;Liakopoulos, TD;Hamodrakas, SJ
通讯作者：
Hamodrakas, SJ
影响因子：
3.4
作者：
Lin, MQ;Rikihisa, Y
通讯作者：
Rikihisa, Y