Cellular electron tomography of the apical complex in the apicomplexan parasite Eimeria tenella shows a highly organised gateway for regulated secretion.
Cellular electron tomography of the apical complex in the apicomplexan parasite Eimeria tenella shows a highly organised gateway for regulated secretion.
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DOI：
10.1371/journal.ppat.1010666
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发表时间：
2022-07
期刊：
影响因子：
6.7
通讯作者：
中科院分区：
文献类型：
--
作者：
顶端复合体的apicomplexan寄生虫是必不可少的宿主细胞的入侵和细胞内的生存，并作为从专门的分泌细胞器，称为棒状体和微丝的调节胞吐的网站。尽管它的重要性，有很少的数据上的三维组织和定量的这些细胞器内的顶端复合物或它们是如何被贩运到这个专门的区域质膜胞吐。在球虫apicomplexans有一个额外的含有微管蛋白的中空桶结构，锥状体，这提供了一个结构网关，这种专门的顶端分泌。使用细胞电子断层扫描和连续块面扫描电子显微镜（SBF-SEM）的组合，我们已经重建了柔嫩艾美耳球虫子孢子的整个顶端;我们报告了圆锥体的三维组织的详细解剖，并显示含有微管蛋白的纤维具有高曲率，这可能与不寻常的逗号形排列的原丝有关。我们量化了细胞内的棒状体和微线体的数量和位置，并显示了一个高度组织化的网关，用于在圆锥体内围绕一组圆锥体内微管的棒状体、微线体和微管相关囊泡的贩运和对接。最后，我们提供了超微结构的证据融合的棒状体直接通过寄生虫质膜感染早期和寄生虫空泡膜中的孔的存在下，棒状体蛋白质如何可能被贩运之间的寄生虫和宿主细胞质提供了结构上的解释。顶复门寄生虫引起广泛的人类和动物疾病。顶端复合体对于运动、宿主细胞侵入和在称为寄生虫液泡的专门液泡内的细胞内存活是必不可少的。我们知道，所有这些过程中的重要分子分泌的顶端复合体通过一套分泌细胞器，有证据表明，一些寄生虫分子可以进入宿主细胞从寄生虫液泡，但很少有人了解这到底是如何发生的。在这里，我们已经使用三维电子显微镜重建整个顶端的球虫apicomplexan寄生虫和整个个人的寄生虫。我们的研究结果提供了重要的见解的结构组织和机制，通过这个重要的领域的细胞的寄生虫分子的交付。
The apical complex of apicomplexan parasites is essential for host cell invasion and intracellular survival and as the site of regulated exocytosis from specialised secretory organelles called rhoptries and micronemes. Despite its importance, there are few data on the three-dimensional organisation and quantification of these organelles within the apical complex or how they are trafficked to this specialised region of plasma membrane for exocytosis. In coccidian apicomplexans there is an additional tubulin-containing hollow barrel structure, the conoid, which provides a structural gateway for this specialised apical secretion. Using a combination of cellular electron tomography and serial block face-scanning electron microscopy (SBF-SEM) we have reconstructed the entire apical end of Eimeria tenella sporozoites; we report a detailed dissection of the three- dimensional organisation of the conoid and show there is high curvature of the tubulin-containing fibres that might be linked to the unusual comma-shaped arrangement of protofilaments. We quantified the number and location of rhoptries and micronemes within cells and show a highly organised gateway for trafficking and docking of rhoptries, micronemes and microtubule-associated vesicles within the conoid around a set of intra-conoidal microtubules. Finally, we provide ultrastructural evidence for fusion of rhoptries directly through the parasite plasma membrane early in infection and the presence of a pore in the parasitophorous vacuole membrane, providing a structural explanation for how rhoptry proteins may be trafficked between the parasite and the host cytoplasm. Apicomplexan parasites cause a wide range of human and animal diseases. The apical complex is essential for motility, host cell invasion and intracellular survival within a specialised vacuole called the parasitophorous vacuole. We know that molecules important for all these processes are secreted from the apical complex via a set of secretory organelles and there is evidence that some parasite molecules can enter the host cell from the parasitophorous vacuole, but there is little understanding of exactly how this occurs. Here we have used three-dimensional electron microscopy to reconstruct the entire apical end of a coccidian apicomplexan parasite and whole individual parasites. Our results provide important insights into the structural organisation and mechanisms for delivery of parasite molecules via this important area of the cell.
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影响因子：
2.4
作者：
Shirley, MW;Harvey, DA
通讯作者：
Harvey, DA
DOI：
10.1073/pnas.2111661119
发表时间：
2022-02-08
影响因子：
11.1
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影响因子：
4.5
作者：
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影响因子：
6.7
作者：
Hu K;Johnson J;Florens L;Fraunholz M;Suravajjala S;DiLullo C;Yates J;Roos DS;Murray JM
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