近日，美国德克萨斯大学教授Nancy A. Moran及其小组发现一种对宿主细胞定殖至关重要的分泌型内共生蛋白。这一研究成果于2026年7月1日发表在国际顶尖学术期刊《自然》上。

在这里，该课题组人员发现了一种未被鉴定的布氏菌蛋白，称为SyeA，存在于布氏菌祖先中，分泌到宿主细胞质中，与细菌病原体的分泌效应物同源，是布氏菌传播所必需的。布赫涅拉病毒是通过母体特化细胞的排出和胚胎的摄取而传播的。该研究团队使用免疫荧光显微镜发现胚胎细胞定植后SyeA水平升高，并伴有进入部位的肌动蛋白积累。SyeA定位于宿主衍生膜和肌动蛋白层外，围绕宿主细胞质内的每个布氏细胞。敲低syeA表达破坏胚胎定植和胚胎发育，提高溶酶体活性，导致布氏菌破坏。他们的发现为了解一个古老的相互关联的、互惠的内共生生物是如何在细胞内生存的提供了见解。SyeA代表了病原起源的遗迹，随后是宿主控制增强的进化和原始的、更复杂的致病性机制的侵蚀。

据悉，在真核生物中，细胞内细菌共生现象已经出现过无数次，仅在昆虫中就有几十种。从蚜虫的专性内共生体Buchnera开始，内共生体的基因组揭示了它们的进化起源和对宿主的代谢贡献。然而，不可培养的内共生体进入宿主细胞并抑制细胞免疫过程的机制尚不清楚。

附：英文原文

Title: A secreted endosymbiont protein essential for colonizing host cells

Author: Maeda, Gerald P., Xue, Allen Z., Yu, Ethan W., Sundar, Aadhunik, Kamp, Derrick L., Elijah Powell, J., Smith, Thomas E., Moran, Nancy A.

Issue&Volume: 2026-07-01

Abstract: Intracellular bacterial symbioses have arisen myriad times in eukaryotes, with dozens known from insects alone1,2. Beginning with Buchnera, the obligate endosymbiont of aphids, genomes of endosymbionts have illuminated their evolutionary origins and metabolic contributions to hosts3,4. However, the mechanisms by which non-culturable endosymbionts enter host cells and suppress cellular immune processes have remained unclear. Here we show that an uncharacterized Buchnera protein, designated SyeA, was present in the Buchnera ancestor, is secreted into the host cytoplasm, is homologous to secreted effectors of bacterial pathogens and is essential for Buchnera transmission. Buchnera is transmitted through expulsion from specialized maternal cells and uptake by embryos5. Using immunofluorescence microscopy, we found elevated SyeA levels after colonization of the embryonic cell, accompanied by actin accumulation at the entry site. SyeA localizes outside the host-derived membrane and actin layer surrounding each Buchnera cell within host cytoplasm. Knockdown of syeA expression disrupts colonization of embryos and embryonic development and elevates lysosomal activity, leading to Buchnera destruction6. Our findings provide insights into how an anciently associated, mutualistic endosymbiont achieves its intracellular existence. SyeA represents a vestige of pathogenic origins that was followed by evolution of increased host control and erosion of the original, more complex pathogenicity machinery.

DOI: 10.1038/s41586-026-10711-4

Source: https://www.nature.com/articles/s41586-026-10711-4

期刊信息

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504

官方网址：http://www.nature.com/

投稿链接：http://www.nature.com/authors/submit_manuscript.html