Structure and replication cycle of a virus infecting climate-modulating alga Emiliania huxleyi

The globally distributed marine alga Emiliania huxleyi produces reflective calcite disks (coccoliths) that increase the albedo of ocean water and thus reduce the heat absorption in the ocean, which cools the Earth’s climate. The population density of E. huxleyi is restricted by Nucleocytoviricota viruses, including E. huxleyi virus 201 (EhV-201). Despite the impact of E. huxleyi viruses on the climate, there is limited information about their structure and replication. Here we show that the dsDNA genome inside the EhV-201 virion is protected by an inner membrane, capsid, and outer membrane decorated with numerous transmembrane proteins. The virions are prone to deformation, and parts of their capsids deviate from the icosahedral arrangement. EhV-201 virions infect E. huxleyi by using their fivefold vertex to bind to a host cell and fuse the virus’s inner membrane with the plasma membrane. Whereas the replication of EhV-201 probably occurs in the nucleus, virions assemble in the cytoplasm at the surface of endoplasmic reticulum-derived membrane segments. Genome packaging initiates synchronously with the capsid assembly and completes through an aperture in the forming capsid. Upon the completion of genome packaging, the capsids change conformation, which enables them to acquire an outer membrane by budding into intracellular vesicles. EhV-201 infection induces a loss of surface protective layers from E. huxleyi cells, which allows the continuous release of virions by exocytosis. Our results provide insight into how EhVs bypass the surface protective layers of E. huxleyi and exploit the organelles of an infected cell for progeny assembly.全球分布的海洋藻类赫氏颗石藻（Emiliania huxleyi）可产生具有反射性的方解石粒（coccoliths），这些颗石粒能够提升海水反照率（albedo），进而减少海洋吸收的热量，对地球气候起到降温作用。赫氏颗石藻的种群密度会受到核胞质大DNA病毒门（Nucleocytoviricota）病毒的限制，其中包括赫氏颗石藻病毒201（EhV-201）。尽管赫氏颗石藻病毒对气候存在影响，但目前关于其结构与复制过程的相关研究仍较为匮乏。本研究显示，EhV-201病毒粒子内部的双链DNA（dsDNA）基因组，由内层膜、衣壳（capsid）以及装饰有大量跨膜蛋白的外层膜共同保护。该病毒粒子易发生形变，其部分衣壳结构偏离了二十面体对称（icosahedral arrangement）排布。EhV-201病毒粒子通过其五倍顶点结合宿主细胞，并将病毒内层膜与宿主细胞膜融合，从而完成对赫氏颗石藻的侵染。尽管EhV-201的复制过程可能发生于细胞核内，但病毒粒子的组装则是在细胞质中、内质网（endoplasmic reticulum）衍生的膜片段表面完成。基因组包装与衣壳组装同步启动，并通过正在形成的衣壳上的开口完成包装。基因组包装完成后，衣壳会发生构象变化，使其能够通过出芽进入细胞内囊泡的方式获得外层膜。EhV-201侵染会导致赫氏颗石藻细胞失去表面保护层，这使得病毒粒子可通过胞吐作用（exocytosis）持续释放。本研究结果为解析赫氏颗石藻病毒如何绕过宿主表面保护层、利用感染细胞的细胞器完成子代病毒组装提供了新的见解。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于感染气候调节海洋藻类Emiliania huxleyi的病毒（EhV-201），通过冷冻电子断层扫描、荧光显微术和蛋白质组学等多模态实验数据，揭示了病毒的结构特征（如三层膜保护和衣壳变形）及其复制周期（包括宿主结合、基因组包装和释放机制）。这些数据有助于理解病毒如何绕过藻类表面保护层并利用细胞器进行后代组装，从而影响藻类种群密度和全球气候调节过程。数据集总容量约293.90 GB，包含原始实验数据、分析脚本和可视化文件，适用于生物科学和结构生物学研究。