美国科罗拉多大学Karolin Luger、法国艾克斯-马赛大学Chantal Abergel等研究人员合作发现，病毒编码的组蛋白类似物是形成核小体样结构所必须的。这一研究成果于2021年7月22日在线发表在国际学术期刊《细胞》上。

研究人员表示，长期以来，基因组DNA组织形成核小体，这一直被视为真核生物的一个标志。这一范式受到了挑战，因为在古细菌中发现了 "最小 "组蛋白，最近又在Marseilleviridae中发现了编码四个真核生物组蛋白融合远程同源物的基因，Marseilleviridae是一类感染变形虫的巨型病毒亚科。

研究人员证明，病毒组蛋白是病毒感染性所必需的，在病毒感染后定位于细胞质病毒工厂，并最终在成熟病毒中发现。病毒核小体样颗粒的冷冻电镜（cryo-EM）结构显示出与真核生物核小体的强烈相似性，尽管序列相似性有限。连接组蛋白链的独特连接因子有助于病毒核小体的不稳定性，并且一些组蛋白尾部承担着结构性作用。这些发现进一步扩大了需要核小体的"生物"范畴，并表明组蛋白在这些不寻常的病毒中具有专门的功能。

附：英文原文

Title: Virus-encoded histone doublets are essential and form nucleosome-like structures

Author: Yang Liu, Hugo Bisio, Chelsea Marie Toner, Sandra Jeudy, Nadege Philippe, Keda Zhou, Samuel Bowerman, Alison White, Garrett Edwards, Chantal Abergel, Karolin Luger

Issue&Volume: 2021-07-22

Abstract: The organization of genomic DNA into defined nucleosomes has long been viewed as a hallmark of eukaryotes. This paradigm has been challenged by the identification of “minimalist” histones in archaea and more recently by the discovery of genes that encode fused remote homologs of the four eukaryotic histones in Marseilleviridae, a subfamily of giant viruses that infect amoebae. We demonstrate that viral doublet histones are essential for viral infectivity, localize to cytoplasmic viral factories after virus infection, and ultimately are found in the mature virions. Cryogenic electron microscopy (cryo-EM) structures of viral nucleosome-like particles show strong similarities to eukaryotic nucleosomes despite the limited sequence identify. The unique connectors that link the histone chains contribute to the observed instability of viral nucleosomes, and some histone tails assume structural roles. Our results further expand the range of “organisms” that require nucleosomes and suggest a specialized function of histones in the biology of these unusual viruses.

DOI: 10.1016/j.cell.2021.06.032

Source: https://www.cell.com/cell/fulltext/S0092-8674(21)00823-0