Nucleocytoplasmic large DNA viruses (NCLDVs) are a group of large viruses that infect a wide range of hosts, from animals to protists. These viruses are grouped together in NCLDV based on genomic sequence analyses. They share a set of essential genes for virion morphogenesis and replication. Most NCLDVs generally have large physical sizes while their morphologies vary in different families, such as icosahedral, brick, or oval shape, raising the question of the possible regulatory factor on their morphogenesis. The capsids of icosahedral NCLDVs are assembled from small building blocks, named capsomers, which are the trimeric form of the major capsid proteins. Note that the capsids of immature poxvirus are spherical even though they are assembled from capsomers that share high structural conservation with those icosahedral NCLDVs. The recently published high resolution structure of NCLDVs, Paramecium bursaria Chlorella virus 1 and African swine fever virus, described the intensive network of minor capsid proteins that are located underneath the capsomers. Among these minor proteins is the elongated tape measure protein (TmP) that spans from one icosahedral fivefold vertex to another. In this study, we focused on the critical roles that TmP plays in the assembly of icosahedral NCLDV capsids, answering a question raised in a previously proposed spiral mechanism. Interestingly, basic local alignment search on the TmPs showed no significant hits in poxviruses, which might be the factor that differentiates poxviruses and icosahedral NCLDVs in their morphogenesis.

中文翻译：

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卷尺蛋白在核质大 DNA 病毒衣壳组装中的作用

核质大 DNA 病毒 (NCLDV) 是一组大型病毒，可​​感染从动物到原生生物等多种宿主。根据基因组序列分析，这些病毒在 NCLDV 中被归为一类。它们共享一组病毒粒子形态发生和复制的必需基因。大多数 NCLDVs 通常具有较大的物理尺寸，而它们的形态在不同的家族中有所不同，例如二十面体、砖形或椭圆形，这引发了对其形态发生可能的调控因素的问题。二十面体 NCLDVs 的衣壳由称为衣壳的小构件组装而成，它们是主要衣壳蛋白的三聚体形式。请注意，未成熟痘病毒的衣壳是球形的，尽管它们是由与那些二十面体 NCLDV 共享高度结构保守性的衣壳组装而成的。草履虫法氏囊小球藻病毒 1 和非洲猪瘟病毒描述了位于衣壳下面的小衣壳蛋白的密集网络。在这些次要蛋白质中，有一个拉长的卷尺蛋白质 (TmP)，它从一个二十面体五重顶点跨越到另一个。在这项研究中，我们专注于 TmP 在二十面体 NCLDV 衣壳组装中所起的关键作用，回答了先前提出的螺旋机制中提出的问题。有趣的是，对 TmPs 的基本局部比对搜索在痘病毒中没有显示出显着的命中，这可能是区分痘病毒和二十面体 NCLDV 的形态发生的因素。