Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas, USA.
Bioinformatics Program, University of Texas at El Paso, El Paso, Texas, USA.
Viral Immunol. 2021 Jan-Feb;34(1):41-48. doi: 10.1089/vim.2020.0038. Epub 2020 Oct 19.
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, 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.
核质大 DNA 病毒（NCLDVs）是一组感染范围广泛的宿主，从动物到原生生物的大型病毒。这些病毒基于基因组序列分析被归类为 NCLDV。它们共享一套用于病毒形态发生和复制的必需基因。大多数 NCLDV 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，如二十面体、砖形或椭圆形，这引发了对其形态发生的可能调节因子的问题。二十面体 NCLDV 的衣壳由称为衣壳蛋白的小构建块组装而成，衣壳蛋白是主要衣壳蛋白的三聚体形式。请注意，尽管不成熟的痘病毒的衣壳是球形的，但它们是由与这些二十面体 NCLDV 共享高度结构保守性的衣壳蛋白组装而成的。最近发表的 NCLDV 的高分辨率结构，即 Chlorella 病毒 1 和非洲猪瘟病毒，描述了位于衣壳蛋白下方的密集的次要衣壳蛋白网络。在这些次要蛋白中，有一种细长的卷尺蛋白（TmP），它跨越一个二十面体五重对称顶点到另一个顶点。在这项研究中，我们专注于 TmP 在二十面体 NCLDV 衣壳组装中所扮演的关键角色，回答了先前提出的螺旋机制中提出的一个问题。有趣的是，对 TmP 的基本局部比对搜索在痘病毒中没有显示出显著的命中，这可能是区分痘病毒和二十面体 NCLDV 在形态发生中的因素。
