阴道毛滴虫双链 RNA 病毒 2 的原子结构,mBio

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阴道毛滴虫双链 RNA 病毒 2 的原子结构
mBio ( IF 5.1 ) Pub Date : 2021-03-30 , DOI: 10.1128/mbio.02924-20
Alexander Stevens _{1,

2,

3} , Katherine Muratore ₁ , Yanxiang Cui ₂ , Patricia J Johnson ₁ , Z Hong Zhou _{2,

4}

Affiliation

阴道毛滴虫是全球最常见的非病毒性性传播感染的致病病原体，它本身经常感染四种类型的小双链 RNA (dsRNA)阴道滴虫病毒（TVV1 至 4，滴虫病毒属，Totiviridae家族）中的一种或多种）。每个 TVV 都将一个非分段基因组包含在一个单层衣壳内，并完全在细胞内复制，就像许多 dsRNA 病毒一样，与呼肠孤病毒科中的病毒不同家庭。在这里，我们通过低温电子显微镜 (cryoEM) 以 3.6 Å 的分辨率确定了 TVV2 的结构，并推导出了其衣壳的原子模型。TVV2 具有二十面体，T = 2*，衣壳由 60 个二十面体不对称单元（两个衣壳壳蛋白 [CSP] 构象异构体 CSP-A 和 CSP-B 的二聚体）组成，是二十面体 dsRNA 病毒衣壳的典型特征。然而，与强大的 CSP 互锁相互作用不同，例如在呼肠孤病毒科中使用辅助“钳位”蛋白，在 TVV2 中仅观察到横向 CSP 相互作用，这与针对 TVV 在其原生动物宿主内的仅细胞内复制周期优化的组装策略一致。原子模型揭示了主要带负电荷的衣壳内部，这有利于松散包装的基因组的移动，以及 5 倍顶点处的通道，我们建议将其作为转录过程中 mRNA 释放的途径。TVV2 与Saccharomyces cerevisiae LA 病毒的结构比较揭示了 CSP 内保守的富含螺旋的折叠和沿着衣壳外部推定的鸟苷酸转移酶结构域，表明Totiviridae中保守的 mRNA 维持策略. TVV 的第一个原子结构提供了一个框架，以指导未来对阴道毛滴虫及其病毒之间相互作用的生化研究。

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Atomic Structure of the Trichomonas vaginalis Double-Stranded RNA Virus 2

Trichomonas vaginalis, the causative pathogen for the most common nonviral sexually transmitted infection worldwide, is itself frequently infected with one or more of the four types of small double-stranded RNA (dsRNA) Trichomonas vaginalis viruses (TVV1 to 4, genus Trichomonasvirus, family Totiviridae). Each TVV encloses a nonsegmented genome within a single-layered capsid and replicates entirely intracellularly, like many dsRNA viruses, and unlike those in the Reoviridae family. Here, we have determined the structure of TVV2 by cryo-electron microscopy (cryoEM) at 3.6 Å resolution and derived an atomic model of its capsid. TVV2 has an icosahedral, T = 2*, capsid comprised of 60 copies of the icosahedral asymmetric unit (a dimer of the two capsid shell protein [CSP] conformers, CSP-A and CSP-B), typical of icosahedral dsRNA virus capsids. However, unlike the robust CSP-interlocking interactions such as the use of auxiliary “clamping” proteins among Reoviridae, only lateral CSP interactions are observed in TVV2, consistent with an assembly strategy optimized for TVVs’ intracellular-only replication cycles within their protozoan host. The atomic model reveals both a mostly negatively charged capsid interior, which is conducive to movement of the loosely packed genome, and channels at the 5-fold vertices, which we suggest as routes of mRNA release during transcription. Structural comparison of TVV2 to the Saccharomyces cerevisiae L-A virus reveals a conserved helix-rich fold within the CSP and putative guanylyltransferase domain along the capsid exterior, suggesting conserved mRNA maintenance strategies among Totiviridae. This first atomic structure of a TVV provides a framework to guide future biochemical investigations into the interplay between Trichomonas vaginalis and its viruses.

更新日期：2021-04-27

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