Structure and assembly of the essential RNA ring component of a viral DNA packaging motor
Structure and assembly of the essential RNA ring component of a viral DNA packaging motor
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DOI：
10.1073/pnas.1016690108
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发表时间：
2011-05-03
影响因子：
11.1
通讯作者：
Ke, Ailong
中科院分区：
文献类型：
--
作者：
Ding, Fang;Lu, Changrui;Ke, Ailong
前体RNA（Prohead RNA，pRNA）是噬菌体phi 29 DNA包装马达组装和运行的重要组成部分。pRNA通过原聚体之间的分子间碱基配对相互作用形成多聚体环，其用于引导驱动DNA包装的环ATP酶的组装。在这里，我们报告的四级结构，这种罕见的多聚体RNA在3.5埃分辨率，结晶为四聚体环。强的四级相互作用和固有的灵活性有助于合理化游离pRNA如何能够在溶液中采用多个寡聚化状态。这些特征还允许晶体学pRNA原聚体与先前的prohead/pRNA cryo-EM重建的良好拟合，支持在DNA包装马达的背景下存在五聚体而不是六聚体的pRNA环。五聚体pRNA环通过与围绕头-尾连接器入口的五重对称衣壳结构特异性相互作用将其自身直接锚定到噬菌体前体。从这些接触中，五个RNA超螺旋从pRNA环突出，在那里它们作为骨架用于环ATP酶的结合和组装，并可能介导马达组件之间的通信。与野生型pRNA具有很小序列相似性的基于结构的设计者pRNA的构建显示完全支持phi 29 DNA的包装。
Prohead RNA (pRNA) is an essential component in the assembly and operation of the powerful bacteriophage phi 29 DNA packaging motor. The pRNA forms a multimeric ring via intermolecular base-pairing interactions between protomers that serves to guide the assembly of the ring ATPase that drives DNA packaging. Here we report the quaternary structure of this rare multimeric RNA at 3.5 angstrom resolution, crystallized as tetrameric rings. Strong quaternary interactions and the inherent flexibility helped rationalize how free pRNA is able to adopt multiple oligomerization states in solution. These characteristics also allowed excellent fitting of the crystallographic pRNA protomers into previous prohead/pRNA cryo-EM reconstructions, supporting the presence of a pentameric, but not hexameric, pRNA ring in the context of the DNA packaging motor. The pentameric pRNA ring anchors itself directly to the phage prohead by interacting specifically with the fivefold symmetric capsid structures that surround the head-tail connector portal. From these contacts, five RNA superhelices project from the pRNA ring, where they serve as scaffolds for binding and assembly of the ring ATPase, and possibly mediate communication between motor components. Construction of structure-based designer pRNAs with little sequence similarity to the wild-type pRNA were shown to fully support the packaging of phi 29 DNA.