RNA Homopolymers Form Higher-Curvature Virus-like Particles Than Do Normal-Composition RNAs
RNA Homopolymers Form Higher-Curvature Virus-like Particles Than Do Normal-Composition RNAs
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RNA 均聚物比正常组成的 RNA 形成更高曲率的病毒样颗粒
DOI：
10.1016/j.bpj.2019.08.012
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发表时间：
2019
影响因子：
3.4
通讯作者：
Gelbart, William M.
中科院分区：
文献类型：
--
作者：
Thurm, Abby R.;Beren, Christian;Duran-Meza, Ana Luisa;Knobler, Charles M.;Gelbart, William M.
与双链DNA不同，单链RNA可以被病毒衣壳蛋白（CP）自发包装成球形衣壳，因为它是一种更致密、更灵活的聚合物。许多系统的调查，这种自组装过程中已经进行了使用CP豇豆褪绿斑驳病毒，具有广泛的序列和长度的单链RNA。在这些研究中，测量了这些RNA进入球形衣壳的相对包装效率。在这项工作中，我们解决了一个基本的问题，已收到很少的关注，即在不同的RNA分子周围形成的衣壳的首选曲率的问题。我们表明，特别是RNA-聚核糖核苷酸和聚核糖腺苷酸的均聚物的形式完全T = 2大小（直径约22纳米）的病毒样颗粒（VLP）混合时，豇豆褪绿斑驳病毒CP，独立于它们的长度，范围从500到超过4000个核苷酸。这与“正常组成”RNA（即，具有四种核苷酸中的每一种的相当数量的分子，因此由于分子内互补性/碱基配对而能够形成大量二级结构）;对于用这样的RNA形成的VLP，优选对应于T = 3大小（直径约28 nm）的曲率。我们的工作是一致的VLP的优选曲率是CP与RNA的相互作用的结果，特别是，存在或不存在短的RNA序列，并表明，平衡大小的衣壳结果从这个最佳的大小和限制的成本之间的权衡。
Unlike double-stranded DNA, single-stranded RNA can be spontaneously packaged into spherical capsids by viral capsid protein (CP) because it is a more compact and flexible polymer. Many systematic investigations of this self-assembly process have been carried out using CP from cowpea chlorotic mottle virus, with a wide range of sequences and lengths of single-stranded RNA. Among these studies are measurements of the relative packaging efficiencies of these RNAs into spherical capsids. In this work, we address a fundamental issue that has received very little attention, namely the question of the preferred curvature of the capsid formed around different RNA molecules. We show in particular that homopolymers of RNA—polyribouridylic acid and polyriboadenylic acid—form exclusively T = 2-sized (∼22-nm diameter) virus-like particles (VLPs) when mixed with cowpea chlorotic mottle virus CP, independent of their length, ranging from 500 to more than 4000 nucleotides. This is in contrast to "normal-composition" RNAs (i.e., molecules with comparable numbers of each of the four nucleotides and hence capable of developing a large amount of secondary structure because of intramolecular complementarity/basepairing); a curvature corresponding to T = 3-size (∼28 nm in diameter) is preferred for the VLPs formed with such RNAs. Our work is consistent with the preferred curvature of VLPs being a consequence of interaction of CP with RNA—in particular, the presence or absence of short RNA duplexes—and suggests that the equilibrium size of the capsid results from a trade-off between this optimum size and the cost of confinement.