Influence of RNA on icosahedral virus particle structure

RNA对二十面体病毒颗粒结构的影响

• 批准号: BB/Y005732/1
• 负责人: George Lomonossoff
• 金额: $ 70.64万
• 依托单位: John Innes Centre
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FY005732%2F1
• 关键词: Influence; RNA; icosahedral; virus; particle

Viruses are extremely successful pathogens that infect organisms of every type, including plants, animals (including humans), fungi, and bacteria of all types. They are essentially intracellular parasites that introduce their genetic material into host cells and subvert the normal cellular functions to make more copies of themselves. They are normally present in the environment in the form of virus particles in which the viral nucleic acid, either DNA or RNA, is surrounded by a shell made up of multiple copies of one or more type of protein subunit encoded by the virus genome. In some cases (enveloped viruses) they are further surrounded by a membrane of host origin. The purpose of the protein shell is to protect the delicate genetic information from the, often harsh, environment outside the cell and to enable the virus to successfully spread to other hosts. This often involves uptake and transmission by vectors, such as insects or fungi, and the nucleic acid must be able to survive this process. Once inside a susceptible host, the virus makes more copies of itself by undergoing a "replication cycle" that includes several stages: uncoating of the particles to release the viral genome, expression of viral genes, replication of the viral nucleic acid and the encapsidation of the newly synthesised nucleic acid into particles that are then released to infect further hosts. This is all a carefully choreographed process, with replication and encapsidation of the viral genome usually closely linked. The specific encapsidation of viral, as opposed to host, nucleic acid into infectious particles is a vital step in the replication cycle of viruses. The process must result in the formation of virus particles that protect the labile genetic material effectively. This has led to the identification of defined RNA sequence elements or "packaging signals" in RNA viruses. Such packaging signals have been envisaged as labelling the viral RNA so that it is effectively "barcoded" in such a way that it is specifically recognised from a mixture of cellular molecules by the coat protein subunits, thereby conferring encapsidation selectivity. However, our recent work has shown that selectivity of packaging is determined by replication of an RNA molecule within infected cells, with synthesis of the coat protein being tightly coupled to RNA replication. In such "replication factories" the viral RNA genome is not in competition with other, non-replicating RNAs, suggesting that "barcoding" may not be required selective packaging. Rather, they may be present to ensure that the incorporation of RNA into particles proceeds efficiently to produce fully infectious virions. We have also obtained evidence that the length of replicating RNA may control the architecture of the resulting particles.To determine the role of potential packaging signals in the context of a replicating RNA, we will use a vector, pEff, based on the plant virus, potato virus X (PVX), that simultaneously produces replicating RNA and the coat proteins within plants. This closely mimics the situation that occurs in vivo during a viral infection. We have recently shown that the replicating RNA from pEff can be encapsidated by the coat protein from different, unrelated viruses. Thus, pEff is an ideal system for examining the role of packaging signals in the context of viral replication. The effect of elimination, duplication or mutation of the packaging signals on the assembly and morphology of the particles will be examined to obtain a more complete understanding of the mechanism of virus assembly. These studies will not only lead to a greater understanding of a critical stage of the viral replication cycle but will also enable specific RNAs to be deliberately packaged in capsids of defined architecture for use in bionanotechnology and the creation of novel RNA delivery systems.

病毒是非常成功的病原体，感染每种类型的生物，包括植物，动物（包括人），真菌和各种类型的细菌。它们本质上是细胞内寄生虫，将其遗传物质引入宿主细胞中并颠覆正常的细胞功能以制作更多的副本。它们通常以病毒颗粒的形式存在于环境中，其中病毒核酸（DNA或RNA）被壳包围，由由病毒基因组编码的一种或多种类型的蛋白质亚基组成的多个副本组成。在某些情况下（包裹病毒），它们被宿主起源的膜进一步包围。蛋白质外壳的目的是保护细腻的遗传信息免受细胞外部的刺激性环境，并使病毒能够成功传播到其他宿主。这通常涉及媒介（例如昆虫或真菌）的摄取和传播，核酸必须能够生存这一过程。一旦进入易感宿主，该病毒就通过经历“复制周期”的“复制循环”来制作更多的自身拷贝，该阶段包括几个阶段：颗粒脱落以释放病毒基因组，病毒基因的表达，病毒核酸的复制以及对新合成的核酸的封装的复制，然后将核酸的粒子封装到然后释放到寄生的宿主中。这是一个经过精心编排的过程，复制和封装了病毒基因组，通常密切相关。病毒的特定封装，而不是宿主，核酸成传染性颗粒是病毒复制周期的至关重要的一步。该过程必须导致形成有效保护不稳定遗传物质的病毒颗粒。这导致了RNA病毒中定义的RNA序列元件或“包装信号”的鉴定。这种包装信号已被设想为标记病毒RNA，以便有效地“条形码”，以使其通过外套蛋白亚基从细胞分子的混合物中特别识别，从而赋予封装选择性。但是，我们最近的工作表明，包装的选择性是通过感染细胞内的RNA分子复制来确定的，并且合成外套蛋白与RNA复制紧密偶联。在这种“复制工厂”中，病毒RNA基因组与其他非复制RNA不竞争，这表明可能不需要选择性包装“条形码”。相反，它们可能存在，以确保将RNA掺入颗粒中有效地进行以产生完全感染性病毒体。我们还获得了证据表明，复制RNA的长度可以控制所得颗粒的结构。为了确定在复制RNA的背景下潜在包装信号的作用，我们将根据植物病毒X（PVX）使用媒介，PEFF，同时产生复制的RNA和涂层蛋白质的植物。这紧密地模仿了病毒感染期间体内发生的情况。我们最近表明，来自PEFF的复制RNA可以被不同无关病毒的外套蛋白封装。因此，PEFF是在病毒复制中检查包装信号的作用的理想系统。将检查包装信号对颗粒组装和形态的消除，重复或突变的影响，以获得对病毒组装机制的更完整理解。这些研究不仅会使人们对病毒复制周期的关键阶段有更深入的了解，而且还将使特定的RNA故意包装在定义的架构的衣壳中，以用于Bionanotechnology和新型RNA传递系统。