A world of virus structures: understanding how non-icosahedral capsids are built

病毒结构的世界：了解非二十面体衣壳是如何构建的

基本信息

批准号：
BB/T004525/1
负责人：
Neil Ranson
金额：
$ 78.56万
依托单位：
University of Leeds
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2020
资助国家：
英国
起止时间：
2020 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FT004525%2F1
关键词：
world virus structures understanding how

项目摘要

Viruses are probably the most successful pathogens on earth. They are everywhere, and they infect every other type of organism, including plants, animals (including humans), fungi, bacteria of all types, and even other viruses. Wherever we have looked for them, they have been found. As a result, they are of huge societal importance, impacting directly on our lives because of their effects on human and animal health, agriculture, and thus on food security on a truly global scale. All viruses face a common challenge, in that they must package their genomic information (either DNA or RNA) within a protective container called a capsid, that shields the genome from the external environment, and delivers it intact to a new cell to start a new round of infection. One way in which these capsids are made is to build a highly symmetric container from a single type of protein. However, to do this the single type of protein has to adopt multiple shapes to build a container of the right size - much like the hexagons and pentagons that are needed to make a football. Building the right capsid, and building it perfectly, is a fundamental part of the viral replication cycle, but our understanding of how this 'conformational switching' happens is very poor. One way that it could occur is for the protein to bind to defined sequences within the genomic DNA or RNA; this binding would drive the conformational change. However, this process is poorly understood. In part, this is because for the vast majority of viruses the capsids have the very high symmetry described above, which means that when we solve their structures, symmetry averaging washes out details of any specific interactions between the protein (which is the same in each position) and the DNA or RNA (which is not, because it has to have a unique sequence that encodes the virus' genes). The high symmetry many viruses rely on is therefore tremendously unhelpful when we try to study the molecular mechanisms involved in assembly. In this proposal we want to exploit two hugely exciting recent discoveries in our laboratories, that will allow us to overcome this barrier and discover, for the first time, the cryptic rules that allow these viruses to efficiently self-assemble. We have been working on two different families of virus that are each important pathogens of food and textile crops globally, and thus are major threats to food security and agricultural economies across the developed and developing world; Geminiviruses and Umbraviruses. In each, the virus has evolved a (different) novel innovation that means the capsid has a "non-standard" structure which is no longer quite as symmetric as is normally the case. Remarkably, in the preliminary structure of each which we have solved with 5-fold symmetry (rather than the 60-fold symmetry for an icosahedral virus), we can now see details of DNA (for Geminiviruses) and RNA (for Umbraviruses) bound to the viral coat proteins. This grant application will allow us to solve high resolution structures of these non-standard virus capsids without any symmetry averaging at all. Together with biochemical and bioinformatics experiments, we will uncover the details of genome binding, how this changes protein conformation, and where these features lie within the viral genome. This will (a) provide fascinating new fundamental biological insights that are important in understanding how viruses work, (b) provide a mechanistic understanding that could lead to new ways to prevent them working, and (c) make clear the rules for virus assembly that could allow us to change the way viruses assemble, to make capsids of, for example, different sizes for biotechnology applications.

病毒可能是地球上最成功的病原体。它们无处不在，并且感染所有其他类型的生物体，包括植物、动物（包括人类）、真菌、所有类型的细菌，甚至其他病毒。无论我们在哪里寻找它们，都可以找到它们。因此，它们具有巨大的社会重要性，直接影响我们的生活，因为它们对人类和动物健康、农业以及真正全球范围内的粮食安全产生影响。所有病毒都面临着一个共同的挑战，因为它们必须将其基因组信息（DNA 或 RNA）包装在称为衣壳的保护性容器内，衣壳保护基因组免受外部环境的影响，并将其完整地传递到新细胞中以启动新的细胞。一轮感染。制造这些衣壳的一种方法是用单一类型的蛋白质构建高度对称的容器。然而，要做到这一点，单一类型的蛋白质必须采用多种形状来构建合适尺寸的容器——就像制作足球所需的六边形和五边形一样。构建正确的衣壳，并完美地构建它，是病毒复制周期的基本组成部分，但我们对这种“构象转换”如何发生的理解非常贫乏。发生这种情况的一种方式是蛋白质与基因组 DNA 或 RNA 内的特定序列结合；这种结合将驱动构象变化。然而，人们对这个过程知之甚少。在某种程度上，这是因为对于绝大多数病毒来说，衣壳具有上述非常高的对称性，这意味着当我们解析它们的结构时，对称性平均会消除蛋白质之间任何特定相互作用的细节（每个病毒的衣壳都是相同的）。位置）和 DNA 或 RNA（不是，因为它必须具有编码病毒基因的独特序列）。因此，当我们试图研究组装所涉及的分子机制时，许多病毒所依赖的高度对称性是非常无益的。在这个提案中，我们希望利用我们实验室最近的两项非常令人兴奋的发现，这将使我们能够克服这一障碍，并首次发现允许这些病毒有效自组装的神秘规则。我们一直在研究两个不同的病毒家族，它们都是全球粮食和纺织作物的重要病原体，因此对发达国家和发展中国家的粮食安全和农业经济构成重大威胁；双生病毒和伞病毒。在每种病毒中，病毒都进化出了一种（不同的）新颖的创新，这意味着衣壳具有“非标准”结构，不再像通常情况那样对称。值得注意的是，在我们用 5 重对称（而不是二十面体病毒的 60 重对称）解出的每个结构的初步结构中，我们现在可以看到 DNA（对于双子病毒）和 RNA（对于伞病毒）结合的细节。病毒外壳蛋白。这项拨款申请将使我们能够解决这些非标准病毒衣壳的高分辨率结构，而无需任何对称性平均。结合生化和生物信息学实验，我们将揭示基因组结合的细节，它如何改变蛋白质构象，以及这些特征在病毒基因组中的位置。这将（a）提供令人着迷的新的基本生物学见解，这对于理解病毒如何发挥作用非常重要，（b）提供一种机制理解，可能导致找到阻止病毒发挥作用的新方法，以及（c）明确病毒组装的规则，可以让我们改变病毒的组装方式，例如为生物技术应用制造不同尺寸的衣壳。