Packaging and Structure of Viral Genomes

描述(申请人提供)：成熟病毒的形成是一个重要的研究领域，不仅因为我们对病毒本身的了解，而且因为病毒是简单的模型系统，用于阐明大分子复合体组装背后的基本原理。这项建议提出了一种模型和实验相结合的方法来研究两种小的、无包膜的二十面体病毒。噬菌体将它们的双链DNA基因组包装成预制的蛋白质衣壳，使用ATP驱动的马达来克服反对包装的静电、弹性和熵力。相比之下，单链RNA病毒自发组装，蛋白质衣壳在RNA基因组外部形成，不需要消耗能量。我们将继续研究噬菌体中DNA包装的结构和热力学方面的问题，重点是DNA-DNA和DNA-衣壳的相互作用，以及DNA的扭结。我们还将对在非病毒系统中反对DNA致密到高密度的力量进行调查。从这些努力中学到的原理将对理解基因组结构和调控原核和真核细胞中的基因表达具有重要意义。我们对RNA病毒的研究将包括开发卫星烟草花叶病毒(STMV)和副病毒(PAV)的改进三维模型；开发RNA病毒组装的建模方法；以及聚阳离子，特别是碱性多肽对RNA缩合的实验研究。关于RNA病毒的工作是基于这样的假设，即组装是由带正电荷的多肽和带负电荷的RNA之间强烈但非特异性的相互作用启动的，导致类似于浓缩DNA的坍塌聚集体，随后形成成熟的病毒。如果这一假设是正确的，则可以为新药设计策略提供基础。这一结果可能也适用于其他大型RNA-蛋白质组合体的形成。 与公共卫生相关的病毒导致许多人类疾病。了解它们是如何组装的将为开发新的抗病毒药物提供重要机会。此外，噬菌体(感染细菌的病毒)过去曾偶尔用于治疗人类的细菌感染。有关噬菌体组装的知识可能对设计新的抗菌剂很有帮助。

DESCRIPTION (provided by applicant): The formation of mature viruses is an important research area, not only because of what we learn about the viruses themselves, but because viruses are simple model systems for elucidating the fundamental principles behind the assembly of large macromolecular complexes. This proposal presents a combined modeling and experimental approach to the investigation of two kinds of small, unenveloped, icosahedral viruses. Bacteriophages package their double-stranded DNA genomes into preformed protein capsids, using an ATP-driven motor to overcome the electrostatic, elastic and entropic forces that oppose packaging. In contrast, single-stranded RNA viruses assemble spontaneously, with the protein capsid forming around the outside of the RNA genome without the expenditure of energy. We will continue our investigations of the structural and thermodynamic aspects of DNA packaging in bacteriophage, focusing our efforts on DNA-DNA and DNA-capsid interactions, and on DNA kinking. We will also undertake an investigation of the forces opposing the compaction of DNA to high density in non-viral systems. The principles learned from these efforts will have implications for the understanding of genome structures and the regulation of gene expression in both prokaryotic and eukaryotic cells. Our investigations on RNA viruses will include the develop of improved three-dimensional models for satellite tobacco mosaic virus (STMV) and pariacoto virus (PaV); the development of methods for modeling assembly of RNA viruses; and experimental investigations of the condensation of RNA by polycations, particularly basic polypeptides. The work on RNA viruses is based on the hypothesis that assembly is initiated by strong but nonspecific interactions between positively charged polypeptides and the negatively charged RNA, leading to a collapsed aggregate resembling condensed DNA, followed by the formation of the mature virus. If correct, this hypothesis could provide the basis for new drug design strategies. The results might well apply to the formation of other large RNA-protein assemblies as well. PUBLIC HEALTH RELEVANCE Viruses cause many human diseases. An understanding of how they are assembled would offer important opportunities for the development of new antiviral drugs. In addition, bacteriophage (viruses that infect bacteria) have been used occasionally in the past to treat bacterial infections in humans. Knowledge about bacteriophage assembly could prove useful in the design of new antibacterial agents.