Role of Cellular Factors in Enterovirus Protein Homeostasis and Function

项目总结(见说明)： 肠道病毒具有高复制率和极端序列可塑性的特点，这使得它们能够快速适应不同的环境和宿主。这些病毒完全依赖宿主蛋白的动态平衡机制，包括分子伴侣和质量控制(QC)组件，如泛素-蛋白酶体系统，以生产和发挥病毒蛋白。肠道病毒复制对细胞蛋白质稳态机制提出了几个挑战，因为在很短的时间内生产大量蛋白质的需要给宿主蛋白质生产和折叠机器带来了巨大的负担。 此外，肠道病毒蛋白往往是大的、复杂的和多功能的，因此可能需要分子伴侣的帮助才能折叠。事实上，我们已经证明，Hsp90伴侣系统对于许多，也许是大多数微小核糖核酸病毒，包括肠道病毒脊髓灰质炎和柯萨奇病毒的衣壳折叠和组装是必不可少的。由于肠道病毒复制的其他方面涉及额外的大型多蛋白复合体，因此很可能在病毒周期的其他方面广泛地需要伴侣。RNA病毒的蛋白质动态平衡面临的一个重要挑战是其极高的突变率，这对病毒蛋白质的稳定性造成了很大的负担，并可能产生高水平的无功能或不稳定的蛋白质。这些突变蛋白必须保持在功能状态或从细胞中消除，以防止对病毒功能的显性负面影响。我们假设，这些功能是由伴侣和泛素-蛋白酶体系统执行的，伴侣可以缓冲亚稳态蛋白，泛素-蛋白酶体系统针对错误折叠的蛋白进行降解。为了了解细胞伴侣和质量控制机制控制病毒蛋白稳态的分子和细胞机制，并允许病毒复制，我们提出了以下目标： 目的1：确定肠道病毒复制所需的伴侣成分。 目标2：确定质量控制(QC)机制在小核糖核酸病毒复制中的作用 目的3：研究病毒感染过程中分子伴侣和QC通路的可塑性和相互作用

PROJECT SUMMARY (See instructions): Enteroviruses are characterized by their high replication rates and extreme sequence plasficity, which allow them to rapidly adapt to different environments and hosts. These viruses depend entirely on the host protein homeostasis machinery, composed of molecular chaperones and quality control (QC) components such as the ubiquitin-proteasome system, for viral protein production and function. Enterovirus replication poses several challenges to the cellular protein homeostasis machinery as the need to produce high amounts of protein in a very short time places a big burden for the host protein production and folding machineries. Furthermore, enteroviral proteins tend to be large, complex and multifunctional, and thus likely to require the assistance of molecular chaperones to fold. Indeed, we have shown that the Hsp90 chaperone system is essential for capsid folding and assembly for many, perhaps most, picornaviruses, including the enterovirus polio- and coxsakie-viruses. Since other aspects of enterovirus replication Involve additional large multlprotein complexes, chaperones are likely to be broadly required for other aspects of the viral cycle. An important challenge to protein homeostasis in RNA viruses arises from their very high mutation rates, which pose a big burden to viral protein stability and are likely to produce high levels of non-functional or destabilized proteins. These mutant proteins must be either maintained in a funcfional state or eliminated from the cell to prevent dominant negative effects on viral function. We hypothesize that these functions are carried out by chaperones, which can buffer metastable proteins, as well as by the ubiquitin-proteasome system, which targets misfolded proteins for degradation. To understand the molecular and cellular mechanisms by which cellular chaperone and quality control machineries control viral protein homeostasis, and allow the virus to replicate we propose the following Aims: Aim 1: Define the chaperone components required for enterovirus replication. Aim 2: Define the role of the Quality control (QC) machinery in picornavirus replication Aim 3: Examine the plasticity and interplay of chaperone and QC pathways during viral infection