CARDIOVIRAL PROTEASES AND GENOME STRUCTURE

小核糖核酸病毒已经进化出强大而有效的机制， 表达它们的蛋白质。新型内部核糖体进入位点 允许基因组绕过5'端的正常翻译要求， 帽结构，并有效地引诱核糖体进入病毒，而不是 细胞通路被捕获的核糖体传递一个单一的，长的 ORF，创造了多聚蛋白，这些多聚蛋白实际上是所有 感染所必需的结构和酶单位。个人 蛋白质片段被同时释放和后释放， 在蛋白水解级联反应中，蛋白水解级联反应是 这个家不少于三种病毒编码的催化实体， 所需的完整处理，其中没有一个有一个确切的细胞 模拟很明显，病毒生命周期的各个方面都是 如果不是由切割位点的速率决定的话， 是由这些酶和自催化机制处理的。 的in 已知背景和结构的体内细微差别会施加关键的 调节蛋白质的有序释放， 传染周期。对这些通道的撞击总是致命的， 尽管有时候是由于研究成熟的 病毒蛋白或RNA。这个节目的重点是鼠 心脏病毒、脑心肌炎病毒（EMCV）和孟戈病毒。的 心脏病毒RNA促进有效翻译的特殊倾向 在无细胞提取物和显着的亲和力的处理 在这些反应中级联，是这些基因组的标志， 使这些分离物成为非常有用的实验对象， 小核糖核酸病毒生命周期的分子解剖。这个的目标 调查是为了探索和确定的关系 小核糖核酸病毒科的其他成员，以及 利用心脏病毒的独特特征来检查基本的 关于小核糖核酸病毒翻译、蛋白水解 加工和形态发生。具体目的是：（1）探讨 合成和天然前导蛋白的翻译结果 突变一IRES依赖性蛋白在体内的表达。(2)到 评估缺陷2A序列和“伪”原发性的作用 在衣壳区加工的致死废除中的切割反应 途径。(3)探索3C催化加工的要求 在VPg依赖的RNA合成起始事件。(4)映射 并定义心脏病毒内的序列和结构元件 3'UTR是翻译、复制和感染所必需的。

The picornavirus have evolved robust and effective mechanisms to express their proteins. Novel internal ribosomal entry sites (IRESes) allow the genomes to bypass normal translational requirements for 5' cap structures, and efficiently lure the ribosomes into viral instead of cellular pathways. The captured ribosomes pass down a single, long ORF, creating polyproteins that are in reality, tandem linkages of all structural and enzymatic units necessary for infection. The individual protein fragments are liberated co-translationally and post- translationally in a proteolytic cascade that is a defining feature of this family. No fewer than three viral encoded catalytic entities are required for complete processing, none of which has an exact cellular analogue. It is clear that all aspects of the viral life cycle are influenced if not determined by the rates at which the cleavage sites are processed by these enzymes and autocatalytic mechanisms. The in vivo nuances of context and structure are known to impose critical regulatory roles governing the orderly release of proteins throughout the infectious cycle. Impingement on these pathways is invariably fatal, though sometimes for reasons not anticipated from study of mature viral protein or RNA. This program focuses on the murine cardioviruses, encephalomyocarditis virus (EMCV) and Mengovirus. The special propensity of cardiovirus RNAs to facilitate efficient translation in cell-free extracts and the remarkable avidity of the processing cascade during these reactions, are hallmarks of these genomes, and make these isolates exceptionally useful experimental subjects for molecular dissection of the picornavirus life cycle. The goals of this investigation are to explore and define the relationship of the cardiovirus genus to other members of the picornavirus family, and to exploit the unique features of cardioviruses to examine fundamental molecular questions about picornaviral translation, proteolytic processing and morphogenesis. The specific aims are: (1) to probe the translational consequences of synthetic and natural leader protein mutations one IRES-dependent protein expression in vivo. (2) To evaluate the role of defective 2A sequences and "pseudo" primary cleavage reactions in the lethal abrogation of capsid region processing pathways. (3) To explore the requirements for 3C catalyzed processing events in the VPg-dependent initiation of RNA synthesis. (4) To map and define the sequence and structural elements within the cardioviral 3'UTR that are required for translation, replication and infectivity.