Assembly of Picornaviral Replication Complexes

描述（由申请人提供）：小核糖核酸病毒是一个小的正义单链RNA病毒家族，其引起广泛的疾病，每年的费用高达数亿美元。成员包括急性甲型肝炎病毒，导致心脏病的科萨基B3病毒，鼻病毒，导致超过一半的普通感冒，以及麻痹性脊髓灰质炎病毒。这些病毒具有共同的生命周期，其中它们的RNA复制和病毒组装发生在组装在来自内质网的囊泡表面上的大的膜锚定复制复合物中。复制过程由病毒编码的RNA依赖性RNA聚合酶（3Dpol蛋白）驱动，该蛋白负责所有病毒RNA的合成。像所有的小核糖核酸病毒蛋白一样，聚合酶是由单个大病毒多蛋白的蛋白水解裂解产生的。越来越多的证据表明，在几种小核糖核酸病毒中，聚合酶及其直接前体直接负责这些复制中心的组装。脊髓灰质炎病毒的3Dpol聚合酶是研究得最好的小核糖核酸病毒，已经显示出沿着蛋白质-蛋白质界面沿着组装成大的片层结构，该蛋白质-蛋白质界面最初在3Dpol的部分晶体结构中鉴定。我们已经在2.0 A分辨率下解决了3Dpol的完整晶体结构，并发现该酶需要一个游离的N-末端来正确折叠活性位点，为聚合酶的加工依赖性激活提供了分子基础。我们正在通过进一步表征3Dpol的构象灵活性并扩展到确定蛋白质-蛋白质界面在3CDpro和其他前体蛋白质组装中的作用来继续脊髓灰质炎病毒蛋白质的结构研究。这些结果将对这组重要病原体的复制产生根本性的见解。

DESCRIPTION (provided by applicant): The picornaviruses are a family of small positive sense single stranded RNA viruses that cause a wide range of diseases at an annual cost well into the hundreds of million dollars. Members include acute hepatitis A virus, the heart disease-causing coxsackie B3 virus, rhinoviruses that cause more than half the occurrences of the common cold, and the paralyzing poliovirus. These viruses share a common life cycle where their RNA replication and viral assembly occurs in large membrane anchored replication complexes assembled on the surfaces of vesicles derived from the endoplasmic reticulum. The replication process is driven by a virally encoded RNA dependent RNA polymerase, the 3Dpol protein, that is responsible the synthesis of all viral RNA. Like all picornaviral proteins, the polymerase is generated by proteolytic cleavage of a single large viral polyprotein. There is mounting evidence in several picornaviruses that the polymerase and its immediate precursors are directly responsible for the assembly of these replication centers. The 3Dpol polymerase of poliovirus, the best studied of the picornaviruses, has been shown to assemble into large sheet structures along a protein-protein interface that was initially identified in a partial crystal structure of 3Dpol. We have solved the complete crystal structure of 3Dpol at 2.0 A resolution and discovered that the enzyme requires a free N-terminus to properly fold the active site, providing a molecular basis for the processing dependent activation of the polymerase. We are continuing our structural studies of the poliovirus proteins by further characterizing the conformational flexibility of 3Dpol and expanding into determining the role of protein-protein interfaces in the assembly of 3CDpro and other precursor proteins. The results will yield fundamental insights into the replication of this important group of pathogens.