ASTROVIRUS NONSTRUCTURAL PROTEINS

人类星状病毒(H-Ast)是一个重要的新的 感染胃肠道的核糖核酸病毒家族。《6.8》 H-Ast的KB正义RNA基因组是以非结构方式组织的 ORF 1a和1b在5‘端编码的蛋白质和衣壳 3‘端由ORF-2编码的蛋白质(S)。序列分析表明， ORF-1a编码一个类似3C的丝氨酸蛋白酶基序和一个核 定位信号(NLS)。ORF-1b编码依赖于RNA的RNA 聚合酶(RdRp)基序，其翻译依赖于(-1) 核糖体在重叠区发现的特定信号的移码 在ORF-1a和-1b之间。通过这种机制，RdRp被表示为 1a/1b多聚蛋白的一部分，必须进一步加工才能 功能齐全。我们的项目重点是确定病毒NSP是如何 加工成功能子单元，并将它们定位在 被感染的细胞。我们假设推定的类似3C的病毒 丝氨酸蛋白酶由ORF-Ia编码，负责切割 ORF-1 a编码产物和1a/1b多聚蛋白为功能亚基， 这些裂解产物中的一些是通过 一种功能性的NLS，是1a蛋白的一部分。我们的具体目标是： 1)确定病毒编码的蛋白水解酶在 非结构基因产物的加工和2)表征 病毒非结构蛋白的亚细胞定位。这些 研究将提供有关处理的重要新信息 H-Ast非结构蛋白及其亚细胞定位。 这些数据应该有助于我们理解病毒复制 最终，病毒的致病机制。

Human astroviruses (H-Ast) are the prototype members of an important new family of RNA viruses that infect the gastrointestinal tract. The 6.8 kb positive sense RNA genome of H-Ast is organized with nonstructural proteins encoded at the 5' end by ORFs 1a and 1b, and the capsid protein(s) by ORF-2 at the 3' end. Sequence analysis indicates that ORF-1a encodes a 3C-like serine protease motif and a nuclear localization signal (NLS). ORF-1b encodes an RNA-dependent RNA polymerase (RdRp) motif, and its translation is dependent on (-1) ribosomal frameshifting at a specific signal found in the overlap region between ORF-1a and -1b. By this mechanism, the RdRp is expressed as part of a 1a/1b polyprotein that must be processed further to be functional. Our project focuses on determining how the viral NSPs are processed into functional subunits and where they are localized within the infected cell. We hypothesize that the putative viral 3C-like serine protease, encoded by ORF- I a, is responsible for cleavage of the ORF-1 a encoded product and 1a/1b polyprotein into functioning subunits, and that some of these cleavage products are directed to the nucleus by a functional NLS that is part of the 1a protein. Our specific aims are: 1) characterizating the role of the virally encoded protease in processing of the nonstructural gene products and 2) characterizing the subcellular localization of the viral nonstructural proteins. These studies will provide significant new information on the processing of the H-Ast nonstructural proteins and their subcellular localization. These data should contribute to our understanding of viral replication and ultimately, viral pathogenesis.