Uncoating of a Helical Virus: Cotranslational and Coreplicational Disassembly Mechanisms

Shaw(肯塔基大学)EPSCoR 9726966揭开螺旋病毒的外壳：共翻译和共复制的分解机制1.动物或植物病毒感染过程的所有阶段的技术，病毒基因组的剥离或病毒颗粒的分解是最不被了解的之一。这项研究检测了烟草花叶病毒(TMV)，因为它的正义RNA基因组被包裹在杆状颗粒中。烟草花叶病毒粒子被导入植物原生质体后进行双向分解。病毒RNA最初在5‘到3’方向上没有被包被，这个过程是通过去除3‘到5’方向上的外壳蛋白分子(亚单位)来完成的。为了解释双向拆解，提出了两个假设：(1)体内剥离开始于共翻译拆解机制，在该机制中，在5‘到3’方向的亚基的去除与病毒RNA的第一个ORF的翻译期间的核糖体移位一致；(2)在体内的剥离是通过共复制的拆解机制完成的，其中病毒聚合酶蛋白(由第一个ORF和/或其通读序列编码)参与了3‘到5’方向的亚基的去除和后代负链和病毒RNA分子的合成。通过确定各种烟草花叶病毒突变体的行为来检验这些假设。还将探索聚合酶蛋白中不参与复制的区域可能是3‘到5’拆解所必需的。这项研究的意义在于它试图了解生命的一个阶段，在这个阶段，病毒在宿主细胞中引发感染的最终成功或失败被决定。2.烟草花叶病毒(TMV)的非技术性颗粒在接种的植物细胞中分解，使基因组得以释放，从而使后代病毒颗粒的产生得以进行，诱导寄主机体处于致病状态。在这个过程中，大约75%的亚基首先被顺序地从病毒基因组的一端开始移除，其余的则从另一端开始移除。第一步可能涉及病毒蛋白质的伴随合成，另一步可能涉及病毒RNA拷贝的产生。实验旨在检验每一种假设机制的有效性。

Shaw (University of Kentucky) EPSCOR 9726966 Uncoating of a Helical Virus: Cotranslational and Coreplicational Disassembly Mechanisms 1. Technical Of all the stages of the infection process by an animal or plant virus, uncoating of the viral genome or disassembly of the virus particle is one of the least understood. This study examines tobacco mosaic virus (TMV), as its positive-sense RNA genome is enclosed (encapsidated) in rod-shaped particles. TMV particles undergo bidirectional disassembly after being introduced into plant protoplasts. The viral RNA is initially uncoated in the 5'-to-3' direction and the process is completed by the removal of coat protein molecules (subunits) in the 3'-to-5' direction. Two hypotheses are set forth to account for the bidirectional disassembly: (1) in vivo uncoating begins by a cotranslational disassembly mechanism in which the removal of subunits in the 5'-to-3' direction is coincident with ribosome translocation during translation of the first ORF of the viral RNA; (2) in vivo uncoating is completed by a coreplicational disassembly mechanism in which the viral polymerase proteins (encoded by the first ORF and/or its readthrough sequence) are involved in the removal of subunits in the 3'-to-5' direction and the synthesis of progeny minus-strand viral RNA molecules. These hypotheses are tested by determining the behavior of various TMV mutants. The possibility that regions in the polymerase proteins that are not involved in replication may be required for 3'-to-5' disassembly will also be explored. The significance of this study lies in its atttempt to understand a stage of life in which the ultimate success or failure of a virus to initiate infection in host cells is determined. 2. Non-technical Particles of tobacco mosaic virus (TMV) disassemble in inoculated plant cells, which allows the genome to be released so that the production of progeny virus particles can proceed, inducing the pathogenic state in the host organism. In this process, about 75% of the subunits is first removed, sequentially, beginning at one end of the viral genome; the remainder is then removed proceeding from the other end. The first step may involve concomitant synthesis of viral proteins, and the other may involve the production of copies of the viral RNA. Experiments are designed to examine the validity of each of these hypothetical mechanisms.