Asurmendi S, Berg R H, Koo J C, Beachy R N
Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA.
Proc Natl Acad Sci U S A. 2004 Feb 3;101(5):1415-20. doi: 10.1073/pnas.0307778101. Epub 2004 Jan 26.
The genome of tobacco mosaic virus (TMV) encodes replicase protein(s), movement protein (MP), and capsid protein (CP). On infection, one or more viral proteins direct the assembly of virus replication complexes (VRCs), in association with host-derived membranes. The impact of CP-mediated resistance on the structures of the replication complexes was examined in nontransgenic and transgenic BY-2 cell lines that produce wild-type CP, mutant CP(T42W), and Ds-Red, which was targeted to endoplasmic reticulum by using immunofluorescence and 3D microscopy. We developed a model of VRCs that shows a clear association of MP with and surrounding the endoplasmic reticulum. Replicase is located within the MP bodies, as well as isolated sites throughout the cell. CP surrounds the VRCs. CP enhances the production of MP and increases the size of the VRC; however, the mutant CP(T42W) reduces the amount of MP and interferes with the formation of VRCs. We propose a regulatory role of the CP in the establishment of the VRC. We suggest that the lack of formation of VRCs restricts the efficiency of virus replication and the formation of virus movement complexes, resulting in restriction of cell-cell spread of infection. This results in higher levels of plant CP-mediated protection provided by CP(T42W).
烟草花叶病毒（TMV）的基因组编码复制酶蛋白、运动蛋白（MP）和衣壳蛋白（CP）。在感染过程中，一种或多种病毒蛋白会指导病毒复制复合体（VRC）与宿主来源的膜结合进行组装。通过免疫荧光和三维显微镜技术，在产生野生型CP、突变型CP（T42W）和Ds-Red（其靶向内质网）的非转基因和转基因BY-2细胞系中，研究了CP介导的抗性对复制复合体结构的影响。我们构建了一个VRC模型，该模型显示MP与内质网及其周围有明显的关联。复制酶位于MP体内以及整个细胞中的孤立位点。CP围绕着VRC。CP增强了MP的产生并增加了VRC的大小；然而，突变型CP（T42W）减少了MP的量并干扰了VRC的形成。我们提出CP在VRC的形成中具有调节作用。我们认为VRC形成的缺乏限制了病毒复制的效率和病毒运动复合体的形成，导致感染的细胞间传播受到限制。这导致CP（T42W）提供了更高水平的植物CP介导的保护。
