Okada Y, Ohno T, Nonomura Y
J Biochem. 1975 Jun;77(6):1157-63.
The in vitro assembly reaction of tobacco mosaic virus (TMV), especially the elongation process of partially reconstituted RNA (PRR) by protein subunits, was observed by electron microscopy. After addition of TMV-protein subunits, the PRR appeared as rods with a clump at one end, believed to be a complex between added protein subunits and the RNA tail protruding from PRR. The subunits entrapped on the RNA tails in the forms of clumps were progressively incorporated into the growing rods on incubation, ending with the formation of completely reconstituted rods. The clumps were also observed after addition of cucumber green mottle mosaic virus (CGMMV) protein subunits to rods partially reconstituted from RNA and TMV-protein. In this case, the protein subunits, seen as clumps, did not become incorporated to form elongating rods. An improved model for the elongation of TMV rods is proposed. The elongation process is composed of two steps, with the first step being the interaction of protein subunits with the RNA tail protruding from the growing rod. Any protein having a specific binding site for TMV-rna, not limited to TMV-protein, will react in the first step. The second step is the incorporation of the protein on the RNA tail into a rod-shaped structure, with consequent elongation of the growing rod. It appears that only protein homologous with that in the partially reconstituted rods can partake in the second step.
通过电子显微镜观察了烟草花叶病毒（TMV）的体外组装反应，特别是蛋白质亚基对部分重构RNA（PRR）的延伸过程。添加TMV蛋白质亚基后，PRR呈现为一端有团块的杆状结构，据信这是添加的蛋白质亚基与从PRR伸出的RNA尾巴之间形成的复合物。孵育时，以团块形式包裹在RNA尾巴上的亚基逐渐整合到正在生长的杆状结构中，最终形成完全重构的杆状结构。向由RNA和TMV蛋白质部分重构的杆状结构中添加黄瓜绿斑驳花叶病毒（CGMMV）蛋白质亚基后，也观察到了团块。在这种情况下，被视为团块的蛋白质亚基并未整合形成延伸的杆状结构。提出了一种改进的TMV杆状结构延伸模型。延伸过程由两个步骤组成，第一步是蛋白质亚基与从正在生长的杆状结构伸出的RNA尾巴相互作用。任何对TMV-RNA具有特异性结合位点的蛋白质，不限于TMV蛋白质，都会在第一步发生反应。第二步是将RNA尾巴上的蛋白质整合到杆状结构中，从而使正在生长的杆状结构延长。似乎只有与部分重构杆状结构中的蛋白质同源的蛋白质才能参与第二步。
