Analysis of assembly mechanism of spherical virus based on its high resolution three-dimensional structure

Tobacco necrosis virus （TNV） is a spherical virus that contains ss-RNA （1.3 x10） as a genome。TNV causes such plants as C. Quinoa和Tulip非正式课程。TNV涂层蛋白有276种氨基酸溶液;氨基酸序列是由肽和DNA测序的组合确定的。180份蛋白质汇编副本，制成T=3个珊瑚壳。Thus， the virus shell has three stereochemically independent subunits （A， B and C） with identical primary structure. TNV crystalliized in space group P4イイD22イエD232， with a= 336. 4.单元格包含两个TNV粒子。TNV crystals的Diffraction data were collected to 2. 25 resolution using synchotron radiation and Weissenberg camera for macromolecules at BL6A， Photon Factory， Tsukuba。该结构由XPLOR将非晶体学单元的电子密度配置成R= 25.3%，该单元有一个折叠的果冻卷β-桶。N终端86、87和56的A、B和C子单元被禁用。仅在C子单元（臂）中生产子单元交互的多样性;子单元表格五折轴上的五折轴上的B单元和C子单元表格六折手在二折轴上，C子单元表格三折轴上的三折轴上的三折臂在C子单元表格中的三折轴上。每一个伊科萨赫德拉尔非对称单元的五个钙离子已被识别。它们位于子单元界面上。

Tobacco necrosis virus (TNV) is a spherical virus that contains ss-RNA (1.3x10ィイD16ィエD1 Da) as a genome. TNV causes such plants as C. quinoa and tulip necrotic lesions. TNV coat protein has 276 amino acid residues; the amino acid sequence was determined by a combination of peptide and DNA sequencing. 180 copies of the protein assemble to form T=3 icosahedral shell. Thus, the virus shell has three stereochemically independent subunits (A, B and C) with identical primary structure.TNV crystallized in space group P4ィイD22ィエD232, with a=336.4Å. Unit cell contains two TNV particles. Diffraction data of TNV crystals were collected to 2.25Å resolution using synchotron radiation and Weissenberg camera for macromolecules at BL6A, Photon Factory, Tsukuba. The structure was solved by averaging the electron density of non-crystallographic units and refined by XPLOR to R=25.3%.The subunits have a fold of jelly roll β-barrel. Respective N-terminal 86, 87 and 56 residues of A,B and C subunits are disordered. The segment ordered only in C subunit (arm) produces diversity of the subunit interactions; A subunits form pentermers at five-fold axis, whereas B and C subunits form hexamers at icosahedral three-fold axis, where three arms of C-subunits form a β-annulus. Five calcium ion per icosahedral asymmetric unit were identified. These are located at the subunit interfaces.