|Budget Amount *help
¥3,500,000 (Direct Cost : ¥3,500,000)
Fiscal Year 1999 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Fiscal Year 1998 : ¥2,200,000 (Direct Cost : ¥2,200,000)
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.