Comparative studies of T = 3 and T = 4 icosahedral RNA insect viruses
Crystallographic and molecular biological studies of T = 3 nodaviruses (180 identical subunits in the particle) and T = 4 tetraviruses (240 identical subunits in the particle) have revealed similarity in both the architecture of the particles and the strategy for maturation. The comparative studies provide a novel opportunity to examine an apparent evolution of particle size, from smaller (T = 3) to larger (T = 4), with both particles based on similar subunits. The BBV and FHV nodavirus structures are refined at 2.8 Å and 3 Å respectively, while the NωV structure is at 6 Å resolution. Nevertheless, the detailed comparisons of the noda and tetravirus X-ray electron density maps show that the same type of switching in subunit twofold contacts is used in the T = 3 and T = 4 capsids, although differences must exist between quasi and icosahedral threefold contacts in the T = 4 particle that have not yet been detected. The analyses of primary and tertiary structures of noda and tetraviruses show that NωV subunits undergo a post assembly cleavage like that observed in nodaviruses and that the cleaved 76 C-terminal residues remain associated with the particle.
KeywordsCoat Protein Capsid Protein Sindbis Virus Icosahedral Symmetry Tomato Bushy Stunt Virus
Unable to display preview. Download preview PDF.
- 6.Prasad BVV (1992) The structure of a calcivirus by cryo-electron microscopy (pers. comm.)Google Scholar
- 7.Hendry DA (1991) Nodaviridae of invertebrates. In: Kurstak E (ed) Viruses of invertebrates. Marcel Dekker, New York, pp 227–276Google Scholar
- 8.Moore NF (1991) The Nudaurelia β family of insect viruses. In: Kurstak E (ed) Viruses of invertebrates. Marcel Dekker, New York, pp 277–285Google Scholar
- 9.Newman JFE, Brown F (1977) Further physicochemical characterization of Nodamura virus. Evidence that the divided genome occurs in a single component. J Gen Virol 38: 83–95Google Scholar
- 21.Reinganum C (1991) Tetraviridae. In: Adams JR, Bonami JR (eds) Atlas of invertebrate viruses. CRC Press, Boca Raton, pp 387–392Google Scholar
- 24.Johnson JE, Fisher AJ (1993) Principles of virus structure. In: Webster RG, Granoff A (eds) Encyclopedia of virology. Academic Press, London, in pressGoogle Scholar
- 27.Williams R (1979) The geometrical foundation of natural structure. Dover, New YorkGoogle Scholar
- 29.von Bonsdorff C, Harrison S (1975) Sindbis virus glycoproteins form a regular icosahedral surface lattice. J Virol 16: 141–145Google Scholar
- 32.Sehnke P, Harrington M, HosurM, Li Y, Usha R, Tucker R, BomuW, Stauffacher C, Johnson J (1988) Crystallization of viruses and virus proteins. J Crystal Growth 90: 222–230. 35Google Scholar
- 35.Zlotnick A, Reddy V, Schneemann A, Dasgupta R, Rueckert R, Johnson J (1993) A buried aspartic acid catalyzes autoproteolytic maturation in a family of insect viruses (in prep. )Google Scholar
- 39.Baker T, Drak J, Bina M (1988) Reconstruction of the three dimensional structure of Simian virus 40 and visualization of the chromatin core. Proc Natl Acad Sci USA 422–426Google Scholar