Structures of T = 1 and T = 3 Particles of Cucumber Necrosis Virus: Evidence of Internal Scaffolding

Citation

Katpally, U., Kakani, K., Reade, R., Dryden, K., Rochon, D., Smith, T.J. (2007). Structures of T = 1 and T = 3 Particles of Cucumber Necrosis Virus: Evidence of Internal Scaffolding. Journal of Molecular Biology, [online] 365(2), 502-512. http://dx.doi.org/10.1016/j.jmb.2006.09.060

Abstract

Cucumber necrosis virus (CNV) is a member of the genus Tombusvirus,1,2 of which tomato bushy stunt virus (TBSV) is the type member. The capsid protein for this group of viruses is composed of three major domains: the R domain, which interacts with the RNA genome: the S domain, which forms the tight capsid shell: and the protruding P domain, which extends ∼40 Å from the surface.3 Here, we present the cryo-transmission electron microscopy structures of both the T = 1 and T = 3 capsids to a resolution of ∼12 Å. The T = 3 capsid is essentially identical with that of TBSV, and the T = 1 particles are well described by the A subunit pentons from TBSV. Perhaps most notable is the fact that the T = 3 particles have an articulated internal structure with two major internal shells, while the internal core of the T = 1 particle is essentially disordered. These internal shells of the T = 3 capsid agree extremely well in both dimension and character with published neutron-scattering results. This structure, combined with mutagenesis results in the accompanying article, suggests that the R domain forms an internal icosahedral scaffold that may play a role in T = 3 capsid assembly. In addition, the N-terminal region has been shown to be involved in chloroplast targeting.4 Therefore, this region apparently has remarkably diverse functions that may be distributed unevenly among the quasi-equivalent A, B, and C subunits. Crown Copyright © 2006.

Publication date

2007-01-12

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