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

Umesh Katpally, Kishore Kakani, Ron Reade, Kelly Dryden, D'Ann Rochon, Thomas J. Smith

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


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

Original languageEnglish (US)
Pages (from-to)502-512
Number of pages11
JournalJournal of Molecular Biology
Issue number2
StatePublished - Jan 12 2007
Externally publishedYes


  • cryo-TEM
  • cucumber necrosis virus
  • scaffold
  • structure
  • virus

ASJC Scopus subject areas

  • Molecular Biology
  • Biophysics
  • Structural Biology


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