The Pro/Hel region is indispensable for packaging non-replicating turnip yellow mosaic virus RNA, but not replicating viral RNA

Mol Cells. 2010 May;29(5):463-9. doi: 10.1007/s10059-010-0057-4. Epub 2010 Apr 12.

Abstract

Turnip yellow mosaic virus (TYMV) is a spherical plant virus that has a single 6.3 kb positive strand RNA. The genomic RNA has a tRNA-like structure (TLS) at the 3'-end. The 3'-TLS and hairpins in the 5'-untranslated region supposedly serve as packaging signals; however, recent studies have shown that they do not play a role in TYMV RNA packaging. In this study, we focused on packaging signals by examining a series of deletion mutants of TYMV. Analysis of encapsidated viral RNA after agroinfiltration of the deletion constructs into Nicotiana benthamiana showed that the mutant RNA lacking the protease (Pro)/helicase (Hel) region was not encapsidated by the coat proteins provided in trans, implicating that a packaging signal lies in the Pro/Hel region. Examination of two Pro(-)Hel(-) mutants showed that protein activity from the Pro/Hel domains was dispensable for the packaging of the non-replicating TYMV RNA. In contrast, the mutant TYMV RNA lacking the Pro/Hel region was efficiently encapsidated when the mutant TYMV was co-introduced with a wild-type TYMV, suggesting that packaging mechanisms might differ depending on whether the virus is replicating or not.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cloning, Molecular
  • Peptide Hydrolases / genetics
  • Peptide Hydrolases / metabolism*
  • Plant Extracts
  • RNA Helicases / genetics
  • RNA Helicases / metabolism*
  • RNA Virus Infections / genetics*
  • RNA Virus Infections / virology
  • RNA, Viral / analysis*
  • Sequence Deletion / genetics
  • Tobacco / virology
  • Tymovirus / physiology*
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*
  • Virus Assembly
  • Virus Replication*

Substances

  • Plant Extracts
  • RNA, Viral
  • Viral Proteins
  • Peptide Hydrolases
  • RNA Helicases