Assemblages of simian virus 40 capsid proteins and viral DNA visualized by electron microscopy

Vered Roitman-Shemer, Jitka Stokrova, Jitka Forstova, Ariella Oppenheim*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

SV40 assembles in the nucleus by addition of capsid proteins to the minichromosome. The VP15VP2/3 capsomer is composed of a pentamer of the major protein VP1 complexed with a monomer of a minor protein, VP2 or VP3. In the capsid, the capsomers are bound together via their flexible carboxy-terminal arms. Our previous studies suggested that the capsomers are recruited to the packaging signal ses via avid interaction with Sp1. During assembly Sp1 is displaced, allowing chromatin compaction. Here we investigated the interactions in vitro of VP15VP2/3 capsomers with the entire SV40 genome, using mutant VP1 deleted in the carboxy-arm that cannot assemble, but retains DNA-binding capacity. EM revealed that VP15VP2/3 complexes bind non-specifically at random locations around the DNA. Sp1 was absent from mature virions. The findings suggest that multiple capsomers attach simultaneously to the viral genome, increasing their local concentration, facilitating rapid, concerted assembly reaction and removal of Sp1.

Original languageEnglish
Pages (from-to)424-430
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume353
Issue number2
DOIs
StatePublished - 9 Feb 2007

Keywords

  • Capsid proteins
  • DNA spreads
  • Electron microscopy
  • Protein-DNA interactions
  • SV40

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