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The gene encoding the major viral structural protein stimulates recombination in polyomavirus DNA

M Bélanger1, S Charbonneau, D Gendron

  • 1Department of Microbiology and Infectious Diseases, Université de Sherbrooke, Sherbrooke, Québec, J1H 5N4, Canada.

Virology
|July 5, 2001
PubMed

Insights

A novel chimeric DNA molecule, RmI, encodes a unique polypeptide (VmP1) essential for releasing infectious polyoma DNA. This VmP1 protein, distinct from VP1, facilitates DNA release, suggesting a new role in viral replication.

Area of Science:

  • Molecular Biology
  • Virology
  • Genetics

Background:

  • The RmI molecule is a chimeric DNA construct based on the polyoma genome.
  • It contains a duplicated VP1-coding region and an insert of murine DNA (Ins).
  • RmI undergoes intramolecular recombination in mouse cells to produce infectious, unit-length polyoma DNA.

Purpose of the Study:

  • To investigate the function of the polypeptide encoded by RmI.
  • To determine the role of this polypeptide in the release of polyoma DNA.
  • To elucidate the mechanism of DNA release and its relation to viral replication.

Main Methods:

  • Transfection of RmI into mouse cells.
  • Site-directed mutagenesis of the VmP1-coding sequence and the VP1-coding sequence.
  • Analysis of polyoma DNA yield and infectivity post-transfection.

Main Results:

  • RmI encodes a 337-amino acid polypeptide, VmP1, comprising the N-terminal 328 amino acids of VP1 and 9 amino acids from Ins.
  • Mutations in the VmP1-coding sequence significantly reduce polyoma DNA yield.
  • Mutations in the non-VmP1 portion of the VP1-coding sequence do not affect DNA yield but abolish infectivity.

Conclusions:

  • The release of polyoma DNA from RmI requires a function of VmP1 distinct from VP1's role in virus assembly.
  • VmP1, arising post-recombination, likely mediates this DNA release function.
  • VmP1 may act in conjunction with VP2 to stimulate recombination and facilitate DNA release.

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