A DNA ligase gene in the Copenhagen strain of vaccinia virus is nonessential for viral replication and recombination

Virology. 1990 Nov;179(1):267-75. doi: 10.1016/0042-6822(90)90295-3.

Abstract

Biochemical and genetic analyses have been conducted to determine whether a vaccinia virus open reading frame (orf) with extensive homology to the Saccharomyces cerevisiae DNA ligase gene encodes a functional ligase activity. This orf in HindIII A, designated A50R, is capable of encoding a 552-amino-acid, 63.4-kDa polypeptide. Full-length A50R mRNA produced in vitro directed the synthesis of a polypeptide with an apparent molecular weight of 57 kDa. Significantly, translation reactions programmed with A50R mRNA were capable of ligating a 3-kb Notl restriction fragment into multimers. DNA ligase activity was not detectable when either truncated sense or full-length antisense mRNA was translated in vitro. In extracts prepared from cells infected with wt vaccinia virus, DNA ligase activity was detected as assayed by the formation of a 57 kDa ligase-AMP adduct which was expressed early in the viral replication cycle. In cells infected with a DNA ligase deletion mutant no equivalent AMP-labeled adduct was detected. Relative to wt virus, the DNA ligase deletion mutant exhibited no significant differences in homologous recombination. These results indicate that the vaccinia orf A50R encodes a functional DNA ligase expressed early in infection, but this DNA ligase is nonessential for either recombination or viral replication.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Chromosome Deletion
  • DNA Ligases / genetics*
  • DNA Ligases / metabolism
  • Denmark
  • Genes, Viral*
  • Molecular Sequence Data
  • Plasmids
  • Recombination, Genetic*
  • Restriction Mapping
  • Sequence Homology, Nucleic Acid
  • Transcription, Genetic
  • Vaccinia virus / enzymology
  • Vaccinia virus / genetics*
  • Vaccinia virus / physiology
  • Vero Cells
  • Viral Structural Proteins / genetics*
  • Virus Replication*

Substances

  • Viral Structural Proteins
  • DNA Ligases