Characterization of an African swine fever virus 20-kDa DNA polymerase involved in DNA repair

J Biol Chem. 1997 Dec 5;272(49):30899-910. doi: 10.1074/jbc.272.49.30899.


African swine fever virus (ASFV) encodes a novel DNA polymerase, constituted of only 174 amino acids, belonging to the polymerase (pol) X family of DNA polymerases. Biochemical analyses of the purified enzyme indicate that ASFV pol X is a monomeric DNA-directed DNA polymerase, highly distributive, lacking a proofreading 3'-5'-exonuclease, and with a poor discrimination against dideoxynucleotides. A multiple alignment of family X DNA polymerases, together with the extrapolation to the crystal structure of mammalian DNA polymerase beta (pol beta), showed the conservation in ASFV pol X of the most critical residues involved in DNA binding, nucleotide binding, and catalysis of the polymerization reaction. Therefore, the 20-kDa ASFV pol X most likely represents the minimal functional version of an evolutionarily conserved pol beta-type DNA polymerase core, constituted by only the "palm" and "thumb" subdomains. It is worth noting that such an "unfingered" DNA polymerase is able to handle templated DNA polymerization with a considerable high fidelity at the base discrimination level. Base excision repair is considered to be a cellular defense mechanism repairing modified bases in DNA. Interestingly, the fact that ASFV pol X is able to conduct filling of a single nucleotide gap points to a putative role in base excision repair during the ASFV life cycle.

Publication types

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

MeSH terms

  • African Swine Fever Virus / enzymology*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Crystallography, X-Ray
  • DNA Repair*
  • DNA, Viral / physiology*
  • DNA-Directed DNA Polymerase / chemistry*
  • DNA-Directed DNA Polymerase / metabolism
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Molecular Weight
  • Protein Conformation
  • Sequence Alignment


  • DNA, Viral
  • DNA polymerase X
  • DNA-Directed DNA Polymerase