Characterization of an African swine fever virus 20-kDa DNA polymerase involved in DNA repair.
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.
Oliveros
M
M
Centro de Biología Molecular "Severo Ochoa" (C.S.I.C.-U.A.M.), Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain.
Yáñez
R J
RJ
Salas
M L
ML
Salas
J
J
Viñuela
E
E
Blanco
L
L
D000358:African Swine Fever Virus / Q000201:enzymology*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018360:Crystallography, X-Ray; D004260:DNA Repair; D004279:DNA, Viral / Q000502:physiology*; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011487:Protein Conformation; D016415:Sequence Alignment
D004279:DNA, Viral; C109534:DNA polymerase X; D004259:DNA-Directed DNA Polymerase