Characterization of SpPol4, a unique X-family DNA polymerase in Schizosaccharomyces pombe

Nucleic Acids Res. 2005 Aug 24;33(15):4762-74. doi: 10.1093/nar/gki780. Print 2005.

Abstract

As predicted by the amino acid sequence, the purified protein coded by Schizosaccharomyces pombe SPAC2F7.06c is a DNA polymerase (SpPol4) whose biochemical properties resemble those of other X family (PolX) members. Thus, this new PolX is template-dependent, polymerizes in a distributive manner, lacks a detectable 3'-->5' proofreading activity and its preferred substrates are small gaps with a 5'-phosphate group. Similarly to Polmu, SpPol4 can incorporate a ribonucleotide (rNTP) into a primer DNA. However, it is not responsible for the 1-2 rNTPs proposed to be present at the mating-type locus and those necessary for mating-type switching. Unlike Polmu, SpPol4 lacks terminal deoxynucleotidyltransferase activity and realigns the primer terminus to alternative template bases only under certain sequence contexts and, therefore, it is less error-prone than Polmu. Nonetheless, the biochemical properties of this gap-filling DNA polymerase are suitable for a possible role of SpPol4 in non-homologous end-joining. Unexpectedly based on sequence analysis, SpPol4 has deoxyribose phosphate lyase activity like Polbeta and Pollambda, and unlike Polmu, suggesting also a role of this enzyme in base excision repair. Therefore, SpPol4 is a unique enzyme whose enzymatic properties are hybrid of those described for mammalian Polbeta, Pollambda and Polmu.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • DNA Nucleotidylexotransferase / metabolism
  • DNA Primers
  • DNA Repair
  • DNA-Directed DNA Polymerase / classification
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / metabolism*
  • Deoxyribonucleotides / metabolism
  • Exodeoxyribonucleases / metabolism
  • Genomic Imprinting
  • Molecular Sequence Data
  • Phosphates / chemistry
  • Phosphorus-Oxygen Lyases / metabolism
  • Purines / metabolism
  • Ribonucleotides / metabolism
  • Schizosaccharomyces / enzymology*
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces pombe Proteins / classification
  • Schizosaccharomyces pombe Proteins / genetics
  • Schizosaccharomyces pombe Proteins / metabolism*
  • Templates, Genetic

Substances

  • DNA Primers
  • Deoxyribonucleotides
  • Phosphates
  • Purines
  • Ribonucleotides
  • Schizosaccharomyces pombe Proteins
  • 5'-deoxyribose phosphate lyase
  • DNA polymerase X
  • POL4 protein, S pombe
  • DNA Nucleotidylexotransferase
  • DNA-Directed DNA Polymerase
  • Exodeoxyribonucleases
  • Phosphorus-Oxygen Lyases