Characterization of SpPol4, a unique X-family DNA polymerase in Schizosaccharomyces pombe.
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.
González-Barrera
Sergio
S
Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma, Madrid, Spain.
Sánchez
Arancha
A
Ruiz
José F
JF
Juárez
Raquel
R
Picher
Angel J
AJ
Terrados
Gloria
G
Andrade
Paula
P
Blanco
Luis
L
D000595:Amino Acid Sequence; D004253:DNA Nucleotidylexotransferase / Q000378:metabolism; D017931:DNA Primers; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D003854:Deoxyribonucleotides / Q000378:metabolism; D005090:Exodeoxyribonucleases / Q000378:metabolism; D018392:Genomic Imprinting; D008969:Molecular Sequence Data; D010710:Phosphates / Q000737:chemistry; D019761:Phosphorus-Oxygen Lyases / Q000378:metabolism; D011687:Purines / Q000378:metabolism; D012265:Ribonucleotides / Q000378:metabolism; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D013698:Templates, Genetic
D017931:DNA Primers; D003854:Deoxyribonucleotides; D010710:Phosphates; D011687:Purines; D012265:Ribonucleotides; D029702:Schizosaccharomyces pombe Proteins; C423906:5'-deoxyribose phosphate lyase; C109534:DNA polymerase X; C503462:POL4 protein, S pombe; D004253:DNA Nucleotidylexotransferase; D004259:DNA-Directed DNA Polymerase; D005090:Exodeoxyribonucleases; D019761:Phosphorus-Oxygen Lyases