Fapyadenine is a moderately efficient chain terminator for prokaryotic DNA polymerases.
Hypoxanthine¿xanthine oxidase¿Fe3+¿ethylenediaminetetraacetate (EDTA) was used to modify ss M13 mp18 phage DNA. The dominant base modifications found by GC/IDMS-SIM were FapyGua, FapyAde, 8-hydroxyguanine, and thymine glycol. Analysis of in vitro DNA synthesis on oxidatively modified template by three DNA polymerases revealed that T7 DNA polymerase and Klenow fragment of polymerase I from Escherichia coli were blocked mainly by oxidized pyrimidines in the template whereas some purines that were easily bypassed by the prokaryotic polymerases constituted a block for DNA polymerase beta from calf thymus. DNA synthesis by T7 polymerase on poly(dA) template, where FapyAde content increased 16-fold on oxidation, yielded a final product with a discrete ladder of premature termination bands. When DNA synthesis was performed on template from which FapyAde, FapyGua, and 8OHGua were excised by the Fpg protein new chain terminations at adenine and guanine sites appeared or existing ones were enhanced. This suggests that FapyAde, when present in DNA, is a moderately toxic lesion. Its ability to arrest DNA synthesis depends on the sequence context and DNA polymerase. FapyGua might possess similar properties.
Graziewicz
M A
MA
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw.
Zastawny
T H
TH
Oliński
R
R
Speina
E
E
Siedlecki
J
J
Tudek
B
B
D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D017104:Bacteriophage M13 / Q000235:genetics; D002417:Cattle; D004249:DNA Damage; D004256:DNA Polymerase I / Q000378:metabolism*; D019951:DNA Polymerase beta / Q000378:metabolism*; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000096:biosynthesis / Q000737:chemistry*; D004279:DNA, Viral / Q000096:biosynthesis / Q000737:chemistry*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D043382:DNA-Formamidopyrimidine Glycosylase; D004492:Edetic Acid; D029968:Escherichia coli Proteins; D017665:Hydroxyl Radical; D019271:Hypoxanthine / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D009699:N-Glycosyl Hydrolases / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011061:Poly A / Q000378:metabolism; D011743:Pyrimidines / Q000737:chemistry*; D013698:Templates, Genetic; D014969:Xanthine Oxidase / Q000378:metabolism
D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D029968:Escherichia coli Proteins; D011743:Pyrimidines; C071023:2,6-diamino-4-hydroxy-5-formamidopyrimidine; D011061:Poly A; C015465:poly(dA); D019271:Hypoxanthine; D017665:Hydroxyl Radical; C039544:4,6-diamino-5-N-formamidopyrimidine; D004492:Edetic Acid; D007501:Iron; D014969:Xanthine Oxidase; C034970:bacteriophage T7 induced DNA polymerase; D004256:DNA Polymerase I; D019951:DNA Polymerase beta; D004259:DNA-Directed DNA Polymerase; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli