2-hydroxydeoxyadenosine-triphosphate and 8-hydroxy-2--deoxyguanosine-5--triphosphate

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenosine Triphosphate; Animals; Deoxyguanine Nucleotides; Deoxyribonuclease (Pyrimidine Dimer); DNA Damage; DNA Repair Enzymes; DNA-Directed DNA Polymerase; Escherichia coli Proteins; GTP Cyclohydrolase; Mutation; Nucleic Acid Precursors; Phosphoric Monoester Hydrolases; Pyrophosphatases

Aberrant oxidation is a property of many tumor cells. Oxidation of DNA precursors, i.e., deoxynucleotide triphosphates (dNTPs), as well as DNA is a major cause of genome instability. Here, we report that human DNA polymerase eta (h Poleta) incorporates oxidized dNTPs, i.e., 2-hydroxy-2'-deoxyadenosine 5'-triphosphate (2-OH-dATP) and 8-hydroxy-2'-deoxyguanosine 5'-triphosphate (8-OH-dGTP), into DNA in an erroneous and efficient manner, thereby inducing various types of mutations during in vitro gap-filling DNA synthesis. When 2-OH-dATP was present at a concentration equal to those of the four normal dNTPs in the reaction mixture, DNA synthesis by h Poleta enhanced the frequency of G-to-T transversions eight-fold higher than that of the transversions in control where only the normal dNTPs were present. When 8-OH-dGTP was present at an equimolar concentration to the normal dNTPs, it enhanced the frequency of A-to-C transversions 17-fold higher than the control. It also increased the frequency of C-to-A transversions about two-fold. These results suggest that h Poleta incorporates 2-OH-dATP opposite template G and incorporates 8-OH-dGTP opposite template A and slightly opposite template C during DNA synthesis. Besides base substitutions, h Poleta enhanced the frequency of single-base frameshifts and deletions with the size of more than 100 base pairs when 8-OH-dGTP was present in the reaction mixture. Since h Poleta is present in replication foci even without exogenous DNA damage, we suggest that h Poleta may be involved in induction of various types of mutations through the erroneous and efficient incorporation of oxidized dNTPs into DNA in human cells.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenosine Triphosphate; Base Sequence; Deoxyguanine Nucleotides; DNA-Directed DNA Polymerase; DNA, Bacterial; Humans; Molecular Sequence Data; Mutation