DNA binding properties of human DNA polymerase eta: implications for fidelity and polymerase switching of translesion synthesis.
The human XPV (xeroderma pigmentosum variant) gene is responsible for the cancer-prone xeroderma pigmentosum syndrome and encodes DNA polymerase eta (pol eta), which catalyses efficient translesion synthesis past cis-syn cyclobutane thymine dimers (TT dimers) and other lesions. The fidelity of DNA synthesis by pol eta on undamaged templates is extremely low, suggesting that pol eta activity must be restricted to damaged sites on DNA. Little is known, however, about how the activity of pol eta is targeted and restricted to damaged DNA. Here we show that pol eta binds template/primer DNAs regardless of the presence of TT dimers. Rather, enhanced binding to template/primer DNAs containing TT dimers is only observed when the 3'-end of the primer is an adenosine residue situated opposite the lesion. When two nucleotides have been incorporated into the primer beyond the TT dimer position, the pol eta-template/primer DNA complex is destabilized, allowing DNA synthesis by DNA polymerases alpha or delta to resume. Our study provides mechanistic explanations for polymerase switching at TT dimer sites.
Kusumoto
Rika
R
Graduate School of Frontier Biosciences, Osaka University, and CREST, Japan Science and Technology Corporation, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan.
Masutani
Chikahide
C
Shimmyo
Shizu
S
Iwai
Shigenori
S
Hanaoka
Fumio
F
D001483:Base Sequence; D004247:DNA / Q000096:biosynthesis*; D004249:DNA Damage; D004256:DNA Polymerase I / Q000378:metabolism; D004258:DNA Polymerase III / Q000378:metabolism; D017931:DNA Primers / Q000378:metabolism; D004260:DNA Repair / Q000502:physiology*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D004795:Enzyme Stability; D006801:Humans; D008969:Molecular Sequence Data; D011740:Pyrimidine Dimers / Q000378:metabolism; D013698:Templates, Genetic; D000099270:Y-Family DNA Polymerases
D004247:DNA; D004256:DNA Polymerase I; D004258:DNA Polymerase III; D017931:DNA Primers; D004259:DNA-Directed DNA Polymerase; D011740:Pyrimidine Dimers; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases