Thymine glycol (Tg) is the most common pyrimidine lesion produced in DNA by oxidation or ionizing radiation. Because of the addition of hydroxyl groups to the C5 and C6 positions of thymine, Tg becomes a strong block to DNA replication and elicits cytotoxic effects. However, the genome-wide distribution of Tg remains unknown owing to the lack of a reliable and sensitive sequencing method for this lesion. Recently, we found that two commercially available DNA polymerases can bypass the Tg lesion and display distinct properties in nucleotide incorporation opposite or near the lesion site. By comparing in parallel the primer extension products formed with these two DNA polymerases, we developed a quantitative analytical method for locating the site of Tg at single-base resolution in synthesized DNA. We are in the process of developing an enrichment method for Tg-containing DNA, which, together with the differential coding properties conferred by the aforementioned polymerases, may allow for the development of a genome-wide sequencing method for this modified nucleoside.

Base-resolution analysis of thymine glycol (Tg) in DNA by polymerase-aided differential coding

2019 Fall National Meeting

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