A convenient spectrometric assay system for intracellular quantitative measurement of DNA glycosylase activity

Cytosine methylation is a vital biology event. However, it is also the source of genomic instability due to deamination of 5'-methylcytosine by spontaneous hydrolysis, which produces thymine and results in G:T mismatches. Thymine DNA glycosylase and methyl-CpG-binding protein 4 are major DNA glycosylases involved in the mismatch repair progress, and their activities have been measured in many related researches. In this study, we developed a convenient spectrometric assay system for specific and quantitative measurement of intracellular DNA glycosylase activity. A G:T mismatch was introduced into the upstream region of firefly luciferase-coding sequence in the pGL3-control plasmid. Only if the G:T mismatches were repaired to G:C, will luciferase be expressed in transfected cells. By measuring luciferase activity, which is simple and convenient, the intracellular DNA glycosylase activity can be determined.